HomeMy Public PortalAbout46085816-1
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
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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
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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
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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.
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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.