[R.O. 2008 §560.060; Ord. No. 5430 §1, 6-25-1996; Ord. No. 8147, 12-10-2018]
A. In developing plans for a residential/commercial subdivision, individual
lots in a residential/commercial subdivision development shall not
be considered to be separate land-disturbing activities and shall
not require individual storm water management permits. Instead, the
residential/commercial subdivision development, as a whole, shall
be considered to be a single land-disturbing activity. Hydrologic
parameters that reflect the ultimate subdivision development shall
be used in all engineering calculations. Individual lot development
with new dwellings or any structure which has more than fifty percent
(50%) added to existing square footage shall require submittal of
topographical maps with before and after elevations for the entire
perimeter of the lot.
1.
If individual lots or sections in a residential/commercial subdivision
are being developed by different property owners, all land-disturbing
activities related to the residential/commercial subdivision shall
be covered by the approved storm water management plan for the residential/commercial
subdivision. Individual lot owners or developers shall sign a certificate
of compliance that all activities on that lot will be carried out
in accordance with the approved storm water management plan for the
residential/commercial subdivision. (See Exhibits A and B of Ord.
No. 5430 which are on file in the City offices).
2.
Residential/commercial subdivisions which were approved for
construction by the City Council prior to the effective date of these
regulations are exempt from these requirements. Development of new
phases of existing subdivisions which were not previously approved
shall comply with the provisions of these regulations.
B. For residential land-disturbing activities involving less than one (1) acre of actual land disturbance which are not part of a larger common plan of development or sale, the person responsible for the land-disturbing activity shall submit a simplified storm water management plan to the Public Works Department meeting the requirements listed below. This plan does not require approval by the municipality and does not require preparation of certification by the designers specified in Section
560.160 of Article
II. All commercial developments regardless of size must conform to Article
II, Sections
560.070 through
560.160, unless a waiver is granted by the municipality.
1.
A narrative description of the storm water management facilities
to be used.
2.
A general description of topographic and soil conditions of
the development site.
3.
A general description of adjacent property and a description
of existing structures, buildings, and other fixed improvements located
on surrounding properties.
4.
A sketch plan to accompany the narrative which shall contain:
a.
A site location drawing of the proposed project, indicating
the location of the proposed project in relation to roadways, jurisdictional
boundaries, streams and rivers;
b.
The boundary lines of the site on which the work is to be performed;
c.
All areas within the site which will be included in the land-disturbing
activities shall be identified and the total disturbed area calculated;
d.
A topographic map of the site;
e.
Anticipated starting and completion dates of the various stages
of land-disturbing activities and the expected date the final stabilization
will be completed; and
f.
The location of temporary and permanent vegetative and structural
storm water management control measures.
5.
Storm water management plans shall contain certification by
the person responsible for the land-disturbing activity that the land-disturbing
activity will be accomplished pursuant to the plan. (See Exhibit C
of Ord. No. 5430 which is on file in the City offices.)
6.
Storm water management plans shall contain certification by
the person responsible for the land-disturbing activity of the right
of the municipality to conduct on-site inspections. (See Exhibit D
of Ord. No. 5430 which is on file in the City offices.)
7.
The municipality reserves the right to require storm water management preparation as in Article
II, Section
560.130, as recommended by the Director of Public Works.
C. For residential land-disturbing activities disturbing greater than or equal to one (1) acre or less than one (1) acre if part of a common development plan of one (1) acre or more and all commercial land-disturbing activities, the requirements of Article
II, Sections
560.070 through
560.160, shall apply.
[R.O. 2008 §560.070; Ord. No. 5430 §1, 6-25-1996]
A. A storm
water concept plan for development shall be submitted for review by
the Public Works Department prior to submission of the storm water
management plan and construction plans for the entire development,
or any portion thereof. The storm water concept plan must identify
the location and type of facilities to be constructed in sufficient
detail to accurately estimate construction costs and enable the Public
Works Department to determine if a storm water management plan is
needed. If they determine a final storm water management plan is not
needed, the storm water concept plan then becomes the storm water
management plan for this development.
B. All preliminary plats of the development shall be consistent with the storm water concept plan required in Subsection
(A), above.
C. Upon
approval of the concept plan by the Director of Public Works, the
applicant shall submit a final storm water management plan (as part
of the construction plans) to the City Council for review and approval.
D. Should
any storm water management plan involve any storm water management
facilities or land to be dedicated to public use, the same information
shall also be submitted for review to the department having jurisdiction
over the land or other appropriate departments or agencies prior to
submission to the City Council for review and approval. The final
storm water management plan shall serve as the basis for all subsequent
construction.
E. If
disapproved by the City Council, the storm water management plan may
be reviewed with the designer, where it will either be changed, modified
or resubmitted. If rejected, changes, additional analysis or other
information needed to approve the next submittal of the concept plan
shall be identified by the City Council. After the receipt of the
revised storm water management plan, the City Council shall issue
a decision approving, rejecting or conditionally approving the plan
with modification.
[R.O. 2008 §560.080; Ord. No. 5430 §1, 6-25-1996]
A. No
final occupancy permit shall be issued without the following:
1. Recorded easement for storm water management facilities.
2. Receipt of an as-built plan which includes a certification of the
storm drainage system.
B. No
site grading permit shall be issued or modified without the following:
1. Right of entry for emergency maintenance if necessary. (See Exhibit
E & F of this Ord. No. 5430 which are on file in the City offices.)
2. Right of entry for inspections. (See Exhibits E & F of this Ord.
No. 5430 which are on file in the City offices.)
3. Any off-site easement needed.
4. An approved storm water concept plan or storm water management plan,
as appropriate.
5. An approved storm water ownership and maintenance plan.
C. The
approved storm water management plan shall contain certification by
the applicant that all land clearing, construction, development and
drainage will be done according to the storm water management plan
or previously approved revisions. Any and all site grading permits
may be revoked at any time if the construction of storm water management
facilities is not in strict accordance with approved plans. (See Exhibit
C of this Ord. No. 5430 which is on file in the City offices.)
D. In
addition to the plans and permits required from the municipality,
applicants shall obtain all State and Federal permits required for
the proposed development.
[R.O. 2008 §560.090; Ord. No. 5430 §1, 6-25-1996]
A list of fees for plan review and other fees associated with
this Chapter can be obtained from the Public Works Department.
[R.O. 2008 §560.100; Ord. No. 5430 §1, 6-25-1996]
A. A site
grading permit may be suspended or revoked if one (1) or more of the
following violations have been committed:
1. Violation(s) of the conditions of the storm water management plan
as approved;
2. Construction not in accordance with the approved plans;
3. Non-compliance with correction notice(s). (See Exhibit G of this
Ord. No. 5430 which is on file in the City offices) or stop work order(s),
(see Exhibit H of this Ord. No. 5430 which is on file in the City
offices); or
4. The existence of an immediate danger in a downstream area in the
judgment of the Director of Public Works or his/her designee.
B. If
one (1) or more of these conditions are found, a written notice of
violation(s) shall be served upon the owner or authorized representative
and an immediate stop work order may be issued. The notice shall set
forth the measures necessary to achieve compliance with the plan.
Correction of these violations must be started immediately or the
owner shall be deemed in violation of this Chapter.
[R.O. 2008 §560.110; Ord. No. 5430 §1, 6-25-1996]
A. The
minimum storm water control requirements shall provide management
measures necessary to accomplish the following:
1. Install storm water management facilities to limit the 2-year and
10-year developed peak discharge rates to pre-developed peak discharge
rates. The design of these facilities shall be based on procedures
contained in the Storm Water Management Design Guide or procedures
approved by the Director of Public Works. The 2-year and 10-year design
storms cover the range of normal flooding. Structures must be analyzed
for both. The 25-year storms are commonly used for structures under
roadways.
2. The requirements or portions thereof, of Subsection
(A)(1) above, may be waived by the City Council if it can be shown by the detailed engineering calculations and analysis which are acceptable to the municipality that one (1) of the following exists:
a. The installation of storm water management facilities would have
insignificant effects on reducing downstream flood peaks;
b. Storm water management facilities are not needed to protect downstream
developments and the downstream drainage system has sufficient capacity
to receive any increase in runoff for the design storm;
c. It is not necessary to install storm water management facilities
to control developed peak discharge rates at the exit to a proposed
development and installing such facilities would increase flood peaks
at some downstream locations; or
d. The Public Works Department determines that storm water management
facilities are not needed to control developed peak discharge rates
and installing such facilities would not be in the best interest of
the municipality.
3. The requirements or portions thereof, of Subsection
(A)(1) above, may not be waived if the municipality determines that not controlling downstream flood peaks would increase known flooding problems, or exceed the capacity of the downstream drainage system.
4. A waiver shall only be granted after a written request is submitted
to the City Manager through the Public Works Department by the applicant
containing descriptions, drawings, and any other information that
is necessary to evaluate the proposed land disturbing activity. A
separate written waiver request shall be required if there are subsequent
additions, extensions, or modifications which would alter the approved
storm water runoff characteristics to a land disturbing activity receiving
a waiver. The municipality will conduct a review of the request for
a waiver.
5. Discharge velocities shall be reduced to provide a non-erosive velocity
flow from a structure, channel or other control measure or the velocity
of the 10-year design storm runoff in the receiving waterway prior
to the land disturbing activity, whichever is greater.
B. For
all storm water management facilities, a hydrologic-hydraulic study
shall be done showing how the drainage system will function with and
without the proposed facilities. For such studies the following land
use conditions shall be used. Existing land use data shall be taken
from the most recent aerial photography and field checked and updated.
1. For the design of the facility outlet structure, use developed land
use conditions for the area within the proposed development and existing
land use conditions for upstream areas draining to the facility.
2. For any analysis of flood flows downstream from the proposed facility,
use existing land use conditions for all downstream areas.
3. All storm water management facilities emergency spillways shall be
checked using the 100-year storm and routing flows through the facility
and emergency spillways. For this analysis, developed land use conditions
shall be used for all areas within the analysis.
4. If accepted for municipal maintenance, the effects of existing upstream
detention facilities can be considered in the hydrologic-hydraulic
study.
[R.O. 2008 §560.120; Ord. No. 5430 §1, 6-25-1996]
A. Storm
water management facilities may include both structural and non-structural
elements. Natural swales and other natural runoff conduits shall be
retained where practicable.
B. When
additional storm water management facilities are required to satisfy
the minimum control requirements, the following measures are examples
of what may be used:
1. Storm water detention structures (dry basins);
2. Storm water retention structures (wet ponds — minimum depth
six (6) feet);
3. Facilities designed to encourage overland flow, slow velocities of
flow and flow through buffer zones;
C. Where
detention and retention structures are used, designs which consolidate
these facilities into a limited number of large structures will be
preferred over designs which utilize a large number of small structures.
D. Storm
water management plans can be rejected by the municipality if they
incorporate structures and facilities that will demand considerable
maintenance, will be difficult to maintain or utilize numerous small
structures if other alternatives are physically possible.
E. The
drainage system and all storm water management structures within the
municipality (including both public and private portions) will be
designed to the same engineering and technical criteria and standards.
The municipality's review will be the same whether the portion of
the drainage system will be under public or private control or ownership.
F. All
storm water management measures shall be designed in accordance with
the design criteria contained in the Storm Water Management Design
Guide using procedures contained in this manual or procedures approved
by the municipality.
[R.O. 2008 §560.130; Ord. No. 5430 §1, 6-25-1996]
A. Storm
water management plans shall include as a minimum the following:
1. A vicinity map indicating a north arrow, scale, boundary lines of
the site and other information necessary to locate the development
site.
2. The existing and proposed topography of the development site.
3. Physical improvements on the site, including present development
and proposed development.
4. Location, dimensions, elevations and characteristics of all storm
water management facilities.
5. All areas within the site which will be included in the land disturbing
activities shall be identified and the total disturbed area calculated.
6. The location of temporary and permanent vegetative and structural
storm water management control measures.
7. An anticipated starting and completion date of the various stages
of land disturbing activities and the expected date the final stabilization
will be completed.
8. A determination that no occupied first (1st) floor elevation of any
structure is below the 100-year plus one (1) foot flood elevation.
9. At the direction of the Director of Public Works, for all portions
of the drainage system which are expected to carry between fifty (50)
and one hundred fifty (150) cfs for the 100-year storm, the 100-year
plus one (1) foot flood elevation analysis, the Public Works Department
will determine that one (1) of the following conditions may exist:
a. The estimated runoff would create a hazard for adjacent property
or residents.
b. The flood limits would be of such magnitude that adjacent residents
should be informed of these limits.
10. For all portions of the drainage system which are expected to carry
one hundred fifty (150) cfs or more for the 100-year storm, the 100-year
plus one (1) foot flood elevation analysis shall be done and flood
limits shall be shown on the storm water management plans.
11. Storm water management plans shall include designation of all easements
needed for inspection and maintenance of the drainage system and storm
water management facilities. As a minimum, easements shall have the
following characteristics:
a. Provide adequate access to all portions of the drainage system and
structures.
b. Provide sufficient land area for maintenance equipment and personnel
to adequately and efficiently maintain the system with a minimum of
ten (10) feet along both sides of all drainage ways, streams, channels,
etc., and around the perimeter of all detention and retention facilities
or sufficient land area for equipment access for maintenance of all
storm water management facilities. The distance shall be measured
from the top of the bank or toe of the dam whichever is applicable.
c. Restriction on easements shall include prohibiting all fences and
structures which would interfere with access to the easement areas
and/or the maintenance function of the drainage system.
12. To improve the aesthetic aspects of the drainage system, a landscape
plan for all portions of the drainage system shall be part of the
storm water management plan. This landscape plan shall address the
following:
a. Tree saving and planting plan.
b. Types of vegetation that will be used for stream bank stabilization,
erosion control, sediment control, aesthetics and water quality improvement.
c. Any special requirements related to the landscaping of the drainage
system and efforts necessary to preserve the natural aspects of the
drainage system.
13. To improve the water quality aspects of the drainage system, the
storm water management plan shall include best management practices
to control the water quality of the runoff during the land disturbing
activities and during the life of the development. This requirement
is in addition to the requirements of the Missouri Department of Natural
Resources Storm Water Pollution Prevention Permit.
14. The storm water management plans shall include all engineering calculations
needed to design the system and associated structures including pre-
and post-development velocities, peak rates of discharge and inflow
and outflow hydrographies of storm water runoff at all existing and
proposed points of discharge from the site.
15. Description of site conditions around points of all surface water
discharge including vegetation and method of flow conveyance from
the land disturbing activity.
16. Construction and design details for structural controls.
17. The expected timing of flood peaks through the downstream drainage
system shall be assessed when planning the use of detention facilities.
18. In determining downstream effects from storm water management structures
and the development, hydrologic-hydraulic engineering studies shall
extend downstream to a point where the proposed development represents
less than ten percent (10%) of the total watershed.
19. All storm water management facilities and all major portions of the
conveyance system through the proposed development (i.e., channels,
culverts) shall be analyzed, using the design and 100-year storms
for design conditions and operating conditions which can reasonably
be expected during the life of the facility. The results of the analysis
shall be included in the hydrologic-hydraulic study.
20. If the storm water management plan and/or design report indicates
that there may be a drainage or flooding problem at the exit to the
proposed development or at any location between the exit point and
the ten percent (10%) downstream point, the Director of Public Works
may require:
a. Water surface profiles plotted for the conditions of pre- and post-development
for the 100-year design storm;
b. Water surface profiles plotted for the conditions of pre- and post-development
for the 100-year design storm;
c. Elevations of all structures potentially damaged by the 10- and/or
100-year flows.
21. All storm water management plans submitted for approval shall contain
certification by the person responsible for the land disturbing activity
that the land disturbing activity will be accomplished pursuant to
the approved plan and that responsible personnel will be assigned
to the project. (See Exhibit C of this Ord. No. 5430 which is on file
in the City offices).
22. All storm water management plans shall contain certification, by
the person responsible for the land disturbing activity, of the right
of the Municipality to conduct on-site inspections. (See Exhibit D
of this Ord. No. 5430 which is on file in the City offices).
23. No storm water management plan shall be considered approved without
the inclusion of an approval signature and date on the plans by the
Director of Public Works or his/her designee. The approval on the
plans is solely an acknowledgement of satisfactory compliance with
the requirements of these regulations. The approval does not constitute
a representation or warranty to the applicant or any other person
concerning the safety, appropriateness or effectiveness of any provision
or omission from the storm water management plan.
24. Approved storm water management plans remain valid for five (5) years
from the date of approval. Extensions or renewals of the plan approvals
may be granted by the City Manager upon written request by the person
responsible for land disturbing activity.
[R.O. 2008 §560.140; Ord. No. 5430 §1, 6-25-1996]
A. The
hydrologic criteria to be used for the storm water concept and storm
water management plans shall be as follows:
1. 25-year design storm for all cross-drain culverts and drainage designs.
2. 10-year design storm for all interior culverts and drainage designs.
3. 2- and 10-year design storms for all detention and retention basins
using procedures contained in the Storm Water Management Design Guide
or approved by the Public Works Department.
4. All drainage designs shall be checked using the 100-year storm for
analysis of local flooding and possible flood hazards to adjacent
structures and/or property.
5. All hydrologic analysis will be based on land use conditions specified in Section
560.110(B).
6. For the design of storage facilities, a secondary outlet device or
emergency spillway shall be provided to discharge the excess runoff
in such a way that no danger of loss of life or facility failure is
created. The size of the outlet device or emergency spillway shall
be designed to pass the 100-year storm as a minimum requirement.
[R.O. 2008 §560.150; Ord. No. 5430 §1, 6-25-1996]
A. Following
are the criteria related to using storm water management facilities
for water quality purposes:
1. Ponds, lakes and reservoirs.
a. When the land disturbing activity consists of the construction of
a pond, lake or reservoir which is singly built and not part of a
permitted land disturbing activity, the following procedures will
apply:
(1)
A storm water management plan will not be required if the pond,
lake or reservoir is permitted under the State Dams and Reservoirs
Safety Act or has received a Certificate of Exemption from the State
Dams and Reservoirs Safety Act. Best management practices should be
used to minimize the impact of erosion and sediment.
(2)
A storm water management plan will be required for the construction
of all ponds, lakes or reservoirs not meeting the conditions in (1)
above that otherwise meet the size requirement for storm water management
plan approval.
b. When ponds are used for water quality protection, the ponds shall
be designed as both quantity and quality control structures. Sediment
storage volume shall be calculated considering the clean out and maintenance
schedules specified by the designer during the land disturbing activity.
Sediment storage volumes may be predicted by the Universal Soil Loss
Equation or other methods acceptable to the Director of Public Works.
c. Storm water runoff and drainage to a single outlet from land disturbing
activities which disturb ten (10) acres or more shall be controlled
during the land disturbing activity by a sediment basin where sufficient
space and other factors allow these controls to be used until the
final inspection. The sediment basin shall be designed and constructed
to accommodate the anticipated sediment loading from the land disturbing
activity and meet a removal efficiency of eighty percent (80%) suspended
solids or 0.5 ML/L peak set table solids concentration, whichever
is less. The outfall device or system design shall take into account
the total drainage area flowing through the disturbed area draining
to the basin.
d. Other practices may be acceptable to the municipality if they achieve
an equivalent removal efficiency of eighty percent (80%) for suspended
solids or 0.5 ML/L peak set table solids concentration, whichever
is less. The efficiency shall be calculated for disturbed conditions
for the 10-year twenty-four (24) hour design storm event.
e. Permanent water quality ponds having a permanent pool shall be designed
to store and release the first (1st) one-half (½) inch of runoff
from the site over a twenty-four (24) hour period. The storage volume
shall be designed to accommodate, at least, one-half (½) inch
of runoff from the entire site.
f. Permanent water quality ponds, not having a permanent pool, shall
be designed to release the first (1st) inch of runoff from the site
over a twenty-four (24) hour period.
g. The use of measures other than ponds to achieve water quality improvement
are recommended on sites containing less than ten (10) disturbed acres.
2. Infiltration practices.
a. Permanent infiltration practices, when used, shall be designed to
accept, at a minimum, the first (1st) inch of runoff from all impervious
areas.
b. Area drainage to infiltration practices must be established and vegetative
filters established prior to runoff entering the system. Infiltration
practices shall not be used if a suspended solids filter system does
not accompany the practice. If vegetation is the intended filter,
there shall be at least a twenty (20) feet width of vegetative filter
prior to storm water runoff entering the infiltration practice.
c. The bottom of the infiltration practice shall be at least two (2)
feet above the seasonal high water table, whether perched or regional,
determined by direct piezometer measurements which can be demonstrated
to be representative of the maximum height of the water table on an
annual basis during years of normal precipitation or by the depth
in the soil at which mottling first occurs.
d. The infiltration practice shall be designed to completely drain of
water within seventy-two (72) hours.
e. Soils must have adequate permeability to allow water to infiltrate.
Infiltration practices are limited to soils having an infiltration
rate of at least 0.30 inches per hour. Initial consideration will
be based on a review of the appropriate soil survey, and the survey
may serve as a basis for rejection. On-site soil borings and textural
classifications must be accomplished to verify the actual site and
seals on high water table conditions when infiltration is to be utilized.
f. Infiltration practice greater than three (3) feet deep shall be located
at least ten (10) feet from basement walls.
g. Infiltration practices designed to handle runoff from impervious
parking areas shall be a minimum of one hundred fifty (150) feet from
any public or private water supply well.
h. The design of infiltration practice shall provide an overflow system
with measures to provide a non-erosive velocity of flow along its
length and at the outfall.
i. The slope of the bottom of the infiltration practice shall not exceed
five percent (5%). Also, the practice shall not be installed in fill
material, as piping along the fill/natural ground interface may cause
slope failure.
j. An infiltration practice shall not be installed on or atop a slope
whose natural angle of incline exceeds twenty percent (20%).
k. Clean outs will be provided, at a minimum, every one hundred (100)
feet along the infiltration practice to allow for access and maintenance.
[R.O. 2008 §560.160; Ord. No. 5430 §1, 6-25-1996]
A. Storm
water concept and storm water management plans and design reports
that are incidental to the overall or ongoing site design shall be
prepared, certified, and stamped/sealed by a qualified registered
Missouri professional engineer, land surveyor, or landscape architect
using acceptable engineering standards and practices. All other storm
water concept, and storm water management plans and design reports
shall be prepared, certified and stamped/sealed by a qualified registered
Missouri professional engineer using acceptable engineering standards
and practices.
B. The
engineer, surveyor or landscape architect shall perform services only
in areas of his/her competence and shall undertake to perform engineering
or land surveying assignments only when qualified by education and/or
experience in the specific technical field. In addition, the engineer,
surveyor or landscape architect must verify that the plans have been
designed in accordance with this Chapter and the standards and criteria
stated or referred to in this Chapter.