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final-rules-regs-amnd-15-oct-12-16-amend16-1 MSD Rules and Regulations and Engineering Design Requirements February 2006 Chapter 16 - Amendments Page Topic 16-2 Amendment No. 1, issued September 26, 2007 16-5 Amendment No. 2, issued July 1, 2010 16-10 Amendment No. 3, issued January 1, 2011 16-13 Amendment No. 4, issued October 15, 2012 16LD-1 List by Date Issued & Amendment # DELETED 16LS-1 List by Section DELETED 16-2 MSD Rules and Regulations and Engineering Design Requirements February 2006 Amendment No. 1 Date Issued: September 26, 2007 Affected Part: 4.080.02.3 Subject: Channel Protection Storage Volume Requirements (Cpv) Abstract: Changes to thresholds and conditions for exemption from requirements. Minor change to orifice size and protection. Changes shown in gray The text of subpart 4.080.02.3 is hereby and of this date amended to the following: 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). 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 4.080.02 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 16-3 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 Cpv may be provided above the WQv storage in stormwater ponds and wetlands; 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. 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 sites may be exempted from the channel protection storage requirement: A.) For sites 5 acres or larger, exempt if: 1.) No detention for Flood Protection Volume (Qp) is required, and 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) And either 4.) or 5.) below 16-4 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 will normally be exempt. C.) For all sites, regardless of size, 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. 16-5 Amendment No. 2 Date Issued: July 1, 2010 Affected Parts: 2.010, 8.020.02, 8.020.03, 8.020.04, 8.030.04, 8.030.05, 8.040, 8.050, 8.070, 9.020, 9.020.02, 9.020.05, 10.020, 10.030 Subject: Stormwater BMP permitting, deposits, and BMP inspection. Abstract: Changes permitting and inspection procedures necessary to facilitate better outcomes from BMP implementation, with greater flexibility for permitting BMPs and a separate BMP construction deposit. Changes shown in gray The text of the affected sections is hereby and of this date added or amended to the following: 2.010 Definitions 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 by detention. 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. 8. APPROVAL AND DEDICATION OF PROJECTS WITH PUBLIC SEWERS AND/OR DISTRICT INSPECTED PRIVATE FACILITIES 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 "Cash Deposit Agreement Guaranteeing Completion of Sewer Improvements". 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 permits will be issued. One original will be returned to the Owner upon execution by the District. 16-6 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. 8.030.04 Stormwater Quality Management Facilities and Cash Deposit Agreement Construction of Stormwater Quality Management Facilities is not required for construction approval. However, prior to the issuance of construction approval: a. The project owner shall execute a "Cash 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. The permittee shall apply for all stormwater BMP permits. The owner executed “Cash Deposit Agreement Guaranteeing Completion of Stormwater Quality Management Facilities" and associated deposit shall be provided to MSD before stormwater BMP permits are issued. 8.030.05 Notification of Construction Approval (New Section Number Only. Formerly 8.030.04) 8.040 Requirements for District Approval of Stormwater Quality Management Facility Construction 8.040.01 Construction Inspection 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 Cash Deposit will be released without the District issuing the BMP Construction Completion Letter. 16-7 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 Escrow (New Section Number Only. Formerly 8.040) 8.050.01 Residential and Commercial Subdivisions, Apartments and Condominiums (New Section Number Only. Formerly 8.040.01) 8.050.02 Sewer Extensions and Single Lot Developments New Section Number Only. Formerly 8.040.02) 8.050.03 Dedication Inspection Fees (New Section Number Only. Formerly 8.040.03) 8.060 Pump Stations (New Section Number Only. Formerly 8.050) 8.070 Abandonment of Work (New Section Number Only. Formerly 8.060) 8.080 Release of Stormwater Quality Management Facilities Cash 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 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 16-8 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 escrow will be released as part of the dedication process. 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 or a cashier’s check, or wire transfer. No vouchers or Letters of Credit 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 Deposits, and As-Built Deposit must be remitted from the Owner, not the Contractor or Engineer. 9.020.02 Construction Deposit The Owner will be required to submit to the District a Construction Deposit in the amount of 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). The Deposit amount will be computed by the District at the time of request for required number of plans. Release of the Construction Deposit will be made as stated in Chapter 8.050. 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. 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. 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. 16-9 10.030 Performance Bond [Amended by Amendment 4] Excluding permits for certain aboveground 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. 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 Appointing Authority. All bonds must be executed by a surety company satisfactory to the District and 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. The surety company must have a policyholder's rating of "A" or better and a financial rating of Class V or higher in BEST'S KEY RATING GUIDE, latest edition. 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. 16-10 Amendment No. 3 Date Issued: January 1, 2011 Affected Parts: 4.080.01, 8.020.02, 8.030.04, 8.04.01, 8.050, 8.080, 9.020, 9.020.02, 9.020.05 Subject: Letters of Credit & Stormwater Management Criteria Abstract: Outlines requirements for District acceptance of Letters of Credit (LOC) for construction and BMP deposits. Includes current stormwater BMP requirements required from the existing Phase II stormwater permit (i.e., the 2008-2013 small MS4 NPDES Stormwater Permit). Changes shown in gray The text of the affected sections is hereby and of this date added or amended to the following: 4.080 General Performance Criteria for Stormwater Management 4.080.01 When Required 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. 8.020.02 Construction Deposit and Construction 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 the 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. 16-11 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: 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. The permittee shall apply for all stormwater BMP permits. The owner executed construction deposit agreement guaranteeing completion of stormwater quality management facilities and associated deposit shall be provided to MSD before stormwater BMP permits are issued. 8.040.01 Construction Inspection 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. 8.050 Dedication and Release of Construction Deposit (New Title Only) 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 16-12 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 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. 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 or Letters of Credit 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 Deposits, and As-Built Deposit must be remitted from the Owner, not the Contractor or Engineer. 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 (see9.020.05 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 required number of plans. Release of the Construction Deposit will be made as stated in Chapter 8.050. 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. 16-13 Amendment No. 4 Date Issued: October 15, 2012 Affected Parts: 3.030.08, 3.030.09, 4.060, 4.070, 4.080.02, 4.080.05, 4.100, 10.030, and 10.090. Subject: Design Requirements for Sanitary Sewers, Requirements for Storm Drainage Facilities, and Construction Permits Abstract: Modifies maximum infiltration rates per MDNR, modifies protection from surcharging wording, updates Figures 3-1 and 3-2 to match local plumbing codes, deletes limitations to areas draining across sidewalks or driveways, deletes threshold for required impervious area to be sewer connected, adds miscellaneous clarifications on storm water quality volume and BMP options, revises Table 4-5 Storm Water Management Requirements for Harlem and Baden Watersheds, and Other Watersheds as Directed by the District, modifies Performance Bond requirements, and updates insurance requirements. Changes shown in gray The text of the affected sections is hereby and of this date added or amended to the following: 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 two hundred (100) (200) 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 5. Location in Conjunction with Water Service Sanitary sewers and manholes shall be at least ten (10) feet horizontally from any existing or proposed water main. 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. MoDNR provisions for waiver will be considered on a case by case basis. 14. 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. 16-14 Due to sewer overcharge and water backup potential, gravity sewer service to basements Is prohibited in some combined sewer areas and as directed by the District in known problem areas served by separate sanitary sewers. This requirement is for all new construction and all rehabilitation construction. Strapped plumbing and grinder pumps serving individual basements shall be used as necessary (See Figure 4-5). Limited variance to this rule will only be granted per the District review of project plans. All variance requests shall be submitted as a District “P-job” for formal review and must include elevations and demonstration of existing sewer system capacity or other allowable relief. 16-15 Figure 3-1 below replaces old SHT NO. 1 OF 2 dated JUNE 2006 Figure 3-1 16-16 Figure 3-2 below replaces old SHT NO. 2 OF 2 dated JUNE 2006 Figure 3-2 16-17 4.060 Limitations on Areas Draining Across Sidewalks or Driveways This section has been removed. 4.070 Impervious Areas – In City of St. Louis This section has been removed. 4.080.02 Unified Stormwater Sizing Criteria 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 site area. The WQv is directly related to the amount of impervious cover created 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 water quality volume WQv for offsite areas is not required. 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) Offsite Drainage Areas: The WQv shall be based on the impervious cover of the proposed site. Offsite existing impervious areas may be excluded from the calculation of the water quality volume requirements. (5)(4) BMP Treatment: The final WQv shall be treated by an acceptable BMP(s) from the list presented in Section 4.080.05, or as approved by the District. (6)(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 4.080.06. (7)(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. 16-18 4.080.05 Acceptable Urban BMP Options d. 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. 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). Wetlands shall not be used for control of water quantity (i.e. flood protection volume). c. Wetlands shall be designed by a qualified and experienced team. 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 infiltration b. Filtering practices may be allowed on commercial projects. They are not allowed on residential projects. c. A maintenance agreement and maintenance schedule shall be required. 16-19 4.100 Detention Report 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. 16-20 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. See “Rules and Regulations and Engineering Design Requirements for Sanitary Sewage and Stormwater Drainage Facilities”, Chapter 4, Section 4.080.02. Differential runoff of 5 cfs or less, use “Zero Increase” for all watersheds and both routing frequencies. **Differential runoff and detention routings should be computed from a completely undeveloped condition for projects in the Harlem & Baden watersheds, Grand & Bates (March 9, 2001) sewershed, and other sewersheds as may be directed by the District, in the City of St. Louis. System capacity has been found overcharged for rainfall events as small as once every two (2) years. Physical limitations of the site may be considered in special cases. **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 16-21 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 4.080.02.2.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. 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. 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. 16-22 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. 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. 10.090 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 indicating that the permittee has obtained and will continue to carry commercial general liability and comprehensive automobile liability. 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: 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 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-thru” 16-23 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. 10.090.02 Commercial General Liability (occurrence form): The Commercial General Liability (CGL) policy shall include the following: 1. Premises – Operations Liability 2. Blanket Contractual Liability 3. Completed Operations Liability 4. Contractor’s Protective Liability (Independent Contractors) 5. Personal Injury Liability 6. Broad Form Property Damage Liability Endorsement 7. Coverage for explosion, collapse and underground hazards (XCU) 8. Blasting (provided that blasting coverage may be excluded if not to be performed in connection with the work) 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 (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 Combined Single Limit per occurrence per project $1,000,000 Personal Injury $1,000,000 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. 16-24 10.090.03 Cancellation & 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.