[Ord. No. 08-1852 §1, 2-19-2008]
A.
When
a site development plan is submitted to the City that is considered
a redevelopment project, decisions on permitting and on-site stormwater
requirements shall be governed by special stormwater sizing criteria
found in the then current Metropolitan St. Louis Sewer District (MSD)
Storm Water Design Manual. These criteria are dependent on the amount
of impervious area created by the redevelopment and its impact on
water quality. Final authorization of all redevelopment projects will
be determined after a review by the City's Planning and Zoning Commission.
The City Engineer is to certify that the MSD sizing criteria is met
prior to the submittal of development plans to the Planning and Zoning
Commission.
B.
All site
designs shall establish stormwater management practices to control
the peak and overflow rates of stormwater discharge associated with
specified design storms and reduce the generation of stormwater. These
practices should seek to utilize pervious areas for stormwater treatment
and to infiltrate stormwater runoff from driveways, sidewalks, rooftops,
parking lots and landscaped areas to the maximum extent practical
to provide treatment for both water quality and quantity.
C.
All stormwater
runoff generated from new development shall not discharge untreated
stormwater directly into a jurisdictional wetland or local water body
without adequate treatment. Where such discharges are proposed, the
impact of the proposal on wetland functional values shall be assessed
using a method acceptable to the City and MSD. In no case shall the
impact on functional values be any more than allowed by the U.S. Army
Corps of Engineers (USCOE) or the Missouri Department of Natural Resources
(MDNR).
D.
Annual
ground water recharge rates shall be maintained by promoting infiltration
through the use of structural and non-structural methods. At a minimum,
annual recharge from the post-development site shall mimic the annual
recharge from pre-development site conditions, where such ground water
conditions are prevalent. Such rates, where applicable, shall be determined
prior to the submission of plans to the Planning and Zoning Commission.
E.
For a
new development, structural stormwater treatment practices shall be
designed to remove eighty percent (80%) of the average annual post-development
total suspended solids load (TSS). It is presumed that a BMP complies
with this performance standard if it is:
[Ord. No. 08-1852 §1, 2-19-2008; Ord. No. 09-1967 §3, 12-21-2009]
The most current or most recent edition of the MSD Rules and
Regulations and Engineering Design Requirements for Sanitary Sewer
and Stormwater Drainage Facilities, the MSD Site Design Guidance —
Tools For Incorporating Post-Construction Stormwater Quality Protection
into Concept Plans and Land Disturbance Permitting, in addition to
conditions and requirements set forth by St. Louis County Phase II
Stormwater Management Plan, shall serve as the City's Stormwater Design
Manual.
[Ord. No. 08-1852 §1, 2-19-2008]
A.
Stormwater
treatment practices that are designed and constructed in accordance
with these design and sizing criteria will be presumed to meet the
minimum water quality performance standards as follows:
|
|
Pollutant removal efficiencies:
| ||
|---|---|---|---|
|
|
Total Suspended Solids (TSS)
|
80%
| |
|
|
Total Phosphorus (TP)
|
40%
| |
|
|
Total Nitrogen (TN)
|
30%*
| |
|
|
Biochemical Oxygen Demand (BOD)
|
50%*
| |
|
|
Total Organic Carbon (TOC)
|
40%*
| |
|
|
Other Metals
|
40%*
| |
|
|
* Requirements subject to review for each development or redevelopment
site.
| ||
|
|
By methods using:
| ||
B.
In calculating
the minimum area for purposes of this Chapter, the measurements shall
not include any existing dedicated streets, roads or detention basins.
C.
There
shall be no stormwater discharged directly into a wetland or local
water body without adequate treatment. There shall be no stormwater
discharged in a manner that is inconsistent with applicable State
or Federal law.
D.
Any and
all stormwater measures and practices identified in the development
plans that were intended to remain in place after construction activities
have been completed shall be maintained as required by a maintenance
agreement.
E.
Each
post-construction stormwater quality measure approved as part of the
development plan shall be installed and maintained per the maintenance
agreement.
F.
The developer
shall provide the City with a narrative description of the maintenance
guidelines for all post-construction stormwater quality measures to
facilitate their proper long-term function and shall identify the
entity or entities responsible for long-term maintenance. It is an
obligation of the project owners and their successors in interest
to provide these narrative descriptions to future parties who acquire
interest in any portion of the real estate or who assume responsibility
for the operation and maintenance of the post-construction stormwater
quality measures.
G.
All drainage
systems and stormwater storage facilities shall be maintained in good
working order.
H.
Natural
drainage for any portion of the real estate not served by a constructed
drainage system shall be maintained.
I.
All erosion
sediment control systems installed on the site or identified as part
of the construction plan, unless such systems were temporary measures
only intended to be in place during construction, shall be maintained.
J.
All drainage
channels and swales installed or identified as part of the construction
plan shall be maintained so they do not cause erosion in the receiving
channel or at the outlet.
K.
All natural
features, such as wetlands and sinkholes, shall be protected from
stormwater runoff pollutants.
L.
The adequacy
of proposed facilities serving the development, including sanitary
sewers, water supply and distribution, stormwater control and recreational
areas, shall be verified to the satisfaction of the City.
M.
The general
layout of the internal street system serving the proposed development,
along with provisions for pedestrian circulation, shall be provided
to the City. The relationship of the proposed development with the
external transportation system serving the site should also be reviewed
for adequacy.
N.
The relationship
of land uses within the affected zoning district to each other and
the relationship of the land uses within affected zoning district
with surrounding external land uses, both present and future, shall
be indicated.
O.
The proposed
treatment of landscaping for the project, including the maintenance
of existing trees, shall be indicated.
[Ord. No. 08-1852 §1, 2-19-2008]
All stormwater management practices will be designed so that
the specific storm frequency storage volumes (e.g., recharge, water
quality, channel protection, 100 year) as identified in the current
Stormwater Design Manual are met, unless the City and MSD grants the
applicant a waiver or the applicant is exempt from such requirements.
In addition, if hydrologic or topographic conditions warrant greater
control than that provided by the minimum control requirements, the
City reserves the right to impose additional requirements deemed necessary
to control the volume, timing and rate of runoff. All supporting engineering
calculations shall be submitted to the City Engineer and the Planning
and Zoning Commission.
[Ord. No. 08-1852 §1, 2-19-2008]
A.
Stormwater
management practices for a site shall be chosen based on the physical
conditions of the site. Among the factors that will be considered
are the following:
B.
Applicants
shall consult the Stormwater Design Manual for guidance on the factors
that determine site design feasibility when selecting a proposed stormwater
management practice.
[Ord. No. 08-1852 §1, 2-19-2008]
A.
All stormwater
management practices shall be designed so as to allow for the maximum
removal of pollutants and reduction in flow velocities. This shall
include, but not be limited to:
B.
The Stormwater
Design Manual shall provide detailed guidance on the requirements
for conveyance for each of the approved stormwater management practices.
[Ord. No. 08-1852 §1, 2-19-2008]
A.
Every
stormwater treatment practice shall have an acceptable form of water
quality pretreatment, in accordance with the pretreatment requirements
found in the current Stormwater Design Manual. Certain stormwater
treatment practices, as specified in the Stormwater Design Manual,
are prohibited, even with pretreatment, in the following circumstances:
1.
Stormwater
is generated from highly contaminated source areas known as "hotspots".
a.
The
following land uses and activities have been deemed by MDNR and other
agencies as being stormwater hotspots:
(1)
Vehicle salvage yards and recycling facilities*
(2)
Vehicle service and maintenance facilities
(3)
Vehicle and equipment cleaning facilities*
(4)
Fleet storage areas (bus, truck, etc.)*
(5)
Industrial sites (reference SIC codes outlined in Appendix D.6. of
the EPA stormwater program)
(6)
Marinas (service and maintenance)*
(7)
Outdoor liquid container storage
(8)
Outdoor loading/unloading facilities
(9)
Public works storage areas
(10)
Facilities that generate or store hazardous materials*
(11)
Commercial container nursery
(12)
Other land uses and activities as designated by MDNR (refer to MDNR
website at http://www.dnr.mo.gov/env/wpp/permits/wpcpermits- stormwter.htm)
|
|
*Stormwater pollution prevention plan implementation is required
for these land uses or activities under the United States Environmental
Protection Agency (EPA) stormwater program (see Appendix D.6).
|
2.
As determined
by the MDNR, a separate permit from the State of Missouri may be required.
3.
Water
quality pretreatment involves the removal of pollutants from urban
runoff through the following types of mechanisms: sedimentation, flotation,
filtration, infiltration, adsorption, biological uptake, biological
conversion, degradation or other scientifically proven method.
4.
While
large highways (average daily traffic volume (ADT) greater than thirty
thousand (30,000) vehicles) and retail gasoline outlet facilities
are generally not designated as stormwater hotspots, it is important
to ensure that highway and retail gasoline outlet stormwater management
plans adequately protect ground water.
[Ord. No. 08-1852 §1, 2-19-2008]
All stormwater management practices shall be designed to capture
and treat stormwater runoff according to the specifications outlined
in the Stormwater Design Manual. These specifications designate the
water quantity and quality treatment criteria that apply to an approved
stormwater management practice.
[Ord. No. 08-1852 §1, 2-19-2008]
All stormwater management practices shall have a landscaping
plan detailing both the vegetation to be in the development or redevelopment
and how and who will manage and maintain this vegetation. All BMP
plans requiring extensive vegetation shall be properly designed by
a qualified professional such as a horticulturist, arborist, engineer,
landscape architect or soil conservation district.
[Ord. No. 08-1852 §1, 2-19-2008]
All stormwater treatment practices shall have an enforceable
operation and maintenance agreement to ensure the system functions
as designed. This agreement shall include any and all maintenance
easements required to access and inspect the stormwater treatment
practices, and to perform routine maintenance, as necessary, to ensure
proper functioning of the stormwater treatment facility. In addition,
a covenant specifying the parties responsible for the proper maintenance
of all stormwater treatment facilities shall be recorded with the
St. Louis County Recorder of Deeds prior to issuance of any permits
for land disturbance activities.
[Ord. No. 08-1852 §1, 2-19-2008]
A.
The use
of non-structural stormwater treatment practices is encouraged in
order to minimize the reliance on structural facilities. Credit in
the form of reductions in the amount of stormwater that must be managed
can be earned through the use of non-structural practices that reduce
the generation of stormwater from the site. These non-structural practices
are explained in detail in the current design manual and applicants
wishing to obtain credit for use of non-structural practices must
ensure that these practices are documented and remain unaltered by
subsequent property owners.
B.
All sites
must be properly stabilized before permanent stormwater BMPs are considered
complete.
