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DRAFT Rules and Regulations, as advertised for public comment August 2017 - Proposed changes indicated in red.August 1, 2017 DRAFT for Public Comment – All Proposed Changes Indicated in Red THE METROP OLI TAN ST. LOUI S SEWER DISTRI C T RULES AND REGULATI ONS AND ENGINEERING DESIGN REQUIREMENTS FOR SANITARY SEWER AND STORMWATER DRAI NAGE FACI LITI ES JANUARY 2018 August 1, 2017 DRAFT FOR PUBLIC COMMENT RULES AND REGULATIONS AND ENGINEERING DESIGN REQUIREMENTS FOR SANITARY SEWER AND STORMWATER DRAINAGE FACILITIES JANUARY 2018 (TENTATIVE) FEBRUARY 2006 TABLE OF CONTENTS T. O. C. STILL TO BE REVISED 1. GENERAL ................................................................................................................................................................ 9 1.010 Projects Requiring Review By the District................................................................................................. 9 1.020 Regulations Governing the Use of Public and Private Sewerage Facilities ............................................. 9 1.020.01 Unlawful Discharges and Sewage Disposal ........................................................................................ 9 1.020.02 Public Sewer Available ......................................................................................................................... 9 1.020.03 Public Sewer Not Available .................................................................................................................. 9 1.020.04 Prohibited Discharges and Waste Disposal Into Sanitary Sewers .................................................. 10 1.020.05 Wastes Having Excessive Biochemical Oxygen Demand (B.O.D.), ................................................. 10 1.020.06 Measurements, Tests or Analyses ...................................................................................................... 11 1.020.07 Furnishing Records ............................................................................................................................. 11 1.030 Submission, Review and Approval of Plans and Specifications ............................................................... 11 1.040 Procedures..................................................................................................................................................... 12 1.040.01 Preliminary Conferences .................................................................................................................... 12 1.040.02 Required Submittals by the Engineer ............................................................................................... 12 1.040.03 Subdivisions ......................................................................................................................................... 13 1.040.04 Projects Normally Requiring a Sewer Connection - Permit Only .................................................. 14 1.040.05 Return of Plans Without Review ....................................................................................................... 14 1.040.06 Return of Plans for Revision .............................................................................................................. 14 1.040.07 Failure to Revise or Correct Plans Promptly ................................................................................... 15 1.040.08 Fees for Review ................................................................................................................................... 15 1.050 Plan Requirements ....................................................................................................................................... 15 1.050.01 Drawing Sizes ...................................................................................................................................... 15 1.050.02 Plans Submitted Shall Include: .......................................................................................................... 15 1.060 Storm Drainage Design Data, Maps and Computation ............................................................................. 16 1.060.01 General Criteria:................................................................................................................................. 16 1.060.02 Basic Design Data To Include: ........................................................................................................... 17 1.070 Sanitary Sewer Design Data, Maps and Computations ............................................................................ 17 1.070.01 General Criteria:................................................................................................................................. 17 1.070.02 Basic Design Data To Consider: ........................................................................................................ 17 2. DEFINITIONS ....................................................................................................................................................... 18 3. DESIGN REQUIREMENTS FOR SANITARY SEWERS ................................................................................ 24 3.010 General .......................................................................................................................................................... 24 3.020 General Requirements of Sanitary Sewer Construction ........................................................................... 24 August 1, 2017 DRAFT FOR PUBLIC COMMENT 2 3.020.01 Size and Shape ..................................................................................................................................... 24 3.020.02 Materials ............................................................................................................................................. 24 3.020.03 Bedding ................................................................................................................................................ 24 3.020.04 Pipe or Conduit Under Streets and Pavements ................................................................................ 25 3.020.05 Joints ................................................................................................................................................... 25 3.020.06 Monolithic Structures ......................................................................................................................... 25 3.020.07 Alignment ........................................................................................................................................... 25 3.020.08 Location .............................................................................................................................................. 26 3.020.09 Flowline ................................................................................................................................................ 26 3.020.10 Manholes ............................................................................................................................................. 27 3.020.11 Sewage Treatment Facilities .............................................................................................................. 28 3.030 Design Requirements .................................................................................................................................... 28 3.030.01 General................................................................................................................................................. 28 3.030.02 Gradients ............................................................................................................................................ 28 3.030.03 Depth and Minimum Cover .............................................................................................................. 29 3.030.04 Flow Design ........................................................................................................................................ 30 3.030.05 Population Factors ............................................................................................................................. 30 3.030.06 Sanitary Flow Table .......................................................................................................................... 30 3.030.07 Hydraulic Grade Line........................................................................................................................ 30 1. Hydraulic Grade Line Limits ................................................................................................................. 30 2. Computation Methods ............................................................................................................................. 31 a. Friction Loss ......................................................................................................................................... 31 b. Curve Loss ............................................................................................................................................ 31 c. Turn Loss .............................................................................................................................................. 31 d. Junction Chamber Loss ......................................................................................................................... 32 e. Losses at Junctions of Several Flows in Manholes ............................................................................... 33 f. Transition Loss ..................................................................................................................................... 34 (1) Closed Conduits ............................................................................................................................... 35 3.030.08 Infiltration .......................................................................................................................................... 36 3.030.09 Special Situations and Design Requirements ................................................................................... 36 l. Connections to Manholes ........................................................................................................................ 36 2. Adjusting Manholes to Grade................................................................................................................. 37 3. Swimming Pools ....................................................................................................................................... 37 4. Storm Sewers Crossing Over Sanitary Sewers ..................................................................................... 37 5. Location in Conjunction with Water Service ........................................................................................ 38 6. Sanitary Sampling Appurtenance .......................................................................................................... 38 7. Abandonment of Sanitary Sewer Services ............................................................................................. 38 8. Private Force Main Connections ............................................................................................................ 39 9. Oil/Gas Separators, Sand Filters, and Grease Traps............................................................................ 39 10. Coldwater Creek Gravity Elevation .................................................................................................. 39 11. Common Laterals ................................................................................................................................ 39 12. Private Lateral .................................................................................................................................... 40 13. Separate Laterals and Sewers ............................................................................................................ 40 14. Protection from Surcharging ............................................................................................................. 41 15. Residential Basement Garage Flooding ............................................................................................ 41 16. Lateral for Commercial Use ............................................................................................................... 38 3.040 Sanitary Detention Requirements ............................................................................................................... 43 3.040.01 Surcharged Sanitary Sewers ............................................................................................................. 43 4. DESIGN REQUIREMENTS FOR STORM DRAINAGE FACILITIES .......................................................... 42 4.010 General ............................................................................................................................................................. 42 4.020 General Requirements of Storm Sewer Construction .................................................................................. 42 August 1, 2017 DRAFT FOR PUBLIC COMMENT 3 4.020.01 Size and Shape .................................................................................................................................... 42 4.020.02 Materials ............................................................................................................................................. 42 4.020.03 Bedding ............................................................................................................................................... 42 4.020.04 Concrete Pipe or Conduit Strengths ................................................................................................. 42 4.020.05 Monolithic Structures ......................................................................................................................... 43 4.020.06 Alignment ............................................................................................................................................ 43 4.020.07 Location .............................................................................................................................................. 43 4.020.08 Sinkhole Areas .................................................................................................................................... 44 1. Sinkhole Report ....................................................................................................................................... 44 2. Procedure for Utilization of Sinkholes ................................................................................................... 45 4.020.09 Flowline ............................................................................................................................................... 45 4.020.10 Manholes ............................................................................................................................................. 46 4.020.11 Overflow/Design System .................................................................................................................... 47 4.030 Stormwater Design Criteria ........................................................................................................................ 47 4.030.01 Flow Quantities .................................................................................................................................. 47 1. Rainfall Frequency .................................................................................................................................. 48 2. Impervious Percentages and Land Use .................................................................................................. 48 3. Reduction in P.I. with Time and Area ................................................................................................... 49 4.030.02 Hydraulic Grade Line for Closed Conduits .................................................................................... 50 1. Computation Methods ............................................................................................................................. 50 a. Friction Loss ......................................................................................................................................... 50 b. Curve Loss ............................................................................................................................................ 51 c. Entrance Loss at Terminal Inlets ........................................................................................................... 51 d. Turn Loss .............................................................................................................................................. 51 e. Junction Chamber Loss ......................................................................................................................... 52 f. Losses at Junctions of Several Flows in Manholes and/or inlets 53 g. Transition Loss ..................................................................................................................................... 59 (1) Closed Conduits ............................................................................................................................... 60 (2) Open Channel Transitions ................................................................................................................ 61 4.030.03 Hydraulic Grade Line Limits ............................................................................................................ 61 4.030.04 Inlets .................................................................................................................................................... 62 4.030.05 Open Channels ................................................................................................................................... 63 1. Size and Shape ......................................................................................................................................... 63 2. Materials................................................................................................................................................... 63 3. Bedding ..................................................................................................................................................... 63 4. Structural Considerations ....................................................................................................................... 63 5. Alignment ................................................................................................................................................. 63 6. Locations .................................................................................................................................................. 63 7. Flowline .................................................................................................................................................... 64 8. Other Open Channel Considerations and Requirements ..................................................................... 64 9. Design Limitations ................................................................................................................................... 65 10. Hydraulic Grade Line......................................................................................................................... 65 a. Computation Methods ........................................................................................................................... 65 (1) Control Sections ............................................................................................................................... 65 (2) Friction Loss .................................................................................................................................... 66 (3) Flow in Curved Channels ................................................................................................................. 66 (a) Curve Losses ............................................................................................................................... 66 (b) Superelevations ........................................................................................................................... 66 (4) Transitions ........................................................................................................................................ 67 (a) Proportioning ............................................................................................................................... 67 (b) Losses .......................................................................................................................................... 67 (c) Freeboard .................................................................................................................................... 67 (d) Hydraulic Jump ........................................................................................................................... 68 (e) Sudden Enlargement and Contraction ......................................................................................... 68 (5) Constrictions .................................................................................................................................... 68 August 1, 2017 DRAFT FOR PUBLIC COMMENT 4 (6) Obstructions ..................................................................................................................................... 69 b. Hydraulic Grade Line Limits ................................................................................................................ 69 11. Hydraulic Jump .................................................................................................................................. 69 12. Open Channel Junctions .................................................................................................................... 69 a. General .................................................................................................................................................. 69 b. Confluence Design Criteria ................................................................................................................... 69 13. Erosion Protection .............................................................................................................................. 70 14. Sanitary Sewer Crossings ................................................................................................................... 70 4.030.06 Culverts ............................................................................................................................................... 70 1. Hydraulic Design ..................................................................................................................................... 70 2. Entrances and Headwalls - Outlets and Endwalls ................................................................................ 70 4.040 Bridges ........................................................................................................................................................... 70 4.040.01 Waterway Capacity and Backwater Effects .................................................................................... 70 4.040.02 Clearance ............................................................................................................................................ 70 4.040.03 Waterway Alignment ......................................................................................................................... 71 4.040.04 Erosion Protection ............................................................................................................................. 71 4.050 Outlet Erosion Protection ............................................................................................................................ 71 4.060 Limitations on Areas Draining Across Sidewalks or Driveways .................. Error! Bookmark not defined. 4.070 Impervious Areas - In City of St. Louis ........................................................... Error! Bookmark not defined. 4.080 General Performance Criteria for Stormwater Management ................................................................. 71 4.080.01 When Required .................................................................................................................................. 71 4.080.02 Unified Stormwater Sizing Criteria ................................................................................................. 73 1. General ..................................................................................................................................................... 73 2. Water Quality Volume (WQv) ................................................................................................................ 74 3. Channel Protection Storage Volume Requirements (Cpv) ................................................................... 74 4. Flood Protection Volume Requirement (Qp2 & Qp100) ........................................................................... 76 4.080.03 Limits of Maximum Ponding in Stormwater Ponds ....................................................................... 77 4.080.04 General Stormwater Basin Design Requirements .......................................................................... 78 4.080.05 Acceptable Urban BMP Options ...................................................................................................... 81 1. BMP Group 1. Stormwater Ponds ......................................................................................................... 82 2. BMP Group 2. Stormwater Wetlands.................................................................................................... 82 3. BMP Group 3. Infiltration Practices ..................................................................................................... 82 4. BMP Group 4. Filtering Practices .......................................................................................................... 83 5. BMP Group 5. Open Channel Practices ................................................................................................ 83 4.080.06 Stormwater Credits ........................................................................................................................... 83 4.080.07 Easement Required ............................................................................................................................ 83 4.080.08 Maintenance Agreement ................................................................................................................... 84 4.090 Dam Permit Requirements .......................................................................................................................... 84 4.100 Detention Report .......................................................................................................................................... 84 EXHIBIT 4-A .............................................................................................................................................................. 85 Check List for Review of Stormwater Detention ................................................................................................ 85 5. FLOOD PLAIN REQUIREMENTS .................................................................................................................... 99 5.010 Flood Plain Study/100 – Year Hydraulic Study ......................................................................................... 99 5.010.01 When Required .................................................................................................................................. 99 5.010.02 Criteria For Preparation ................................................................................................................... 99 5.010.03 Filling in Flood Plain Areas ............................................................................................................ 101 August 1, 2017 DRAFT FOR PUBLIC COMMENT 5 5.010.04 Detention Basins in Flood Plains .................................................................................................... 101 5.010.05 Bridges in Flood Plains .................................................................................................................... 101 5.010.06 Parking Lots in Flood Plains ........................................................................................................... 102 5.010.07 Site Plan Requirements ................................................................................................................... 102 6. RECOUPMENT RULES AND REGULATIONS ............................................................................................. 103 6.010 General ........................................................................................................................................................ 103 6.020 Contract Between District and Owner(s) ................................................................................................. 103 6.030 Recoupment Provisions .............................................................................................................................. 103 6.040 Recoupment Procedures and Project Costs ............................................................................................. 103 6.050 Objections to Certified Completed Construction Costs .......................................................................... 103 6.060 Recoupment Fees ........................................................................................................................................ 103 6.070 Areas Served by More Than One Sewer Facility Under Recoupment .................................................. 104 6.080 Connection to Recoupment Sewer Facility............................................................................................... 104 6.090 Reports of Owner of Sewer Facility .......................................................................................................... 104 6.090.01 Annual ................................................................................................................................................ 104 6.090.02 Interim ............................................................................................................................................... 104 6.100 Extent of and Time Limits of Recoupment ............................................................................................... 104 7. EASEMENTS ....................................................................................................................................................... 105 7.010 General ........................................................................................................................................................ 105 7.020 Use of Existing Easements ......................................................................................................................... 105 7.030 Location of Easements ............................................................................................................................... 105 7.040 Width of Easements .................................................................................................................................... 105 7.050 Wording of Easements ............................................................................................................................... 105 7.060 Easement Plat Preparation Information Guidelines ............................................................................... 106 7.060.01 Label Established Lines Affecting Tract and/or Mentioned in its Legal Description: .............. 106 7.060.02 Identify Parcel or Tract: ................................................................................................................. 106 7.060.03 Provide Accurate Title Box Information: ...................................................................................... 106 7.060.04 Easement Plat Drafting Guidelines ................................................................................................. 107 7.070 Vacation of Easements ............................................................................................................................... 108 7.080 Easement Encroachment............................................................................................................................ 108 7.090 Indemnity Agreement ................................................................................................................................. 109 8. APPROVAL AND DEDICATION OF PROJECTS WITH PUBLIC SEWERS ........................................... 110 August 1, 2017 DRAFT FOR PUBLIC COMMENT 6 8.010 General ........................................................................................................................................................ 110 8.020 Requirements for Plan Approval and Issuance of Permits ..................................................................... 110 8.020.01 Agreement to Dedicate .................................................................................................................... 110 8.020.02 Construction Escrow Deposit and Cash Deposit Agreement ....................................................... 110 8.020.03 Conditional Plan Approval ............................................................................................................. 110 8.020.04 Flexibility for BMP Permitting & Inspection 102 8.030 Requirements for Construction Approval ................................................................................................ 111 8.030.01 Construction Inspection .................................................................................................................. 111 8.030.02 Field Changes and Plan Revisions ................................................................................................... 111 8.030.03 As-Built Drawings ............................................................................................................................ 111 1. Storm, Sanitary and Combined Sewers ............................................................................................... 112 2. Detention Basin ...................................................................................................................................... 112 3. Pump Station Construction................................................................................................................... 112 4. Subdivision Plats .................................................................................................................................... 113 5. Geotechnical Engineer's Certification ................................................................................................. 113 6. State Plane Coordinates ........................................................................................................................ 113 a. Horizontal Data ................................................................................................................................... 113 b. Vertical Data ....................................................................................................................................... 113 c. Deliverables ........................................................................................................................................ 113 8.030.04 Stormwater Quality mangem Facilities and Construction Deposit Agreement .......................... 114 8.030.05 Notification of Construction Approval 106 8.040 Requirments for District Approval of Stormwater Management Facility Construction ..................... 106 8.040.01 Contruction Inspections ................................................................................................................... 106 8.040.02 Field Changes and Plan Revisions ................................................................................................... 106 8.040.03 As-Built Drawings ............................................................................................................................. 107 8.050 Dedication and Release of Construction Deposit ..................................................................................... 107 8.050.01 Residential and Commercial Subdivisions, Apartments and Condominiums 107 a. Initial Dedication Inspection 107 b. Final Dedication Inspection 107 8.050.02 Sewer Extensions and Single Lot Developments 108 8.050.03 Dedication Inspection Fees 108 8.060 Pump Stations ............................................................................................................................................. 108 8.070 Abandonment of Work 109 8.080 Release of Stormwater Quality Management Facilities Construction Deposit 109 9. FEES AND DEPOSITS REQUIRED BEFORE PLAN APPROVAL AND ISSUANCE OF CONSTRUCTION PERMITS ................................................................................................................................. 119 9.010 Fees Required Before Plan Approval ....................................................................................................... 119 9.010.01 Submittal Fee .................................................................................................................................... 119 9.010.02 Review Fee ........................................................................................................................................ 119 9.010.03 Connection and System Development Fees .................................................................................... 119 9.010.04 Recording Fees ................................................................................................................................. 119 9.020 Deposits Required Before Issuance of Construction Permits ................................................................. 119 9.020.01 As-Built Deposit ............................................................................................................................... 120 9.020.02 Construction Deposit ....................................................................................................................... 120 9.020.03 Pump Station Escrow Deposit ......................................................................................................... 120 August 1, 2017 DRAFT FOR PUBLIC COMMENT 7 9.020.04 Conditional Plan Approval Deposit................................................................................................ 120 9.020.05 BMP Deposit 112 10. CONSTRUCTION PERMITS .......................................................................................................................... 121 10.010 General ........................................................................................................................................................ 121 10.010.01 Permits Required ............................................................................................................................. 121 10.010.02 Defaults ............................................................................................................................................. 121 10.020 Permittee ..................................................................................................................................................... 121 10.030 Performance Bond ...................................................................................................................................... 121 10.040 Construction and Connection Permit and Fees ....................................................................................... 122 10.040.01 Connection Permit and Fee .............................................................................................................. 122 10.040.02 Construction Permit and Fee ........................................................................................................... 122 10.040.03 Machine Tap Permit and Fee ........................................................................................................... 122 10.050 Inspection Fee Deposit ............................................................................................................................... 122 10.060 Expiration and Extension of Permits and Approved Plans .................................................................... 122 10.060.01 Approved Plans ................................................................................................................................ 122 10.060.02 Construction and Connection Permits ........................................................................................... 123 10.070 Cancellation of Permits and Refunds of Fees and Deposits .................................................................... 123 10.070.01 Prior to the Start of Work ............................................................................................................... 123 10.070.02 After the Start of Work ................................................................................................................... 123 10.070.03 Connection Permits .......................................................................................................................... 123 10.080 Final Determination of Construction Inspection Fees ............................................................................. 124 10.090 Minimum Insurance Requirements for Off Site Construction ............................................................... 124 10.090.01 Comprehensive Automobile Liability: ........................................................................................... 117 10.090.02 Commercial General Liability (occurrence from): ....................................................................... 117 10.090.03 Cancellation & Replacement Policy ............................................................................................... 117 11. INSPECTION .................................................................................................................................................... 127 11.010 General ........................................................................................................................................................ 127 11.020 Privately Constructed Sewers and Treatment Facilities ......................................................................... 127 11.030 Maintenance and Operation Inspection ................................................................................................... 127 11.040 Fees .............................................................................................................................................................. 127 11.050 Inspection ................................................................................................................................................... 127 12. REGULATION AND CORRECTION OF IMPROPER PRIVATE SEWER FACILITIES ..................... 128 12.010 General ........................................................................................................................................................ 128 12.020 Notification to Owner................................................................................................................................. 128 12.030 Expiration of Period Without Work Being Done .................................................................................... 128 August 1, 2017 DRAFT FOR PUBLIC COMMENT 8 12.040 District to Proceed with Work................................................................................................................... 128 12.050 Cost of Work - A Lien ................................................................................................................................ 128 12.060 Appeal from Decision to Proceed with Work ........................................................................................... 128 13. SEWAGE PUMPING STATIONS ................................................................................................................... 129 13.010 General ........................................................................................................................................................ 129 13.020 Pump Station Plan Review Procedure ...................................................................................................... 129 13.020.01 Design Report .................................................................................................................................... 129 13.020.02 Design Drawings .............................................................................................................................. 129 13.020.03 Required Submittal .......................................................................................................................... 130 13.030 Low Pressure Sewer Systems (LPSS) ....................................................................................................... 130 13.030.01 General............................................................................................................................................... 130 13.030.02 LPSS Plan Review Procedure ......................................................................................................... 130 1. Low Pressure Sewer System Design Report: ....................................................................................... 130 2. Design Drawings: ................................................................................................................................... 131 13.030.03 Required Submittal ........................................................................................................................... 131 14. APPENDIX – VOLUMETRIC METHOD 15. AMENDMENTS RESERVED (FOR FUTURE INDEX) August 1, 2017 DRAFT FOR PUBLIC COMMENT 9 THE METROPOLITAN ST. LOUIS SEWER DISTRICT 1. GENERAL The readers of this document should be aware that parts of this document may change from time to time. Those changes, including effective dates will be described in Chapter 15 – Amendments. Going forward, Chapter 15 will memorialize previous version information; it will indicate any newly added, deleted, or changed information. The latest version of the complete document will contain the effective date in the lower left area of each page. Hard copies of this document will not be printed by the District. Please see www.stlmsd.com for the most recent version. of revised pages and date of most recent change will be available on the District’s website by link at www.stlmsd.com. Design engineers must verify that they are using the most recent version. 1.010 Projects Requiring Review by the District All public or private sewerage and drainage works proposed to be constructed, altered or reconstructed by any person or corporation, public or private, within the District boundaries, require review by the District. This includes any altering of any storm drainage channel, site drainage or flood plain within those boundaries. 1.020 Regulations Governing the Use of Public and Private Sewerage Facilities The following sections are summarized from the District Sewer Use Ordinance. The current Sewer Use Ordinance in effect shall be considered the governing document and should be consulted for elaboration. Requests for variances or clarification of these regulations should be addressed to the attention of the Director with information supporting the request. A request for variance will be reviewed by the Director or his designee(s) and either granted or rejected in whole or part. 1.020.01 Unlawful Discharges and Sewage Disposal 1. Discharges and deposits of any sewage, industrial wastes, garbage, polluted water or any other substance that constitutes a nuisance or hazard to the public health or welfare into any natural outlet, drainage channel, or watercourse, are prohibited. 2. No cesspool, septic tank or other facility intended or used for the disposal of sewage shall be installed except as hereinafter provided. 1.020.02 Public Sewer Available A public sanitary or combined sewer shall be considered to be available if it is within two hundred (200) feet of any part of the property to be connected to the sewer. Under such conditions a direct connection must be made to the public sewer. Where an extension of the sewer system is required to make this connection, such extension shall be made public to insure other areas within the District of adequate sanitary disposal and conformance with 3.030.09.12. Combined sewers and storm sewers shall also comply with 3.030.09.12 with some exceptions for certain storm pipes. 1.020.03 Public Sewer Not Available Where a public sanitary or combined sewer is not available to service an existing or proposed residential property which is 3.0 acres or larger (or has sufficient lot area, proper soil conditions, and proper lot grade elevations for adequate sanitary sewage disposal for the building or land use proposed), and if the District approves in writing, the sewer lateral from the building shall be connected to an approved private or semi-public sewer or sewage disposal or sewage treatment facility complying with the rules and regulations of the District and any other appropriate authority. When a public sewer becomes available and a direct connection to it is made, any septic tank, cesspool, or other private or semi-public sewage disposal or treatment facilities shall be abandoned as approved by the District. August 1, 2017 DRAFT FOR PUBLIC COMMENT 10 Newly developed residential lots that are less than 3.0 acres will be required to connect to the public sewer regardless of the proximity of the property to the public sewer. All new non-residential development and redevelopment or modification to an existing non- residential development will be required to connect to the public sewer, regardless of the proximity of the development to the public sewer. An exception will be made, however, for an expansion of an existing building involving minimal extra water usage and where its original private treatment system is certified to still have adequate capacity after the proposed addition. 1.020.04 Prohibited Discharges and Waste Disposal into Sanitary Sewers 1. Surface water, stormwater, groundwater, roof runoff, subsurface drainage, uncontaminated cooling water, unpolluted industrial process waters, shall not be discharged to a sanitary sewer. 2. No person shall deposit or throw into any sewer, or into any private drain connecting with a public sewer any waste, product or material of manufacture, rags or garbage which has not been properly shredded, or any substance which may constrict, cause a nuisance, dam or otherwise obstruct any sewer. 3. No gasoline service station, garage, car wash facility, refining plant, chemical plant, packing house, slaughter house, lard rendering establishment, dairy, steam plant, or any other establishment from which any substance would be discharged into the sewers which could tend to obstruct or damage the sewers, or cause a nuisance, or endanger the public health or safety, or endanger persons who might be in such sewers, shall be connected with any public sewer, or to any private sewer which discharges directly or indirectly into any public sewer. EXCEPTION would be through one or more District approved interceptors or traps. Any approved trap shall be maintained and operated in a manner satisfactory to the District, and the substance removed from such traps shall not be deposited in a way or place not previously approved by the District. Where grease, oil and grit interceptors, and other preliminary treatment facilities are provided, they shall be maintained continuously in satisfactory and efficient operation by the owner at his expense. Such facilities shall be subject to inspection by the District at all times. A sampling appurtenance (“T” or manhole) may be required that would be easily accessible by the District. If the substance discharged by any establishment is deemed harmful to the sewer, detrimental to the public health or safety, and dangerous to persons who may enter such sewers, the discharge from such establishment shall be entirely excluded from the sewer. 1.020.05 Wastes Having Excessive Biochemical Oxygen Demand (B.O.D.), Suspended Solids or Toxic Elements If excessive B.O.D., suspended solids or toxic elements could occur and constitute a nuisance or adversely affect the operation of any existing force main, gravity system, sewage lift or pump station or proposed sewage treatment plant or overload any sewage treatment plant owned or operated by the District, the owner shall provide, at his expense, such preliminary treatment as may be necessary to: 1. Control objectionable characteristics or constituents in such a manner as to not obstruct or interfere with the maintenance or operation of any public sewerage facility. August 1, 2017 DRAFT FOR PUBLIC COMMENT 11 b.2. Control the quantities and rates of discharge of such waters or wastes. Plans, specifications, and other pertinent information relating to proposed preliminary treatment facilities shall be submitted for the approval of the District, and construction of such facilities shall not commence until such approval is granted in writing. 1.020.06 Measurements, Tests or Analyses The District shall be provided means to monitor the discharge into the public sewers of any waters or wastes discharging into sewer or any treatment facility maintained and operated by the District that contain any quantity of substances having the characteristics described in Section 1.020.04, or have an average daily flow greater than two percent (2%) of the average daily sewage capacity of the treatment facility. All discharges shall be subject to the analytical inspection and approval of the District. Measurements, tests, and analyses of the characteristics of the water and wastes referred to in Sections 1.020.04 and 1.020.05 shall be determined in accordance with the current edition of "Standard Methods for Examination of Water and Wastewater" published jointly by the American Public Health Association, the American Water Works Association and the Water Environment Federation. Other approved testing methods as specified by the Environmental Protection Agency in 40 CFR PART 136 may also be used. Additional methods of making measurements, tests or analyses of the characteristics of water or wastes may be provided by the Director with the approval of the Board of Trustees of the District, when, in the opinion of the Director, they are necessary. All measurements, tests or analyses shall be upon suitable samples taken at the sampling appurtenance ("T" or manhole) All non-residential facilities shall have a six (6) inch (minimum) diameter, straight "T" vent or 42-inch (minimum) standard manhole for taking samples. This "T" vent or manhole shall be located on the lateral line outside the building. The "T" or manhole placement shall be before the lateral connects to the public sewer and downstream from any grease traps, interceptors, or any other private wastewater treatment system. 1.020.07 Furnishing Records It shall be the duty of every person, public utility or institution holding a permit to operate a sewerage system or sewage treatment plant to furnish records as may be required by the District to ascertain compliance with the rules and regulations and ordinances of the District. 1.030 Submission, Review and Approval of Plans and Specifications Designs, plans and specifications of all sewerage and drainage works proposed to be constructed, altered or reconstructed by any person or corporation, private or public, within District boundaries, shall be submitted to the District for review, revision, approval or rejection. In addition, for projects with facilities requiring industrial pretreatment, an Industrial Wastewater Survey Form must be completed and a set of plans submitted to the Division of Environmental Compliance of the District. Such designs, plans and specifications (excluding house connections, curb cuts, etc.) shall be prepared and sealed by a Professional Engineer, registered in the State of Missouri, and shall meet the minimum standards of the District and Missouri Department of Natural Resources before approval is granted. The District is designated as the Missouri Department of Natural Resources reviewing agency. Plans for projects that will be reviewed by the District, but will not require permits to be issued by the District and do not involve site grading and storm sewer construction, may be allowed to be sealed by an Architect registered in the State of Missouri. This will be up to the discretion of the District. A Surveyor’s seal is required for As-Built plans, but will not be accepted for Proposed Construction plans. August 1, 2017 DRAFT FOR PUBLIC COMMENT 12 The District will accept designs sealed by a Professional Landscape Architect in which MSD’s requirements would be satisfied solely by the application of non-structural post construction stormwater BMPs. Non-structural practices include amended soils disconnection, natural area conservation, disconnection of rooftop runoff, disconnection of non-rooftop impervious areas, sheet flow to buffers, and environmentally sensitive development. Note that if the practice of engineering applies to other MSD requirements for a project, or if directed by other agencies, a Professional Engineer’s seal will be required. The final set of plans submitted to the District for approval must be signed, sealed and dated by the Professional Engineer in accordance with the Missouri Revised Statutes, Chapter 327, of the Missouri Board for Architects, Professional Engineers, Professional Land Surveyors and Landscape Architects, except if noted otherwise as above. If sealing date is more than a year old, the design professional must resubmit newly sealed plans, or provide a new current seal on each plan sheet if the project conditions have not changed, or provide a current sealed letter stating project conditions have not changed and the design is still current. Plans must be resubmitted if sealing date is more than a year old or if site or project conditions have changed. Missouri Rule 4 CSR 30-3.030 and MSD’s requirements will be deemed met if the following procedures are used. Place the original signature, wet seal and date on each sheet of one set of final plans submitted for approval. Other sets may be reproductions, with wet seal, signature, and date only on the cover sheet along with a list of sheets which comprise the set. 1.040 Procedures 1.040.01 Preliminary Conferences Prior to formal submission of project plans, the owner's Engineer can request a preliminary conference to obtain informal guidance in project plan preparation, particularly in instances when unique or unusual situations are encountered.. Preliminary conferences are encouraged in unique or unusual situations. Most projects, however, should not require a preliminary conference or conceptual approval, nor can more than a few be currently provided as a courtesy. Use of non-structural best management practices (BMPs) and site designs that conserve natural resources to meet water quality requirements are also encouraged. They are best considered by the Consultant and the Developer, prior to land disturbance at site; from the perspective of “Master” planning; and with an eye towards sustainability for the long term. This is in the ultimate Owner’s best interest. 1.040.02 Required Submittals by the Engineer Note: Final publication of this document may include information on electronic submittal requirements for new MSD Plan Review, Permitting, and Construction Inspection Software to be implemented soon. Refer to the District's information sheet, the District Form (E.2), for information to be submitted. Plan Review may be delayed if all required information is not provided. To facilitate the review of plans before approval for construction, the Engineer shall submit with the plans all necessary data, maps and computations in support of the designs and plans. The following listed requested information is a minimum and may be supplemented by any additional information, which the Engineer considers to be helpful in the review process. 1. The following information shall be provided, as applicable: a. Engineer's name, email address, mailing address, telephone number, fax number and contact name. August 1, 2017 DRAFT FOR PUBLIC COMMENT 13 •b. Owner and/or developer's name, email address, mailing address, telephone number, fax number and contact name. c. Accurate location of property relative to an intersection. d. "Wunnenberg's" page and grid number for the project, the District Base Map Number, the St. Louis County Locator Number for the property, and the property address. e. Total acreage of property, and impervious acres if other than residential. f. Land use of the improvement area, i.e.; commercial, residential, etc. g. For connection fee calculations: total number of dwelling units or lots, and domestic use water tap size (especially for non-residences, and not including fire and irrigation component). h. The District reference number shall be used in all subsequent correspondence concerning the project, and shall be utilized as soon as possible after issued. The St. Louis County Permit Application Center (PAC) number shall also be used as soon as possible. i. If the submittal is a revision or addendum to a previous project, the previous project shall be properly identified, and the particulars of the revision or addendum shall be described. j. For any project, a very brief description giving scope and significant characteristics. 2. Number of Copies of Plans and Supporting Data to be submitted. Plans shall be complete and a minimum of three (3) sets of plans and two (2) sets of the storm and sanitary hydraulic calculations will be required. Complete submittals include number and extent of multi-stories and basements or sub basements and lowest floor elevations. Flood Plain: Submit one (1) additional set of plans and a total of one (1) sets of The Flood Plain Report. Detention: Submit one (1) additional set of plans and a total of two (2) sets of the detention calculations. Water Quality: Submit one (1) additional set of plans for BMPs and a total of two (2) sets of water quality calculations. Pump Station: Submit three (3) additional sets of plans and a total of four (4) copies of the pump station design report and specifications. 1.040.03 Subdivisions and Other Property Line Modifications For projects within a proposed subdivision, a subdivision plat shall be provided substantially ready for filing, adequately dimensioned and located from well-established points and lines to permit accurate platting on record maps. The Engineer shall provide a statement concerning the established zoning requirements of the governing municipality, including the City of St. Louis or St. Louis County, as appropriate, together with any other pertinent information. August 1, 2017 DRAFT FOR PUBLIC COMMENT 14 Any change to property line configuration, (some examples include boundary adjustment, resubdivision, lot split, lot consolidation, subdivision, etc.) shall require submittal of site improvement plans to the District for review and approval, unless directed otherwise by the District. 1.040.04 Projects Normally Requiring a Sewer Connection Permit Only Plans for connections to existing storm and/or sanitary sewers for commercial, industrial, public or private non-residential projects, for parking areas and for multiple-dwelling projects with paved areas shall show thereon: 1. Location, size and elevations of the existing sanitary, storm or combined sewer to which connections for the project are to be made. 2. The location, size and elevation of the required sanitary sewer connection at the point of origin. 3. The location, size and elevations of proposed storm drainage facilities. 4. Existing and proposed grade elevations with limits and direction of stormwater flows tributary to drainage facilities within the property. 5. Private sewers requiring permits from municipalities, the City of St. Louis, or St. Louis County may require project approval by such municipality or the County prior to submittal of permit application to the District. In some single lot, single-family residential instances where: a.) a sanitary or storm connection permit is necessary; b.) there will be no changes to property lines; and c.) the project will disturb less than one acre; at the discretion of the District a connection permit may be issued without full submittal and review of site improvement plans. 1.040.05 Return of Plans Without Review Plans lacking the required information or those that are difficult to read or interpret due to poor drafting, poor arrangement or poor writing, will be returned without review for correction, additional information, or redrafting as may be required. 1.040.06 Return of Plans for Revision On completion of the review, one set of plans or a letter with comments with requested revisions and notations will be returned to the Engineer for revision of the original tracings. The assigned District reference number and Base Map number shall be shown in or near the Title Block upon resubmittal of the plans. Additional sets of plans for further review or final approval will then be requested. August 1, 2017 DRAFT FOR PUBLIC COMMENT 15 1.040.07 Failure to Revise or Correct Plans Promptly Plans returned to the Owner's Engineer for revision, correction or additional information shall be modified and returned to the District within one year for final approval or the project will be considered abandoned. Project plans with missing requirements, fees, etc. that have had no activity for more than one year will also be considered abandoned. Further review will be continued only upon resubmittal as a new project, complete with all necessary data, submittal fee, review fee, etc. 1.040.08 Fees for Review See Chapter 9 for fees required for plan submittal and approval. 1.050 Plan Requirements 1.050.01 Drawing Sizes Plan sizes shall be uniform for each set. Where practical, plan and profile sheets 24" x 36" are preferred. No drawings shall exceed 30” 36" x 42". When the sheet size is considerably smaller than 24" x 36", a size which is a multiple of 8½" x 11", or 11” x 17” is preferred for filing convenience. White line prints on blue background will not be approved. Good drafting practice, either manual or automated, at a suitable scale to facilitate the plan review and field construction shall be followed. The scale for a residential subdivision shall be a minimum of fifty (50) feet to the inch. The District reserves the right to require a larger scale to improve clarity. Not-to-scale (NTS) details are very strongly discouraged, and may be rejected. 1.050.02 Plans Submitted Shall Include: 1. Location of the project with respect to arterial roads, local streets, or subdivisions. 2. Key map of the entire project to scale, showing easements, sewer lines and facilities, both existing and to be constructed. 3. Recorder of Deeds book and page from City of St. Louis or St. Louis County for existing recorded easements when not part of a recorded subdivision plat. 4. Plans and profiles of each sewer line, channel or retaining wall showing location, size, flowline elevations, design flows for all segments, construction gradients, hydraulic grade lines, materials, proposed and original ground lines, boring information and rock elevations along the proposed sewer line, location, depths and sizes of adjacent or crossing sewer lines and utilities and special construction requirements such as a concrete cradle or encasement, type of backfill, strength class of pipe, etc. Sanitary or combined sewer profiles shall include the following information for each lateral connection: station, side (LT or RT based on view from downstream manhole looking upstream), Lot Number, Basement Lowest Finished Floor Elevations and Property Address. 5. All elevations shall be based upon U.S.G.S. datum with location of the benchmark indicated on the plans. Acceptable benchmarks include those established by the District, St. Louis County Department of Transportation, Highways and Traffic, Missouri Department of TransportationState Highway and Transportation Department, or City of St. Louis August 1, 2017 DRAFT FOR PUBLIC COMMENT 16 Street Department. To convert from the City of St. Louis datum to U.S.G.S. datum, add 413. 69 feet to City of St. Louis datum (relates to Sandy Hook, New Jersey MSL.). 6. Profiles and typical cross-sections of existing and proposed swales, ditches or channels. 7. Details of special structures, channel improvements, culverts, transitions, headwalls, aprons and junction chambers, all adequately detailed and dimensioned, including placement of steel in reinforced concrete structures. Unless otherwise indicated, standard the standard District structures are assumed to be utilized. Use of not-to-scale (NTS) details will generally not be allowed. Past use and experience has shown resulting conflicts, misperceptions and unrealized poor to even unbuildable designs and otherwise unnecessary unexpected “field changes”. Details “practically drawn to scale” however, may use NTS, if key elevations and dimensions are shown. 8. A drainage area map showing original and proposed topography with drainage areas identified. 9. A subdivision plat, dimensioned and substantially complete and ready for filing. 10. The location of all utilities anticipated to be encountered during construction shall be shown. Plans must be submitted to all utility companies for verification of conflicts. Storm and sanitary sewers shall be located to comply with state laws and regulations governing such placement. 11. Plans must contain sufficient and verifiable, record information regarding size and location of existing water taps and their use to the project (to be used-in-place or destroyed) and the size of any proposed domestic water services and including service line(s), meter(s) and tap(s) to mains. •12. Details of all structural and non-structural best management practices (BMPs) for meeting water quality requirements. 13. Easement and other required exhibits and associated text, including specialized ones (e.g. pump station easements). 1.060 Storm Drainage Design Data, Maps and Computation (Also see Part 4 "Design Requirements For Storm Drainage Facilities") 1.060.01 General Criteria: The project drainage area map or maps shall accurately show the watershed boundary lines and areas tributary to each inlet, sewer and channel section. The established elevations, gradients and contours of the finished graded surfaces and streets shall be shown in support of the inlet drainage area lines and indicated directions of flow. The information shown shall be the same as given on a development plat usually required by financing agencies, which shows the project, the dwellings, streets, walks, finish grades at corners of the buildings, finish contours, street elevations and gradients, inlet, sewer and utility locations. Sufficient information showing locations, elevations, cross-sections of downstream watercourses, channels, sewers, culverts, structures and adjoining land shall be provided to determine the effects of the stormwater discharge and the possible needs for special easement requirements and/or downstream drainage modifications or protection. August 1, 2017 DRAFT FOR PUBLIC COMMENT 17 1.060.02 Basic Design Data To Include: 1. Rainfall frequency. 2. Tributary area in acres with percentage of imperviousness. 3. Runoff factor(s) used. 1.070 Sanitary Sewer Design Data, Maps and Computations (Also see Part 3 "Design Requirements For Sanitary Sewers") 1.070.01 General Criteria: Sufficient information shall be provided as to location, elevations, sizes, slopes, capacities, downstream pump stations and treatment facilities of the proposed project. 1.070.02 Basic Design Data To Consider: 1. Delineation of land use type(s). 2. Persons per dwelling unit. 3. Average and peak flow rate per person and per non-residential connection. 4. Commercial/Industrial User Wastewater Survey if required. 5. Population equivalent for industrial/commercial areas, schools, parks, hotels/motel institutions, and/or public buildings. 6. Point of connection to existing or proposed sewer and capacity of outfall system, including effects on next pump station downstream if one exists. 7. Allowances for future extension of proposed sewer to serve upstream areas of the watershed shall include both capacity and physical access. Lowest floor elevations of homes near the project or along an outfall line may be required. 2.8. Treatment facility to receive flows. 9. Some sources of useful equivalents are in parts of the 10 State Standards, MDNR, the District Design and planning factors, et cetera. August 1, 2017 DRAFT FOR PUBLIC COMMENT 18 2. DEFINITIONS 2.010 Definitions In addition to words and terms that may be defined elsewhere in this manual, the following words and terms shall have the meanings defined below: AASHTO: American Association of State Highway and Transportation Officials. Allowable Release Rate: The pre-development or existing condition peak flow corresponding to a selected rainfall frequency event. Backfill: The material used to fill an excavation. Base Flood: The flood having a one (1) percent chance of being equaled or exceeded in any given year. (The base flood, adopted by the Federal Emergency Management Agency (FEMA), is the 100-year flood.) Bedding: The material on which the pipe or conduit is supported and protected. BMP: “Best Management Practices”. Structural and non-structural stormwater management methods designed to improve stormwater quality by meeting pollutant removal goals; to reduce stormwater runoff volume and discharge rate from a site; and, for certain features, to provide a degree of channel protection. B.O.D.: "Biochemical Oxygen Demand"; means the quantity of oxygen utilized in 5 days in the biochemical oxidation of carbonaceous and nitrogenous compounds and certain inorganic materials in water or wastewater using procedures in 40 CFR 136 and expressed in milligrams per liter. the quantity of oxygen utilized in the biochemical oxidation of organic matter in 5 days as determined by Standard Methods and expressed in milligrams per liter. Board: The Board of Trustees of the District. Building Structure: Walled or roofed building that is principally above ground, as well as a manufactured home, and a gas or liquid storage tank that is principally above ground. Channel: A natural or artificial water course. Channel Protection Storage Volume: The storage needed for extended detention of the one-year 24-hour storm event to reduce erosion and sediment in natural water courses. Combined Flow: A combination of stormwater and wastewater. Combined Sewer: A pipe or conduit designed and intended to receive and convey wastewater, storm water including roof and street drainage, unpolluted water and cooling water. A sewer receiving both surface runoff and wastewater. Common Lateral: A lateral serving more than one property or unit owner, including the potential for same. Condominiums: Multiple residential or commercial units in a building where each unit is separately owned. August 1, 2017 DRAFT FOR PUBLIC COMMENT 19 Culvert: A closed conduit for the free passage of surface drainage water under a highway, railroad, or other embankment. Curve, Long: A curve having a centerline length of curve equal to or greater than one hundred fifty (150) feet. Curve, Short: A curve having a centerline length of curve of less than one hundred fifty (150) feet. Dedication: The process by which the owner gives approved sanitary, combined and/or storm sewers and facilities to the District for public use and maintenance. Detention: (See Sanitary Detention) (See Stormwater Detention) Developed Runoff Rate: The peak flow corresponding to a selected rainfall event as a result of developed site conditions. Differential Runoff Rate: The difference between the pre-developed runoff rate and the developed runoff rate normally using PI factors. Differential Volume of The amount of differential stormwater volume Stormwater: between the pre-developed and developed runoff rates which the detention basin must detain (hold). Director: The Executive Director of the Metropolitan St. Louis Sewer District, or his duly authorized representative. properly authorized agents. District: The Metropolitan St. Louis Sewer District. Drainage Facility: Any system of artificially constructed drains, including open channels, whether lined or unlined, and separate storm sewers used to convey storm water, surface water or groundwater. A drainage facility may also convey effluent discharged pursuant to an NPDES permit when such use is approved by the Director. and sewers used to convey stormwater, surface or groundwater, either continuously or intermittently to natural watercourses. Drop: A structural configuration where flow falls into a structure from an incoming pipe. Engineer: A registered Professional Engineer currently certified by law in the State of Missouri. FEMA: Federal Emergency Management Agency. Flood Insurance Floodway Maps: Current maps from the Federal Emergency Management Agency Flood Insurance Study. Flood Insurance Study: The Official Report provided by the Federal Emergency Management Agency containing flood profiles; flood boundaries; floodway maps and the water surface elevation of the base flood. Flood Plain: A geographic area susceptible to periodic inundation from the overflow of natural waterways during the base (100-year) flood. August 1, 2017 DRAFT FOR PUBLIC COMMENT 20 Flood Plain Study: An Engineering analysis to determine the hydraulic effect, if any, of the proposed development to the existing Flood Plain. Floodway: The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than one foot and so delineated in the Flood Insurance Study. Force Main: A pressurized sewer carrying wastewater. Foulwater Drops: A structure permitting sanitary flow to pass from an incoming pipe at a higher elevation to an outgoing pipe at a lower elevation. Freeboard: The difference in elevation (expressed in feet) between the hydraulic grade line elevation and (1) the inlet sill elevation; or (2) the top of structure elevation; or (3) the top of channel bank elevation; or (4) the top of wall elevation. House Lateral: Private sewer from building drain to the public sewer. This shall include the connection to the sewer. Hydraulic Grade Line: A line coinciding with the level of flowing water at any given point along an open channel or sewer; or the level to which water would rise in a vertical tube connected to any point along a pipe or closed conduit flowing under pressure. HS-10: The live truck wheel loads as designated by the AASHTO Specifications. HS-20: The live truck wheel loads as designated by the AASHTO Specifications. Improved Channel: Improved stormwater channels are open trapezoidal or vertical walled channels designed to certain standards and typically constructed from man- made structural materials, such as poured concrete, concrete block, placed stone, or gabion baskets. Improved Sinkhole: A sinkhole with an MSD approved drainage structure on top. Industrial Waste Survey: The District form to be submitted to the Environmental Compliance Department of the District for review and recommendations. Inlet Time: The overland flow time for runoff to reach the inlet. Intrados: The inside top of the sewer pipe. Junction Structure: A special design buried underground chamber used to join two or more large sewers (greater than 24” diameter sewers). Lateral Sewer: A sewer that discharges into a branch or other sewer and has no other common sewer tributary to it. Long Curve: A curve having a centerline length of curve equal to or greater than one hundred fifty (150) feet. Low Sill: The lowest elevation of any opening in a building. August 1, 2017 DRAFT FOR PUBLIC COMMENT 21 Main Sewer: The principal sewer to which branch sewers and submains are tributary; also called trunk sewers. MDNR: The Missouri Department of Natural Resources. Micro-Detention: A single or a series of small stormwater detention areas that absorb or detain some or all of the stormwater runoff in a development site. It works by temporarily storing stormwater near where it falls as precipitation. Micro-detention can include common landscaping features such as small garden areas, tree grates, perimeter hedges, and bioretention areas such as rain gardens. It may also include non-vegetated areas such as sub-surface storage areas with regulated outflow. Micro-detention is one of several best management practices that can be used to treat and/or infiltrate stormwater or collect it for reuse at a development site. MSD: The Metropolitan St. Louis Sewer District. MS4: (Municipal Separate Storm Sewer System) - As defined in 10 CSR 20- 6.200: an MS4 is a conveyance or system of conveyances including roads and highways with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, paved or unpaved channels, or storm drains designated and utilized for routing of stormwater which, does not include any waters of the state: is contained within the municipal corporate limits or is owned and operated by the state, city, town, village, county, district, association, or other public body created by or pursuant to the laws of Missouri having jurisdiction over disposal of sewage, industrial waste, stormwater, or other liquid wastes; is not a part or portion of a combined sewer system; and is not a part of a publicly owned treatment works as defined in 40 CFR 122.2. “n” Value: A dimensionless coefficient used in the Manning’s Equation to account for frictional losses in steady uniform flow. Ordinance: An Ordinance duly adopted by the Board of Trustees of the District. Outfall: Any point of discharge into a watercourse, or other body of surface or groundwater. The point location or structure where wastewater or drainage discharges. PAC: Permit Application Center (of St. Louis County). Person: Any individual, firm, proprietorship, partnership, company, association, public or private corporation, joint stock company, trust, estate, political subdivision, or any agency, board, department, or bureau of the State or Federal government, or any other legal entity. municipality, association, society, corporation, group, or other entity. Plan of the District: The document also known as the “Charter” of the Metropolitan St. Louis Sewer District, as approved by the voters on February 9, 1954. Pre-Developed Runoff Rate: The amount of flow from an existing site prior to new development or improvements as computed by the Rational Formula. Prismatic Channel: A channel characterized by uniform cross sections and constant bottom slope. August 1, 2017 DRAFT FOR PUBLIC COMMENT 22 Private Sewer: A sewer within the boundaries of the District but not owned or controlled by the District. A sewer not accepted for public maintenance as determined by the District. PSDR: Pump Station Design Requirements Public Sewer: A sewer which has been accepted for public maintenance by the District. Reach: A distance, in pipe or channel, between two identified points. Resolution: Any Resolution duly adopted by the Board of Trustees of the District. Sampling Appurtenance: A manhole or a riser section “T” installed on the buildings private lateral for purposes of monitoring wastewater discharged. Sanitary Detention: An “On-Site” private facility to collect and store the sanitary wastewater of a development for such time as may be required until it can be pumped or otherwise discharged into the downstream sanitary sewer system. Sanitary Sewer: A pipe or conduit designed and intended to receive and convey wastewater as defined herein. A sewer which carries wastewater. Semi-Public: A governmental, institutional, educational or municipal property. building, structure or facility. Separate Sewer: A sewer intended to receive only wastewater or stormwater runoff. Sewer: A pipe or conduit for conveying wastewater, storm water or cooling water or other disposed wastes. A pipe or closed conduit carrying wastewater, stormwater or a combination thereof. Short Curve: A curve having a centerline length of curve of less than one hundred fifty (150) feet. Sinkholes: Natural depressions or collapsed areas formed by dissolution of carbonate bedrock. Stormwater typically drains into the subsurface.A topographic depression with no natural surface drainage outlet. Springline: The line or plane in which an arch rises from its impost. In circular conduits, the horizontal plane through the midpoint of the section. Standard Details of Sewer Construction: Plans of structures or devices or construction details commonly used on District work and referred to on the plans or in the specifications. Steady Flow: The quantity of water passing a cross section is constant, i.e.; has patterns and magnitudes which do not vary with time. Stormwater Detention: A stormwater runoff facility or feature designed to detain (hold) stormwater temporarily during and immediately after a runoff event. Stormwater Quality Management Facility: A stormwater runoff facility or feature designed to improve quality of and/or reduce volume of stormwater runoff (generally referred to as a BMP). These facilities, to be approved, must properly use appropriate techniques and features as approved by MSD over time and for intended water quality and/or volume reduction strategies and compliance goals. August 1, 2017 DRAFT FOR PUBLIC COMMENT 23 Stormwater Sewer: Enclosed and typically underground piping that transports stormwater runoff from properties and streets to streams.A sewer which carries surface runoff and subsurface waters. Swales: Shallow trough-like depressions designed to divert or channel stormwater flows. Examples include ditches and other grading to direct flow to specific areas, including MSD infrastructure.A broad shallow water course. Time of Concentration: Consists of inlet time plus the travel time in the sewer or channel from the most remote point in the watershed to the point under consideration. Travel Time: The time it takes for the runoff to flow through the drainage system from one point of reference to the next point of reference. Trunk Sewer: The principal sewer to which branch sewers and subtrunks are tributary; also called main sewers. Uniform Flow: The flow in a channel, conduit or pipe, having a uniform cross section and velocity at every location within a given reach. Unimproved Channel: Stormwater channels that have not been improved, including natural streams, stone revetments, and grade controls. U.S.G.S.: United States Geological Survey. Utilities: Public service facilities for supplying gas, electricity, water, power, steam, cable T.V., telephone and fiber optic communication, railway transportation, and the like. Sewers are not considered utilities. Wastewater: The water-borne wastes, industrial waste and/or sanitary wastewater as defined herein, emanating from residential and non-residential sources together with such groundwater, surface water, or storm water as cannot be avoided. The spent water of a community. Watercourse: A natural or manmade surface drainage channel or body of water (including a lake or pond) in which a flow of water occurs, either continuously or intermittently. A stream of water or a natural channel through which water may flow. Water Quality Volume: The storage needed to capture and treat runoff from the 90th percentile 90% of the recorded daily rainfall events to reduce stormwater nonpoint source pollution. Wunnenberg’s: A commercial street guide, published by St. Louis Area Maps, Inc., for the St. Louis Metropolitan Area. Zero Increase Rate: A routed release rate for a 24-hour storm, which represents no allowed increase in peak discharge. August 1, 2017 DRAFT FOR PUBLIC COMMENT 24 3. DESIGN REQUIREMENTS FOR SANITARY SEWERS 3.010 General This section gives the minimum technical design requirements of the District for sanitary sewerage and sewage treatment facilities. Adherence to these will expedite review and approval of plans. In general, the formulae presented herein for hydraulic design represent acceptable procedures not necessarily to the exclusion of other sound and technically supportive formulae. Any departure from these design requirements shall should be brought to the attention of the District and discussed before submission of plans for approval, and shall should be justified. Minimum standards as specified by the Missouri Department of Natural Resources shall be followed for instances not governed by this regulation or directed by MSD. All construction details pertaining to sanitary sewer improvements shall be prepared in accordance with the District Standard Construction Specifications unless otherwise noted. 3.020 General Requirements of Sanitary Sewer Construction All sanitary sewers shall meet the following general requirements: 3.020.01 Size and Shape The minimum diameters of pipe for combined sewers shall be twelve (12) inches, and for sanitary sewers, eight (8) inches. Sewers shall not decrease in size in the direction of the flow. Circular pipe sewers shall be used for all sizes of sanitary sewers. 3.020.02 Materials All materials shall conform to the District Standard Construction Specifications, including periodically updated “Approved Materials”. Trench backfill material for sewers beneath street pavement may be as required by the local jurisdiction for the street pavement and its maintenance. That shall not alter standard pipe bedding, cradling or immediate pipe covering procedures or materials, however, unless otherwise specifically approved by MSD. 3.020.03 Bedding and Backfill The project Plans and Project Specifications shall indicate the specific type or types of bedding, cradling, or encasement required in the various parts of the sanitary sewer construction if different than the current District Standard Construction Specifications. Special design and bedding provisions shall be made for pipes laid under or over fills or embankments in shallow or partial trenches either by specifying extra strength pipe for the additional loads due to differential settlement, or by special construction methods, including ninety (90%) modified proctor compaction of fill, to prevent or to minimize such additional loads. Special considerations shall be made for pipe material and bedding for unsuitable soil conditions or other conditions within the project area that may affect the pipe design. Compacted granular backfill shall be required in all trench excavation within public (or private) streets rights-of-way or areas where street rights-of-way are anticipated to be dedicated for public use. Under areas to be paved, the compacted granular backfill shall be placed to the subgrade of the pavement. Under unpaved areas, the compacted granular backfill shall be placed to within two (2) feet of the finished surface, and generally not more than two (2) feet beyond street pavement or curb lines. Local street jurisdiction shall govern, where more stringent. For new residential site developments, in areas outside of street right- of-way, where private driveways are not yet constructed, granular backfill will not be required. Pipes having a cover of less than three (3) feet shall be encased in concrete, or a stronger pipe be used, unless otherwise directed by the District. August 1, 2017 DRAFT FOR PUBLIC COMMENT 25 If the storm and sanitary sewers are parallel and in the same trench, the upper pipe shall be placed on a shelf and the lower pipe shall be bedded in compacted granular fill to the flow line of the upper pipe. If the sewers are within eighteen (18) inches of each other, the lower pipe shall be concrete encased. 3.020.04 Pipe or Conduit Under Streets and Pavements Any pipe or conduit material beneath a highway, road, street, or pavement, or with reasonable probability of being so located, shall have ample strength for all vertical loads, including the live load required by the highway authority having jurisdiction, but in no case shall provide for less than an AASHTO HS-20 loading. For other locations, the minimum live load shall be the HS-10 loading. Special considerations may be required for adverse conditions. Compacted granular backfill shall be utilized to the base of the pavement. For new residential site developments, in areas outside of street right-of-way, where private driveways are not yet constructed, granular backfill will not be required. 3.020.05 Joints The joint type required for the type of pipe used and the application shall conform to the latest standards set forth in the District Standard Construction Specifications of the District or as approved by the District. 3.020.06 Monolithic Structures Monolithic reinforced concrete structures shall be designed structurally as continuous rigid units. Wall thickness shall be 8” minimum with one row of reinforcement, horizontal and vertical. Wall thickness 10” and greater shall require 2 rows of reinforcement, horizontal and vertical. (Where approved, District precast structures are allowed, less steel & thickness may be accepted). 3.020.07 Alignment Sanitary sewer alignments are normally limited by the available easements, which in turn should reflect proper alignment requirements. Sanitary sewers shall be aligned: 1. To be in a straight line between structures for all pipe sewers thirty inches (30) in diameter and smaller. 2. To be parallel with or perpendicular to the centerlines of straight streets unless otherwise unavoidable. Deviations may be made only with approval of the District. 3. To avoid meandering, off-setting and unnecessary angular changes. 4. To make angular changes in alignment for sewers thirty (30) inches in diameter or smaller in a manhole located at an angle point and for sewers thirty-three (33) inches in diameter or larger, by a uniform curve between two tangents. Curves shall have a minimum radius of ten times the pipe diameter, with manhole(s) located as described in section 3.020.10, item 1. 5. To avoid angular changes in direction greater than necessary and any exceeding ninety (90) degrees. August 1, 2017 DRAFT FOR PUBLIC COMMENT 26 3.020.08 Location Sanitary sewer locations are determined primarily by the requirements of service and purpose. It is also necessary to consider accessibility for construction and maintenance, site availability and competing uses, and effects of easements on private property. Sanitary Sewers shall be located: 1. To serve all property conveniently and to best advantage. 2. In public streets, roads, alleys, rights-of-way, or in sewer easements dedicated to the District. 3. In easements on private property only when unavoidable. 4. On private property along property lines or immediately adjacent to public streets, avoiding crossing through the property. 5. At a sufficient distance from existing and/or proposed buildings (including footings) and underground utilities or other sewers to avoid encroachment and reduce construction hazards. 6. To avoid interference between house connections to foulwater or sanitary sewers and stormwater sewers. 7. In unpaved or unimproved areas whenever possible. 8. To avoid, whenever possible, any locations known to be or probably to be beneath curbs, paving or other improvements particularly when laid parallel to centerlines. 9. To avoid sinkholes and creeks. 1.10. No sanitary lateral clean outs or sampling tees shall be placed within the area of the stormwater overflow path. 2.11. No sanitary sewer shall be within ten (10) feet horizontally or eighteen (18) inches vertically of a water main. 3.020.09 Flowline The flowline of sanitary sewers shall meet the following requirements: 1. The flowline shall be straight or without gradient change between the inner walls of connected structures. 2. Gradient changes in successive reaches normally shall be consistent and regular, with small or insignificant differences in successive reaches. Gradient designations less than the nearest 0.001 foot per foot, except under special circumstances and for larger sewers, shall be avoided. 3. For sanitary or combined sewers the hydraulic grade line shall not rise above the intrados of the pipe. August 1, 2017 DRAFT FOR PUBLIC COMMENT 27 4. When the grade of a sewer is twenty percent (20%) or greater, a concrete cradle or collars at each pipe joint is required. For grades exceeding fifty percent (50%) a special design and Project Specifications are required. 3.020.10 Manholes Manholes provide access to sewers for purposes of inspection, maintenance and repair. They also serve as junction structures for connecting lines. Requirements of sewer maintenance determine the main characteristics of manholes. 1. Manholes shall be located at changes in direction, changes of pipe size, flowline gradient, and at junction points with connecting sewers. For sewers thirty-three (33) inches in diameter and larger, manholes shall be located on special structures at junction points with other sewers and at changes of size, alignment, or gradient. These special structures are identified as Junction Structures, and are described further in section 3.030.09. A manhole shall be located at each end of a short or long curve. 2. Spacing of manholes shall not exceed four hundred (400) feet for pipe sewers thirty- six (36) inches in diameter and smaller, five hundred (500) feet for pipe sewers forty- two (42) inches in diameter and larger, except under special approved conditions. Spacing shall be approximately equal, whenever possible. In addition, street access manholes should be located at a spacing of not more than 1200 feet apart to facilitate sewer maintenance requirements. “Street access manholes” are those manholes in or adjacent to a paved street accessible to MSD. 3. Manholes on sanitary and combined sewers ten (10) inches through thirty-six (36) inches shall be a minimum of forty-eight (48) inches in diameter and/or have a square bottom section with sides of forty-eight (48) inches, depending on the sewer diameter. Manholes on sewers eight (8) inches in diameter shall have a minimum bottom section of forty-two (42) inches. Manholes on sewers greater than thirty-six (36) inches in diameter shall be built in accordance with the Standard Specifications. 4. At stream and channel crossings, manholes shall be located on both sides of the crossing at changes in pipe material. The manholes shall be a minimum of ten (10) feet horizontally back from the top of the bank on both sides of the crossing. 5. All manholes on sanitary sewers that are built in existing or proposed paved areas subject to flooding or ponding, or within the 100-year flood limits, the stormwater overflow path, swales or ditches, or in other areas determined to be subject to flooding or ponding, shall be provided with lock type, sealing, watertight manhole frames and covers. This requirement applies to newly constructed manholes, as well as existing manholes that are to be adjusted to grade or otherwise modified or connected into. 6. Manholes for sanitary or combined sewers shall be precast concrete or poured in place type and waterproofed on the exterior, as approved by the District. August 1, 2017 DRAFT FOR PUBLIC COMMENT 28 3.020.11 Sewage Treatment Facilities 1. New treatment plants will not be allowed. 2. Treatment using a septic system for continued use of an existing individual residence may be considered only where the District determines that no public sanitary sewer is available. Replacement of a burned down or otherwise destroyed individual residence may also be so considered, but only if an affidavit is provided from an “A” rated insurance company to show non-arson and claims approval for residence replacement. Approval from the local Plumbing Authority will be required. Availability of sanitary sewers is assumed if any point on the property to be served is within a distance of two hundred (200) feet of a public sanitary sewer. In any case, the District will make the final determination based on specific site conditions. 3. For properties or lots less than three (3) acres, septic systems shall not be allowed, unless the District approves a waiver from this requirement. Septic systems will not be allowed for a property or a lot size less than three (3) acres. 4. For new or replacement construction or development, including residential, refer to 1.020.03 3.030 Design Requirements 3.030.01 General All sanitary sewers shall be designed and constructed as to conform to these design requirements. Hydraulic calculations must be submitted as part of the plan review for all public sewer construction. Calculations must be submitted for the existing and ultimate upstream development condition. 3.030.02 Gradients The following minimum slopes of sanitary pipe sewers are those giving at least three (3) feet per second velocities flowing full, based on Manning's formula using an "n" value of 0.013 unless otherwise directed by the District. Slopes greater than these minimums shall be used wherever possible. Variation from these minimums will only be considered by the District under extenuating circumstances due to existing and unavoidable site conditions. For sewers with a design grade less than one percent (1%), field verification of the pipe grade will be required for each installed reach of sewer, prior to any surface restoration or installation of any surface improvements. The District may require the submittal of revised hydraulic calculations for any sewer reach having an as-built grade flatter than the design grade by more than 0.1%. Based on a review of this hydraulic information, the District may require the removal and replacement of any portion of the sewer required to ensure sufficient hydraulic capacity and cleansing velocity of the system. August 1, 2017 DRAFT FOR PUBLIC COMMENT 29 Pipe Size Minimum Slope in Ft. per 100 Ft. (% Grade) 6 (house lateral)* 2.0 8 1.0 10 0.6 12 0.6 15 0.4 18 0.3 21 0.3 24 0.2 27 0.2 30 0.2 36 0.1 Pipes larger than thirty (36) inches in diameter shall maintain a minimum cleansing velocity of three (3) feet per second. Where velocities are greater than 15 feet/second, special provisions to protect against displacement by erosion and impact shall be made. 3.030.03 Depth and Minimum Cover Sewer depths shall be determined primarily by the requirements of pipe or conduit size, utility obstructions, required connections, future extensions, and adequate cover. The minimum depth requirements shall be as follows: 1. For sewers which may be extended in the future, the minimum depth shall be nine (9) feet below the finish grade to flowline, except where upstream topography indicates that this depth is not necessary as determined by the District. 2. The minimum depth of sewers shall be not less than three (3) feet plus the sewer diameter. The flowline of the sewer must have a vertical distance from the low point of a basement or low floor of not less than 2.5 feet plus the sewer diameter. *The minimum depth shall be increased as required to insure a minimum of two percent (2%) slope and 2.5 feet of cover for a six (6) inch house lateral. 3. At stream and channel crossings, a minimum depth of three two (32) feet shall be allowed where greater depths cannot be achieved. Where this minimum cover can not be achieved, a casing pipe shall be installed to encase the sewer Schedule 50 ductile iron pipe with Field Lok Mechanical restrained joints or approved equal must be used from manhole to manhole unless otherwise directed by the District. Stream and channel crossings must be protected with rock blanket or other approved stream stabilization/channel protection methods. Concrete encasement is not an option. Aerial crossings are not allowed unless attached to a bridge. 4. Sewer depths at manholes shall be sufficient to ensure the use of standard manholes. Special manholes will only be allowed upon approval by the District. 5. In situations where fill is being added, minimal cover is proposed, or the sewer is being subjected to additional live or dead load, the design engineer shall provide structural calculations to verify the sewer is able to support the proposed loading. August 1, 2017 DRAFT FOR PUBLIC COMMENT 30 3.030.04 Flow Design All lateral and sub-main or collecting sewers shall be designed on the basis of an average per capita use of not less than one hundred (100) gallons per day, and on that basis shall be designed with capacities of four hundred (400) gallons per capita per day at peak flow unless otherwise directed by the District. Sanitary flow from day schools with gymnasiums, showers and cafeterias shall be computed on the basis of thirty (30) gallons per capita per day discharged in eight (8) hours. On this basis the daily peak flow rate shall be 90 x 4 gallons per capita per day for the lateral sewers. Sanitary flow from tourist camps and trailer courts shall be computed on the basis of 2.5 persons per each unit for each twenty four (24) hour period at fifty (50) gallons per capita per day times a peak factor of four (4). Sanitary flow from apartments, boarding schools and condominiums and other smaller facilities shall be computed at the same rate as residential property. Sanitary flow from all other types of institutions, commercial property, industrial plants, etc., shall be separate and individual studies based on a conservative ultimate anticipated flow multiplied by the peak factors applicable to each case, or, where not covered by this Regulation, MDNR Design Guides (10 CSR 20-8) may be referenced in determining design flows. In the case of industrial flow, when the rate and volume can be predetermined with a reasonable degree of accuracy, no dilutions or diminishing factor shall be applied against this flow in the outfall, sub-trunk or trunk sewers. 3.030.05 Population Factors Family population factors for the various areas in the District are to be determined from the latest United States Census Tracts. An acceptable figure is 3.7 persons per household unit. 3.030.06 Sanitary Flow Table Population Unit Cu. Ft./Sec. One Person @ 400 G/D 0.00062 One Household Unit @ 3.7 Persons 0.00229 @ 400 G/C/D Where G/C/D = Gallons per Capita per Day Basic Formula: Flow in Cu. Ft./Sec. = Population x Flow(in G/C/D) / 646,317 3.030.07 Hydraulic Grade Line 1. Hydraulic Grade Line Limits The hydraulic grade line for sanitary and combined sewers shall not rise above the pipe intrados. The beginning point for the hydraulic grade line computations shall be the higher (i.e. more conservative) elevation as determined below: For connection to existing pipe systems a. Top of pipe intrados or inlet control calculation at least two reaches downstream of the connection point to the existing system; or August 1, 2017 DRAFT FOR PUBLIC COMMENT 31 b. The hydraulic grade line computed for the existing system, especially where the downstream system has suspected or known lack of capacity issues. Field verified structure and flowline elevations, pipe sizes and characteristics shall be used. 2. Computation Methods Sanitary or combined sewers shall be designed to flow not more than 80% full at ultimate peak design flow conditions. The hydraulic grade line shall be computed to show its elevation at manholes, transition structures, and junction points of flow in pipes, and shall provide for the losses and the differences in elevations as required below. a. Friction Loss The major energy loss in a sanitary or combined sewer will be the energy loss due to friction. It is determined by the equation: hf = L x Sh Where: hf = difference in water surface elevation, or in length L L = length in feet of pipe Sh = hydraulic slope required for a pipe of given diameter and for a given roughness "n", expressed as feet of slope per foot of length From Manning's formula: Sh = [(V)(n) /(1.486 R0.667)]2 Where: R = hydraulic radius of pipe or conduit in feet V = velocity of flow in feet per second n = Manning's value for coefficient of roughness; where n = .013 for concrete, vitrified clay and plastic pipe; n = .012 for concrete pipe greater than forty eight (48) inches in diameter b. Curve Loss Curve loss in pipe flow is the additional head required to maintain the required flow because of curved alignment, and is in addition to the friction loss of an equal length of straight alignment. If concrete pipe, it may be evaluated from Figure 4-2 which includes an example. c. Turn Loss Head losses in manholes due to change in direction of flow (turns) will be determined in accordance with the following: August 1, 2017 DRAFT FOR PUBLIC COMMENT 32 Multiplier of Change in Direction Velocity Head of of Flow (A) Water Being Turned (K) 90 Deg. 0.7 60 Deg. 0.55 45 Deg. 0.47 30 Deg. 0.35 15 Deg. 0.18 0 Deg. 0.0 Other Angles By Interpolation Formula: HL = K(VL)2/2g Where: HL = Feet of head lost in manhole due to change in direction of pipe flow VL = Velocity of flow in pipe in Ft/Sec g = Acceleration of gravity, 32.2 Ft/Sec/Sec K = Multiplier of Velocity Head of water being turned d. Junction Chamber Loss A sewer junction occurs for large pipes or conduits too large to be brought together in a forty two (42) inch diameter manhole where one or more branch sewers enter a main sewer. Allowances should be made for head loss due to curvature of the paths and due to impact at the converging streams. A MainManhole DIAGRAM August 1, 2017 DRAFT FOR PUBLIC COMMENT 33 Losses in a junction chamber for combining large flows shall be minimized by setting flowline elevations so that pipe centerlines (spring lines) will be approximately in the same planes. At junction points for combining large flows, a manhole with a slotted or lock-down cover shall be required depending on the type of sewer. A computation method for determining junction chamber losses is presented below: Hj = ∆y + Vh1 - Vh2 Where: Hj = junction chamber loss ∆y = change in hydraulic grade line through the junction in feet Vh1 = upstream velocity head Vh2 = downstream velocity head Where: y = [(Q2V2)-((Q1V1) + (Q3V3CosӨ3) + (QnVnCosӨn))] 0.5(A1+A2)g Where: Q2 = Discharge in cfs at the exiting conduit V2 = Velocity in fps at the exiting conduit A2 = Cross section area of flow in sq. ft. for the exiting conduit. Q1 = Discharge in cfs for the incoming pipe (main flow) V1 = Velocity of fps for the incoming pipe (main flow) A1 = Cross sectional area of flow in sq. ft. for the incoming pipe (main flow) Q3,Qn = Discharge(s) in cfs for the branch pipe(s) V3,Vn = Velocity(ies) in fps for the branch pipe(s) Ө3, Өn = The angle between the axes of the exiting pipe and the branch pipe(s) g = Acceleration of gravity, 32.2 ft/sec/sec. Where: Ө= The angle between the axes of the outfall and the incoming pipe(s) e. Losses at Junctions of Several Flows in Manholes The computation of losses in a manhole with several flows entering the structure should utilize the principle of the conservation of energy. This involves both the elevation of water surface and momentum (mass times the velocity head). Thus, at a manhole with two or more incoming pipes, the sum of the energy content for inflows is equal to the sum of the energy content of the outflows plus the additional energy required by the turbulence of the flows passing through the structure. August 1, 2017 DRAFT FOR PUBLIC COMMENT 34 DIAGRAM: The upstream hydraulic grade line may be calculated as follows: Hu = [VD2/2g]-[((QU/QD)(1-K)(VU2/2g))+((QL1/QD)(1-K)(VL12/2g))+ ((QLN/QD)(1-K)(VLN2 /2g))] + HD Where: HU = Upstream hydraulic grade line in feet QU = Upstream main line discharge in cubic feet per second QD = Downstream main line discharge in cubic feet per second QL1-QN =Pipe discharges in cubic feet per second VU = Upstream main line velocity in feet per second VD = Downstream main line velocity in feet per second VL1-VLN =Pipe velocities in feet per second HD = Downstream hydraulic grade line in feet K = Multiplier of Velocity of Water being turned g = Acceleration of gravity, 32.2 ft/sec/sec The above equation does not apply when two (2) almost equal and opposing flows, each perpendicular to the downstream pipe, meet and no other flows exist in the structure. In this case the head loss is considered as the total velocity head of the downstream discharge. f. Transition Loss The relative importance of the transition loss is dependent on the velocity head of the flow. If the velocity and velocity head of the flow are quite low, the transition losses cannot be very great. However, even small losses may be significant in flat terrain. The sewer design shall provide for the consideration of the necessary transitions and resulting energy losses. The possibility of objectionable deposits is to be considered in the design of transitions. For design purposes it shall be assumed that the energy loss and changes in depth, velocity and invert elevation, if any, occur at the center of the August 1, 2017 DRAFT FOR PUBLIC COMMENT 35 transition. These changes shall be distributed throughout the length of the transition in actual detailing. The designer shall carry the energy head, piezometric head, and invert as elevations, and work from the energy grade line. (1) Closed Conduits Transitions in small sewers may be confined within a manhole. Special structures may be required for larger sewers. The energy loss in a transition shall be expressed as a coefficient multiplied by the change in velocity head (V2/2g) in which V is the change in velocity before and after the transition. The coefficient may vary from zero to one, depending on the design of the transition. If the areas before and after a transition are known, it is often convenient to express the transition loss in terms of the area ratios and either the velocity upstream or downstream. For an expansion: HL = K(V1-V2)2/2g ≈ {K(V1)2/2g}[1-(A1/A2)]2 in which HL is the energy loss; K is a coefficient equal to 1.0 for a sudden expansion and approximately 0.2 for a well-designed transition, and the subscripts 1 and 2 denote the upstream and downstream sections, respectively, i.e., A1 = Area Before Transition and A2 = Area After Transition. For a contraction: HL = K[(V2)2/2g][(1/Cc)-1]2 ≈ K[(V2)2/2g][1-(A2/A1)]2 in which K is a coefficient equal to 0.5 for a well-designed transition, Cc is a coefficient of contraction, and the other terms and subscripts are similar to the previous equation. Losses in closed conduits of constant area are expressed in terms of (V2/2g). The above equations may be applied to approximate the energy loss through a manhole for a circular pipe flowing full. If the invert is fully developed, that is, semi-circular on the bottom and vertical on the sides from one-half depth up to the top of the pipe, for the expansion A1/A2 = 0.88, and for the contraction A2/A1 = 0.88. The expansion is sudden; therefore, K = 1. The contraction may be rounded if the downstream pipe has a bell or socket. In this case, K may be assumed to be 0.2. The expansion energy loss is 0.014 [(V1)2/2g] and the contraction energy loss is 0.010 [(V2)2/2g]. Thus it may be seen that if the invert is fully developed, the manhole loss is small. August 1, 2017 DRAFT FOR PUBLIC COMMENT 36 3.030.08 Infiltration An additional amount of flow due to infiltration shall be evaluated. All sanitary sewers shall be limited to a maximum of one hundred (100) gallons per inch of diameter per day per mile of line, as required by MDNR Specifications, when tested by appropriate water of low pressure air testing. In addition, there shall be no visible leaks. 3.030.09 Special Situations and Design Requirements l. Connections to Manholes a. The invert of incoming sanitary sewers shall enter the manhole at the manhole flowline elevation. Under special circumstances, and only as approved by the District, up to a two (2) foot interior free-fall drop will be allowed for incoming sewers. Such special circumstances may include sewer construction in bed rock or utility conflicts. b. Foul water drops are required only for sewers containing sanitary flow and then only when it is necessary that sanitary flow enter a manhole at a height more than two (2) feet above its flowline. If an inside drop is to be used, a forty-eight (48) inch diameter manhole is required. However, new inside drops are generally, no longer allowed. Sewer lines shall not enter the manhole in the transition conical section, or through a joint. The slope on incoming pipes should be limited to a maximum one percent (1%) for inside drops; slopes greater than this require an outside drop structure. Incoming pipe, upstream of an outside drop, should be limited to a maximum slope of 5%. Manhole inverts should be shaped to assure proper flow through drop structures. The largest size to be used for an outside drop is twelve (12) inches. c. If it is necessary to enter a manhole with a force main this should be done within twelve (12) inches of the flowline of the manhole, and the manhole invert should be shaped to insure proper flow through the structure. Consideration shall be given to the detention time of the sewage in the force main, and the potential detrimental effects of the release of hydrogen sulfide from the force main on the concrete structure of the manhole. Where it is determined that the release of hydrogen sulfide may be a problem, the concrete manhole shall be protected by a cementitious or plastic liner or epoxy coating, as approved by the District. Prior to the manhole lining, existing manhole steps that are in poor condition, or are without copolymer polypropylene plastic exterior, shall be removed flush with manhole interior wall, and then new standard manhole replacement steps as approved by the District shall be installed. Prior to the manhole lining, each step shall be wrapped except for the initial 2” portion protruding from the wall; this to allow for the new manhole lining to completely cover the initial 2” of each step out from the manhole wall. Wrap to be removed after manhole liner completely cures. All existing manholes will have steps removed prior to the installation of any form of protective sealant, such as epoxy coatings or plastic liners. All new manholes will not have steps installed if the structure is to be sealed from H2S exposure. Connection of a public force main to a manhole will require manhole lining protection that protections for at least one manhole and possibly as many as five (5) downstream. Connection of a private forced lateral may require some similar protection. August 1, 2017 DRAFT FOR PUBLIC COMMENT 37 d. The number of sewers coming into one manhole should be kept to a minimum. A special detail may be required to assure the proper constructability and maintenance of the structure, especially for larger pipes, angled approaches or multiple incoming pipes. e. Pipes entering and exiting manholes at the flowline should project toward the center of the structure and the manhole invert should be shaped to assure proper flow through the structure. f. Private house lateral connections should be made to the main sewer, at existing wyes of record. In the absence of a wye, connect to the public sewer pipe using another approved method, and not to the manholes unless an 8 inch or larger private sewer lateral connecting to an 8 inch or larger public sewer. g. All connections to sanitary manholes are subject to the District review and approval and will be made at the District's discretion. h. Connections to existing structures may require rehabilitation or reconstruction of the structure being utilized. This work will be considered part of the project being proposed. i. Junction Structures shall be required to have a ground surface access with a minimum of a standard 48” diameter manhole riser section(s). The junction Structure flow channels and benches shall be built into the bottom of the structure. The entry angle from a sewer connection from the side shall not exceed 20 degrees as measured between the centerlines of the two sewers being connected. 2. Adjusting Manholes to Grade When a project requires a manhole to be adjusted to grade, a maximum of twelve (12) inches of rise is allowed if not previously adjusted. When adjustments to raise or lower a manhole are required, the method of adjustment must be stated on the project plans and approved by the District. Metal grade rings shall not be allowed. 3. Swimming Pools and Fountains Swimming pool backwash and fountain backwash connections to the sanitary sewer must not exceed fifty gallons per minute (50 gpm). Commercial swimming pools and commercial fountains will require a Missouri State Operating Permit. Maintenance and seasonal drainages shall be directed to an adequate stormwater outlet under provisions specified in the Missouri State Operating Permit. 4. Storm Sewers Crossing Over Sanitary Sewers When a new storm pipe crosses over a new sanitary sewer and the vertical clearance is less than two (2) feet, the sanitary sewer must be encased in concrete through the crossing and for ten (10) lineal feet each side of the crossing unless otherwise directed by the District. When new storm pipe crosses over an existing sanitary sewer and the vertical clearance is less than two (2) feet, the sanitary sewer shall be protected and the upper half of the sanitary sewer shall be carefully exposed and then concrete encased within the limits of the new storm sewer trench. August 1, 2017 DRAFT FOR PUBLIC COMMENT 38 5. Location in Conjunction with Water Service No cross connections. Outer limit of sSanitary sewers and manholes shall be at least ten (10) feet horizontally from outer limit of any existing or proposed water main. Sewers and water mains shall be placed in separate trenches. If this is not possible, the water main shall be placed on an undisturbed earth shelf, the bottom of the water main shall be at least 18” above the top of the sewer, and the sewer must be constructed of slip-on or mechanical joint pipe or continuously encased and pressure tested to 150 psi to assure watertightness. On crossings, a minimum vertical clearance of eighteen (18) inches shall be provided between the outside of the water main and outside of the sanitary sewer. Sewer pipe joints shall be equidistant and as far as possible from the water main joints. Structural support shall be provided for sewer crossing over a water main. If it is not possible to obtain proper horizontal and vertical separation, either: a.) The sewer shall be designed and constructed equal to water pipe and pressure tested to assure water tightness prior to backfilling, or b.) Water main or sewer line is continuously encased or enclosed in a watertight carrier pipe of approved material which extends 10’ in both directions, measured perpendicular to the water main. MoDNR provisions for waiver will be considered on a case by case basis. 6. Sanitary Sampling Appurtenance A sanitary sampling appurtenance (“T” or manhole) is required for non-residential, commercial, and industrial projects. A sampling appurtenance shall be located on each private building lateral, in a location readily accessible to the District personnel, downstream from any traps, interceptors or other pretreatment facilities, and before connection to the public sewer. Each sampling appurtenance shall be fitted with a cover that can readily be removed for sampling access. If a locking cover is desired for security purposes, the District’s Office of Environmental Compliance shall be provided with any keys or special tools required to remove the cover. (See sections 1.020.04 and 1.020.06, also.) a. For all industrial projects the sampling appurtenance shall be a standard manhole in accordance with Chapter 3, Sections 3.020.10 or a similar structure which affords an equivalent degree of access for the installation of flow monitoring and sampling equipment. An industrial project is any development, which will be occupied by an “industrial user” as defined by the District’s Sewer Use Ordinance. b. For commercial projects, the sampling appurtenance shall be a minimum of a “T” of the same diameter as the private lateral except that no sampling “T” shall be less than six (6) inches in diameter. The District may, at its discretion, require a standard manhole or equivalent structure, as described above in lieu of a sampling “T” for a commercial project. 7. Abandonment of Sanitary Sewer Services Sanitary sewer laterals, from buildings to be demolished, shall be plugged with concrete unless the lateral is to be used for the replacement building. The lateral shall be plugged with concrete at the foundation wall or at the last trap leaving the August 1, 2017 DRAFT FOR PUBLIC COMMENT 39 building. The District need not be notified unless the lateral is being cut off or plugged at the main sewer. A detail must be provided. 8. Private Force Main Connections Private force lateral main connections to the public gravity sewers will only be considered where site topography does not allow for gravity lateral service to the sanitary sewer or the gravity extension of the sanitary sewer is not feasible. See Chapter 13.1 for requirements for connecting into a public force main or a private force main extending outside its property line. Make the force connection into a public gravity sewer by one of the following two methods: 10.• Directly into a manhole one foot above its flowline. See Section 3.030.09.1b. 11.• Connect the private small diameter force main into a private 6” clean-out assembly. From the clean-out, install a 6” gravity lateral with a two percent slope into the public sewer through a wye connection. For all properties, the operation and maintenance of private grinder pumps and their pressure laterals shall be the responsibility of the property owner. 9. Oil/Gas Separators, Sand InterceptorsFilters, and Grease InterceptorsTraps If required by the District, grease, oil and sand interceptors or traps shall be provided when such devices are necessary for the proper handling of liquid wastes containing grease or oil in excessive amounts or any flammable wastes, sand, or other harmful materials which can be interceptedtrapped. Such interceptors or traps shall not be required for private dwelling units. Prior to the installation of any interceptoror trap, drawings and specifications shall be submitted to the District for approval. All interceptors and traps shall be located so as to be readily accessible for cleaning and visual inspection on influent and effluent sides. An exterior location shall be the norm. Design and permitting of interceptors and traps shall be per local plumbing codes. Discharge of wastewater into the MSD sewer system shall not exceed sewer use ordinance limits and prohibitions. Grease and oil interceptors or traps shall be constructed of impervious materials capable of withstanding sudden and extreme changes in temperature. All such devices shall be of substantial construction, water-tight, and equipped with easily removable covers which, when bolted in place, shall be gas tight and watertight, unless otherwise approved by the District. All grease, oil and sand interceptors or traps shall be maintained in effective operation at all times by and at the expense of the user. 10. Coldwater Creek Gravity Elevation In the Coldwater Creek watershed, the elevation of the lowest gravity outlet from any building shall not be lower than U.S.G.S. Elevation 470.5. 11. Common Laterals A common lateral will only be allowed for a building of same use, vertically stacked condominiums, i.e. one owned unit above a unit owned by another, all residential or commercial. For side by side, non-vertically stacked condominium units, each unit shall have its own lateral and each lateral shall be connected directly to a public August 1, 2017 DRAFT FOR PUBLIC COMMENT 40 sewer. In all other cases, each building shall be provided with a separate lateral sewer for each use from the building to the public or private main within the boundaries of the property line extensions. Connection of a building’s lateral to a private sewer will only be allowed where the District determines future subdividing without the District approval is highly unlikely, or structurally impossible per a building code official. Free-standing commercial leaseholds which could become outlots and any leaseholds which could become separately owned (unstacked) will each be connected directly and separately to a public sewer. The lateral shall be installed in accordance with the local building code, and in a manner consistent with these Rules and Regulations. 12. Private Lateral Where a private sanitary sewer crosses a property line it must be immediately and directly connected to a public sewer in the District easement or public right-of-way. Where the receiving public sewer is immediately across the street or alley, the private lateral may extend directly across the street or alley to it. Existing private sewers traversing multiple properties or parts of properties shall be made public upon failure of the existing private sewer or any further development of such properties and in the manner described first above. New private sewers shall not serve multiple properties beyond the property in which the private sewer originates, except where otherwise allowed in these Rules as a common lateral or as a private sewer in a common industrial complex or institutional campus setting. A new private sewer serving two or more properties is not allowed. Legally recorded consolidation of multiple properties into one property is another acceptable method of eliminating the situation. Conversely, subdividing or other creation of multiple properties will necessitate conforming public sewers, as part of Plat and Plan approvals, to assure the availability of proper sewer maintenance and service for future owners. Private sewers are not to utilize public easements or public right-of-ways for long distances or to cross same as long diagonals. Crossings are to be kept to a minimum, be direct and should not course in front of an adjacent owners property. Reasonable, traditional, semi-radial patterns in cul-de-sac situations and the like may be allowed, unless prohibited by another jurisdiction. 13. Private Sewer in Common Industrial Complex or Institutional Campus Setting For some industrial or institutional situations where the same entity owns adjacent parcels and lot consolidation is not possible, private sewers crossing property lines of these adjacent parcels may be considered by the District on a case by case basis. Upon receipt of a letter request from the property owner(s) stating owner(s) agree that the sewer will remain private and they agree to own and maintain the sewer, the District will consider the following factors in making its decision as to whether or not a common private sewer will be allowed: a. Reason property owner is making the request b. The property owner’s ability to maintain the private sewer c. Restrictions on site accessibility by MSD operations department d. Number of owners served by the sewer e. A common sample point for pretreatment f. A common plan of development August 1, 2017 DRAFT FOR PUBLIC COMMENT 41 Where two or more properties are served by a common private sewer, the sewer must be at least 8-inches in size and shall be constructed to MSD Standards. A private sewer maintenance agreement shall be executed by each of the property owner(s), and the agreement shall be recorded against all affected properties. The sewer shall be labeled “private” on the approved plans and on MSD mapping. 12.14. Separate Laterals and Sewers New or reused sewers and laterals constructed as part of all development or redevelopment within areas served by existing combined sewers shall be separated storm and sanitary systems to outside the property line . Combined sewers currently serving redevelopment areas shall be removed or fully grout filled and abandoned, unless suitable for recycling as public separate sewer. Construction of new combined sewers is not allowed unless approved by the District for special cases only. If existing public combined sewers can be recycled as separate storm sewers with needed capacity, then that is more desirable. However, lining or other refurbishing or stabilization/repair may be required, especially for the very old sewers. 13.15. Protection from Surcharging Due to sewer overcharge and water backup potential, building structures shall be protected with appropriate backflow prevention measures (i.e. approved backwater valves or strapped plumbing) as outlined in local plumbing codes. It is noted that the District may prohibit gravity sewer service to basements in some combined sewer areas and some known problem areas served by separate sanitary sewers. In these situations a backwater valve will not suffice for surcharge protection and instead strapped plumbing shall be required as directed by the District. See most recent Figures 3-1 and 3-2. 14.16. Residential Basement Garage Flooding Basement garages will only be allowed as directed by the District. Driveways to basement garages shall be designed whenever possible to allow for positive drainage away from the garage and to an acceptable location such as the street gutter. When sump driveways are necessary and allowed by the District, gravity drains shall be provided to intercept stormwater and discharge to an acceptable surface location or storm or combined sewer. Pumped discharge will not be allowed. Finished floor elevations of sump (basement) garages shall be a minimum of 1 foot below the lowest basement finished floor elevation and sanitary sewer floor drain elevation. The District reserves the right to deny construction of sump (basement) garages. 15.17. Lateral for Commercial Use For mixed use buildings (example: commercial on lower floors, with residential on upper floors) separate sanitary laterals shall be provided for each “use-section” of the building (example: commercial sanitary lateral and a residential lateral). These “use- section” sanitary laterals may be connected together on private property outside the building limits and downstream of any external grease traps or sampling appurtenance. August 1, 2017 DRAFT FOR PUBLIC COMMENT 42 16.18. Levee Protected Areas and High Groundwater Table Areas In areas protected by levees and in areas with a high groundwater table, to help minimize infiltration and inflow, a more shallow gravity sanitary system shall be considered and may be required. This configuration may utilize more intermittent sanitary lift stations. Special pipe materials and joint configurations may be required. For gravity mains, machine tap connections will not be allowed; instead, roll-in connections will be required. Strapped plumbing configuration may be required for buildings in these areas. Buoyancy shall be considered during design of all components, with appropriate construction techniques utilized as needed. For below ground structures, size the structure with a floatation safety factor of 1.1 minimum. Assume in the floatation calculations that the structure is empty, the top slab is removed, and neglect the weight of any equipment, pipes, or other appurtenances. Additionally, piered footings, spread footings, special pipe bedding, or other techniques may be required to minimize settlement of manholes, pump stations, sewers, or other structures. A geotechnical assessment may be required. 19. Lateral Tracer Wire Any new or reconstructed sewer lateral (gravity or pressure connection) installed or fully replaced within public right-of-way shall have tracer wire and access point installed as incorporated within local plumbing code requirements per Missouri Revised Statute 319.033.1. 20. Connections to Brick, Non-Reinforced Concrete or Other Non-Circular Sewers When connecting to an existing brick, non-reinforced concrete, or other non-circular sewer, the design engineer shall take into consideration the type of material and condition of the existing sewer and provide detailed design (structural and hydraulic), specifications, and plans for the connection to minimize impacts to the existing sewer system. 21. Connections to Drop Shafts When connecting a combined, sanitary, or storm sewer to an existing tunnel drop shaft or to an existing sewer system that may impact the existing tunnel drop shaft and tunnel system, additional hydraulic conditions must be considered. Items to be considered include, but are not limited to: capacity of the inlet and drop shaft, energy dissipation after the drop, de-aeration and air venting requirements, stability of the outflow, loads applied by hydraulic forces, and odor control. The design engineer shall address these issues as part of the design plans submittal. August 1, 2017 DRAFT FOR PUBLIC COMMENT 43 3.040 Sanitary Detention Requirements 3.040.01 Surcharged Sanitary Sewers When it has been determined that the outfall sewer or the downstream system serving a proposed development is overcharged, the District may require the developer to provide special facilities that the District deems necessary, for example, a sanitary holding tank providing detention storage for a specified amount of time (detention) for eighteen (18) hours of storage, with discharge during the off-peak hours or upgrading the downstream system to provide additional capacity. Detention sizing and release characteristics shall take into account the receiving system’s level of service, diurnal pattern, presence of SSOs/CSOs, and other factors as determined by the District. In the design of such facilities, consideration shallshould be given for the protection of structures and equipment against corrosive and/or explosive gasses that may result from the detention of sewage. August 1, 2017 DRAFT FOR PUBLIC COMMENT Figure 3-1 August 1, 2017 DRAFT FOR PUBLIC COMMENT Figure 3-2 August 1, 2017 DRAFT FOR PUBLIC COMMENT 46 4. DESIGN REQUIREMENTS FOR STORM DRAINAGE FACILITIES 4.010 General Stormwater sewers or channels provide the facility for removing and transporting surface runoff produced from rainfall. Design requirements differ from those for either sanitary or combined sewers. This section gives the minimum technical design requirements of the District storm drainage facilities. In general, the formulae presented herein for hydraulic design represent "acceptable" procedures not necessarily to the exclusion of other sound and technically supportive formulae. Any departure from these design requirements should be discussed before submission of plans for approval and should be justified. All construction details pertaining to storm sewer improvements shall be prepared in accordance with the District Standard Construction Specifications unless otherwise noted. 4.020 General Requirements of Storm Sewer Construction All storm sewers shall meet the following general requirements: 4.020.01 Size and Shape The minimum diameters of pipe for stormwater or combined sewers shall be twelve (12) inches. Sewers shall not decrease in size in the direction of the flow unless approved by the District. Circular pipe sewers are preferred for stormwater sewers, although rectangular or elliptical conduits may be used with special permission. 4.020.02 Materials All materials shall conform to the District Standard Construction Specifications. Reinforced concrete pipe joints shall be Type "A" or better, as required. 4.020.03 Bedding and Backfill The Project Plans and Specifications shall indicate the specific type or types of bedding, cradling, or encasement required in the various parts of the storm sewer construction if different than current the District Standard Construction Specifications. Special design and bedding provisions shall be made for pipes laid within fills or embankments and/or in shallow or partial trenches, either by specifying extra strength pipe for the additional loads due to differential settlement, or by special construction methods, including ninety percent (90%) modified proctor compaction of fill to prevent or to minimize such additional loads. Special considerations shall be made for pipe material and bedding for unsuitable soil conditions or other conditions within the project area that may affect the pipe design. Compacted granular backfill shall be required in all trench excavation within public (or private) streets rights-of-way or areas where street rights-of-way are anticipated to be dedicated for public use. Under areas to be paved, the compacted granular backfill shall be placed to the subgrade of the pavement. Under unpaved areas, the compacted granular backfill shall be placed to within two (2) feet of the finished surface, and generally not more than two (2) feet beyond street pavement or curb lines. Local street jurisdiction shall govern where more stringent. For new residential site developments, in areas outside of street right-of-way, where private driveways are not yet constructed, granular backfill will not be required. Pipes having a cover of less than three (3) feet shall be encased in concrete, unless otherwise directed by the District. When The Sstorm and sanitary sewers are parallel and in the same trench, the upper pipe shall be placed on a shelf and the lower pipe shall be bedded in compacted granular fill to the flow line of August 1, 2017 DRAFT FOR PUBLIC COMMENT 47 the upper pipe. If sewers are within eighteen (18) inches of each other, the lower pipe shall be concrete encased. In situations where fill is being added, minimal cover is proposed, or the sewer is being subjected to additional live or dead load, the design engineer shall provide structural calculations to verify the sewer is able to support the proposed loading. 4.020.04 Concrete Pipe or Conduit Strengths Reinforced Concrete pipe shall be Class II, minimum. Any concrete pipe, conduit or culvert beneath a street right-of-way, or with reasonable probability of being so located, shall be a minimum of Class III, but also shall account for all vertical loads, including the live load required by the highway authority having jurisdiction. In no case shall the design provide for less than HS-20 loading of the AASHTO. For other locations, the minimum design live load shall be the HS-10 loading. 4.020.05 Monolithic Structures Monolithic reinforced concrete structures shall be designed structurally as continuous rigid units. Generally these are poured in place units. Wall thickness shall be 8” minimum with one row of reinforcement, horizontal and vertical. Wall thickness 10” and greater shall require 2 rows of reinforcement, horizontal and vertical. (Where approved District precast structures are allowed, less steel & thickness may be accepted). 4.020.06 Alignment Sewer alignments are normally limited by the available easements, which in turn should reflect proper alignment requirements. Since changes in alignment affect certain hydraulic losses, care in selecting possible alignments can minimize such losses and use available head to the best advantage. Sewers shall be aligned: 1. To be in a straight line between structures, such as manholes, inlets, inlet manholes and junction chambers, for all pipe sewers thirty (30) inches in diameter and smaller. 2. To be parallel with or perpendicular to the centerlines of straight streets unless otherwise unavoidable. Deviations may be made only with approval of the District. 3. To avoid meandering, off-setting and unnecessary angular changes. 4. To make angular changes in alignment for sewers thirty (30) inches in diameter or smaller in a manhole located at the angle point, and for sewers thirty- three six (336) inches in diameter or larger, by a uniform curve between two tangents. Curves shall have a minimum radius of ten times the pipe diameter, with manholes located as indicated in section 4.020.10, item 1. 5. To avoid angular changes in direction greater than necessary and any exceeding ninety (90) degrees. 4.020.07 Location Storm sewer locations are determined primarily by the requirements of service and purpose. It is also necessary to consider accessibility for construction and maintenance, site availability and competing uses, and effects of easements on private property. August 1, 2017 DRAFT FOR PUBLIC COMMENT 48 Storm sewers shall be located: 1. To serve all property conveniently and to best advantage. 2. In public streets, roads, alleys, rights-of-way, or in sewer easements dedicated to the District. 3. On private property along property lines or immediately adjacent to public streets, avoiding diagonal crossings through the central areas of the property. 4. At a sufficient distance from existing and proposed buildings including footings, and underground utilities or other sewers to avoid encroachments and reduce construction hazards. 5. To avoid interference between other stormwater sewers and house connections to foulwater or sanitary sewers. 6. In unpaved or unimproved areas whenever possible. 7. To avoid, whenever possible, any locations known to be or probably to be beneath curbs, paving or other improvements particularly when laid parallel to centerlines. 8. To avoid sinkhole areas if possible. However, if sinkhole areas cannot be avoided, see sub-section 4.020.08 for requirements. 9. Crossing perpendicular to street, unless otherwise unavoidable. 10. In areas protected by levees and in areas with a high groundwater table, to help minimize infiltration and inflow, special pipe materials and joint configurations may be required. Buoyancy shall be considered during design of all components, with appropriate construction techniques utilized as needed. For below ground structures, size the structure with a floatation safety factor of 1.1 minimum. Assume in the floatation calculations that the structure is empty, the top slab is removed, and neglect the weight of any equipment, pipes, or other appurtenances. Additionally, piered footings, spread footings, special pipe bedding, or other techniques may be required to minimize settlement of manholes, pump stations, sewers, or other structures. A geotechnical assessment may be required. 4.020.08 Sinkhole Areas As this regulation governs post-construction stormwater management, sinkholes are considered natural resources that warrant protection under the region’s MS4 permit. Projects that are located within the tributary area of a sinkhole shall employ Best Management Practices (BMPs) to protect the water quality and preserve the sinkhole’s existing hydrologic condition (tributary flow rate and tributary flow volume) to the maximum extent practicable. Any stormwater management BMPs used to accomplish this shall be located within the area tributary to the sinkhole, but not on top of or over any sinkhole. Sinkholes shall not be integrated within a BMP. Work proposed in these areas shall also comply with all local municipal requirements, including, but not limited to the following: land disturbance permitting, erosion control, site grading, and sinkhole setback requirements. August 1, 2017 DRAFT FOR PUBLIC COMMENT 49 1. Sinkhole Report Where improvements are proposed in any area identified as sinkhole areas, a sinkhole report will be required. This report is to be prepared by a Professional Engineer, registered in the State of Missouri, with demonstrated expertise in geotechnical engineering, and shall bear his or her seal. The sinkhole report shall verify the adaptability of grading and improvements with the soil and geologic conditions available in the sinkhole areas. Sinkhole(s) shall be inspected to determine its functional capabilities with regard to handling drainage. The report shall contain provisions for the sinkholes to be utilized as follows: a. All sinkhole crevices shall be located on the plan. Functioning sinkholes may be utilized as a point of drainage discharge by a standard drainage structure with a properly sized outfall pipe provided to an adequate natural discharge point, such as a ditch, creek, river, etc. b. Non-functioning sinkholes and sinkholes under a proposed building may be capped. c. If development affects sinkholes, they may be left in their natural state; however they will still require a properly sized outfall pipe to an adequate natural discharge point. d. An overland flow path shall be required for all sinkholes assuming the outfall pipe and sinkhole become blocked. e. Storm water routing calculations may be required, as directed by the District. Where the topography will not allow for an overland flow path: 1. The storm sewer shall be designed for the 100-year, 20-minute storm, and 2. If this storm pipe is smaller than thirty six (36) inches in diameter, a designated ponding area shall be identified, assuming the pipe is blocked, and 3. The ponding area shall be based on the TR-55 100-year, 24-hour storm, and 4. The low sill of all structures adjacent to the ponding area shall be a minimum of two (2) feet above the 100-year highwater elevation. 5. Special siltation measures shall be installed during the excavation of sinkholes and during the grading operations to prevent siltation of the sinkhole crevice. August 1, 2017 DRAFT FOR PUBLIC COMMENT 50 2. Procedure for Utilization of Sinkholes a. Excavation. Prior to filling operations in the vicinity of a sinkhole, the earth in the bottom of the depression will be excavated to expose the fissure(s) in the bedrock. The length of fissure exposed will vary, but must include all unfilled voids or fissure widths greater than one-half (1/2) inch maximum dimensions which are not filled with plastic clay. b. Closing Fissures. The fissure or void will be exposed until bedrock in its natural attitude is encountered. The rock will be cleaned of loose material and the fissures will be hand-packed with quarry-run rock of sufficient size to prevent entry of this rock into the fissures, and all the voids between this hand-packed quarry-run rock filled with smaller rock so as to prevent the overlying material's entry into the fissures. For a large opening, a structural (concrete) dome will be constructed with vents to permit the flow of groundwater. c. Placing Filter Material. Material of various gradations, as approved, will be placed on top of the hand-packed rock with careful attention paid to the minimum thicknesses. The filter material must permit either upward or downward flow without loss of the overlying material. The fill placed over the granular filter may include granular material consisting of clean (no screenings) crushed limestone with ten (10) inch maximum size and one (1) inch minimum size or an earth fill compacted to a minimum density of ninety percent (90%) modified Proctor as determined by ASTM D-1557. d. Supervision. Periodic supervision of the cleaning of the rock fissures must be furnished by the Engineer who prepared the Soil Report. Closing of the rock fissures will not begin until the cleaning has been inspected and approved by that Engineer. During the placement and compaction of earth fill over the filter, supervision by the Engineer shall be continuous. Earth fill densities will be determined during the placement and compaction of the fill in sufficient number to insure compliance with the specification. The Engineer is responsible for the quality of the work and to verify that the specifications are met. After construction is completed the geotechnical engineer shall provide a P.E. sealed certification letter stating the project was constructed in accordance with the design plans and geotechnical report. This certification shall be submitted to MSD prior to close-out of any MSD construction permits for sinkhole treatment. 4.020.09 Flowline The flowline of storm sewers shall meet the following requirements: 1. The flowline shall be straight or without gradient change between the inner walls of connected structures; that is, from manhole to manhole, manhole to junction chamber, inlet to manhole, or inlet to inlet. 2. Gradient changes in successive reaches normally shall be consistent and regular. Gradient designations less than the nearest 0.001 foot per foot, except under special circumstances and for larger sewers, shall be avoided. August 1, 2017 DRAFT FOR PUBLIC COMMENT 51 3. Sewer depths shall be determined primarily by the requirements of pipe or conduit size, utility obstructions, required connections, future extensions and adequate cover. 4. Stormwater pipes discharging into lakes shall have the discharge flowline a minimum of three (3) feet above the lake bottom at the discharge point or no higher than the normal water line. 5. A concrete cradle is required when the grade of a sewer is twenty (20) percent or greater. A special design and specification is required for grades exceeding fifty percent (50%). 6. For sewers with a design grade less than one percent (1%), field verification of the sewer grade will be required for each installed reach of sewer, prior to any surface restoration or installation of any surface improvements. 7. The District may require the submittal of revised hydraulic calculations for any sewer reach having an as-built grade flatter than the design grade by more than 0.1%. Based on a review of this hydraulic information, the District may require the removal and replacement of any portion of the sewer required to ensure sufficient hydraulic capacity of the system. 4.020.10 Manholes Manholes provide access to sewers for purposes of inspection, maintenance and repair. They also serve as junction structures for lines and as entry points for flow. Requirements of sewer maintenance determine the main characteristics of manholes. Cast in place or precast manhole structures are generally allowable, though the former requires approved shop detail drawings. 1. For sewers thirty (30) inches in diameter or smaller, manholes shall be located at changes in direction; changes in size of pipe; changes in flowline gradient of pipes, and at junction points with sewers and inlet lines. For sewers thirty-three (33) inches in diameter and larger, manholes shall be located on special structures at junction points with other sewers and at changes of size, alignment change and gradient. A manhole shall be located at one end of a short curve and at each end of a long curve. These special structures are identified as Junction Structures, and are described further in section 3.030.09. A manhole shall be located at each end of a short or long curve. 2. Spacing of manholes shall not exceed four hundred (400) feet for pipe sewers thirty-six (36) inches in diameter and smaller; five hundred (500) feet for pipe sewers forty-two (42) inches in diameter and larger, except under special approved conditions. Spacing shall be approximately equal, whenever possible. 3. When large volumes of stormwater are permitted to drop into a manhole from lines twenty-one (21) inches or larger, the manhole bottom and walls below the top of such lines shall be of reinforced concrete. Special structural design may be required for large pipes and/or large drops. 4. Manholes shall be avoided in driveways or sidewalks. 5. Connections to existing structures may require rehabilitation or reconstruction of the structure being utilized. This work will be considered part of the project being proposed. August 1, 2017 DRAFT FOR PUBLIC COMMENT 52 6. When a project requires a manhole to be adjusted to grade a maximum of twelve (12) inches of rise is allowed if not previously adjusted. When adjustments to raise or lower a manhole is required, the method of adjustment must be stated on the project plans and approved by the District. Metal grade rings shall not be allowed. 4.020.11 Overflow/Design System The "design" components of the drainage system include the inlets, pipe, storm sewers, and improved and unimproved channels that function during typical rainfall events. The "overflow" system comprises the major overflow routes such as swales, streets, floodplains, detention basins, and natural overflow and ponding areas. The purpose of the overflow system is to provide a drainage path to safely pass flows, which cannot be accommodated by the design system without causing flooding of adjacent structures. The criteria for the design of the overflow and design systems shall be as follows: 1. The "design" system shall be designed in accordance with Section 4.030. 2. The "overflow" system shall be designed for the 100-year, 20-minute event, assuming the "design" system is completely blocked. The capacity of the "overflow" system shall be verified with hydraulic calculations at critical cross-sections. The "overflow" system shall be directed to the detention facility, or as approved by the District. 3. The low sill of all structures adjacent to the "overflow" system swales shall be above the 100-year highwater elevation. 4. Where the topography will not allow for an overland flow path: a. The storm sewer and inlet capacity shall be designed for the 100-year, 20-minute storm, and b. If this storm pipe is smaller than thirty-six (36) inches in diameter, a designated ponding area shall be identified, assuming the pipe is blocked, and c. The ponding area shall be based on the TR-55 100-year, 24-hour storm, and d. The low sill of all structures adjacent to the ponding area shall be above the 100-year highwater elevation. 5. The "overflow" system and ponding areas shall be designated on the drainage area map and on the grading plan, with sufficient allowances/setbacks from locations where patios, swimming pools, decks, retaining walls, and other improvements are proposed or may be constructed by future end users. 6. All overflow systems will be considered on a site specific basis. Modifications to identified ponding areas and overland flow paths shall not be made without obtaining approvals from the agency having jurisdiction over grading and MSD. 7. The stormwater design for projects within designated levee districts such as Monarch- Chesterfield, Earth City and Riverport will be based on the Stormwater Master Plan for these districts. August 1, 2017 DRAFT FOR PUBLIC COMMENT 53 4.030 Stormwater Design Criteria 4.030.01 Flow Quantities Flow quantities are to be calculated by the "Rational Method" in which: Q = API where: Q = runoff in cubic feet per second A = tributary area in acres I = Average intensity of rainfall (inches per hour) for a given period and a given frequency P = runoff factor based on runoff from pervious and impervious surfaces P (Runoff Factors) for various impervious conditions are shown in Table 4-1. P.I. values for various impervious conditions are shown in Table 4-2. 1. Rainfall Frequency A twenty (20) year rainfall frequency is to be used in the City of St. Louis and areas of St. Louis County where combined sewers are used. A fifteen (15) year rainfall frequency is to be used in areas of St. Louis County where storm sewers are separated from sanitary sewers. In the design of local storm sewer systems, a twenty (20) minute time of concentration shall be used, unless drainage area and time of concentration dictates a different duration as indicated in item 3 below. Figure 4-1 gives rainfall curves for 2, 5, 10, 15, 20 and 100 year frequencies. 2. Impervious Percentages and Land Use Minimum impervious percentages to be used are as follows: a. For manufacturing and industrial areas, 100%* b. For business and commercial areas, 100%* c. For residential areas, including all areas for roofs of dwellings and garages; for driveways, streets, and paved areas; for public and private sidewalks; with adequate allowance in area for expected or contingent increases in imperviousness: In apartment, condominium and multiple dwelling areas: 75%* In single family areas: 1/4 Acre or less 50% 1/4 Acre to 1/2 Acre 40% 1/2 Acre to 1 Acre 35% One acre or larger Calculate impervious percentage* Playgrounds (Non-Paved) 20-35%* d. For small, non-perpetual charter cemeteries, allow 30% August 1, 2017 DRAFT FOR PUBLIC COMMENT 54 For parks and large perpetual charter cemeteries 5% *NOTE: Drainage areas may be broken into component areas, with the appropriate run-off factor applied to each component, i.e. a proposed development may show one hundred percent (100%) impervious for paved areas and five percent (5%) impervious for grassed areas. Use of actual component areas may be required, however, where minimum impervious percentages are deemed misleading, or too approximate. The design engineer shall provide adequate detailed computations for any proposed, expected or contingent increases in imperviousness and shall make adequate allowances for changes in zoning use. If consideration is to be given to any other value than the above for such development, the request must be made at the beginning of the project, must be reasonable, fully supported, and adequately presented, and must be approved in writing before its use is permitted. Although areas generally will be developed in accordance with current zoning requirements, recognition must be given to the fact that zoning ordinances can be amended to change the currently proposed types of development, and any existing use. Under these circumstances the possibility and the probability of residential areas having lot sizes changed or re-zoned to business, commercial, or light manufacturing uses should be given careful consideration. e. Average 20-minute values of P.I. (cfs per acre) to be used are as follows: Percent 20 Minute Duration Imperviousness 15 Year 20 Year 5 1.70 1.78 10 1.79 1.87 20 2.00 2.09 30 2.19 2.28 40 2.39 2.50 50 2.58 2.69 90 3.36 .. 3.50 100 3.54 3.70 *Roofs (Combined Sewer Areas City of St. Louis) 20-year 20 minute PI 6.00, 100-year 20 minute PI 7.75 *Roofs (Separate Sewer Areas Other than City of St. Louis) 15-year 20 minute PI 4.20, 100-year 20 minute PI 5.62 *When connected directly to sewerFor Direct Connection to Sewer 3. Reduction in P.I. with Time and Area Reduction in P.I. values for the total time of concentration exceeding twenty (20) minutes, and for tributary areas exceeding three hundred (300) acres will be allowed only in trunk sewers and main channels. The reduced average P.I. value for the tributary area shall not be less than the value determined as follows on the basis of: a. Time. As the time of concentration increases beyond twenty (20) minutes, select the appropriate P.I. value from Table 4-2. The travel time through a drainage channel should be based on an improved concrete section. These reduced values shall be used unless a further reduction is allowed for area. August 1, 2017 DRAFT FOR PUBLIC COMMENT 55 b. Area. As the total tributary area at any given location in a channel increases in excess of three hundred (300) acres, the P.I. value may be further reduced by multiplying it by an area coefficient "Ka". (The area coefficient is obtained from data in a special study of a major storm in the St. Louis area by the U.S. Corps of Engineers.) The average rainfall rate, for a given storm, for a given period for the tributary area, is less than the corresponding point value as determined from recording rainfall gauges. The curve data is as follows: P.I. Coefficients Ka Area (Abscissas) "Ka" (Ordinates) 300 to 449 Acres 1.00 450 to 549 Acres .99 550 to 749 Acres .98 750 to 999 Acres .97 1000 to 1280 Acres .96 1281 to 1600 Acres .95 1601 to 1920 Acres .92 1921 to 2240 Acres .91 4.030.02 Hydraulic Grade Line for Closed Conduits 1. Computation Methods The hydraulic grade line is a line coinciding with (a) the level of flowing water at any given point along an open channel, or (b) the level to which water would rise in a vertical tube connected to any point along a pipe or closed conduit flowing under pressure. The beginning point for hydraulic grade line computations for storm sewers shall be at least the higher of the elevations listed in 3.030.07.1. Field-verification shall also apply. The hydraulic grade line shall be computed to show its elevation at all structures and junction points of flow in pipes, conduits and open channels, and shall provide for the losses and the differences in elevations as required below. Since it is based on design flow in a given size of pipe or conduit or channel, it is of importance in determining minimum sizes of pipes within narrow limits. Sizes larger than the required minimum generally provide extra capacity, however consideration must still be given to the respective pipe system losses. There are several methods of calculating "losses" in storm sewer design. The following procedures are presented for the engineer's information and consideration. It is expected that the design will recognize the reality of such "losses" occurring and make such allowances, as good engineering judgment requires. a. Friction Loss The hydraulic grade line is affected by friction loss and by velocity head transformations and losses. Friction loss is the head required to maintain the required flow in a straight alignment against frictional resistance because of pipe or channel roughness. It is determined by the equation: August 1, 2017 DRAFT FOR PUBLIC COMMENT 56 hf =L x Sh Where: hf = difference in water surface elevation, or head in feet in length L L = length in feet of pipe or channel Sh = hydraulic slope required for a pipe of given diameter or channel of given cross- section and for a given roughness "n", expressed as feet of slope per foot of length From Manning's formula: Sh = [V n /(1.486 R0.667)]2 Where: R = hydraulic radius of pipe, conduit or channel (feet) (Ratio of flow area/wetted perimeter) V = velocity of flow in feet per second (fps) n = Manning's value for coefficient of roughness Use: n = .013 for pipes of concrete, vitrified clay, and PVC pipe n = .012 for formed monolithic concrete, i.e., vertical wall channels, box culverts and for R.C.P. over 48" in diameter n = .015 for concrete lining in ditch or channel inverts and trapezoidal channels n = .020 for grouted riprap lining on ditch or channel side slopes n = .033 for gabion walled channels Note: "n" will have a weighted value for composite lined channels. "n" values for unlined channels to be determined on an individual basis. b. Curve Loss Curve loss in pipe flow is the additional head required to maintain the required flow because of curved alignment, and is in addition to the friction loss of an equal length of straight alignment. It should be determined from Figure 4-2, which includes an example. c. Entrance Loss at Terminal Inlets Entrance loss is the additional head required to maintain the required flow because of resistance at the entrance. The entrance loss at a terminal inlet is calculated by the formula: Hti = (V2/2g) Where: V = Velocity in flow of outgoing pipe g = Acceleration of gravity (32.2 Ft/Sec/Sec) d. Turn Loss August 1, 2017 DRAFT FOR PUBLIC COMMENT 57 Head losses in structures due to change in direction of flow (turns) in a structure, will be determined in accordance with the following: Multiplier of Change in Direction Velocity Head of of Flow (A) Water Being Turned (K) 90 Deg. 0.7 60 Deg. 0.55 45 Deg. 0.47 30 Deg. 0.35 15 Deg. 0.18 0 Deg. 0.0 Other Angles By Interpolation DIAGRAM: Formula: HL = K(VL)2/2g Where: HL = Feet of head lost in manhole due to change in direction of lateral flow VL = Velocity of flow in lateral in Ft/Sec g = Acceleration of gravity, (32.2 Ft/Sec/Sec) K = Multiplier of Velocity Head of water being turned e. Junction Chamber Loss A sewer junction occurs for large pipes or conduits too large to be brought together in the usual forty two (42) inch diameter manhole or inlet where one or more branch sewers enter a main sewer. Allowances should be made for head loss due to curvature of the paths and due to impact at the converging streams. Losses in a junction chamber for combining large flows shall be minimized by setting flowline elevations so that pipe centerlines (springlines), will be approximately in the same planes. At junction points for combining large storm flows, a manhole with a slotted cover shall be provided. August 1, 2017 DRAFT FOR PUBLIC COMMENT 58 A computation method for determining junction chamber loses is presented below: Hj = y + Vh1 - Vh2 Where: Hj = junction chamber loss (ft.) Vh1 = upstream velocity head Vh2 = downstream velocity head y = change in hydraulic grade line through the junction in feet Where: y = [(Q2V2)-((Q1V1) + {(Q3V3Cos θ3) + (QnVnCosӨn)})] 0.5(A1+A2)g Where: Q2 = Discharge in cubic feet per second (cfs) at the exiting conduit V2 = Velocity in feet per second (fps) at the exiting conduit A2 = Cross sectional area of flow in sq. ft. for the exiting conduit Q1 = Discharge in cfs for the incoming pipe (main flow) V1 = Velocity in fps for the incoming pipe (main flow) A1 = Cross sectional area of flow in Sq. Ft for the incoming pipe (main flow) Q3,Qn = Discharge(s) in cfs for the branch lateral(s) V3,Vn = Velocity(ies) in fps for the branch lateral(s) Ө3, Өn = The angle between the axes of the exiting pipe and the branch laterals(s) g = Acceleration of gravity (32.2 ft/sec/sec) Where: Ө = is the angle between the axes of the outfall and the incoming laterals f. Losses at Junctions of Several Flows in Manholes and/or Inlets The computation of losses in a manhole, inlet or inlet manhole with several flows entering the structure should utilize the principle of the conservation of energy. This involves both the elevation of water surface and momentum (mass times the velocity head). Thus, at a structure (manhole, inlet or inlet manhole) with laterals, the sum of the energy content for inflows is equal to the sum of the energy content of the outflows plus the additional energy required by the turbulence of the flows passing through the structure. August 1, 2017 DRAFT FOR PUBLIC COMMENT 59 DIAGRAM: The upstream hydraulic grade line may be calculated as follows: Hu = [VD2/2g]-[((QU/QD)(l-K)(VU2/2g))+((QL1/QD)(l-K)(VL12/2g)) +((QLN/QD)(l-K)(VLN2/2g))] + HD Where: HU = Upstream hydraulic grade line in feet QU = Upstream main line discharge in cubic feet per second QD = Downstream main line discharge in cubic feet per second QL1-QLN = Lateral discharges in cubic feet per second VU = Upstream main line velocity in feet per second VD = Downstream main line velocity in feet per second VL1-VLN= Lateral velocities in feet per second HD = Downstream hydraulic grade line in feet K = Multiplier of Velocity of Water being turned g = Acceleration of gravity, 32.2 ft/sec/sec The above equation does not apply when two (2) almost equal and opposing flows, each perpendicular to the downstream pipe, meet and no other flows exist in the structure. In this case the head loss is considered as the total velocity head of the downstream discharge. g. Transition Loss The relative importance of the transition loss is dependent on the velocity head of the flow. If the velocity and velocity head of the flow are quite low, the transition losses cannot be very great. However, even small losses may be significant in flat terrain. The sewer design shall provide for the consideration of the necessary transitions and resulting energy losses. The possibility of objectionable deposits is to be considered in the design of transitions. August 1, 2017 DRAFT FOR PUBLIC COMMENT 60 For design purposes it shall be assumed that the energy loss and changes in depth, velocity and invert elevation, if any, occur at the center of the transition. These changes shall be distributed throughout the length of the transition in actual detailing. The designer shall carry the energy head, piezometric head (depth in an open channel), and invert as elevations, and work from the energy grade line. Because of inherent differences in the flow, transitions for closed conduits will be considered separately from those for open channels. (1) Closed Conduits Transitions in small sewers may be confined within a manhole. Special structures may be required for larger sewers. If a sewer is flowing surcharged, the form and friction losses are independent of the invert slope; therefore, the transition may vary at the slopes of the adjacent conduits. The energy loss in a transition shall be expressed as a coefficient multiplied by the change in velocity head (V2/2g) in which V is the change in velocity before and after the transition. The coefficient may vary from zero to one, depending on the design of the transition. If the areas before and after a transition are known, it is often convenient to express the transition loss in terms of the area ratios and either the velocity upstream or downstream. For an expansion: HL = K(V1-V2)2/2g≈[K(V1)2/2g][1-(A1/A2)]2 in which HL is the energy loss; K is a coefficient equal to 1.0 for a sudden expansion and approximately 0.2 for a well-designed transition and the subscripts 1 and 2 denote the upstream and downstream sections, respectively, i.e., A1 = Area Before Transition and A2 = Area After Transition. For a contraction: HL = [K(V2)2/2g][(1/Cc)-1]2≈[K(V2)2/2g][1-(A2/A1)]2 in which K is a coefficient equal to 0.5 for a well-designed transition, Cc is a coefficient of contraction, and the other terms and subscripts are similar to the previous equation. Losses in closed conduits of constant area are expressed in terms of (V2/2g). The above equations may be applied to approximate the energy loss through a manhole for a circular pipe flowing full. If the invert is fully developed, that is, semi-circular on the bottom and vertical on the sides from one-half depth up to the top of the pipe, for the expansion (A1/A2) = 0.88, and for the contraction (A2/A1) = 0.88. The expansion is sudden; therefore, K = 1. The contraction may be rounded if the downstream pipe has a bell or socket. In this case, K may be assumed to be 0.2. The expansion energy loss is 0.0l4 [(V1)2/2g] and the contraction energy loss is 0.010 [(V2)2/2g]. If the invert is fully developed, the manhole loss is small, but if the invert is only developed for one-half of the depth, or not at all, the losses will be of considerable magnitude. August 1, 2017 DRAFT FOR PUBLIC COMMENT 61 (2) Open Channel Transitions The hydraulics of open channel transitions are further complicated by possible changes in depth. As a first approximation to the energy loss, unless a jump occurs, the equations given above may be used with a trial-and-error solution for the unknown area and velocity. The K value for a well-designed expansion should probably be increased to 0.3 or 0.4. Whether the properties of the upstream or downstream section will be known will depend on the characteristics of the flow and the channel, but can be determined by a profile analysis. In transitions for supercritical flow, additional factors shall be considered. Standing waves of considerable magnitude will be produced in transitions. The height of these waves must be estimated to provide a proper channel depth. In addition, in long transitions, air entrainment will cause bulking of the flow with resultant greater depths of the air-water mixture. 4.030.03 Hydraulic Grade Line Limits The hydraulic grade line shall not rise above the following limits as determined by flow quantities calculated per Section 4.030.01. Stormwater conveyance systems are usually designed for 15 year or 20 year, 20 minute rainfall frequencies per 4.030.01.1. 1. The hydraulic grade line at any inlet or storm manhole shall not be higher than two (2) feet below the inlet sill or top of manhole, except where controlled by existing tail water conditions when sufficient overland flow path and ponding protection exist. 2. Storm sewers shall not flow with greater than three (3) feet of surcharged head. 3. The hydraulic grade line for combined sewers shall not rise above the pipe intrados. 4. The beginning point for the hydraulic grade line computations shall be the higher (i.e. more conservative) elevation as determined below: a. For connection to existing pipe system: (1) Top of pipe intrados of at least two reaches downstream of the connection point of the existing system; or (2) The hydraulic grade line computed for the existing system. Note if the downstream system is surcharged, the elevation where flow exits the system should be considered. b. For connection to channels or ditches: (1) Top of pipe intrados of the proposed pipe, or (2) The hydraulic grade line computed for the channel or ditch as approved by the District. c. For upstream system pipe connection to dry and wet detention basins: (1) The starting hydraulic grade line for all incoming pipes shall be the 100 year-24 hour blocked low flow water surface elevation, where County maintained streets are located adjacent to or upstream of the basins. August 1, 2017 DRAFT FOR PUBLIC COMMENT 62 (2) The starting HGL for all other situations may be the 100 year – 24 hour unblocked low flow water surface elevation, unless the local road authority requires something higher. 5. When storm sewers are designed to convey 100 year flows, effusion at low lying inlets is not allowed, unless 100 year ponding easements are so delineated, granted, and recorded. Those associated temporary “ponding” easements however, should not be confused with 100 year overland flow paths, for which no conveyance area easements are presently required. Also, such intentional effusive designs may be prohibited for St. Louis County maintained streets or highways. 4.030.04 Inlets Inlets function entirely as entry points for stormwater flow. They also may be constructed to serve as a manhole on separate stormwater sewers, and are then termed inlet-manholes. Steep gradients may give such low inlet capacities that additional inlets should be located at more favorable grade locations or special inlets designed for steep gradients must be used. Provision must be made to control by-pass flow and to provide additional capacity in the inlet and line affected by such increased flow. Six (6) inch open throat inlets should be used at all times. The open throat should not be obstructed or otherwise restricted by bars, wires or screens. Grated inlets, without an open throat or other provision for overflow shall be avoided except under exceptional conditions, and are prohibited in grade pockets. Any exceptions shall be used only with District approval. Curb inlets shall be placed at street intersections or driveways such that no part of the inlet structure or sump is within the curb rounding. 17.1. Inlets are shown in the Standard Details of Sewer Construction. The minimum depth of a terminal inlet is four (4) feet from the top of the inlet to the flowline of the outlet pipe. Greater depth shall be used for intermediate inlets if necessary for the required depth of the hydraulic grade line. Trapped inlets shall have the depth shown in the Standard Details of Sewer Construction. 2. Inlet capacity should not be less than the quantity flow tributary to the inlet and by- pass flow shall be avoided whenever possible. “Multiple type” inlets, used in the past, had one integral chamber shallower than the other chamber, and tops of different size stones, as well. Use of “multiple type” inlets is prohibited for new construction, as are bars, screens, or wires across inlet openings. Use “double inlets” instead, if necessary for capacity. Bypass, if unavoidable, must be identified, including amount and spread; local road jurisdiction approval must also be provided. Inlets at low points or grade pockets should have extra capacity to compensate for possible flow by-pass of upstream inlets. Figure 4-3 shows inlet capacity/maximum gutter capacity with a given gutter line grade and flow. Inlets angled in opposition to direction of vehicular travel may be dangerous and are to be avoided. 3. Connections to existing structures may require rehabilitation or reconstruction of the structure being utilized. This work will be considered part of the project being proposed. 4. Grated trough drains will not be accepted for dedication to the District. Where appended to the District curb inlet structures, design shall provide clear and workable separation for purposes of maintenance responsibility by others for their part of the drain. August 1, 2017 DRAFT FOR PUBLIC COMMENT 63 4.030.05 Improved Open Channels *NOTE: This section contains some excerpts relating to design and are attributed to Open Channel Hydraulics by Ven Te Chow, a McGraw-Hill work published in 1959. In general, channelizing of natural streams shall be minimized, and shall meet all applicable requirements of the Corps of Engineers. Existing stream/channel fluvial geomorphological conditions shall be evaluated – not only within the project site, but also consideration given to impacts of the proposed improvement to the stream channel and appropriate mitigation counter measures taken as part of the design. All improvedopen channels shall meet the following requirements: 1. Size and Shape ImprovedOpen channels shall not decrease in size in the direction of flow. ImprovedOpen channels shall be vertical walled except in special cases where other approved materials are being considered. 2. Materials Channels may be constructed with reinforced concrete or other approved material. Gabions, articulated mattresses or other systems may be approved. However, the District shall have the right to approve or disapprove any channel material and shall select the appropriate channel material if a proposed material is rejected. Swales shall be sodded unless velocities are excessive (greater than 5 fps or where velocities are less than 2 fps causing deposition of soil particles, then concrete swales may be used. Swales used as BMP’s shall be appropriately vegetated and maintained, or otherwise stabilized in an approved manner. 3. Bedding Special provisions shall be made for channels or paved swales laid over fill on non- supportive soils to support the channel on paved swales. Pipes extended to the channel in a fill area shall have compacted crushed limestone bedding for support. 4. Structural Considerations Provision must be made for all loads on the channel. 5. Alignment ImprovedOpen channel alignments may be limited by available easements, physical topography, existing utilities, buildings, residential development, stormwater detention basins and BMPs, maintenance access and roadways. 6. Locations Storm channel locations are determined primarily by natural drainage conditions. It is also necessary to consider accessibility for construction and maintenance, site availability and competing uses, and evaluating effects of easements on private property. August 1, 2017 DRAFT FOR PUBLIC COMMENT 64 Storm channels shall be located: a. To serve all adjacent property conveniently and to best advantage. b. In easements or rights-of-way dedicated to the District if applicable, as determined by the District. c. In Eeasements to be on common ground when feasible. d. On private property along property lines or immediately adjacent to public streets, avoiding crossings through the property. e. At a sufficient distance from existing and proposed buildings, and underground utilities, or sewers, stormwater detention basins and BMPs to avoid future problems of flooding or erosion. f. To avoid interference between stormwater sewers and house connections to foulwater or sanitary sewers. g. In unpaved or unimproved areas whenever possible. h. Crossing perpendicular to streets, unless unavoidable. 7. Flowline The flowline of improvedopen channels shall meet the following requirements: a. Gradient changes shall be kept to a minimum and be consistent and regular. b. Gradient designations less than the nearest 0.001 foot per foot shall be avoided. c. Channel and swale depths shall be determined primarily by the requirements of the channel size, utility obstructions and any required connections. 8. Other ImprovedOpen Channel Considerations and Requirements a. All natural channels and ditches shall be improved unless otherwise authorized by the District. ba. Drainage within private property should be controlled to prevent damage to the property crossed. Swales, or broad shallow grass lined ditches with non-erosive slopes, are generally located at or near rear lots and along common property lines. New developments shall provide sufficient separation between these features and locations where patios, swimming pools, decks, retaining walls, and other improvements may be constructed by future end users. If a paved gutter is utilized, then appropriate erosion protection shall be used at both ends. cb. Drainage channels and water courses draining through a subdivision may shall be enclosed if the required pipe size does not exceed sixty (60) inches unless a BMP plan is approved which incorporates the channel specifically. Drainage channels originating within a project site are encouraged to be incorporated into the development’s stormwater management plan. When it is undesirable or impractical to enclose a channel with a pipe across a road or street, a suitable bridge or culvert shall be required. August 1, 2017 DRAFT FOR PUBLIC COMMENT 65 dc. For flows greater than 4 cfs, area inlets or inlet manholes are required to intercept the gutter or swale flow unless part of a workable, recognized and approved BMP. ed. All improved concrete channels shall have a forty eight (48) inch chain link fence on each side of the channel, or other protective measures as directed by the District. fe. Improved cChannels and water courses draining large areas shall be located in rights-of-way or easements if applicable, as determined by the District, previously approved by the District as a part of an adequate overall plan for drainage. 9. Design Limitations a. The flow quantity shall be calculated by the method presented in Section 4.030.01 of this manual. b. If the channel is within an area designated in a community's flood insurance study, then the channel shall also meet all District and the community's floodplain requirements. c. Other agencies of jurisdiction, for example FEMA or MoDNR, may have requirements which must be met. A U.S. Army Corps of Engineers permit may be required for any construction affecting a watercourse. 10. Hydraulic Grade Line a. Computation Methods In improvedopen channels the water surface is identical with the hydraulic grade line. The hydraulic grade line shall be computed throughout the channel reach to show its elevation at junctions with incoming pipes or channels and at the ends of the channel reach under consideration. It shall also provide for the losses and differences in elevations as required below. Since it is based on design flow in a given channel, it is of importance in determining minimum sizes within narrow limits. The depth at which the actual flows will occur is controlled by the two end conditions of the reach considered, and by the relationship between the energy available and by the energy required to overcome the losses that are encountered along the channel. There are several methods of calculating "losses" in channel design. The following procedures are presented for the engineer’s information and consideration. It is required that the design recognize the reality of such "losses" occurring and make such allowances as good engineering judgment indicates. (1) Control Sections The engineer should locate all possible control sections for the reach in question. A control section refers to any section at which the depth of flow is known or can be controlled to a required stage. At the control section, flow must pass through a control depth which may be the critical depth, the normal depth or any other known depth. Three types of control sections include (a) Upstream Control Section; (b) Downstream Control Section; (c) Artificial Control Section, which occurs at a control structure, such as a weir, dam, sluice gate, roadway embankment, culvert, bridges or at the confluence with a major river or stream. August 1, 2017 DRAFT FOR PUBLIC COMMENT 66 (2) Friction Loss The friction loss may be calculated by the same procedure as is presented in Section 4.030.02 of this chapter. (3) Flow in Curved Channels The centrifugal force caused by flow around a curve produces a rise in the water surface on the outside wall and a lowering of the inner wall. This phenomenon is called superelevation. The flows tend to behave differently according to the state of flow. In subcritical flow, friction effects are of importance, whereby in supercritical flow, the formation of cross-waves is of major concern. (a) Curve Losses Curve losses may be estimated from Figure 4-2 by replacing D, diameter, with b, width of channel. (b) Superelevations In addition to curve losses, an evaluation of superelevations should be considered and, if required, an allowance made in the top elevation of outside wall. Equations are presented below which may be used to determine the superelevation at channel bends. 1) Trapezoidal Channels Subcritical Flow: ΔHw = 1.15(V2/2grc)[b+D(ZL+ZR)] Supercritical Flow: ΔHw = 2.6(V2/2grc)[b+D(ZL+ZR)] 2) Rectangular Channels Subcritical Flow: ΔHw = (V2b/2grc) Supercritical Flow: ΔHw = (V2b/grc) Where: ΔHw = Change in water height above the centerline water surface elevation. V = Average velocity of design flow in Fps g = Acceleration of gravity (32.2 Ft/Sec/Sec) rc = Radius of curve on horizontal alignment in feet b = Base width of channel in feet D = Depth of flow in straight channel ZL = Left side slope (ft/ft) ZR = Right side slope (ft/ft) August 1, 2017 DRAFT FOR PUBLIC COMMENT 67 (4) Transitions Transitions should be designed to accomplish the required change in cross section with as little flow disturbance as possible. The following features are to be considered in design of transition structures. (a) Proportioning For a well designed transition, the following rules should be used: 1) The optimum maximum angle between the channel axis and a line connecting the channel sides between the entrance and exit sections is 12.5o. 2) Sharp angles in the structure should be avoided. (b) Losses The energy loss in a transition consists of the friction loss and the conversion loss. The friction loss may be estimated by the Manning Formula. The conversion loss is generally expressed in terms of the change in velocity head between the entrance and exit sections of the structure. Ht = Kt ΔVH Where: Ht = Conversion loss Kt = Coefficient of head loss in transition ΔVH = Absolute change in velocity head Average design values for Kt are presented in the table below: Contracting Expanding Type of Transition Section Section Warped 0.10 0.20 Wedge 0.20 0.50 Cylinder-quardrant 0.15 0.25 Straight Line 0.30 0.50 Square End 0.40 0.75 See Figure 4-4 for sketches of each type of transition. (c) Freeboard A transition shall have a minimum of one (1) foot of freeboard above the hydraulic grade line. August 1, 2017 DRAFT FOR PUBLIC COMMENT 68 (d) Hydraulic Jump The existence of a hydraulic jump in a transition may become objectionable, and the design of the transition should be checked for such. (e) Sudden Enlargement and Contraction A sudden enlargement results when an intense shearing action occurs between incoming high-velocity jet and the surrounding water. As a result, much of the Kinetic energy of the jet is dissipated by eddy action. The head loss at a sudden enlargement, HLe, is: HLe = Ke( ΔV2/2g) Where: Ke = Coefficient of head loss for enlargements = 1 ΔV = Change in velocities between incoming and outgoing sections g = Acceleration of gravity (32.2 Ft/Sec/Sec) The flow in a sudden contraction is first contracted and then expanded resulting in high losses as compared to a sudden enlargement. Thus the head loss at a sudden contraction, HLc, is: HLc = Kc( ΔV2/2g) Where: Kc = Coefficient of head loss for contractions = 0.5 ΔV = Change in velocities between incoming and outgoing sections g = Acceleration of gravity, (32.2 Ft/Sec/Sec) (5) Constrictions A constriction results in a sudden reduction in channel cross section. The effect of the constriction on the flow depends mainly on the boundary geometry, the discharge and the state of flow. When the flow is subcritical, the constriction will induce a backwater effect that extends a long distance upstream. If the flow is supercritical, the disturbance is usually local and will only affect the water adjacent to the upstream side of the constriction. A control section may or may not exist at a constriction. The control section, when it exists, may be at either side of the constriction (upstream or downstream), depending on whether the August 1, 2017 DRAFT FOR PUBLIC COMMENT 69 slope of the constricted channel is steep or mild. The entrance and outlet of the constriction then acts as a contraction and an expansion, respectfully. (6) Obstructions An obstruction in open-channel flow creates at least two paths of flow in the channel. Typical obstructions include bridge piers, pile trestles, and trash racks. The flow through an obstruction may be subcritical or supercritical. b. Hydraulic Grade Line Limits (1) The hydraulic grade line at any point along a channel shall not be higher than one (1) foot below the top of the channel wall. (2) The hydraulic grade line at any point along a channel shall not cause the hydraulic grade limits of the storm sewer system to be exceeded as stated in Section 4.030.03 of this manual. 11. Hydraulic Jump When flow changes from the supercritical to subcritical state, a hydraulic jump may occur. A study should be made on the height and location of the jump, and for discharges less than the design discharge, to ensure adequate wall heights extend over the full ranges of discharge. 12. ImprovedOpen Channel Junctions a. General (1) Consideration shall be given in the design of improvedopen channel junctions to the geometry of the confluence of flows in order to minimize undesirable hydraulic effects due to supercritical velocities. b. Confluence Design Criteria (1) The momentum equation can be applied to the confluence design if the below stated criteria is used. (2) The design water-surface elevations in the two joining channels should be approximately equal at the upstream end of the confluence. (3) The angle of the junction intersection can vary from 0-12 degrees. (4) The width of the main channel shall be expanded below the junction to maintain approximate flow depths throughout the junction. (5) Flow depths should not exceed ninety percent (90%) of the critical depth. August 1, 2017 DRAFT FOR PUBLIC COMMENT 70 13. Erosion Protection Properly designed rock blankets, minimum twoone (21) foot thick, shall be required at each end of the improved channel. The minimum length of the rock blanket shall be twenty five (25) feet. A rock toe wall, minimum fourtwo (42) foot deep, shall be constructed at the free end of each blanket. Alternative erosion protection products may be considered, such as articulated block mattresses, etcetera. 14. Sanitary Sewer Crossings The characteristics of any sanitary sewer crossing shall be given consideration in the design of the channel floor. 4.030.06 Culverts The design of culverts shall include consideration of many factors relating to requirements of hydrology, hydraulics, physical environment, imposed exterior loads, construction and maintenance. With the design discharge and general layout requirements determined, the design requires detailed consideration of such hydraulic factors as shape and slope of approach and exit channels, allowable head at entrance (and ponding capacity, if appreciable), tailwater levels, hydraulic and energy gradelines, and erosion potential. 1. Hydraulic Design The hydraulic design of a culvert for a specified design discharge involves (1) selection of a type and size, (2) determination of the position of hydraulic control, and (3) hydraulic computations to determine whether acceptable headwater depths and outfall conditions will result. Hydraulic computations will be carried out by standard methods based on pressure, energy, momentum and loss considerations. 2. Entrances and Headwalls - Outlets and Endwalls Where an existing culvert is to be extended, the possibility for maintaining or improving existing capacity should be investigated. Marked improvement may be obtainable by proper entrance design. All culverts shall be designed for possible extension unless there are extenuating circumstances. 4.040 Bridges Bridges shall be designed to meet the current criteria of the governing agencies. 4.040.01 Waterway Capacity and Backwater Effects Sufficient capacity will be provided to pass the runoff from the design storm determined in accordance with principles given elsewhere in this manual. 4.040.02 Clearance The lowest point of the bridge superstructure shall have a (freeboard) clearance of two (2) feet above design water surface elevation for the 15-year frequency in St. Louis County (20-year frequency in the City of St. Louis) and one (1) foot for the 100-year frequency. August 1, 2017 DRAFT FOR PUBLIC COMMENT 71 4.040.03 Waterway Alignment The bridged waterway will be aligned to result in the least obstruction to stream flow, except that for natural streams consideration will be given to future realignment and improvement of the channel. 4.040.04 Erosion Protection To preclude failure by scouring, abutment and pier footings will usually be placed either to a depth of not less than five (5) feet below the anticipated depth of scour, or on firm rock if such is encountered at a higher elevation. Large multispan structures crossing alluvial streams may require extensive pile foundations. To protect the channel, revetment on channel sides and/or bottom, consisting of concrete or grouted rock blanket should be placed as required. The governing authority should be contacted regarding their design requirements. 4.050 Outlet Erosion Protection If outlet velocities exceed 5 fps, an appropriate erosion protection must be provided. Erosion protection may be required at outlets where velocities are less than 5 fps if soil conditions warrant. For paved channels a cutoff wall will be required at the termini with appropriate protection. The cutoff wall shall extend a minimum depth of fourtwo (42) feet into the existing ground line. 4.060 General Performance Criteria for Stormwater Management for Development and Redevelopment Projects 4.060.01 When Required 1. The requirements of stormwater quantity and quality management shall be evaluated for all projects submitted to the District for review and approval. Stormwater management facilities shall be provided and designed in accordance with the requirements of this section. If another local jurisdiction requires more stringent design standards, then they shall govern in that locale. A Stormwater Management Facilities (BMP) Operation and Maintenance Design Report and Plan, including specific continuing resources, procedures and schedules to be used, shall be submitted for approval. If required and approved, the Plan shall be included in a recorded Maintenance Agreement by reference. 2. Stormwater quality quantity and quantity quality management requirements shall be evaluated for all projects, and specifically, will be required for projects including: a. For MS4 Permit stormwater quality compliance (primarily in the separate storm sewer area); allAll new development and redevelopment projects that disturb greater than or equal to one acre, including projects less than 1 acre that are part of a larger common parcel or project that is greater than one acre. However, existence of downstream stormwater problems may require quantity detention on the proposed site, where less than 2 cfs differential is proposed. b. For stormwater quantity compliance; pProjects which have a differential runoff of 2 cfs or greater for the 15-year, 20-minute event (separate sewer areasin St. Louis County) or for the 20-year, 20 minute event (combined sewer areas). The differential runoff is calculated by the Rational Method using PI factors. For areas tributary to downstream stormwater problems, an undeveloped existing condition shall be assumed for calculating differential runoff, unless directed otherwise by the District. Existence of downstream stormwater problems may require quantity management on the proposed site, even where less than 2 cfs differential is proposed. August 1, 2017 DRAFT FOR PUBLIC COMMENT 72 Subsequent development or redevelopment of sites without prior stormwater detention shall provide detention or retention, when cumulative differential increase, since January 15, 2000, equals 2 cfs or greater. Projects with prior detention shall provide additional detention or retention for increasing runoff irrespective of the 2 cfs threshold. The degree of commonality between subsequent or concurrent projects, sites or parcels within same watershed shall be as determined by the District for purposes of this section. All project plans shall include a note indicating disturbance and runoff differential as follows: Project Disturbance = Acres Project Runoff Differential = CFS Any future land disturbance and/or increase in impervious area on this site may require additional stormwater management per MSD regulations in place at that time (including total land disturbance and/or imperviousness added on this plan). 3. When existing stormwater management facilities are going to be used to accommodate additional site disturbance and/or additional runoff from building or parking lot expansions or subdivision additions, the facilities shall be retrofitted to meet the current stormwater management requirements for the drainage area served by the facility. Projects which cannot meet this requirement due to physical constraints will be evaluated for alternatives on a case by case basis. Managing stormwater per current Regulations for the current proposed disturbance area may be an option. 4. The stormwater design for projects within designated levee districts such as Monarch- Chesterfield, Earth City, Howard Bend, and Riverport will be based on the Stormwater Master Plan for these districts. If the Stormwater Master Plan does not address water quality, the requirements of this manual shall apply. 5. Controls shall be designed and implemented to prevent or minimize water quality impacts by reasonably mimicking pre-construction runoff conditions on all “new development” projects to the maximum extent practicable. (This is a Small MS4 NPDES Stormwater Discharge Permit requirement. It necessitates controls and practices that reduce runoff volume through infiltration, evapotranspiration, and/or rainwater harvesting.) On “redevelopment” sites, controls shall be designed and implemented to prevent or minimize water quality impacts by effectively utilizing water quality strategies and technologies, including those that reduce runoff volume, to the maximum extent practicable. When micro-detention is required in the combined sewer area to address sewer capacity problems, these controls should also apply runoff reducing strategies and technologies. Sites with 20 percent or less existing imperviousness are considered new development for determining if the “mimicking pre-construction runoff conditions” requirement is applicable. Any subsequent or additional development or expansion projects on those sites will also be considered new development. Subdividing does not affect that requirement. 5. Stormwater quality BMPs may include a combination of structural and non-structural BMPs. Before MSD can approve the development plans, MSD must be able to determine from the information provided by the engineer: a. Whether the proposed work is new development or redevelopment. Sites with 20 percent or less existing impervious area are generally considered new development. Any subsequent or additional development or expansion projects on those sites will also be considered new development. Subdividing does not affect this determination. In some instances as determined by the District, the area of development proposed will be evaluated versus existing conditions for that area, to determine whether new development or redevelopment stormwater management criteria will be required. August 1, 2017 DRAFT FOR PUBLIC COMMENT 73 b. Whether there are sensitive areas on the development site that should be protected by BMPs. For all new development projects, the engineer shall prepare an Existing Site Conditions Map to identify sensitive areas and natural resources. This Map shall be based on the current version of the Site Design Guidance found on the MSD website. c. Whether the development plan adequately protects sensitive areas and minimizes the creation of stormwater pollution. The engineer shall prepare a Site Development Plan that adequately protects sensitive areas and natural resources and that does not generate unwarranted amounts of stormwater pollution. This Plan shall be based on the current version of the Site Design Guidance found on the MSD website. d. Whether the development plan utilizes BMPs that effectively remove stormwater pollution. See Section 4.060.05 for a list of acceptable BMPs. BMPs shall be sized to capture the 90th percentile daily rainfall depth or 90 percent of annual rainfall (using continuous simulation modeling). For all new development sites, BMPs shall reasonably mimic pre-development run-off conditions by reducing runoff volume to calculated pre- development levels, to the maximum extent practicable. 6. When stormwater management is required in the combined sewer areas, these controls shall also apply runoff reducing strategies and technologies to the maximum extent practicable. 7. In areas protected by levees and in areas with a high groundwater table, buoyancy shall be considered during design of all components, with appropriate construction techniques utilized as needed. For below ground structures, size the structure with a floatation safety factor of 1.1 minimum. Assume in the floatation calculations that the structure is empty, the top slab is removed, and neglect the weight of any equipment, pipes, or other appurtenances. Additionally, piered footings, spread footings, special pipe bedding, or other techniques may be required to minimize settlement of manholes, sewers, or other structures. A geotechnical assessment may be required. Groundwater elevation and fluctuation shall also be considered when designing stormwater management facilities. A high groundwater table may preclude certain BMP types. 4.060.02 Unified Stormwater Sizing Criteria 1. General This section presents a unified approach for sizing stormwater Best Managements Practices (BMP’s) to meet pollutant removal goals, reduce channel erosion and prevent flooding and pass extreme floods. A very brief summary is listed below. SUMMARY OF THE KEY COMPONENTS AND STORMWATER CRITERIA Water Quality Volume (WQv ) (acre-feet) WQv = [(P)(Rv)(A)]/12 P = rainfall depth in inches and is equal to 1.14 Rv = volumetric runoff coefficient, and A = area in acres Channel Protection Storage Volume (Cpv) Cpv = 24 hour extended detention of post-developed one-year, 24 hour storm event Flood Protection Volume (Qp2 & Qp100) The post-developed routed peak flow from the site may not exceed the existing routed peak flow for the 2-year and 100-year, 24-hour events, or the allowable release rate for differential runoff greater than 5 cfs. For areas tributary to downstream stormwater problems, an undeveloped existing condition shall be assumed for calculating existing routed peak flow, unless a lower release rate is required for the watershed. August 1, 2017 DRAFT FOR PUBLIC COMMENT 74 The following sub-sections provide more expanded information, directories, explanations and resource references. 2. Water Quality Volume (WQv) a. The Water Quality Volume (denoted as the WQv) is the storage needed to capture and treat the runoff from 90% of the recorded daily rainfall events. In numerical terms, it is equivalent to 1.14 inches of rainfall multiplied by the volumetric runoff coefficient (Rv) and BMP tributary site area. The WQv is directly related to the amount of impervious cover created within the tributary area at a site. A minimum WQv of 0.2 inches per acre shall be met at all sites where WQv is required. b. As a basis for determining water quality treatment volume the following assumptions may be made: (1) The following equations are used to determine the storage volume, WQv (in acre- feet of storage): WQv = [(P)(Rv)(A)]/12 P = 1.14 inches of rainfall Where: WQv = water quality volume (in acre-feet) Rv = 0.05 + 0.009 (I) where I is percent impervious cover A = drainage area to BMP in acres (2) Measuring Impervious Cover: The measured area of a site plan that does not have vegetative or permeable cover shall be considered total impervious cover. (3) Multiple Drainage Areas: When a project contains or is divided by multiple drainage areas, the WQv volume shall be addressed for each drainage area. (4) BMP Treatment: The final WQv shall be treated by an acceptable BMP(s) from the list presented in Section 4.0680.05, or as approved by the District. (5) Subtraction for Non-structural Practices: When non-structural practices are employed in the site design, the WQv volume can be reduced in accordance with the conditions outlined in Section 4.0680.06. (6) Extended Detention for Water Quality Volume: The water quality requirements can be met by providing a 24-hour draw down of a portion of the water quality volume (WQv) in conjunction with a stormwater pond or wetland system. Referred to as ED, this is different than providing the extended detention of the one-year storm for the channel protection volume (Cpv). The ED portion of the WQv may be included when routing the Cpv. 3. Channel Protection Storage Volume Requirements (Cpv) a. General To protect channels from erosion, a 24-hour extended detention of the one-year, 24-hour storm event shall be provided. The rationale for this criterion is that runoff will be stored and released in such a gradual manner that critical erosive velocities during bankfull and near-bankfull events will seldom be exceeded or prolonged in downstream channels. A detention pond or underground vault is normally needed to meet the CPv requirement (and subsequent flood protection criteria Qp2 and Qp100). August 1, 2017 DRAFT FOR PUBLIC COMMENT 75 b. As a Basis for determining Channel Protection Storage Volume the following assumptions may be made: 1) The model TR-55 (or approved equivalent) shall be used for determining peak discharge rates. (See 4.060.02 Paragraph 4.b.(1) for additional TR-55 information. (2) The rainfall depth for the one-year, 24-hour storm event is 2.50 inches. Use Type II rainfall distribution. (3) The length of overland flow used in time of concentration (tc) calculations is limited to no more than 100 feet for post project conditions. (4) The 24-hour extended detention is defined as providing a 24-hour detention lag time (T) for the one-year storm. The lag time is defined as the interval between the center of mass of the inflow hydrograph and the center of mass of the outflow hydrograph. (5) A Cpv orifice diameter of less than 3.0” will require a special internal control for orifice protection. For Cpv orifice between 3” and 1 1/2” diameter, an internally controlled orifice shall be used with slot width less than or equal to 1/3 of orifice diameter. Less than 1 ½” orifice will not be allowed. (6) Cpv shall be addressed for the entire site. If a site consists of multiple drainage areas, Cpv may be distributed proportionately to each drainage area. (7) Extended detention storage provided for the Cpv does not fully meet the WQv requirement (that is Cpv and WQv should be treated separately). (8) The stormwater storage needed for WQv Cpv may be nested within the CPv provided above the WQv storage in stormwater ponds, and wetlands, and bioretention basins where applicable; thereby meeting all storage criteria in a single facility with appropriate hydraulic control structures for each storage requirement. (9) Infiltration is not recommended for Cpv control because of large storage requirements. If proven effective, appropriate and desirable however, in some rare situations it may be permissible when integrated within certain volume reduction BMPs. c. Exemptions To protect channels from erosion, a 24-hour extended detention of the one-year, 24-hour storm event shall be required at all sites that do require Flood Volume Detention (Qp). Also, the existence of downstream stormwater problems may require treatment for channel protection (CPv), regardless of any other possible exemptions. At some sites however, the provision of traditional extended detention (Cpv) may not be effective or may be best achieved by other means. Specifically, the following types of sites might may qualify for an exemption to the be exempted from the channel protection storage requirement: A.) For sites 5 acres or larger, exempt if: 1.) No new detention for Flood Protection Volume (Qp) is required, and August 1, 2017 DRAFT FOR PUBLIC COMMENT 76 2.) The project is a redevelopment site (at least 20% of the existing site was impervious coverage as of January 15, 2000) and 3.) The watershed is a less sensitive, i.e. “zero increase” watershed (per Table 4-5). (For release rate watersheds, the District may consider an exemption if there is no new Qp requirement, differential runoff is negative, the site is a redevelopment site and the disturbance occurs in areas that have been disturbed in the past by previous development, and there is an absence of known downstream stormwater problems). And either 4.) or 5.) below 4.) Surface BMP’s are utilized to treat the required WQv and more pervious area is created on the site and within the tributary area. OR 5.) Underground devices are utilized to treat the required WQv but the proposed site will be at least 20% more pervious than the existing site. B.) All sites less than 5 acres with no new Flood Protection Volume (Qp) requirement will normally be exempt. C.) For all sites, regardless of size, with no new Flood Protection Volume (Qp) requirement, exempt if any of the following apply: 1.) The project site will be 100% pervious, and does not increase annual or more frequent discharge from site (for a 1-year event per TR-55). 2.) The project is a redevelopment site (at least 20% of the existing site was impervious coverage as of January 15, 2000) and the project reduces the site impervious area to less than 10% of the total site area. 3.) The project is located within levee district boundaries or within the very flat portions of the FEMA defined flood plain of the Mississippi, Missouri, or Meramec Rivers. 4.) The project is located upstream of permanent lakes, concrete lined channels, or enclosed pipe systems. However, the presence of any intervening reach or downstream, natural channel which does need extended detention channel protection may then nullify this exemption. 4. Flood Protection Volume Requirement (Qp2 & Qp100) a. To protect downstream areas from flooding stormwater shall be detained on site or offsite as approved and released at a rate not to exceed the allowable release rates for the 2-year and 100-year 24-hour events, as determined by the District for the watershed in question. The allowable release rates have been determined by watershed modeling (see Table 4- 5). The engineer has the option to calculate a site specific release rate based on procedures provided by the District's Engineering Department (Volumetric Method). Note that stormwater pipes, downstream from the control structure, shall be sized to carry the runoff from the 15-year 20-minute or 20-year 20-minute (as applicable) design storm for the total tributary upstream watershed. No reduction in outfall pipe size shall be permitted because of detention. August 1, 2017 DRAFT FOR PUBLIC COMMENT 77 b. As a Basis for Determining the Flood Protection Volume the following assumptions may be made. (1) The 2-year and 100-year, 24-hour inflow hydrographs shall be determined by using Technical Release 55 (TR-55), "Urban Hydrology for Small Watersheds" from the Natural Resources Conservation Service, formerly Soil Conservation Service (SCS). The inflow hydrograph shall be developed based on the actual flow and timing characteristics upstream of the detention facility. The rainfall distribution shall be Type II. The rainfall quantities to be used are from Illinois State Water Survey Bulletin 71, and shall be as follows: 3.1” for the 2-year, 24- hour storm and 7.2” for the 100-year, 24-hour storm. (2) The volume of detention may be provided through permanent detention facilities such as dry basins or ponds, permanent ponds or lakes, underground storage facilities or in parking lots. It is noted that when runoff volume reduction BMPs are utilized within the tributary area upstream of a flood volume detention basin, the quantified runoff reduction may be used to adjust tributary area TR55 Curve Numbers (CN) for detention basin sizing. The engineer shall make every effort to locate the detention facility at or near the lowest point of the project such that all of the on-site runoff will be directed into the detention facility. Multiple use of detention basins is encouraged. Multiple use may include parking lots, ball fields, tennis courts, play grounds and picnic areas. This is subject to the approval of the District. Flows from offsite, upstream areas should be bypassed around the detention facility to ensure that the proposed detention facility will function as designed and will provide effective control of downstream flows with development in place. If offsite flows are directed into a detention facility, the allowable release rates shall not be modified without District approval. Modifying the release rate to accommodate offsite flows may reduce or eliminate the effectiveness of the detention facility, because it will no longer control the increased volume of runoff during the critical time period of the watershed. As stated in Item 4.a above, the engineer has the option to calculate a site specific release rate based on procedures provided by the District's Engineering Department. The engineer shall provide detailed modeling to prove that the increase in runoff volume has been limited to existing conditions during the critical time period of the watershed (For Volumetric Method see Chapter 14). Appendix –forthcoming). (3) Detention basin volume will be based on routing the post-developed 2-year and 100 year, 24-hour inflow hydrographs through the detention facility while satisfying the appropriate allowable release rate. The routing computations shall be based on an application of the continuity principle, (i.e., level pool routing). Municipalities or St. Louis County may by ordinances, have other volume requirements. The more stringent volume requirements will govern. 4.060.03 Limits of Maximum Ponding in Stormwater Ponds 1. The maximum ponding elevation shall be calculated based on a routing of the design storm (100-year, 24-hour event) assuming the low flow and any intermediate flow openings are fully outlet is blocked with water ponded to the overflow structure’s sill, unless directed otherwise by the District. August 1, 2017 DRAFT FOR PUBLIC COMMENT 78 2. The limits of maximum ponding in dry basins or ponds and permanent lakes or ponds shall not be closer than thirty (30) feet horizontally to any building, and not less than two (2) feet vertically below the lowest sill elevation of any building. 3. The limits of maximum ponding in parking lots shall not be closer than ten (10) feet horizontally from any building and not less than (1) foot vertically below the lowest sill elevation of any building. 4. A minimum of one (1) foot of freeboard shall be provided from the top of the basin to the maximum ponding elevation. 5. Micro-Detention will be looked at case by case but in general the following apply: a. 12” Freeboard Requirement Exceptions allowed: (Freeboard 6” or less) (1) Upper terraces of multiple in-line detention basin(s). (2) If the basin’s outfall is directed onto a natural water way with no downstream property to be impacted. This could be obtained by providing swales and/or using existing swales that are around the downstream perimeter of the site and which direct flows to natural waterways or property with no future build out possibilities (6” freeboard still preferred). b. Other Exceptions: 30’ Requirement for Horizontal Distance from HW Elevation •1) If the basin is very shallow 2) If the basin’s H.W. elevation is 2’ below the low sill of building 3) Elements of the basin’s design mitigate the potential for seepage against adjacent structures and properties. It is recommended that additional construction and grading notes be put on the plans, as well as a landscape schedule of plantings. Grading tolerances should be kept at + 0.1 and as-builts provided. Infiltration rates should be accurate for basins without outfall structure. Copy of maintenance and operations notes should be included on the plans. 4.060.04 General Stormwater Basin Design Requirements 1. Underground Basins’ Special Requirements: a. Adequate access for basin maintenance and inspection shall be provided. A means of visual inspection from the ground surface of the low flow device, overflow weir, and outlet structure is necessary. Access shall also be provided to allow for cleaning of the low flow device from the ground surface. b. The basin should have sufficient volume and spillway capacity to pass/contain the 100-year 24-hour event with the low flow outlet blocked. In some situations it may be desirable to have control structures with at least 2 outlet openings, one above the other. c. Underground basins shall be acceptable for non-residential projects only, except by special municipal request, cooperation and a lack of other technical options. (See also sub-section 4.080.05.1.c also). August 1, 2017 DRAFT FOR PUBLIC COMMENT 79 d. Acceptable materials for underground basins are poured in place reinforced concrete, RCP, HDPE, HDPP, and aluminized CMP. The CMP gauge shall be approved by the District prior to installation. Restricted use of other systems may be allowed in the future. e. Provide immediate manhole access from ground surface for both sides of the low flow device. Also provide a manhole at upstream end of underground basins, for access, inspection, to facilitate maintenance and air release. f. Adequate flowline spot elevations, sections and profiles including pipe length and slope shall be labeled to define basin and pipe geometry. 2. General Detention Report Requirements For detention facilities in general, the Engineer must submit 2 copies of a report sealed by a Missouri Registered Professional Engineer containing the following for review of the detention facility: (see 4.100 also) a. Elevation vs Discharge tables or curves for all frequencies. b. Elevation vs Storage tables or curves for all frequencies. c. Inflow calculations and data for all frequencies. d. Hydraulic gradeline computations for pipes entering and leaving the basin for all frequencies. e. If the embankment contains fill material a geotechnical report may be required. f. Site plan showing appropriate design information. g. Structural calculations for the outlet control structures (if required). h. Cross sections defining the size, shape and depth of the detention basin shall be required. At a minimum, three sections, one at each end and one in the middle of the basin will be required. 3. All ends of pipes discharging into a dry basin or pond shall be connected with the low flow pipe or control structure, by means of a permeable swale. The swale shall a minimum 4:1 lateral (25%) slope to the center and a minimum 2.0% longitudinal slope to ensure positive drainage. Swales shall be a minimum of six (6) inches deep and four (4) feet wide or 1.3 times the diameter of the pipe entering the basin, whichever is greater. . The bottom of the basin shall be sloped a minimum of two percent (2%). towards the edge of the swale. No concrete swales will be allowed unless approved by the District. Permanent erosion control protection must be provided at the ends of discharging pipes. Lengths of the swale in which the velocity exceeds 2 feet per second analyzed by the 15 year –20 minute storm event, shall have appropriate permanent erosion control protection. Aggregate, porous concrete blocks or appropriate vegetation are required, unless otherwise approved. 4. Where retaining walls are proposed to support an embankment, design elements shall be used to protect the basin from failure, and also to protect against nuisance to downgradient properties due to seepage or hydrostatic pressure under its ponding conditions. Such design elements shall be supported by recommendations by a Geotechnical Engineer. August 1, 2017 DRAFT FOR PUBLIC COMMENT 80 5. Railroad tie walls cannot be used where water will be in contact with the railroad tie wall. 6. Permanent detention ponds or lakes are to be designed to minimize fluctuating lake levels. Maximum fluctuation from the permanent pool elevation to the maximum ponding elevation shall be six (6) feet. 7. The maximum side slopes for dry basins or ponds, and the fluctuating area of permanent ponds or lakes shall be 3:1 (three feet horizontal, one foot vertical) without fencing. 8. Dry basins or ponds and the fluctuating areas of permanent ponds or lakes are to be appropriately vegetated to the maximum high water elevation. . Areas above that elevation shall be appropriately stabilized and vegetated. Sod and mowing above that elevation may be approved and is required for dam embankment slopes and downstream toe areas for wet basins where riprap is not appropriate. 9. Control structures and overflow structures are to be reinforced concrete, including precast. Only for underground proprietary or aluminized CMP basins may other approved materials be allowed. 10. The outflow pipe shall be sized for the fully developed flow rate. This is the 15-year 20- minute flow or 20-year 20 minute flow as applicable. Flow rate calculated shall assume no effect from detention or other stormwater management measures (i.e. the undetained flow). Overland flow path criteria must also be considered. 11. In basins with concrete walls or rip rap covered slopes, provisions should be made for mowing equipment to reach the bottom (ramps, etc.). 12. Maximum Depths: a. The maximum depth of water in a dry detention basin or pond shall not exceed eight (8) feet. Projects which need a deeper basin to attain the required detention volume due to physical constraints may be evaluated on a case by case basis. The design and construction of dams greater than eight (8) feet or as directed by the District must be sealed and certified by a Professional Engineer registered in the State of Missouri with demonstrated expertise in geotechnical engineering. b. Parking lots used for automobiles shall have a maximum depth of eight (8) inches of water. c. Parking lots used for trucks or truck trailers shall have a maximum depth of water of twelve (12) inches. 13. Detention Basin Fencing A four (4) foot (minimum height) approved fence shall be provided around the perimeter of any basin where the side slopes exceed 3:1 (three (3) feet horizontal, one (1) foot vertical). Fencing such as post and rail, or fencing which prevents easy observation of required detention basin maintenance, such as tall privacy fencing, should not be used. 14. Detention Basin Elevation If the detention basin discharges to a piped sewer system, the low elevation of the detention basin shall be above the 15-year, 20-minute hydraulic elevation of the receiving storm system, or the 20 year, 20 minute hydraulic elevation of the receiving August 1, 2017 DRAFT FOR PUBLIC COMMENT 81 combined systems, as applicable. Basin backflow contamination must be prevented, if the downstream combined system is known to surcharge. 15. If the detention basin discharges to an open channel, or to a piped sewer system affected by flood levels in a nearby downstream open channel, then the low elevation of the basin is desirable to be above the 100-year flood elevation in the open channel as established by the FEMA Flood Insurance Study or the District SSMIP, whichever is greater. 16. In all cases mentioned above, if the low elevation of the basin is below the receiving system hydraulic grade or channel flood elevation, then the basin shall be sized to store the entire design storm volume, unless directed otherwise by the District. 17. The District may consider waiving the flood volume detention requirement (Qp) if a site is directly tributary to a major river (Mississippi, Missouri, or Meramec) and there are no other properties located between the proposed development and the river itself. 4.060.05 Acceptable Urban BMP Options This section sets forth five acceptable groups of BMPs that can be used to meet the Water Quality volume criteria (WQv). The design and selection of these BMPs shall comply with the Maryland Stormwater Design Manual, Volumes I & II (October 2000; effective date July 1, 2001), as prepared by the Center For Watershed Protection and the State of Maryland Department of the Environment (MDE). Where the District criteria or requirements are more stringent, then they shall govern. Adaption to local Missouri environment and natural conditions should be expected but shall be as approved by the District or a higher authority. The Manual can be obtainedpurchased through MDE’s website. A simple search for Maryland Stormwater Design Manual will provide a direct link. The acceptable BMP designs are assigned into five general categories for stormwater quality control (WQv): BMP Group 1 stormwater ponds BMP Group 2 stormwater wetlands BMP Group 3 volume reduction infiltration practices BMP Group 4 filtering practices BMP Group 5 open channel practices To be considered an effective BMP for stand-alone treatment of WQv, a design shall be capable of: 1. capturing and treating the required water quality volume (WQv) 2. removing 80% of the TSS, and 3. having an acceptable longevity rate in the field A combination of BMPs and/or credits is normally required at most development sites to meet all three stormwater sizing criteria. NOTE: Groundwater sump pump discharge may be problematic if directed towards storm water BMPs. In general this practice should be avoided unless otherwise allowed by the District. August 1, 2017 DRAFT FOR PUBLIC COMMENT 82 1. BMP Group 1. Stormwater Ponds a. Practices that have a combination of permanent pool, extended detention or shallow wetland equivalent to the entire WQvs include: P-1 micropool extended detention pond P-2 wet pond P-3 wet extended detention pond P-4 multiple pond system P-5 pocket pond 2. BMP Group 2. Stormwater Wetlands a. Practices that include significant shallow wetland areas to treat urban stormwater but often may also incorporate small permanent pools and/or extended detention storage to achieve the full WQv include (Modification of existing wetland areas will require a CWA 404/401 permit: W-1 shallow wetland W-2 ED shallow wetland W-3 pond/wetland system W-4 pocket wetland b. U.S. Army C.O.E. Jurisdictional Wetlands shall not be used for control of water quantity (i.e. the flood protection volume 3. BMP Group 3. Volume Reduction Infiltration Practices a. Practices that capture and temporarily store the WQv before allowing it to infiltrate into the soil over a continuous two day period and/or evaporate, evapotranspire, or be reused, includinge: bioretention/rain gardens permeable pavement amended soils rainwater harvesting systems combination treatment & infiltration practices I-1 infiltration trench I-2 infiltration basin b. Infiltration practices will be allowed on sites where it is proven that infiltration will work. This must be supported by a soils report and geotechnical investigation. The use of infiltration practices in fill areas is discouraged and may not be allowed. c. Consideration must be given to downgradient properties and potential for seepage, water table fluctuations, or other nuisance concerns August 1, 2017 DRAFT FOR PUBLIC COMMENT 83 4. BMP Group 4. Filtering Practices a. Practices that capture and temporarily store the WQv and pass it through a filter bed of sand, organic matter, soil or other media are considered to be filtering practices. Filtered runoff may be collected and returned to the conveyance system. Design variants include: F-1 surface sand filter F-2 underground sand filter F-3 perimeter sand filter F-4 organic filter F-5 pocket sand filter F-6 bioretention* F-7 proprietary filtering system *may also be used for volume reductioninfiltration 5. BMP Group 5. Open Channel Practices a. Vegetated open channels that are explicitly designed to capture and treat the full WQv within the dry or wet cells formed by check dams or other means include: O-1 dry swale O-2 wet swale O-3 filter strips b. Open channel practices shall be designed with the proper plantings. They are not allowed on single-family residential projects. They may be allowed on condominium or apartment projects if maintenance is provided by a management company. c. Wet swales shall be designed to drain out over time. 4.060.06 Stormwater Credits Non-Structural BMPs are increasingly recognized as a critical feature of stormwater BMP plans, particularly with respect to site design. In most cases, non-structural BMPs shall be combined with structural BMPs to meet all stormwater requirements. The key benefit on non-structural BMP is that they can reduce the generation of stormwater from site; thereby reducing the size and cost of structural BMPs. In addition, they can provide partial removal of many pollutants. The non-structural BMPs have been classified into seven broad categories. To promote greater use of non-structural BMPs, a series of credits and incentives are provided for developments that use these progressive site planning techniques. Further details can be found in Chapter 5 of the Maryland Stormwater Design Manual, Volumes I & II (October 2000). 12.• natural area conservation 13.• disconnection of rooftop runoff 14.• disconnection of non-rooftop impervious area 15.• reserved buffers 16.• open channel use/grass channel credit 17.• environmentally sensitive development 18.• impervious cover reduction 4.060.07 Easement Required In subdivisions, the detention basin, BMP’s, access roads or paths, control structures, and outfall pipes are to be located in easements dedicated to the subdivision trustees. Lack of appropriate easement(s) will August 1, 2017 DRAFT FOR PUBLIC COMMENT 84 not relieve trustees of responsibility for required maintenance of the Stormwater Management System BMP’s. 4.060.08 Maintenance Agreement Prior to plan approval the property owner(s) of the stormwater management Detention Basin site(s) shall execute a District Maintenance Agreement for the urban BMPs and the detention basin or pond to insure the urban BMPs and the detention area will be kept in working order, to the satisfaction of the District. The District will not be responsible for maintenance of detention basins or BMPs. Annual trustee or non-residential Property Owner’s certification and reporting of performance of required maintenance, operation and repairs shall commence upon MSD Construction Approval of BMPs/detention facilities; final closeout of the subdivision or project SWPPP; or as otherwise specified. The annual report will be required for those projects where the recorded Maintenance Agreement requires the reporting directly or by reference included in the Agreement (see Sub-section 4.0680.01 Item 1. regarding need for BMP Maintenance Plan). The annual report shall be submitted to the Metropolitan St. Louis Sewer District – Division of Environmental Compliance, c/o Phase II Stormwater Management Program, 10 E. Grand Avenue, St. Louis, MO 63147 Engineering Department, Design Division, Development Review at 2350 Market St., St. Louis MO, 63103 (return receipt requested). 4.070 Dam Permit Requirements Dams with a height of thirty five (35) feet or greater will require approval from the Missouri Department of Natural Resources. 4.080 Detention Report 1. A Detention Report shall be submitted. 2. The Detention Report shall contain a complete table of contents and a summary. 3. The Detention Report shall be signed, dated and sealed by the Missouri Professional Engineer who is responsible for its preparation. If the report is prepared by another person, a note on the cover shall state the preparer’s name and that he or she is under the direct supervision of the Missouri Professional Engineer whose seal is shown. 4. The Detention Report shall be in a binder, not loose leaf. 5. The engineer shall submit two copies of the Detention Report. 6. A copy of tThe current “Checklist for Review of Storm Water Detention” shall be completed by the design engineer and submitted with the reports. The checklist is shown on Exhibit 4-A hereinafter, or on the website if updated in the future. August 1, 2017 DRAFT FOR PUBLIC COMMENT 85 EXHIBIT 4-A Check List for Review of Stormwater Detention The following check list is intended to provide guidance in reviewing detention designs. It is not intended to supersede any criteria stated in the latest version of the District’s “Rules and Regulations and Engineering Design Requirements for Sanitary Sewage and Stormwater Drainage Facilities” the District P-No Project Name: Location: 1. Check planning maps for downstream problems. 2. Check SSMIP report for downstream problems. 3. Detention required if differential runoff, per 4.060.01.2(b), is greater than 2 cfs, or if required by the District due to flooding problems. 4. If differential runoff is greater than 5 cfs, use watershed release rates if applicable (see release rate table, figure 4-5) _______ 5. For building and parking lot additions, detention is required if there is existing detention. Check existing calculations to see if addition is covered. 6. No reduction in outfall pipe size permitted because of detention. 7. Basin located at or near lowest point of site such that on-site runoff will be directed to basin. 8. Offsite flows bypassed around basin. _______ 9. If site specific release rate is used (volumetric procedure), no increase in runoff volume during the critical time period of the watershed. 10. Underground basin has adequate access for maintenance. 11. Provide means of visual inspection of both sides of low flow device from ground surface for underground basin. 12. Underground basin has volume and spillway capacity to pass/contain 100-year, 24-hour event with low and intermediate flow openings fully blocked and water ponded to sill of overflow structure, unless directed otherwise by the District. It is further recommended that the control structure have at least 2 openings, one above the other. 13. Check flow capacity of downstream pipe with inlet control nomographs found in Hydraulic Design of Highway Culverts, U.S. Department of Transportation publication. _______ 14. Check inlet control constants as entered in the analysis to match the Hydraulic Design of Highway Culverts per US Department of Transportation. August 1, 2017 DRAFT FOR PUBLIC COMMENT 86 15. Aluminized corrugated metal pipe (CMP) allowed for commercial projects only, gauge specified. 16. No underground basins allowed for residential projects, except by special municipal request, cooperation and a technical lack of other options. _______ 17. TR-55 or similar SCS method used for hydrology; Type II rainfall distribution. 100 foot maximum distance for sheet flow component of time of concentration. Also be sure to use proper n-value from TR-55 Table 3-1 for sheet flow component. 18. 2-year and 100-year, 24-hour rainfall amounts of 3.1” and 7.2”, respectively. _______ 19. Legible Detention Basin Area maps showing total acres tributary to each point of interest, flow paths used in time of concentration calculations with each flow segment indicated and labeled, and CN values for existing and proposed conditions, 24” X 36” exhibits are preferred, (Existing Conditions Map is not applicable to a “Fixed” Release Rate Analysis). _______ 20. CNs for vegetated areas located within the post-construction disturbance limits shall be assumed to be hydrologic soil group D during modeling of post-construction conditions, unless soil amendments are used. 21. Elevations vs. Discharge table, including modeling data. 22. Elevation vs. Storage table. 23. Hydraulic gradeline calculations for incoming and outgoing pipes. 24. Provide a copy of the NRCS web soil survey SCS soils map and label site. 25. Geotechnical report may be required for embankment. 26. Structural calculations may be required for control structure. 27. Details of control structure showing reinforcing. _______ 28. Minimum of 3 cross sections through basin for as-built calculations tied to a baseline or known point or to Property Line. 29. Incoming pipes should discharge at the toe of the slope in dry basins. 30. Pervious pilot swale provided from incoming pipes to control structure. 31. Pervious pilot swale is a minimum of 6 inches deep. 32. Details for permanent erosion control for earthen swales with slopes greater than 3%. 33. Minimum longitudinal slope of pilot earthen swale is 2.0%, slope called out on plan. 34. Bottom of basin is sloped a minimum of 2% laterally towards earthen swale and called out on plan. 35. Rock blanket provided along outside of curved swale downstream of incoming pipe to prevent erosion. 36. Concrete headwall provided around protruding low flow pipe. 37. Trash rack provided for low flow openings less than 6” wide. 38. No railroad tie walls within ponding area of basin. August 1, 2017 DRAFT FOR PUBLIC COMMENT 87 39. Maximum fluctuation above permanent pool is 6’. 40. Maximum side slopes are 3:1 without fencing. _______ 41. Dry basins and the fluctuating areas of lakes are to be appropriately vegetated to the maximum high water elevation, call out on plan. Sod and mowing may be approved above that level and on dam slopes (required, if not riprapped). _______ 42. Control structures are to be reinforced concrete; no brick allowed; wall thickness is at least 8” w/one row of steel or 10” w/two rows of steel. 43. In basins with walls, provide access ramp. 44. No wetland mitigation in detention basin. 45. Maximum depth of water in a dry basin is 8’ exceptions on a case-by-case basis. 46. Maximum depth of water in a parking lot is 8”, 12” for truck parking lots. ________ 47. Maximum ponding elevation calculated with low and intermediate flow openings fully blocked and water ponded to sill of overflow structure, unless directed otherwise by the District. _______ 48. Limits of maximum ponding are 30’ horizontally and 2’ vertically from a building; 10’ horizontally and 1’ vertically for parking lot detention. 49. Freeboard from top of berm to maximum ponding elevation is at least 1’. 50. Basin is located in common ground or easement dedicated to subdivision trustees. 51. Owners of the basin execute a District Maintenance Agreement. 52. Four foot high fence required if side slopes are steeper than 3:1, including walls. 53. Low elevation of basin is above 15-yr 20-min or 20-yr 20-min (as applicable) hydraulic elevation of receiving system; or detain per section 4.060.04.14, 15 and 16 whole storm and provide a backflow preventer (Tideflex) normally installed inside of the outfall structure. 54. Dams with a height of 35’ or greater require MDNR approval. _______ 55. Hydraulic calculations showing 100-year flow is conveyed to basin; calculations at ditch sections, sills of structures set above 100-yr elevation. _______ 56. Smallest low flow opening is 1.5” diameter. 3” diameter or 4” x 2” slot. However, special trashrack or opening protection may be required. _______ 57. Detention cannot cross watershed boundary. Watershed and sub-watershed tributary areas to each point of interest shall remain unchanged when comparing existing and proposed conditions. 58. Discharge pipe into wet basin shall be a minimum of 3’ above bottom, or flowline of pipe shall be no higher than the normal pool elevation. 59. The report shall have a Table of Contents which is sealed by a Missouri Professional Engineer. 60. The report shall containhas a Table of Contents, a a written summary describing the existing and proposed conditions and the design/modeling approach used to manage stormwater. All calculations shall be included. Hard copies shall beand is bound. August 1, 2017 DRAFT FOR PUBLIC COMMENT 88 _______ 61. The starting hydraulic grade line for all incoming pipes shall be the 100 year – 24 hour blocked low flow water surface elevation, or an elevation approved by the District. _______ 62. For some channel and wetlands work, a 404 and/or 401 permit may be required from the Corps and MoDNR, respectively. August 1, 2017 DRAFT FOR PUBLIC COMMENT 89 August 1, 2017 DRAFT FOR PUBLIC COMMENT 90 August 1, 2017 DRAFT FOR PUBLIC COMMENT 91 August 1, 2017 DRAFT FOR PUBLIC COMMENT 92 August 1, 2017 DRAFT FOR PUBLIC COMMENT 93 TABLE 4-5 WATERSHED RELEASE RATES FOR DESIGN OF ROUTED DETENTION FACILITIES FOR DEVELOPMENTS WITH A POST-DEVELOPMENT DIFFERENTIAL RUNOFF GREATER THAN 5 CFS* Note: *Differential runoff based on the 15-year, 20 minute storm or 20-year, 20 minute storm, as applicable. See “Rules and Regulations and Engineering Design Requirements for Sanitary Sewage and Stormwater Drainage Facilities”, Chapter 4, Section 4.0680.012. Differential runoff of 5 cfs or less, use “Zero Increase” for all watersheds and both routing frequencies. **Projects which have any increase in differential runoff in the Harlem & Baden watersheds, Grand & Bates sewershed, and other sewersheds as may be directed by the District will have stormwater management requirements as shown in items A.) through D.) as follows: WATERSHED FINAL ROUTED RELEASE RATE 100-YEAR 24 HOUR STORM FINAL ROUTED RELEASE RATE 2-YEAR 24 HOUR STORM VOLUMETRIC METHOD CRITICAL TIME PERIOD OF WATERSHED Baden ** Zero Increase Zero Increase NA Bonfils (Cowmire) 1.0 cfs/acre 0.4 cfs/acre Hour 12.0-14.0 Bonhomme 1.8 cfs/acre 0.25 cfs/acre Hour 12.0-15.5 Caulks 1.4 cfs/acre 0.2 cfs/acre Hour 12.0-14.0 Coldwater Zero Increase Zero Increase NA Creve Coeur 1.2 cfs/acre 0.13 cfs/acre Hour 12.0-17.2 Deer Zero Increase Zero Increase NA Dunn 1.0 cfs/acre 0.4 cfs/acre Hour 12.0-13.0 Fee Fee 1.3 cfs/acre 0.15 cfs/acre Hour 12.0-14.1 Fenton Zero Increase Zero Increase NA Fishpot 1.5 cfs/acre 0.3 cfs/acre Hour 12.0-14.7 Grand Glaize Zero Increase Zero Increase NA Gravois Zero Increase Zero Increase NA Harlem ** Zero Increase Zero Increase NA Kiefer 2.2 cfs/acre 0.7 cfs/acre Hour 12.0-13.0 Maline Zero Increase Zero Increase NA Martigney Zero Increase Zero Increase NA Mattese Zero Increase Zero Increase NA Mill 1.5 cfs/acre .13 cfs/acre Hour 11.5-15.5 River Des Peres Zero Increase Zero Increase NA Spanish Lake 1.0 cfs/acre 0.37 cfs/acre Hour 11.0-16.0 University City Zero Increase Zero Increase NA Watkins Zero Increase Zero Increase NA Williams 0.7 cfs/acre 0.2 cfs/acre Hour 12.0-15.1 Yarnell 1.3 cfs/acre 0.3 cfs/acre Hour 12.0-14.0 August 1, 2017 DRAFT FOR PUBLIC COMMENT 94 STORMWATER MANAGEMENT REQUIREMENTS FOR HARLEM AND BADEN WATERSHEDS AND OTHER WATERSHEDS AS DIRECTED BY THE DISTRICT A.) For project differential increase 0 to < 2 cfs: Volume reduction type BMPs sized for 75% of the 90th % rainfall 1.14” WQv calculation as shown in 4.0680.02.2.b(1). In general, the minimum amount of tributary impervious area to be treated by the BMPs shall be the acreage of added impervious area. The BMPs shall be designed to capture 75% of the WQv from the total drainage area tributary to the BMP. The BMP shall be designed to drain down completely in 2 days. The BMP overflow path shall be designed for the 100-year, 20- minute storm. For an example, see MSD website BMP toolkit. In some situations when project differential increase is less than 2 cfs, design of stormwater management facilities may be required to meet section B.) below, as directed by the District. Some examples include: where multiple stormwater outfalls exist for a single project, where a project is built in several phases, when downstream stormwater problems exist, or when a site has a previous detention or other stormwater management requirement. B.) For project differential increase 2 cfs or >: TR55 analysis for 2-year and 100-year events, with level pool routing to meet release rates as specified in Table 4-5. Volume reduction techniques shall be incorporated into the detention design to the maximum extent practicable. C.) In the case of new directly sewer connected roof area replacing existing pavement area, MSD will evaluate these on a case-by-case basis. D.) For all cases, where localized downstream flooding or localized downstream sewer surcharging occurs, differential runoff calculations and detention routings shall be computed from a completely undeveloped condition as directed by the District. August 1, 2017 DRAFT FOR PUBLIC COMMENT 95 Based on HYDRO-35 and TP-40 August 1, 2017 DRAFT FOR PUBLIC COMMENT 96 August 1, 2017 DRAFT FOR PUBLIC COMMENT 97 August 1, 2017 DRAFT FOR PUBLIC COMMENT 98 August 1, 2017 DRAFT FOR PUBLIC COMMENT 99 5. FLOOD PLAIN REQUIREMENTS 5.010 Flood Plain Study/100 – Year Hydraulic Study 5.010.01 When Required 1. A flood plain study will be required for all tracts or parcels of ground located in the 100-year flood plain shown on the current Federal Emergency Management Agency's (FEMA) Flood Boundary and Floodway Map. In incorporated areas, a letter will be required from the municipality stating that the project is in compliance with the municipality’s flood plain ordinance. 2. A 100 – year hydraulic study will be required for any watercourse, not identified by FEMA, for which the 15-year, 20-minute design storm exceeds the capacity of a (60) inch diameter sewer. 3. A flood plain study/100 – year hydraulic study will be required when development of any type, i.e., new construction, additions to existing facilities, rehabilitation of existing facilities, or site grading is planned within an area subject to 100-year flooding. 5.010.02 Criteria For Preparation 1. The flood plain study /100 – year hydraulic study shall be submitted by a Professional Engineer, registered in the State of Missouri. Each page of tThe study shall be signed and sealed. a. All assumptions shall be clearly stated in the report. The modeling process, review of existing data, necessary background, purpose, flooding potential of the existing land, existing or previous studies, existing computer model input and output, proposed conditions computer model input and output, 100-year and 15-year water surface elevations, cross-sections and profiles should all be included in the report. An electronic copy of the models shall be submitted on a disk. b. Sufficient information shall be submitted to verify that the project is in compliance with the municipality’s flood plain ordinance. Sufficient hydraulic computations shall be submitted for review to verify the 100-year and 15-year water surface elevations with the proposed development in place. The computations should also verify that the conveyance characteristics of the water course are not restricted by the proposed development when compared with the pre-developed conditions. 2.c. Flood plain elevations and design of bridges and culverts will be reviewed by the District using the flow and elevation numbers that provide the most protection to the public. The FEMA flow/elevation will be used for those instances where these values will provide the most protection for the residents and public since that is the official guide. However, since the FEMA numbers were developed based on an empirical equation representing all the St. Louis area and upon existing conditions at the time of the FEMA modeling (late 70’s and early 80’s generally) they may not accurately reflect the current situation and knowledge. The Stormwater System Master Improvement Plans (SSMIP) contain more current information based upon SWMM modeling having been performed during the 1995-1999 time period and are based upon actual gauged or measured rainfall/runoff to calibrate the model. Consequently, the SWMM flow/elevation numbers in several instances provide a better estimate of actual current conditions within the watersheds. Therefore, the District will use the more conservative flow/elevation values for each location (either August 1, 2017 DRAFT FOR PUBLIC COMMENT 100 FEMA or SWMM depending on which provides the most conservative value) on all review of future projects. 1.2. A St. Louis County Department of Transportation A Metropolitan St. Louis Sewer District bench mark and U.S.G.S. datum shall be referenced and shown on the study with reference made to the on-site temporary bench mark. 3. The study shall determine the 100-year high water elevation through the site using the elevations obtained from the most recently published Federal Emergency Management Agency Flood Insurance Study or, if more conservative, from the District’s SSMIP watershed studies. 4. The method used to determine the water surface elevation shall be dependent on the stream characteristics. a. FEMA Streams For streams for which a detailed Flood Insurance Study has been performed by FEMA, the water surface elevation shall be computed by the same method as used in the FEMA Flood Insurance Study. b. Non-FEMA Streams The method used to determine the water surface elevation for streams for which a hydraulic model has not been developed by FEMA, shall depend on the conveyance characteristics of the stream. For generally prismatic streams with a mild, constant slope, the water surface elevation shall be computed using the direct-step method. For non-prismatic streams with varying channel shape or slopes, the standard- step method shall be used. Both the direct-step and standard-step methods are described in detail in Open Channel Hydraulics by Ven Te Chow, a McGraw-Hill work published in 1959. 7.5. The determination of a starting water surface elevation used in the hydraulic computations must be stated in the study. The high water elevations shall be checked against data showing downstream influences, such as culvert restrictions and/or flood elevations of larger streams or rivers. The downstream and upstream study limits shall be measured from the most downstream and upstream edges of the development. The hydraulic computations shall extend a minimum of one hundred (100) feet beyond the edges of the development. cross section where the post and pre-development water surface elevations are coincident. There may be situations where the post and pre- development water surface elevations are not coincident. In those situations, the post development water surface elevation must be lower than the pre-development water surface elevation. Also, the hydraulic slope and energy grades should not indicate a possible rise in water surface elevation beyond the post development water surface elevation within the one hundred (100) feet study limits. A sufficient number of cross sections should be utilized within the study limits to accurately determine the water surface elevation. The District reserves the right to extend the study limits. August 1, 2017 DRAFT FOR PUBLIC COMMENT 101 6. If a new channel or channel realignment is proposed which would require a FEMA map amendment, the municipality must submit to FEMA all information required by the current FEMA "Conditions and Criteria for Floodway Revisions." Those projects, which require map revisions, will not be approved until a conditional letter of map revision (CLOMR) is provided by FEMA to the municipality. 1.7. If the development is in an area where no discharge data exists, the Engineer shall use the following guidelines for establishing the discharge for the study: a. Determine the 100-year discharge value from the last known discharge, at most upstream portion of the receiving stream, as shown in the Flood Insurance Study (FIS). b. Determine the 100-year discharge by using the Rational Method as outlined in the Storm Drainage section of this manual. c. The 100-year Rational Method discharge shall be used until that value equals the FIS discharge determined above d. If the 100-year discharge determined by the District’s SSMIP watershed study is more conservative than the above value, then the SSMIP discharge shall be used. 2.8. For flood plain areas not covered by FEMA regulations, the District will not allow offsite rise in the 100-year water surface elevation due to an encroachment in the channel or overbanks. 5.010.03 Filling in Flood Plain Areas 1. If a tract of land, located in the flood plain, has been the subject of unauthorized fill, the flood plain study shall be based on ground conditions prior to placement of unauthorized fill. 2. Placement of fill shall be in accordance with FEMA guidelines as allowed by the governing municipality's flood plain ordinance and consistent with any other governmental restrictions. In Unincorporated St. Louis County, the floodway fringe may be filled without providing equivalent storage in the flood plains of the Missouri River, the Mississippi River and the Meramec River. However, there may be the need for wetland delineation first, since flood plain areas have high probability for wetlands. 3. Placement of fill, roadway embankments or placement of buildings may occur within areas designated as a floodway on the Flood Insurance RateFloodway maps, but only as allowed by municipal Floodplain Ordinance and supported approved calculations. 5.010.04 Detention Basins in Flood Plains Detention basins will be allowed in flood plain areas if all other flood plain requirements are satisfied. 5.010.05 Bridges in Flood Plains c.1. Bridges, culverts, roadway embankments or any encroachment planned in the floodway shall not increase the 100-year water surface elevation adjacent to or beyond the project site. d.2. Bridges in flood plain areas shall be designed on a 100-year storm frequency and shall provide a minimum of one (1) foot of freeboard between the bottom of the superstructure and the 100-year water surface elevation. August 1, 2017 DRAFT FOR PUBLIC COMMENT 102 5.010.06 Parking Lots in Flood Plains 1. No parking lots will be allowed within the 15-year flood plain. 5.010.07 Site Plan Requirements b.1. The site plan shall show existing and proposed contours, existing and proposed 100-year floodway limits, and existing and proposed 100-year high water elevations as a minimum. The contour interval shall be two (2) feet or less. The site plan shall also show locations of the proposed encroachment and structure(s), together with existing topography. c.2. The site plan shall show the entire flood plain (not just the project site area) a minimum of two hundred (200) lineal feet downstream and upstream of the proposed project. 3. Cross section locations and alignment shall be shown on the site plan. The sections should be located perpendicular to the flow in both the channel and overbanks. The sections shall be taken and plotted left to right looking downstream. The flood profile shall be plotted for inclusion in the study. 4. Cross sections shall show the following items: a. 100-year water surface elevation. b. Manning's "n" values c. Top of bank locations d. Horizontal stationing, vertical elevations e. Existing and proposed ground lines f. Existing and proposed sewers g. Cross section identification as it relates to the site plan and hydraulic study h. Existing or proposed structures i. Floodway limits 5. Crossroad culverts in the flood plain shall be designed on a 100-year storm frequency and provide a minimum of two (2) feet of freeboard at the road shoulder line. 8.6. Basement elevations, with the exception of walkouts, must be one (1) foot above the 100-year flood elevation. Basements outside the flood plain limits may be below the 100-year flood elevation if a sanitary pump is installed in the basement with the outgoing plumbing located above the 100-year elevation. 7. The lowest finished floor elevation of all new or redevelopment structures, including slab on grade, shall be minimum of one (1) foot above the 100-year flood elevation. . The low sill of all structures in or adjacent to the floodplain shall be a minimum of two (2) feet above the 100-year flood elevation. 8. Channel and overbank (flood plain) velocities should generally not increase by more than fifty percent (50%) over pre-developed conditions. Velocities in excess of five (5) feet per second (fps) in channels shall require erosion protection. August 1, 2017 DRAFT FOR PUBLIC COMMENT 103 6. RECOUPMENT RULES AND REGULATIONS 6.010 General Any owner or owners of real property within the District and within the area to be sewered may make application to the District for the private construction of sanitary sewers, combined sewers, pumping station, sewage disposal plants and any other sewer facilities which will herein-after be known as "sewer facility" for purposes of those recoupment rules and regulations. The Board of Trustees of the District shall decide whether or not it is in the public interest to proceed with such private construction under the recoupment program. 6.020 Contract Between District and Owner(s) If the Board finds it is in the public interest to privately construct the sewer facility, the Director shall have the power to contract with the owners of the real estate for the construction of the sewer facility to serve the area in which the real estate is located, and such other area as can be efficiently served by the sewer facility to be constructed. Approval of the contract by the Board of Trustees is necessary to make it binding. 6.030 Recoupment Provisions Any contract discussed in Section 6.020 shall also provide for the reimbursement to the owners by any owner of real estate who directly or indirectly taps into or uses the same and did not contribute to the original cost of the sewer facility. The reimbursement amount shall be the fair pro-rata share of the cost of construction of said sewer facility, subject to such reasonable rules and regulations as the Director may provide, before plan approval by the District. Construction inspection and final inspection shall be performed on all construction of recoupment sewer facilities. The recoupment is only for the additional cost of sewer facilities built larger, i.e. greater in size, than the minimum size required for the project outfall. An 8” diameter sanitary sewer is the normal minimum size of pipe for a project. However, a very large project could require a larger size minimum diameter. No guarantee is made of full recovery within the term of the contract. The contract has a 10-year term and is non-interest bearing. It is paid out of 75% of the connection fee collected by MSD from subsequent, tributary development by others, if any during the life of the contract. The costs as described in Section 6.040 shall be furnished to the District and certified by the Owner for approval as further described in Section 6.040. 6.040 Recoupment Procedures and Project Costs A formal letter requesting recoupment must be initiated by the owner. Plans, specifications and three competitive sealed bids of the complete cost of construction or a copy of the proposed contract for the construction and a tributary area map must be submitted to and receive the approval of the District before plan approval by the District. Construction inspection and final inspection shall be performed on all construction of recoupment sewer facilities. Certified costs actually expended for labor and materials, obtaining rights-of-way, permit and inspection fees, insurance, bond premiums, legal and engineering fees, and other costs essential to the construction of the sewer facility shall be furnished to the District for approval. Proof of payments are required. The Executive Director shall examine these costs and upon his approval, as rendered or as adjusted, they shall be certified by him as the complete construction costs of the facility. 6.050 Objections to Certified Completed Construction Costs Any person objecting to the amount of the approved total construction costs of the sewerage facility, as certified by the Executive Director, may appeal to the Board of Trustees of the District by filing, in writing, with the Secretary of said Board the specific objections to said costs. Upon receiving such appeal, the Board of Trustees will consider the matter, and after consideration of all the facts will finally certify the approved total construction costs of the sewerage facility. 6.060 Recoupment Fees Recoupment fees shall be determined by applicable ordinances of the District. They shall be payable to the District and/or its Agents or Assigns. August 1, 2017 DRAFT FOR PUBLIC COMMENT 104 6.070 Areas Served by More Than One Sewer Facility Under Recoupment For properties served by two or more sewer facilities constructed under separate recoupment agreements, charges shall be divided proportionately between the builders of the facilities based upon the ratio of the actual cost of each recoupment agreement to the total actual cost under all agreements. 6.080 Connection to Recoupment Sewer Facility The District shall not approve any plan or issue any permit for a connection to the sewer facility until payment has been made to the District or its Agents or Assigns, of the pro-rate share of the certified cost of the sewer facility. 6.090 Reports of Owner of Sewer Facility 6.090.01 Annual Each year, on or before January 31, a report shall be filed with the District giving the correct name and address of the owner of the sewer facility, and a record of all payments received for connections to said sewer facility prior to January 1 of the year for which the report is filed, along with a statement of the remaining balance. Failure to file this report shall cause the District to send by registered mail, a notice to the last recorded address of the owner of the sewer facility registered with the District. If the owner fails to file the required report within the designated time noted in said notice, the recoupment contract shall then become null and void and no further recoupment fees shall be collected. 6.090.02 Interim If at any time the Executive Director has probable cause to suspect that the owner of any recoupment sewer facility is not performing any of the covenants of the recoupment agreement, he may make demand, by registered mail, for a report giving the information required in the annual report, for that portion of the calendar year prior to the date of such demand. If the owner fails to file such report within the designated time noted after the date of such demand, the recoupment contract shall then become null and void and no further recoupment fees shall be collected. 6.100 Extent of and Time Limits of Recoupment The right to recoup construction costs shall continue until the total amount of all pro-rata shares collected from all parcels connected to the sewer facility, excluding interest where applicable, equals the certified construction cost of the sewer facility as approved by the District. This recoupment period shall last for a period of time to be established by the District. August 1, 2017 DRAFT FOR PUBLIC COMMENT 105 7. EASEMENTS 7.010 General All sewers shall be constructed in easements with working room. Existing easements without working room may only be used if revised to include working room. All public sewers, storm drains and open channels shall be constructed in public rights-of-way or in easements. No permit for construction or improvement of any public sewer, drain or storm channel will be issued without the provision of suitable permanent easements. Easements required shall be acquired and submitted to the District except for recorded subdivision plats. The District shall record all easements before plans will be approved. Recording fees are paid by the Developer and not the District, for private development and municipal projects. Easement plats shall be prepared in full accordance with the District's *Plan Preparation Guidelines (http://www.stlmsd.com/Contractors/PlanPrepGuide/PlanPrepGuide.asp), latest edition. An example easement plat is included at the end of this chapter. All easement plats shall be sealed, signed, and dated by a Missouri Registered Professional Land Surveyor. The District may also require stormwater discharge easements and ponding easements where applicable. 7.020 Use of Existing Easements Every existing easement to be used shall be shown on the plans submitted for review and approval. The information on the plans shall include the City or County book and page numbers of the recorded instrument. All restrictive clauses as to the use of the easements, i.e. for utility purposes, storm sewers only, sanitary sewers only, etc. shall be noted on the plan adjacent to the pertinent easement. Construction of a sewer in the same easement with a water or gas main will not be approved unless the easement is of such size that the locations of the sewer and utility relative to each other comply with dimensional clearances required by the regulatory authorities. 7.030 Location of Easements In locating easements, consideration shall be given to the property owner's interests. Undue splitting and angling across property shall be avoided. Easement locations shall be fixed by distances to known property lines or public right-of-way lines and, where necessary, by angles. 7.040 Width of Easements The width of the easement shall be sufficient to allow proper access for maintenance of the sewer. Easement widths shall provide a two (2) feet minimum clearance between outside limit of structures to easement line with a ten (10) foot minimum width. All easements shall include additional space adjacent to the right-of-way so granted as may be required for working room. 7.050 Wording of Easements Easements should be prepared on the District standard forms, which carry the proper wording for the easement dedication. There are various forms, some for easements on property owned by an individual or individuals, and some for corporate owners. Examples of which forms to use and how to fill them out can be found in the District’s Plan Preparation Guidelines (http://www.stlmsd.com/Contractors/PlanPrepGuide/index1.html). A sample of the cover sheet required by the Recorder’s offices can be found also. Variations in wording are acceptable only where necessary, and approved by the District. Print and original signatures and initialing shall be in black or dark blue ink. Easement Plat "Exhibit A" shall also be initialed and dated in ink by grantor(s). August 1, 2017 DRAFT FOR PUBLIC COMMENT 106 7.060 Easement Plat Preparation Information Guidelines 7.060.01 Label Established Lines Affecting Tract and/or Mentioned in its Legal Description: The following lines shall be shown, where pertinent: 1. Lot lines c.2. Subdivision lines (affected, adjacent, or near) 3. Section lines (or sub-section lines) 4. U.S. Survey lines 5. Street, road, highway and alley right-of-way lines with widths Property is to be located in relation to known corners along the above listed established lines. 7.060.02 Identify Parcel or Tract: The following written information shall be shown, where pertinent: 1. Legal subdivision name, with Lot and Block, Plat Book and Page; if in a recorded subdivision 2. For metes and bounds described parcels, the current owner with Book and Page labeled across tract; add N/F (Now or Formerly) preceding owners' names. 3. Fully dimension owner's property (or as much as shown) 4. Show "North" arrow and scale with "North" to top or side of plat 5. Above owner's name indicate property locator number per current assessor’s records 7.060.03 Provide Accurate Title Box Information: The following information shall be shown, where pertinent: 1. Label as "Easement Plat" 2. Describe only where easement is sought, not wherein all the owner's land lies 3. Use as applicable in St. Louis County: a. Subdivision name, Lot Number, Block Number, and Plat Book Number and Page Number, followed by municipality (if incorporated), followed by "St. Louis County, MO", OR b. Section Number (or fractional section), followed by Township and Range, followed by Municipality (if incorporated), followed by "St. Louis County, MO" OR c. U.S. Survey No., followed by Township and Range, followed by Municipality (if incorporated), followed by "St. Louis County, MO" August 1, 2017 DRAFT FOR PUBLIC COMMENT 107 4. Within the City of St. Louis use as applicable City Block Number, Outlot Number, Subdivision Name, Lot Number (if within subdivision), Block Number, Plat Book Number, and Page Number, followed by "City of St. Louis, MO." 5. The plat shall be sealed, signed, and dated by a Missouri Registered Professional Land Surveyor. 7.060.04 Easement Plat Drafting Guidelines (Refer to current Plan Preparation Guidelines (http://www.msd.st-louis.mo.us/Contractors/PlanPrepGuide/index1.html) that elaborate on the following:) 1. General a. The standard blank plat labeled "Exhibit A" is to be used in preparation of easement plats or temporary construction licenses. Mylars will not be accepted. 1.b. Use line weights, symbols, style, and size of lettering in uniform direction that will make an uncluttered, easy-to-read plat; i.e. show all that is necessary, but nothing extraneous. For clarity purposes, dark blue or black lettering and lines should be used. a.(1) No lettering shall be smaller than (8) point print or #80 "Leroy" lettering guide, assuming easement is not to be reduced when recorded. b.(2) The resultant easement plat or temporary construction license should be easily understandable by property owners and portray all information necessary for a surveyor, with adequate field notes, to stake it out on the ground. 2.c. No title blocks of any kind, other than shown in examples, shall be used. 3.d. At the top left hand corner, outside of plat border, indicate the District's exact project name and reference number as appropriate. 4.e. In the bottom left hand corner outside of the plat border, indicate the date of the most recent version of the Easement Plat. 2. Show complete location and alignment of Easement required with: a. Distances along intersected property line to nearest property corners b. Bearing (or angle) and distance for each course of easement across property 1.c. All calculated and set distances are to be to the nearest hundredth of a foot and bearings to the nearest second 2.d. Indicate easement width(s), and information so that a metes and bounds description for the easement could be written and the area calculated. Show existing easements and indicate appropriate Deed Book and Page, or Plat Book and Page 3.e. Show only pertinent information. Do not show items such as building lines, sewers, areas, etc. August 1, 2017 DRAFT FOR PUBLIC COMMENT 108 7.070 Vacation of Easements The District shall consider vacating its rights within an easement or public right-of-way when it determines that the easement or right-of-way is not required for any existing or future sewer or drainage facility. The vacation of an easement or the District's rights within a public right-of-way can only be accomplished with the approval of the Director. In order to determine if the easement or right-of-way can be vacated, and to prepare the vacation document, the following information must be provided to the District: 1. A letter from the petitioner stating the reason or the request to vacate. 2. A legal description of the area to be vacated, prepared by a registered land surveyor, and an Easement Vacation Plat, prepared in the format outlined in Section 7.060.7.06. If the District determines that there is no future need for the easement or right-of-way in question, a vacation document will be prepared. If the easement to be vacated is part of a project still under review or construction, a vacation will not be prepared until such time as the project has received construction approval or by special permission of the Director. The exhibit A Easement Vacation Plat however will still be reviewed as part of the Plan Review process. In certain situations, if as-built/construction approval is being delayed, easement vacation may proceed by special approval of the Director. Upon the Director’s approval of the vacation, the petitioner will be required to submit the recording fee, payable to MSD for the recording of the vacation. Should the District determine that it is necessary to retain its rights within the easement or public right-of- way in question; the petitioner will be notified in writing that the request has been denied. 7.080 Easement Encroachment Easement encroachments, especially for buildings or other such structures are to be strongly discouraged; are undesirable to the District for private development projects, and are an undesirable position for both future project Owners and the District to be put in. Sewer location and alignment requirements of sub section 3.020.07, 3.020.085, 4.020.06 and 4.020.07 are consistent with and intended to reduce the need for such encroachments. The District shall consider allowing the encroachment of a structure over or onto an easement in which it has rights, only in cases when there is no reasonable way to relocate the existing sewer or drainage facility or relocate the proposed structure or other encroachment. The District may require that the structure which would encroach over or onto an easement be constructed with a pier and grade beam foundation design, with the piers extending a minimum of 2 feet below the flowline of the sewer or drainage facility. In some situations, casing pipe may be used. The casing pipe must be sized adequately to allow the “carrier pipe” to be properly placed within, and to accept the designed load on the casing pipe. The length of the casing pipe will extend beyond the geogrid or similar reinforcement of the modular block retaining wall. After the casing pipe is in place, the pipe within the casing pipe shall be placed on and supported by steel rails or other approved supports. Both ends of the casing pipe shall be sealed. In addition, the District may require that the sewer or drainage facility be structurally rehabilitated before allowing such encroachment. All costs associated with this rehabilitation will be the responsibility of the petitioner. August 1, 2017 DRAFT FOR PUBLIC COMMENT 109 The following information must be submitted before the District will consider an encroachment: 1. A letter of request from the petitioner stating the reason for the encroachment. 2. Three (3) sets of plans showing the existing sewer or drainage facility, the existing easement, the proposed structure, and the proposed foundation design in plan and profile relative to the sewer. The foundation design calculations must also be submitted. Upon receipt of this information, the existing sewer will be inspected to determine its condition. Based on this inspection and a review of the plans, the District will determine if the encroachment will be allowed and what, if any, sewer rehabilitation, will be required. If the encroachment is to be allowed, the property owner will be required to enter into an "Encroachment Agreement" with the District. The property owner will also be required to submit a recording fee, payable to MSD for the recording of this document. If the encroachment is denied, the petitioner will be notified in writing of this denial. 7.090 Indemnity Agreement The District will consider entering into an Indemnity Agreement with the property developer when the developer is unable to acquire a stormwater discharge easement from the adjacent property owner, for the discharge of stormwater onto the adjacent property. The property developer must submit the following items for the District's consideration: 1. A letter of request to enter into an Indemnity Agreement in lieu of acquiring the Stormwater Discharge Easement. 2. Adequate documentation verifying that reasonable effort was made to acquire the Stormwater Discharge Easement. 3. A site plan indicating the proposed location of the stormwater outfall structure and energy dissipater (as required). Hydraulic calculation for the energy dissipater design will be required. Will add easement plat example with Professional Land Surveyor’s seal on next page August 1, 2017 DRAFT FOR PUBLIC COMMENT 110 8. APPROVAL AND DEDICATION OF PROJECTS WITH PUBLIC SEWERS 8.010 General The District will accept for dedication, all public sewers, pump stations and sewerage treatment facilities within easements dedicated to the District that have been constructed to the District standards and for which the requirements stated herein have been met. The maintenance of these public facilities will remain the responsibility of the project Owner until such time that they have been accepted for dedication by the District. 8.020 Requirements for Plan Approval and Issuance of Permits 8.020.01 Agreement to Dedicate An executed "Agreement to Dedicate" will be required for projects involving construction of public sewer facilities. The District will provide two (2) copies of this document to the Owner as part of the plan review process. These forms must be executed by the record Owner and returned to the District. The District will execute the documents and return one (1) copy to the Owner. Plan Approval will not be given for a project having public sewer facilities until the "Agreement to Dedicate" has been executed by both parties. An "Agreement to Dedicate" will not be required from the State of Missouri, any incorporated municipality, the City of St. Louis or St. Louis County or other tax supported government utility (school/fire district). All Projects submitted by these entities will be dedicated at the time construction approval is issued by the District. 8.020.02 Construction Escrow Deposit and Cash Deposit Agreement Prior to the issuance of construction permits, a Construction Deposit for all public facilities, as well as an As-Built Deposit will be required as stated in Chapter 9. In addition, the project Owner will be required to execute a Construction Deposit Agreement Guaranteeing Completion of Sewer Improvements. Two (2) copies of this document will accompany the Plan Approval Notice to the Owner. The agreements must be executed and returned to the District before construction permits will be issued. One original will be returned to the Owner upon execution by the District. 8.020.03 Conditional Plan Approval Conditional plan approvals may be issued in very limited instances, with a written agreement with the District. In such cases an additional Construction Deposit in the amount of $10,000.00, may be assessed upon compliance with all requirements as noted in the “Conditional Plan Approval” the District will release the Deposit within fourteen (14) days of review/approval by the Plan Reviewer. 8.020.04 Flexibility for BMP Permitting and Inspection Developments with BMPs placed on each lot but for which no new public sewers are constructed may be divided into individual “P#’s” for the purpose of tracking BMP inspections and collecting and releasing the BMP deposits. The Developer’s Engineer shall indicate the Developer’s interest to do this prior to plan approval. Once plans are approved, these requests cannot be accommodated. Additional administrative costs are required to provide for this flexibility. These costs will generally include a submittal fee and review fee proportional to the level of effort required to set up each individual “P#”, the amount to be determined on a case-by-case basis. August 1, 2017 DRAFT FOR PUBLIC COMMENT 111 8.030 Requirements for Construction Approval 8.030.01 Construction Inspection All public sewer facilities must be inspected by the District. It is the responsibility of the Owner's Contractor to contact the District's Construction Department to arrange for this inspection. The District will not grant Construction Approval for any public sewer facilities, which were not constructed in accordance with approved plans and with the District inspection. The District will not allow the physical connection of the new public sanitary sewer construction to the existing system until construction approval has been given. Occupancy permits will be withheld by St. Louis County or the local municipality until Construction Approval is given. 8.030.02 Field Changes and Plan Revisions It is the intent and purpose of "Field Change" approvals to minimize the need for a formal plan revision for minor changes to the approved plans, and to minimize delays in construction. The following are the general procedures for processing a Field Change. 4.1. Initial requests for a change may be made verbally to the Engineering Department by the Owner, the Owner's Engineer or the Owner's Contractor, and followed up with a letter of request for file documentation. The petitioner should state the requested changes and the reason for the change. 5.2. Upon receipt of the request, the District will evaluate the proposed change to determine if it is to be allowed. In addition, if the request is made by someone other than the Owner's Engineer, the District will formally contact the Engineer to obtain authorization for the change, and request a letter of authorization for file documentation. 6.3. If determined to be necessary, revised hydraulic calculations may be required from the Owner's Engineer. 7.4. If the change is allowed, the Owner's Engineer will be required to submit the “required number” sets of the plan sheet(s) indicating the change. These plans may be copies of the original plans with the change noted in red. On occasion 11” X 17” excerpts of the original plan sheet(s) may be allowed. They should be to original scale and sealed. 8.5. The Engineering Department will notify the Construction Department of the approved field change and send copies of the changed plans to the appropriate District personnel, the Owner, Engineer, Contractor and municipal agencies. 9.6. The Contractor will be responsible for payment of all inspection fees associated with the change prior to Construction Approval. 7. Field changes must be indicated on the "As-Built" drawings. Significant change(s) to the HGL; the need for additional special structure(s), or additional permit(s) or significant fees or deposits; or, significant revisions to the project or missing requirements will preclude use of a “field change” format. In that case a formal plan revision will be necessary, instead. 8.030.03 As-Built Drawings As-built drawings and State Plane Coordinates, certified by a Land Surveyor or Engineer registered in the State of Missouri, must be submitted to the District for review and acceptance prior to construction approval. As a minimum, the following information shall be provided for the As-Builts: August 1, 2017 DRAFT FOR PUBLIC COMMENT 112 1. Storm, Sanitary and Combined Sewers As-built drawings and State Plane Coordinates shall indicate the vertical and horizontal location of the storm, sanitary and combined sewers and structures in plan and profile view, including any and all changes from the Approved Plans and “Field Changes”. Special attention shall be paid to situations where sewers have moved out of easements. In those cases, additional easement(s) to be obtained must be so shown and so labeled. 2. Detention Basin a. A field survey of the basin shall be made to confirm the basin's location, size, shape and depth. As a minimum the as-built drawings and State Plane Coordinates shall include: (1). As-built cross-sections of the basin plotted over the design cross- sections. (2) Spot elevations shown in plan, defining the location and elevation of the basin berm and overflow spillway. (3) Location, length, size, shape and flowline elevation of the detention basin concrete swale. (4) Control and overflow structure location, configuration, size, elevations, and any other information relevant to the proper operation of the structure (i.e.; opening size; low flow and outlet pipe size, slope and flowline and sill, orifice, weir elevations; etc.). b. Based on the field survey information, an elevation vs. storage table or curve of the detention basin should be submitted. c. Should the District be concerned that the as-built detention basin varies significantly enough from the approved basin design that it may not function as designed the District will require that new detention calculations be submitted for review. Based on this review, modifications to the detention basin may be required before acceptance of the as-built plans and release of any escrow. 3. Pump Station Construction Digital copies of all Manuals and Drawings are required, including CADD drawings of electrical schematics. a. As-Built Drawings and State Plane Coordinates shall indicate the physical location of the pump station, retention, access road force main, tuned locator markers and other related structures. GPS survey of all force mains is required, and this shall be coordinated with District Operations staff – Pump Station Division. b. Shop Drawings of all structures. c. Equipment manuals and pump operating curves for any items which differ from the original design as a result of a field change. August 1, 2017 DRAFT FOR PUBLIC COMMENT 113 d. For the pump(s) actually installed, and at the end of the job and in addition to the Manual and pump curve(s) from the equipment supplier, also provide the District Pump Station Division with pump serial number(s), model number, impeller trim, et cetera. e. The pump(s) will need to be run under actual conditions. Actual discharge pressures will then be used to determine actual operating point on the curves. Pumps running at the end of the curve will not be accepted. 4. Subdivision Plats A recorded copy of the subdivision plat must be submitted with the As-Built drawings. 5. Geotechnical Engineer's Certification Geotechnical Engineer's Certification will be required verifying that all work associated with the treatment of sinkholes, placement of compacted fill, and other soils-related work was completed in accordance with the approved Geotechnical Report. 6. State Plane Coordinates State Plane Coordinates as detailed below, are required on all improvements requiring As-built Drawings by the District. a. Horizontal Data All horizontal data provided on facilities will be in State Plane Coordinates – Missouri East Zone, NAD 83(HARN). All horizontal coordinates provided shall have an accuracy of 50mm. b. Vertical Data Vertical Datum shall be referenced to the North American Vertical Datum of 1988 (NAVD 1988) and provide a conversion to NVGD 29 (A.K.A. U.S.G.S.). (NVGD 29 is the datum used for the St. Louis County & St. Louis City Benchmark Books). NVGD 29 may be submitted with conversion to NAVD 1988 provided it has been previously approved by an MSD representative All vertical data provided on facilities will be according to the NGVD29 (St. Louis County & St. Louis City Benchmark Books Datum). All vertical data shall have an accuracy of 60mm. c. Deliverables An electronic points file of all state plane information will be required. The electronic points file shall be delivered as electronic media in the format described below, along with electronic version of as-built drawings in pdf format, at 300 dpi resolution. The format for the electronic points file should be as follows: Electronic points file: Comma delimited text file with the extension of file type of ASC. The format of the file should be: Electronic points file: August 1, 2017 DRAFT FOR PUBLIC COMMENT 114 The file shall be a comma delimited text file with the extension of file type TXT or ASC. No spreadsheets or any other file types are acceptable. The file shall be in the precise format indicated below, and contain no other entries of any kind (example, No Title, Header, Footer, Column Headings, Spaces or Tabs as delimiters or otherwise, Extra Lines or Hard Returns between lines, etc.): Point, Northing, Easting, Elevation, Description (P, N, E, Z, D) where Point: Survey point number Northing: Horizontal Data for Northing of State Plane coordinate Easting: Horizontal Data for Easting of State Plane coordinate Elevation: Vertical Data for Elevation of Top of Structure, Manhole Lid, etc. Description: Identifying number assigned to structure or location that corresponds with how the point is labeled on the plans. Example: File name: P-12345-00.ASC Sample: File Contents: 22,1020432.283,850432.952,501.82,MH23 23,1020641.663,850350.877,503.96,MH24 24,1022447.353,848806.986,507.24,MH25 8.030.04 Stormwater Quality Management Facilities and Construction Deposit Agreement Construction of Stormwater Quality Management Facilities is not required for construction approval. However, prior to the issuance of construction approval items a.) and b.) below shall be completed: a. The project owner shall execute a "Construction Deposit Agreement Guaranteeing Completion of Stormwater Quality Management Facilities". Two (2) copies of this document will accompany the Plan Approval Notice to the Owner. This document must be executed and returned to the District before construction approval will be issued. One original will be returned to the Owner upon execution by the District. b. The project owner shall provide a construction deposit for all stormwater quality management facilities, as stated in Chapter 9. c. BMP permits shall be obtained prior to BMP construction. 8.030.05 Notification of Construction Approval The District will notify the Owner and the Owner's Contractor when construction approval is given. In addition, St. Louis County or the local municipality will be notified that occupancy permits may be released. 8.040 Requirements for District Approval of Stormwater Quality Management Facility Construction 8.040.01 Construction Inspection August 1, 2017 DRAFT FOR PUBLIC COMMENT 115 All permitted stormwater quality management facilities must be inspected by the District. It is the responsibility of the Owner's Contractor to contact the District's Construction Department to arrange for this inspection. The District will issue a “BMP Construction Completion Letter” when its inspection indicates that stormwater quality management facilities were constructed satisfactorily and in compliance with approved plans. The District will not issue a BMP Construction Completion Letter for any facilities which were not constructed in accordance with approved plans and without District inspection. No portion of the Stormwater Quality Management Facilities Construction Deposit will be released without the District issuing the BMP Construction Completion Letter. Stabilization of the drainage area tributary to stormwater quality management facilities is very important to the facility’s function. The District will also perform an inspection of the drainage area tributary to stormwater quality management facilities. The District’s determination of drainage stability will be determined when the drainage area’s final landscape cover is established. Any vegetated covers should provide a uniform, evenly distributed final vegetative cover with a minimum density of 80 percent. MSD reserves the ability to require additional site stabilization measures, where construction sediment or other construction materials are affecting BMP performance. 8.040.02 Field Changes and Plan Revisions Requirements for field changes and plan revisions for stormwater quality management facilities are the same as those listed in 8.030. 8.040.03 As-Built Drawings As-built drawing requirements for stormwater quality management facilities are similar as those listed in 8.030 for detention basins. As-built drawings shall be submitted to the District for review and acceptance prior to issuance of the BMP Construction Completion Letter. MSD may waive as-built drawings for stormwater BMPs on a case-by-case basis. In general, this waiver will be limited to smaller surface BMPs that serve small, controlled drainages (e.g., bioretention fed by roof downspouts). This waiver, when applicable, will be noted by MSD on approved plans. 8.050 Dedication and Release of Construction Deposit It is noted that this section is independent of Section 8.080 - (Release of Stormwater Quality Management Facilities Construction Deposit). In most cases it is not necessary to have stormwater BMPs complete in order to be eligible to receive 100% dedication on the sewer construction and release of sewer construction escrow. 8.050.01 Residential and Commercial Subdivisions, Apartments and Condominiums AB. Initial Dedication Inspection Upon completion of fifty percent (50%) of the lots in the total residential or commercial subdivision, or fifty percent (50%) of the buildings in an apartment or condominium development, the District will perform a dedication inspection upon receipt of a written request from the Owner. 1. If there are no deficiencies, the District will release one-half of the monies held in deposit within fourteen (14) days of the receipt of a properly executed "Sewer Dedication Agreement" form. August 1, 2017 DRAFT FOR PUBLIC COMMENT 116 2. If deficiencies are noted within the system, the Owner has ninety (90) days to correct these deficiencies. a. If the deficiencies are not corrected within this period, the District will contact St. Louis County or the local municipality and request that all unissued building permits and occupancy permits be withheld until the deficiencies are corrected. Extensions may be granted for inclement weather or other extenuating circumstances. b. Upon correction of the deficiencies, the Owner will be responsible for requesting a reinspection of the system. c. The District will release one-half of the monies held in deposit within fourteen (14) days of the second inspection, provided all deficiencies have been corrected to the District's satisfaction and receipt of a properly executed "Sewer Dedication Agreement" form. B. Final Dedication Inspection Upon completion of one hundred percent (100%) of the lots in the total residential or commercial subdivision, or one hundred percent (100%) of the buildings in an apartment or condominium development, and within three (3) years of the execution of the Cash Deposit Agreement, the District will perform a final dedication inspection upon receipt of a written request from the Owner. 1. If there are no deficiencies, the District will release the remaining Deposit within fourteen (14) days of the inspection, provided both the Owner and the District execute a Sewer Dedication Agreement (if not already executed at the fifty percent (50%) completion stage). 2. If deficiencies are noted within the system, the Owner must correct these deficiencies before the remaining monies will be released. a. Upon correction of the deficiencies, the Owner will be responsible for requesting a reinspection of the system. b. The District will release the remaining Deposit and within fourteen (14) days of the second inspection, provided all deficiencies have been corrected to the District's satisfaction, and the Sewer Dedication Agreement is executed by both the Owner and the District (if not already executed at the fifty percent (50%) completion level). c. Fees for multiple inspections will be required as stated in sub-section 8.040.03. 3. If the development is not completed within three (3) years of the execution of the Construction Cash Deposit Agreement, the remaining Deposit will not be returned to the Owner and will be used by the District, at its discretion and in any manner the District sees fit, to complete any improvements or correct deficiencies. 8.050.02 Sewer Extensions and Single Lot Developments The District may release fifty percent (50%) of the Deposit for small sewer extensions and single lot commercial and residential developments at the time of construction approval, provided the “Sewer Dedication Agreement" is executed by both the Owner and the District. August 1, 2017 DRAFT FOR PUBLIC COMMENT 117 The remaining fifty percent (50%) would be released as stated in 8.0540.01.B - Final Dedication Inspection. 8.050.03 Dedication Inspection Fees A. All projects with public sewer facilities will receive a total of four (4) dedication inspections (four (4) for Pump Station inspections) by the District without charge as follows: 1. The first inspection and the reinspection at the fifty percent (50%) development completion. 2. The first inspection and the reinspection at the one hundred percent (100%) development completion. 3. One inspection and one reinspection at each stage of the pump station construction. Inspection fees, as determined by the District, will be required for each additional inspection. The amount of these fees will be deducted from the Deposit to be released to the Owner. 8.060 Pump Stations Pump Stations will be accepted for dedication upon Construction Approval of the project. The “Sewer Dedication Agreement” for pump stations constructed as part of a subdivision, apartment or condominium project will not be executed until all items in 8.040.01 have been completed. The District will release the Pump Station Deposit upon completion of the two stages of the pump station construction as described below. The Owner must submit a written request to the Escrow Section of the Engineering Department for inspection and release of the Pump Station Deposit. Only one (1) inspection may be requested within a thirty (30) day period. The inspection and release of the Deposit will be made only if the District agrees that the necessary work is complete and no discrepancies have been identified. Pump Station Deposit Account: A. Stage One 1. “Fifty percent (50%) Inspection” and Release of Deposit a. One hundred percent (100%) of the construction of the pump station structure, storage tank, force main and pump bases. This inspection requires the wet well floor to be dry. B. Stage Two 1. “One hundred percent (100%) Inspection” and Release of Deposit a. All electrical and mechanical equipment installed and in operating condition. All paving, fencing, site restoration, and any additional easement requirements completed and written notice of Construction Approval. Operation of the pumps must be within August 1, 2017 DRAFT FOR PUBLIC COMMENT 118 acceptable limits of pump curves. Flow into station must be less than or equal to projected flow. Flow must be free from excessive grease and other foreign substances. b. Letter of completion from installing paving contractor, guaranteeing all pavement and pavement subsurfaces have been installed per the District Pump Station Design Requirements document. 8.070 Abandonment of Work Upon receipt of a written statement from the Owner that further work on the project has been abandoned, the District shall determine whether or not the uncompleted work is required to ensure the public health, safety and welfare. Should it be determined that completion of the work is necessary, the District shall utilize the monies deposited in the Construction Deposit for the project to complete this work. Should the District determine that the completion of the work is not required; the Construction Deposit shall be released in accordance with Section 8.040. 8.080 Release of Stormwater Quality Management Facilities Construction Deposit The District will release up to seventy-five percent (75%) of the deposit upon issuance of BMP Construction Completion Letter. For sites with multiple (more than four (4)) permitted BMPs, the District will consider proportionally releasing the deposit at twenty-five percent (25%) and fifty (50%) percent of the total number of BMPs constructed. Where dedication of public sewers is not required, the The District will also perform an inspection of the drainage area tributary to stormwater quality management facilities. MSD will hold the balance of the stormwater quality management facility deposit until the BMP drainage areas (for which the developer has disturbed or has reasonable control over) is sufficiently stable for stormwater quality management facility operation and all BMPs are functioning properly. Where dedication of public sewers is required, the District will perform the inspection of the drainage area tributary to stormwater quality management facilities as part of the dedication inspection process. The balance of the BMP deposit will be released as part of the dedication process. August 1, 2017 DRAFT FOR PUBLIC COMMENT 119 9. FEES AND DEPOSITS REQUIRED BEFORE PLAN APPROVAL AND ISSUANCE OF CONSTRUCTION PERMITS 9.010 Fees Required Before Plan Approval The District will require that certain fees be paid prior to the acceptance of the plans for review, or the subsequent approval of these plans. Failure to submit the fees in a timely manner could delay the review and approval of the plans. No plans will be approved until all required fees have been paid. Since the amount of these fees are subject to change, no amount for these fees is given herein. Please see the District website contact the District for a current list of fee types and amountsfees. Some of the more common fees are described below: 9.010.01 Submittal Fee A submittal fee in the amount indicated on the District Engineering Form E.2 must be submitted along with the plans and Form E.2. Failure to submit this fee, Form E.2 or the appropriate number of plans, will result in the rejection of the plans for review. 9.010.02 Review Fee The District will charge a fee to review the project based on the acreage of the development. This fee will be determined by the District, and the Owner will be notified of the amount as part of the review process. The Review Fee must be paid prior to with the second (2nd) submittal of Plan sets. Review of second submittal will not begin until after receipt of Review Fee. 9.010.03 Connection and System Development Fees A Connection Fee will be required for all projects, which require sanitary sewer service. This fee will be based on the domestic water tap size for the project in accordance with the District Ordinance 9346, or successor. In addition, a System Development Fee may be required if the project is located in an area where a subdistrict, impact area or recoupment area has been established by Ordinance. These fees will be determined by the District, and the Owner will be notified of the amount as part of the review process. 9.010.04 Recording Fees The Owner will be responsible for paying the recording fees for all documents to be recorded with the Recorder of Deeds for St. Louis County or the City of St. Louis. Checks are to be made payable only to MSD. Documents are to be reviewed by the District prior to execution. After execution and notarizations, the documents are to be delivered to the District for transport to the Recorders Office and MSD will then pay the Recording Fees. (Subdivision plats are not recorded by the District for private development projects). 9.020 Deposits Required Before Issuance of Construction Permits For projects with public sewer facilities, detention facilities or private facilities requiring the District construction inspection, certain deposits will be required prior to the issuance of construction permits. All Construction Deposits, Stormwater Quality Management Facility Deposits, and Conditional Plan Approval Deposits must be in the form of cash, a cashier’s check, wire transfer, or letter of credit. No vouchers will be accepted. As-Built deposits may be cash, cashier checks, corporate checks personal checks or wire transfer. The Construction Deposit, Stormwater Quality Management Facility Deposit, and As-Built Deposit must be remitted from the Owner, not the Contractor or Engineer. August 1, 2017 DRAFT FOR PUBLIC COMMENT 120 9.020.01 As-Built Deposit An As-Built Deposit will be required for projects with public sewers which are to be dedicated to the District, and for projects with detention facilities. The As-Built deposit will be released to the Owner upon Construction Approval of the project and review and approval of the As-Built drawings by the District. 9.020.02 Construction Deposit The Owner will be required to submit to the District a Construction Deposit. When the deposit is in the form of cash, the amount of the deposit shall be ten percent (10%) of the estimated construction cost of the public sewers and private facilities to be constructed under the District inspection, not including stormwater quality management facilities (see 9.020.05 for BMP deposits). When the deposit is in the form of a letter of credit, the amount is also ten percent (10%), however, the minimum amount of the letter of credit shall be $30,000. The Deposit amount will be computed by the District at the time of request for final plans for approval.required number of plans. Release of the Construction Deposit will be made as stated in Chapter 8.050. 9.020.03 Pump Station Escrow Deposit The Owner will be required to submit to the District a Pump Station Deposit in the amount of one hundred percent (100%) of the estimated construction cost of the pump station, force main and storage system. The Deposit amount will be computed by the District at the time of request for required number of plans. Release of the Pump Station Deposit will be made as stated in Chapter 8.0670. 9.020.04 Conditional Plan Approval Deposit The owner will be required to submit to the District a Conditional Plan Approval Deposit. The Deposit amount will be determined by the District at the time a request for a Conditional Plan Approval is made. Release of the Conditional Plan Approval Deposit will be made as stated in Chapter 8.020.03. 9.020.05 BMP Deposit The Owner will be required to submit to the District a BMP Deposit (Stormwater Quality Management Facility Deposit) in the amount of fifty percent (50%) of the estimated construction cost of the stormwater quality management facilities constructed under the District inspection. When the deposit is in the form of a letter of credit, the minimum amount of the letter of credit shall be $30,000. The Deposit amount will be computed by the District at the time of request for required number of plans. Release of the BMP Deposit will be made as stated in Chapter 8.080. It is noted that the BMP deposit can be paid later in the construction process (i.e. after MSD permits have been issued for sewer construction). However, the BMP deposit must be paid prior to: a.) issuance of MSD BMP permits, and b.) MSD construction approval for sewer construction August 1, 2017 DRAFT FOR PUBLIC COMMENT 121 10. CONSTRUCTION PERMITS 10.010 General 10.010.01 Permits Required Any person, firm or corporation desiring to construct, install, relocate, connect or reconnect any sanitary, combined, or stormwater sewer or drainage facility, whether public or private, within the boundaries of the District shall cause plans and specifications therefore to be prepared by a registered professional engineer, licensed in the State of Missouri, and shall cause the same to be submitted to the District for examination, revision, and approval according to the design standards of the District. Such approval shall be a condition precedent to the issuance of a permit for the construction of such facilities, and no such facilities shall be constructed without a permit therefore from the District. All such plans and specifications shall be prepared in such form and manner as may be prescribed by the District. 10.010.02 Defaults No person shall be entitled to a permit while such person is in default in the performance of any of the obligations to the District with respect to a previous permit issued to such person by the District. 10.020 Permittee Excluding certain aboveground stormwater quality best management practices, all applications for permits for construction of sewer and drainage facilities, for connection to such facilities and for repair of a connection to such facilities shall be made by a master drainlayer having a certificate of qualification or other applicable license to perform work as a master drainlayer issued in his name by the Board of Examiners of Plumbers and Drainlayers of the City of St. Louis or of St. Louis County or other applicable licensing authority. For permit application for aboveground stormwater quality best management practices: where the permittee is not a master drainlayer, the permittee shall provide MSD a certificate of General Liability Insurance meeting the requirements of Section 10.090.01 and 10.090.02 before permits are issued 10.030 Performance Bond Excluding permits for certain above ground stormwater quality best management practices, no construction or connection permit shall be issued unless the applicant shall first have filed with the District a cash or corporate bond in an amount not less than Ten Thousand Dollars ($10,000.00). Such bond shall run to the District and shall be conditioned as follows: That the permittee, his agents and servants, shall comply with all of the terms, conditions, provisions, requirements and specifications of the District's applicable Rules and Regulations and Standard Construction Specifications. A permittee may elect to maintain such bond with respect to all permits issued hereunder during the period of the bond or with respect to a single permit. Before acceptance, all bonds shall be approved by the Director or a designee thereof. All bonds must be executed by a surety or insurance company satisfactory to the District with the following qualifications: • Duly authorized to transact business in Missouri as evidenced by a Certificate of Authority granted by the Insurance Commissioner, Department of Insurance, State of Missouri. • Having a financial strength rating of "A" or better and a financial size category of Class V or higher per AM Best Company. August 1, 2017 DRAFT FOR PUBLIC COMMENT 122 If a cash bond is offered, it shall be deposited with the Secretary-Treasurer, who shall give his official receipt therefore, reciting that the cash has been deposited in compliance with and subject to the provisions of applicable Rules and Regulations. 10.040 Construction and Connection Permit and Fees In addition to the fees stated in Chapter 9, the following fees, deposits, or escrows may be required prior to the issuance of the Construction and Connection permits. 10.040.01 Connection Permit and Fee Each applicant for a connection permit shall, at the time of filing an application, pay to the District a permit fee as applicable. No refunds will be given for connection permit fees. If the permittee is unable to locate a wye according to the measurements given on the permit, the District's Permit Office shall be contacted. Indiscriminate tapping in any sewer line is not permitted. District ordinance prohibits leaving any sewer connection "... open, unsealed, or incomplete in a manner which permit stormwater, ground water, or surface water to enter any District sanitary sewer.” Any person found guilty of violation is subject to fine and/or imprisonment. 10.040.02 Construction Permit and Fee Each applicant for a construction permit shall, at the time of filing an application, pay to the District a fee for the issuance of a construction permit. 10.040.03 Machine Tap Permit and FeeSaddle Permit and Fee In all cases where a connection is to be made to an existing sewer, at a point where an existing stub or “wye” is not available, the physical connection to such existing sewer shall be made by the permittee only when District personnel are present to inspect the work. In cases where the permittee is not using a tee saddle, inserta tee or “rolling in” a wye, MSD will furnish a saddle and apparatus for connections up to twenty-four (24) inches in diameter. The saddle type connection fitting shall be designed for the type of pipe(s) which are to be connected. The permittee shall furnish the labor and the balance of materials required at the site, including the connecting sewer pipe. Fees are assessed when the permit is applied for or if unknown, fees will be assessed after completion of work. 10.050 Inspection Fee Deposit Each applicant for a construction permit shall, at the time of filing application, deposit with the District an estimated inspection fee. If the sum so deposited shall exceed the inspection costs as finally fixed, and the permittee has complied with District requirements, the excess amount of such deposit over costs shall be refunded upon written notice of Construction Approval. If the sum so deposited shall be less than the inspection costs as finally fixed, the permittee shall pay to the District the amount of the deficiency. 10.060 Expiration and Extension of Permits and Approved Plans 10.060.01 Approved Plans Plans approved for construction, for which construction permits have not been issued, shall be held by the District for no more than one year, at which time the documents shall be destroyed. New plans, and the appropriate submittal and review fees, must be submitted for review and approval before permits will be issued. August 1, 2017 DRAFT FOR PUBLIC COMMENT 123 10.060.02 Construction and Connection Permits •1. Construction Permits for which work has not been started within ninety (90) days after the issuance of the permit shall become void unless a written request is made prior to the expiration date. •2. Connection Permits for which work has not been started within ninety (90) days after the issuance of the permit shall become void unless a written request is made prior to the expiration date. 3. Reinstatement of an expired permit will be granted providing a written request for the reinstatement is received by the District within the period for which an extension could be granted. 8.4. Written requests for an extension or reinstatement shall be addressed to the Permit Section of the Engineering Department. 9.5. Not more than one extension shall be granted on any permit without showing cause and the approval of the Appointing Authority. 10.070 Cancellation of Permits and Refunds of Fees and Deposits 10.070.01 Prior to the Start of Work A refund of the permit and inspection fees and cancellation of the construction permit will be made for any permit which has not expired upon receipt of a written statement from the Owner that the project has been abandoned. The construction permit must be submitted with the written statement. No refund of the permit and inspection fees shall be made for construction permits, which have expired. Written statements should be sent to the attention of the Permit Section of the Engineering Department. 10.070.02 After the Start of Work A partial refund of the inspection fee for construction permits may be given after the start of the work upon receipt of a written statement from the Owner that further work on the project has been abandoned, and the District agrees that the work is not required. The construction permit must be submitted with the written statement. Upon receipt of the written statement, the cost of the inspection of work completed shall be determined by the District. Inspection fees paid to the District in excess of the actual cost shall be refunded. No refund shall be made for any portion of the permit fee. Written statements should be sent to the attention of the Permit Section of the Engineering Department. 10.070.03 Connection Permits No refunds will be given for connection permit fees. August 1, 2017 DRAFT FOR PUBLIC COMMENT 124 10.080 Final Determination of Construction Inspection Fees Upon completion of construction of a project, receipt of final as-built documents, and after the permittee has complied with all other terms of these rules and regulations, the District shall compute the actual inspection fee based on field measurements. The District shall be paid therefore, or refund shall be made to the permittee, as the case may be. All outstanding fees must be made before Construction Approval is given. 10.090 Minimum Insurance Requirements for Off Site Construction The District may require proof of insurance when projects require off site sewer construction. The need for insurance will be noted on the Approved Project Plans. If proof of insurance is required, the permittee must provide a copy of an executed Certificate of Insurance on ISO ACORD 25 form or current equivalent indicating that the permittee has obtained and will continue to carry commercial general liability and comprehensive automobile liability. If MSD is providing cost reimbursement in excess of $100,000, the permittee shall also provide proof of pollution liability insurance. The permittee shall carry and maintain adequate commercial general liability insurance for bodily injury, personal injury and property damage with a company satisfactory to the District and which is: a.1. Licensed to do business in the State of Missouri (Admitted) with a financial strength rating of “A-” or better and a financial size category of Class VI or higher per AM Best Company; or b.2. Not licensed in the State of Missouri (Non-admitted) with a financial strength rating of “A” or better and a financial size category of Class IX or higher per AM Best Company. The insurance company will be acceptable regardless of the above requirements if the insurance company furnishes a bond guarantee or policy containing a provision (commonly referred to as a “cut-through” endorsement) giving all claimants thereunder a direct right of recovery against the company’s reinsurer, provided the reinsurer meet one of the qualifications listed above. The limits of liability shall not be for less than the amounts listed below and shall be in larger amounts if such are required by the District. 10.090.01 Comprehensive Business Automobile Liability: Insurance shall apply to all owned, non-owned and hired vehicles. $1,000,000 Liability Coverage each occurrence -and- $5,000,000 Excess (Umbrella) 1 1Limits of Excess (Umbrella) coverage for Projects less than $100,000 may be reduced to $2,000,000. August 1, 2017 DRAFT FOR PUBLIC COMMENT 125 10.090.02 Commercial General Liability (occurrence form): The Commercial General Liability (CGL) policy shall include the following: 1)1. Premises – Operations Liability 2)2. Blanket Contractual Liability 3)3. Products & Completed Operations Liability 4)4. Contractor’s Protective Liability (Independent Contractors) 5)5. Personal Injury Liability 6)6. Broad Form Property Damage Liability Endorsement 7)7. Coverage for explosion, collapse and underground hazards (XCU) 8)8. Blasting (provided that blasting coverage may be excluded if not to be performed in connection with the work) If using a non-standard policy form (Form CG 00 01 04 13 or equivalent), then additional endorsements may be required. A specific endorsement may be needed if non-standard coverage is provided. The following wording must be stated in the Description of Operations section of the Certificate: “No amendments to the ISO Commercial General Liability policy have been made” NOTE: If any exceptions or exclusions have been made to the standard CGL policy, the exceptions and exclusions must be specifically listed and identified in the Description of Operations section of the Certificate of Insurance and must be submitted to the District for approval.” (with the exception of: _______________)”. The District shall be named as an Additional Insured with respect to the Project. Required Limits of Liability $1,000,000 Each Occurrence Combined Single Limit per occurrence per project $1,000,000 Personal Injury $1,000,000 Aggregate/Per project General Aggregate per project or location -and- $5,000,000 Excess (Umbrella) 2 2Limits of Excess (Umbrella) coverage for Projects less than $100,000 may be reduced to $2,000,000. The District reserves the right to require additional commercial general liability insurance as deemed necessary. 10.090.03 Pollution Liability (Required if MSD is providing cost reimbursement in excess of $100,000) For MSD reimbursement contracts in excess of $100,000 the Contractor shall maintain in force for the full period of the Contract, pollution liability insurance coverage in the minimum amount set forth below for losses caused by sudden and non-sudden pollution conditions as that arise from the operations of the contractor. Such insurance shall apply to bodily injury and property damage, including loss of use of the damaged property or property that has not been physically injured, and shall cover clean up, transportation, disposal, remediation and defense cost, including all expenses incurred in the investigation, defense, payment or settlement of claims. $2,000,000 Per Claim or Occurrence $2,000,000 Aggregate August 1, 2017 DRAFT FOR PUBLIC COMMENT 126 If claims are made, the insurance coverage shall be retroactive to the earlier of the date of the reimbursement contract or the commencement of the Contractor’s work on the Project, and Contractor shall cause the same to remain in effect for a period of at least four (4) years after the final acceptance of the Project by the District or such other period as may be set forth in the reimbursement contract. 10.090.043 Cancellation/Material Alteration & Replacement Policy Should any of the required insurance coverage be cancelled prior to the expiration date, the contractor/permittee must provide at least sixty (60) days written notice to the District prior to the cancellation. For policy cancellation for non-payment of premium, the contractor/permittee must notify the District at least ten (10) calendar days prior to the cancellation. Should any of the required insurance coverage be cancelled, terminated or materially altered, the contractor/permittee will send written notice to MSD at least sixty (60) days prior to the effective date of said cancellation, termination or alteration. Upon receipt of any notice of insurance cancellation, termination or alteration, the contractor/permittee shall within thirty (30) days procure other policies of insurance identical in all respects to the policy or policies about to be cancelled, terminated or altered and shall provide the District with evidence of coverage before the cancellation or termination date; and if the contractor/permittee fails to provide, procure and deliver acceptable policies of insurance and satisfactory certificates or other evidence thereof, the District may obtain such insurance at the cost and expense of the contractor/permittee without notice to the contractor/permittee and elect to pursue any other remedy permitted by law and/or the applicable contract. August 1, 2017 DRAFT FOR PUBLIC COMMENT 127 11. INSPECTION 11.010 General Before approval of the construction of any sewerage or drainage works, a field inspection will be made by the District personnel, to verify that such works have been installed and constructed in accordance with the plans, designs and specifications approved by the District before the start of the construction. Before final approval or acceptance of any dedication to the District of a completed sewerage or drainage facility, the District shall determine whether or not all requirements due under terms of any and all permits issued by and contracts with the District with respect to such sewerage to drainage facilities have been satisfied. 11.020 Privately Constructed Sewers and Treatment Facilities All privately constructed sewers and sewage treatment facilities shall have obtained the proper permits and shall have had District inspection during construction, supplemented by a final inspection before approval as either a recoupment facility or for dedication acceptance upon completion. These sewers and facilities shall have had "As-built" plans submitted for final review and approval before dedication or acceptance for recoupment. 11.030 Maintenance and Operation Inspection Operation and maintenance of any private, semi-public or industrial sewage disposal, pump station or treatment facility shall be subject to inspection by the District at all times. 11.040 Fees For house connections and industrial connections, and for the repair of house connections and industrial connections, the inspection fee is combined with the permit fee. No permits will be issued for construction or repair of house and industrial connections, or for construction of sewerage and sewage disposal, pump station or treatment facilities until the required inspection fee or inspection fee has been paid to the District. 11.050 Inspection His/Her agent must notify the District 24 hours prior to commencing construction of permitted work. Failure to notify the District may result in the removal and replacement of the uninspected sewer and/or appurtenances. August 1, 2017 DRAFT FOR PUBLIC COMMENT 128 12. REGULATION AND CORRECTION OF IMPROPER PRIVATE SEWER FACILITIES 12.010 General Some buildings within the District's boundaries have leaking or failing septic tanks, sanitary lines which connect into storm sewers or discharge on open ground, broken or improper sanitary sewers, and other improper sewerage facilities, which constitute a public nuisance. Further, it is frequently impossible or impractical to persuade the Owner of such property to repair such sewers or to make a connection of such improper sewer facilities to a public sewer when such public sewer is available. Consequently, the following procedures and regulations are followed by the District. 12.020 Notification to Owner Whenever the District determines that any building has improper sewerage facilities which are creating a public nuisance and the use of such improper sewerage facilities is a menace to public health, the District shall send a notice to the owner or his agent by mail, informing him of such condition and permitting him a period of 30 days after date of such notice to correct such condition by making repairs or making such connection to a public sewer. The time of thirty (30) days can be extended at the discretion of the District. 12.030 Expiration of Period Without Work Being Done If the corrective work is not done within the thirty (30) day period given in Section 12.020 or the authorized extension thereof, the owner or his agent may appear before the Executive Director or his representative on the day and hour given in the notification (see Section 12.020) and show cause why the District should not make such repairs or make such connection with its own forces and assess the costs thereof as a tax against the property for which such work is done. 12.040 District to Proceed with Work Within 10 days after the owner or his agent have appeared to show cause why the District should not make such repairs or such connection, the Executive Director shall make his decision regarding such work. If, in his opinion, the owner or his agent have failed to show cause why such repair or construction should not be made, he shall direct the Director of Operations to estimate the probable cost of the work, and if such estimated cost does not exceed $5,000, to cause such work to be done under his direction and to his satisfaction, and an accurate account kept of the cost of all labor, including supervision, and material entering into such work. 12.050 Cost of Work - A Lien Upon completion of such work as is authorized as set out in Section 12.040, the District shall determine the actual total cost of the work, which shall be assessed as a special lien against each lot or ground chargeable therewith in the name of the owner thereof. Such assessments shall become a lien upon the property charged therewith upon filing with the Recorder of Deeds of the City of St. Louis or of St. Louis County, as the case may be. 12.060 Appeal from Decision to Proceed with Work Should the property owner or his agent be dissatisfied with the decision or order of the Executive Director or his authorized representative, to proceed with the repairs or construction, he may appeal the decision or order to the Board of Trustees of the District, by filing a written notice of appeal, which shall be served on the Executive Director within ten (10) days after such decision or order has been given. The Board of Trustees will then set the matter down for hearing within thirty (30) days. Should the Board, after a full and complete hearing, uphold the decision of the Executive Director or his authorized representative, then he may proceed as indicated in Section 12.040 and 12.050. Should the owner or his agent be still dissatisfied, he may appeal from such order or decision to the appropriate Circuit Court as set forth in Section 12.110 of the PLAN OF THE DISTRICT, except that the proceedings upon such order as appealed from the decision of the Board shall not be stayed unless a restraining order shall be granted by a court of competent jurisdiction. August 1, 2017 DRAFT FOR PUBLIC COMMENT 129 13. SEWAGE PUMPING STATIONS 13.010 General A sanitary sewage pump station will only be considered where a thorough study of all alternatives clearly indicates a gravity collection and disposal system is not practical or feasible. The minimum size of a pump station dedicated to the District shall have an average daily flow rate influent of 6 gallons per minute (GPM) or greater. In residential terms, this is 20 homes or more. Where the construction of a sanitary sewage pump station is being considered, the current guidelines regarding plan review procedures, construction drawing preparation, easements, specifications and acceptance will be provided by the District in a document called Pump Station Design Requirements (PSDR). Reasonable variances to the PSDR may be granted by the District. Variance requests must be made in writing and must clearly state why the variance is necessary. Additional protection of the existing downstream gravity system (e.g. coatings, linings) and odor control/treatment facilities may also be required. A brief summary of the plan review procedure is described below: 13.020 Pump Station Plan Review Procedure In order to comply with District asset management procedures, plans for the pump station and force main components of the project shall be submitted for review and approval separately from the plan submittal for the remainder of the development project (i.e. separate project numbers will be assigned for the pump station/force main project plans and for the development plans). The following material must be submitted to the District Engineering Department for review. 13.020.01 Design Report 1. The Pump Station Design Report shall be typed and bound in 8½ inch by 11 inch booklet form. 2. The following information shall be included in the report: a. Title page b. Sewer system information c. Pump station and force main design calculations d. Cycle times/Detention Pipe Design Calculations e. Summary of results from design calculations f. Manufacturer's specifications for the mechanical and electrical components g. Pump performance curves 13.020.02 Design Drawings 1. The design drawings shall be individual 24 Inch by 36 Inch Design Plan Sheets 2. The following information shall be included on the drawings: a. Cover sheet b. General site plan (Scale 1” = 50’) c. Pump station site plan (Scale 1/4 inch = 1 foot) d. Force main plan and profile (Scale 1” = 10’ vertical, 1” – 50’ horizontal?) e. Gravity sewer plan and profiles with elevations for the building lateral and the lowest finished floor connection indicated f. Pump station structure sheet (Scale ½ inch = 1 foot) g. Pump station mechanical sheet (Scale 1” = 1 foot) 4.f. Electrical plans and details j. Miscellaneous details (service panels, alarm towers, etc.) i. Pump station design requirements August 1, 2017 DRAFT FOR PUBLIC COMMENT 130 (*Note-Thrust Blocks are no longer required since change to certain approved mechanical joint restraints.) 13.020.03 Required Submittal For any project utilizing a pump station, three (3) additional sets of plans and a total of four (4) sets of pump station design report must be submitted to the Engineering Department. Refer to Section 1.040.02 of this manual for further information. Incomplete sets will not be reviewed by Engineering or the Pump Station Division and shall be returned to the Engineer with a request for missing material. 13.020.04 Preconstruction Meeting Required The developer’s contractor/drain layer shall arrange a preconstruction meeting with MSD Construction Inspection and Pump Station Division staff after permits are obtained for the pump station and force main work. This meeting is required prior to start of construction. 13.020.05 Pump Station Radio Connection Fee Each applicant for a construction permit that includes a pump station radio shall, at the time of filing a permit application pay the District a Radio Connection Fee. The current amount of the fee shall be as shown on the District website. This fee covers the cost of a radio supplied by the District and installed by the applicant. 13.030 Low Pressure Sewer Systems (LPSS) 13.030.01 General A sanitary sewage low pressure sewer system will only be considered where a thorough study of all alternatives clearly indicates a gravity collection and disposal system or a sewage pump station is not practical or feasible. This will include developments requiring pumping but fall below the 6 GPM average daily flow rate. Where the construction of a sanitary low pressure sewer system is being considered, the current guidelines regarding plan review procedures, construction drawing preparation, easements, specifications and acceptance will be provided by the District in a document called Low Pressure Sewer System Design Requirements. Additional protection of the existing downstream gravity system (e.g. coatings, linings) and odor control/treatment facilities may also be required. A brief summary of the plan review procedure is described below. 13.030.02 LPSS Plan Review Procedure In order to comply with District asset management procedures, plans for the LPSS portion of the project shall be submitted for review and approval separately from the plan submittal for the remainder of the development project (i.e. separate project numbers will be assigned for the LPSS project plans and for the development plans). The following material must be submitted to the District Engineering Department for review: 1. Low Pressure Sewer System Design Report: a. The Low Pressure Sewer System Design Report shall be typed and bound in 8-1/2” x 11” booklet form. b. The following information shall be included in the report: (1) Title page August 1, 2017 DRAFT FOR PUBLIC COMMENT 131 (2) Sewer system information (3) Pump station and force main design calculations (4) Downstream pump station detention pipe design calculations (5) Summary of results from design calculations (6) Pump performance curves 2. Design Drawings: a. The design drawings shall be individual 24” x 36” design plan sheets b. The following information shall be included on the drawings: (1) Cover sheet (2) General site plan (3) Force main plan and profile (4) Miscellaneous details 13.030.03 Required Submittal For any project utilizing a low pressure sewer system, three (3) additional sets of plans and a total of four (4) sets of the low pressure sewer system design report must be submitted to the Engineering Department. Refer to Section 1.040.02 of this manual for further information. Incomplete sets will not be reviewed by Engineering or the Pump Station Division and shall be returned to the Engineer with a request for missing material. 13.030.04 Preconstruction Meeting Required The developer’s contractor/drain layer shall arrange a preconstruction meeting with MSD Construction Inspection and Pump Station Division staff after permits are obtained for the LPSS work. This meeting is required prior to start of construction. August 1, 2017 DRAFT FOR PUBLIC COMMENT 132 14. APPENDIX – VOLUMETRIC METHOD Introduction The volumetric design procedure is to be used in cases where detention cannot be designed using the simple maximum release rate procedure and involves detailed modeling of the local tributary drainage system. The volumetric approach would be necessary to do the following: 1.• Determine the release rate when there are off-site upstream flows that cannot be bypassed around the detention facility. 2.• Determine whether a detention rate less than the prescribed watershed release rate might meet the planning criteria. 3.• Evaluate “interim” conditions when a regional detention facility is planned. 4.• Determine the detention basin release needed to compensate for development areas that cannot be drained to the detention pond. The volumetric procedure has been demonstrated to lead to detention basin designs that are consistent with the objectives and criteria established for the Stormwater System Master Improvement Plan (SSMIP). Procedures Regulatory Requirements and Approach Prior to conducting the analysis, the regulatory requirements for the watershed should be determined. This is best accomplished by meeting with MSD staff. At the meeting, the following information can be obtained: a.)• Planning watershed available information. b.)• MSD regulatory release rate. c.)• MSD special requirements due to special watershed problem or capacity limitations. d.)• Availability of MSD SWMM model at the project location. The meeting will assist the engineer in determining whether the volumetric approach is required and which computer model strategy is appropriate. An appropriate model such as SWMM, HEC-1, or TR-55 plus a routing package must be used. Analysis The following steps outline the basic modeling procedure to develop or verify a volumetric-based release rate for a detention facility. Some of this information may not be needed for simple cases: 1. Delineate sub-basins a. Proposed development area draining to pond. b. Proposed development area not draining to pond (should be minimized). c. Off-site areas draining to proposal pond. d. Off-site areas draining to proposed bypass. August 1, 2017 DRAFT FOR PUBLIC COMMENT 133 2. Define hydrologic parameters, such as area, % impervious, curve number, sub-basin width and time of concentration. Requirements depend on whether SWMM, HEC-1, or TR-55 is being used. Determine parameters for: a. Existing land use. b. Post development land use. 3. Determine design rainfall distributions for the 2-year and 100-year 24-hour storm events using the SCS TYPE II distribution. 4. Run Model for 100-year rainfall and obtain the following runoff hydrographs: a. Existing land use hydrograph for area to be developed plus off-site upstream area draining to detention basin. b. Future land use hydrograph for development plus off-site areas (using existing conditions) draining to detention basin. c. Future land use hydrograph for area to be developed but not draining to detention basin. d. Future conditions flow to be bypassed. 5. Determine Critical Time Period The critical time period will be based on SWMM model results developed during the MSD watershed planning. The critical time period will be determined by MSD using the following definitions: a. Start of Critical Time Period is the time of peak runoff from the proposed development under future land use conditions b. End of the critical time period is the peak of the existing conditions hydrograph at the downstream outlet of the watershed or as determined by previous study. If the SWMM watershed model is not yet available then an approximate critical time period will be defined as starting at the time of peak rainfall intensity with a duration equal to the time of concentration for the planning watershed. 6. Determine Critical Time Period outflow volume. This is the existing conditions runoff volume from the area to be developed plus any runoff from offsite area that will be routed through the detention basin. The volume is computed based on flow during the Critical Time Period from the hydrograph in step 4a. above. The runoff volume during the critical time period must be limited to this volume using detention. 7. Obtain first estimate of the release rate. The Critical Time Period outflow volume divided by the length of the critical time period in seconds is the average release rate allowed during the critical time period. 8. Obtain first estimate of required storage. The required storage is the difference between average release rate in 7. above and overall future hydrograph. (The overall future hydrograph may the sum of hydrographs 4b and 4c). 9. Conduct analysis of future detention. August 1, 2017 DRAFT FOR PUBLIC COMMENT 134 The hydrograph from step 4b. is routed through the proposed detention basin. The detention basin outflow is then combined with hydrograph from step 4c. if there is one. This is the proposed site outflow hydrograph. The site outflow volume during the critical time period must be less than or equal to the existing conditions volume for the same drainage area. Adjust outlet structure and storage volume until site outflow volume during critical period is equal to existing conditions target volume. 10. Repeat step 4 for the 2-year, 24-hour storm hydrograph. Adjust the outlet design as needed to limit 2-year flows to the prescribed maximum release. 11. Plot performance results Plot hydrographs of existing conditions flow (4a.) and proposed site outflow (routed pond outflow plus additional site runoff). The plot should show the critical time period and the target volume expressed as an average outflow. August 1, 2017 DRAFT FOR PUBLIC COMMENT 135 15. AMENDMENTS TO RULES AND REGULATIONS