[1]
Editor's Note: The procedural manual "Stormwater Management Procedures" was adopted 9-20-2021 by Ord. No. 1550 and is on file with the City Administrator.
[R.O. 2008 § 420.010; R.O. 2004 § 520.010; CC 1990 § 520.010; Ord. No. 638 § 1, 1-4-1988; Ord. No. 787 § 1, 12-16-1993]
This Chapter seeks to provide those standards, criteria, procedures and controls necessary to minimize the harmful physical and economic effects of erosion and flooding from stormwater within or directed toward the City of Pevely. This is to be accomplished through the requirement of special measures to mitigate erosion both during and after development and the retention and controlled discharge of the runoff from any property whereon any grading, excavation, filling or other disturbance of the natural vegetation or any construction, erection or alteration of a building or structure is to be undertaken.
[R.O. 2008 § 420.020; R.O. 2004 § 520.020; CC 1990 § 520.020; Ord. No. 638 § 1, 1-4-1988; Ord. No. 787 § 1, 12-16-1993; Ord. No. 1172 § 1, 8-4-2008]
A. 
Definitions. As used in this Chapter, the following terms shall have these prescribed meanings:
DEVELOPED PROPERTY
Any tract of land in the City of Pevely whereon any grading, excavation, filling or other disturbance of the natural vegetation, or any construction, erection or alteration of a building or structure has been undertaken.
PROPERTY
Any tract of land in the City of Pevely.
UNDEVELOPED PROPERTY
Any tract of land in the City of Pevely whereon neither grading, excavation, filling or other disturbance of the natural vegetation, nor any construction, erection or alteration of a building or structure has been undertaken.
B. 
General. A stormwater runoff control permit is required for all development. Except as provided in Subsection (F) of this Section, it shall be unlawful for any person to develop or improve on any property within the City unless there is in force a stormwater runoff control permit issued as required under the provisions of this Chapter.
C. 
Construction Or Alteration Of Buildings. Except as provided in Subsection (F) of this Section, it shall be unlawful for any person to construct any new building or structure or to enlarge or otherwise alter any existing building or structure on any property within the City unless there is in force a stormwater runoff control permit issued as required under the provisions herein.
D. 
Change In Ownership Of Property. The provisions of this Chapter shall apply to a property when the ownership of the property changes and a stormwater runoff control permit has not been previously issued.
E. 
Change Or Disturbance Of Terrain. Except as provided in Subsection (F)(4) of this Section, it shall be unlawful for any person to clear, grade, excavate, fill, remove topsoil from or change the contour of any land in the City unless there is in force a stormwater runoff control permit issued under the provisions of this Chapter.
F. 
Exceptions. The provisions of this Chapter shall not apply to:
1. 
Any reconstruction, repair or alteration of any existing building or structure when no land, trees, shrubs, grass or other vegetation is to be disturbed, destroyed or removed.
2. 
Any previously subdivided lot zoned "A" or residential for one (1) single-family dwelling.
3. 
The purchase or acquisition of any undeveloped property zoned "A" or residential. However, development of such property will require a stormwater runoff control permit.
4. 
(Reserved)
5. 
The planting, trimming, pruning or removal of trees, shrubs, grass, weeds, vegetation, ground cover or other plant material when such actions are incidental to and part of the normal maintenance of land and property in the City of Pevely.
6. 
(Reserved)
[R.O. 2008 § 420.030; R.O. 2004 § 520.030; Ord. No. 787 § 1, 12-16-1993]
A. 
General Standards.
1. 
Zoning classification and permitted land use determine the stormwater retention requirements for any given property. Minimum lot size and percent imperviousness are major factors in determining the future runoff from a property. An additional volume of stormwater will be caused to leave a property due to development thereon. The volume of stormwater which must be retained in accordance with the provisions of this Chapter is the difference between the volume of water expected to leave the property in an undeveloped condition [roughly five percent (5%) impervious] and the volume of water which will be cause to leave the property due to all development (existing and proposed) thereon.
2. 
Runoff rates for all categories of projects shall be evaluated by the Rational Formula. The runoff coefficients in the following table for a storm event with a fifty-year frequency and an assumed twenty-minute inlet time shall be used to calculate runoff volumes.
Average C.I. Factors in Cubic Feet per Second per Acre (cfs/acre)
20-Minute Inlet Time
Zoning District
Uses
% Imp.1
C
C.I. Factor2
25-Yr.
50-Yr.
100-Yr.
A Agricultural
All uses
5
0.37
2.00
2.18
2.37
R-1 Residential
Single-family
All other uses
45
60
0.54
0.60
2.92
3.24
3.19
3.54
3.46
3.84
R-2 Residential
Single-family
Two-family
All other uses
47
47
75
0.548
0.548
0.665
2.96
2.96
3.59
3.23
3.23
3.92
3.51
3.51
4.26
R-3 and R-4 Residential
Single-family
Two-family
Multiple-family
All other uses
49
60
70
70
0.556
0.60
0.645
0.645
3.01
3.24
3.48
3.48
3.28
3.54
3.81
3.81
3.56
3.84
4.13
4.13
PRD Planned Residential Development
Same as R-3
Same as R-3
Same as R-3
Same as R-3
Same as R-3
Same as R-3
MH Mobile Home Park
Single-family
Mobile homes
Nursery/day nursery
Kindergarten
Primary school
Jr. high school
Sr. high school
Collegiate
Church
Fire stations
Public/not-for-profit libraries
49
60
60
70
60
60
60
60
70
70
70
0.556
0.60
0.60
0.645
0.60
0.60
0.60
0.60
0.645
0.645
0.645
3.01
3.24
3.24
3.48
3.24
3.24
3.24
3.24
3.48
3.48
3.48
3.28
3.54
3.54
3.81
3.54
3.54
3.54
3.54
3.81
3.81
3.81
3.56
3.84
3.84
4.13
3.84
3.84
3.84
3.84
4.13
4.13
4.13
B-1 - Commercial
Residential R-3 all other uses
Same as R-3
85
Same as R-3
0.705
Same as R-3
3.81
Same as R-3
4.16
Same as R-3
4.51
B-2 Commercial
Residential
All other uses
Same as R-3
85
Same as R-3
0.705
Same as R-3
3.81
Same as R-3
4.16
Same as R-3
4.51
B-3 Planned Commercial
Same as B-1 and B-2
Same as B-1 and B-2
Same as B-1 and B-2
Same as B-1 and B-2
Same as B-1 and B-2
Same as B-1 and B-2
I-1 Light Industrial
All uses
90
0.73
3.94
4.31
4.67
I-2 Heavy Industrial
All uses
90
0.73
3.94
4.31
4.67
PID Planned Industrial Development
Same as I-1 and I-2
Same as I-1 and I-2
Same as I-1 and I-2
Same as I-1 and I-2
Same as I-1 and I-2
Same as I-1 and I-2
NOTES:
1
The percent impervious (% Imp.) values were based upon the minimum lot size requirements specified for each use included in the draft "Revised Zoning Code and Subdivision Regulations of Pevely, Missouri" dated September 30, 1992.
2
The C.I. factors were derived from the U.S. Weather Bureau Technical Paper No. 40: "Rainfall Frequency Atlas of the United States for Durations from Thirty (30) Minutes to Twenty-Four (24) Hours and Return Periods from One (1) to One Hundred (100) Years."
B. 
Retention Facilities. In general, retention facilities shall be provided with obvious and effective control strategies. The following shall be considered in determining the effectiveness and safety of these facilities in relation to the intent and purpose of this Section.
1. 
(Volume of runoff from the developed property) = C.I. factor × area of property (in acres) × 30 minutes × 60 seconds/minute.
2. 
(Volume of runoff from the property in undeveloped condition) = 2.00 cfs/acre × area of property (in acres) × 30 minutes × 60 seconds/minute.
3. 
Volume of retention for the developed property = (Volume of runoff from developed property) – (Volume of runoff from the property in an undeveloped condition)
4. 
Tributary (Q) peak runoff to basin.
5. 
Balanced maximum outflow rate from the low-flow structure.
6. 
Ratios of inflow to outflow rates.
7. 
Sizing of the overflow facilities.
8. 
Stability of retention dikes.
9. 
Safety features.
10. 
Maintenance features.
C. 
Open Dry Reservoirs.
1. 
Wet weather ponds or dry reservoirs shall be designed with proper safety, stability and ease of maintenance features and shall not retain stormwater to a depth greater than four (4) feet if specifically permitted by site plan review by the Planning and Zoning Commission in consideration of a special demonstrated need and special provisions to avoid safety hazards of such greater hazards of such greater depths.
2. 
Maximum side slopes for grass-edged reservoirs shall not exceed one (1) foot vertical for two (2) feet horizontal (2:1) unless adequate measures are included to provide for the stability of these slopes.
3. 
In no case shall the limits of maximum ponding elevation be closer than thirty (30) feet horizontally from any building and less than two (2) feet vertically below the lowest sill elevation.
4. 
The entire reservoir area shall be seeded, fertilized and mulched, sodded or paved prior to release of escrows.
D. 
Permanent Lakes Used For Retention.
1. 
Permanent lakes with fluctuating volume controls may be used as retention areas provided that the limits of maximum ponding elevations are no closer than thirty (30) feet horizontally from any building and less than two (2) feet below the lowest sill elevation of any building.
2. 
Maximum fluctuation from permanent pool elevation to maximum ponding elevation shall be three (3) feet.
3. 
Special consideration shall be given to measures to ensure the safety of small children in the design of permanent lakes especially when located in residential areas.
E. 
Parking Lots Used For Retention.
1. 
Retention is permitted in parking lots to a maximum depth of twelve (12) inches.
2. 
In no case should the maximum limits of ponding be designed closer than ten (10) feet from a building unless proper provision is made for the waterproofing of the building and for pedestrian accessibility.
3. 
The minimum freeboard from the maximum ponding elevation to the lowest sill elevation shall be two (2) feet.
4. 
Closed Retention Tanks. Facilities which are fully enclosed to retain stormwater may be of any depth.
F. 
Discharge Systems.
1. 
The design discharge (Q) for the low-flow pipe shall not exceed the twenty-five year (frequency) twenty-minute duration (inlet time) runoff from the tributary area for five percent (5%) imperviousness (2.0 cfs per acre). The maximum discharge shall be designated to take place under total anticipated design-head conditions.
2. 
Low-flow pipes shall not be smaller than four (4) inches in diameter to minimize maintenance and operating problems, except in parking lot and roof retention where minimum size of the opening shall be designed specifically for each condition. The low-flow pipe shall be provided with a bar-screen on a minimum 2:1 slope to reduce blockage by debris.
3. 
The overflow opening or spillway shall be designed to accept the total peak runoff of the improved tributary area, with discharge velocity not to exceed five (5) feet per second unless special provisions are made.
4. 
Proper engineering judgment shall be exercised in analysis of secondary routing of discharge of greater intensity than the design twenty-five-year frequency in order to avoid economic losses or damage downstream. Review with twenty-five- and fifty-year frequencies is recommended.
5. 
Sizing of the system below the control structure shall be for the total improved peak runoff tributary to the structure with no allowance for retention, with discharge velocity not to exceed five (5) feet per second unless special provisions are made.
G. 
Erosion Control Principles. In general, the basic principles of erosion control that the developer should be aware of include the following:
1. 
Clearing, grading and excavating should be performed on ground on which construction will commence within twelve (12) months.
2. 
Cut or fill slopes should not be left steeper than two (2) horizontal to one (1) vertical unless slope stabilization is planned.
3. 
Excavations and fills near adjoining property boundaries shall be supported to protect the adjoining property from erosion, sliding or settling.
4. 
No fill is to be placed where excess sediment may erode upon the premises of another or soil placed adjacent to the bank of a channel as to create bank failure or reduce the natural capacity of the stream.
5. 
Permanent final vegetation and structures shall be installed as soon as practical.
6. 
Provisions shall be made to effectively accommodate the increased runoff caused by changed surface conditions during development by designing and providing for stormwater retention facilities.
H. 
Erosion Control Practices. Erosion control practices must be incorporated within all grading plans submitted to the Planning and Zoning Commission and must comply with the provisions set forth in Section 3012.0 Protection of Adjoining Property of the 1990 BOCA Code. These practices may include any of the following or others submitted by the developer after consultation with the Planning and Zoning Commission:
1. 
Diversion Channel. A channel with a supporting ridge on the lower side constructed across a slope. The purpose of the diversion channel is to direct stormwater over a hillside in such a manner as to result in minimum erosion and therefore minimum deposition of sediment downstream. The side slopes of the diversion channel shall be three (3) horizontal to one (1) vertical or flatter.
2. 
Grade Stabilization Structures. Structures that stabilize the grade or control head cuttings in channels which are installed to control erosion in natural or artificial channels. These structures reduce the advance of gullies and slow the erosion process. Examples include overflow structures of concrete, metal, rock riprap or other suitable material used to lower water from one level to another. These structures are applicable where the watercourse elevation must be dropped over a very short horizontal distance. Adequate protection must be provided to prevent erosion or scour upstream, downstream and sides of the overflow structure.
3. 
Grassed Waterways. Natural or constructed waterways sloped or graded to carry away runoff. The side slopes of a grassed waterway must be a minimum four (4) horizontal to one (1) vertical.
4. 
Mulching. Applying material to the soil to enhance the growth of plant cover and to retard runoff and erosion. Satisfactory mulching materials include:
a. 
Hay or straw applied at one and one-half (1.5) and two and one-half (2.5) tons per acre, respectively, with anchoring requirements based on local conditions.
b. 
Wood chips at six (6) to nine (9) tons per acre.
5. 
Seeding/Sodding.
a. 
Stabilizing potentially erosive areas by fertilizing and seeding or by sodding. Fescue and fescue mixtures should be applied to the rate of thirty (30) pounds per acre; agricultural lime should be applied at the rate of two (2) tons per acre.
b. 
Should sod be used for stabilization, the sod strips should be laid on the contour, not up and down the slope. Furthermore, sod should be laid from the bottom up the slope and should be laid snug with even joints to retard erosion and rutting.
[R.O. 2008 § 420.050; R.O. 2004 § 520.050; Ord. No. 787 § 1, 12-16-1993]
A. 
Retention facilities, when mandatory, are to be built in conjunction with the storm sewer installation and/or grading. Since these facilities are intended to control increased runoff, they must be partially or fully operational soon after the clearing of the vegetation.
B. 
Silt and debris connected both with early construction and with general erosion from the site and elsewhere in the watershed after construction shall be removed periodically from the retention area and control structure in order to maintain full storage capacity.
C. 
The responsibility of maintenance of the retention facilities in subdivision projects shall remain with the developer until such time as applicable escrows are released. Upon release of escrows the maintenance responsibility shall be vested in the trustees of the subdivision by virtue of the trust indenture. The indenture of the trust shall clearly indicate resident responsibility for maintenance in cases of projects without common ground.
D. 
The responsibility of maintenance of the retention facilities in single-owner development projects shall remain with the general contractor until final inspection of the development is performed and approved and a legal occupancy permit is issued. After legal occupancy of the project, the maintenance of retention facilities shall be vested with the owner of the project.
[R.O. 2008 § 420.060; R.O. 2004 § 520.060; Ord. No. 787 § 1, 12-16-1993; Ord. No. 794 § 1, 4-21-1994; Ord. No. 885 § 1, 2-2-1998; Ord. No. 1172 § 3, 8-4-2008]
A. 
Requirement For Stormwater Runoff Control Permit.
1. 
A stormwater permit is required for all development except as provided in Section 420.020(F). A fee for the issuance of a stormwater permit shall be paid to the City in accordance with the fee schedule maintained by the Building Official.
2. 
The developer shall be liable for any extended reviews, any subsequent reviews or for any meetings which may be requested by the developer or his/her representative.
3. 
The full balance of all engineering reviews shall be paid prior to the issuance of a stormwater runoff control permit.
4. 
The issuance of this permit shall be in combination with Chapter 430, Land Disturbance and Maintenance, and shall not supersede any requirements established in Chapter 430.
B. 
Requirement For Building Or Grading Permit. No permit shall be issued to construct, erect or alter any building or structure or to clear, grade, excavate, fill, remove topsoil from or change the contour of any property within the City until a stormwater runoff control plan has been submitted to and approved by the City Engineer and a stormwater runoff control permit has been issued by the City of Pevely in accordance with the provisions of this Chapter, except as provided in Section 420.020(F).
C. 
Requirement For Occupancy Permit. No permit shall be issued for occupancy of any building or structure within the City until a stormwater runoff control permit has been issued by the City of Pevely in accordance with the provisions of this Chapter, except as provided in Section 420.020(F).
D. 
Procedure.
1. 
Application for an approved stormwater runoff control plan, as required, shall be submitted to the Administrator by the owner of the land prior to the time any work subject to this Chapter is begun on the land.
2. 
The application for a stormwater runoff control permit must include a stormwater runoff control plan.
3. 
Upon receipt of any application and plan, the City Administrator with the advice of the City Engineer shall consider the plan in light of the provisions of this Chapter and shall approve the plan, disapprove the plan or approve the plan with modifications, noting thereon any changes that will be required.
4. 
Upon approval of the plan, the City will issue a stormwater runoff control permit. In the case where the plan has been approved with modifications, a permit will not be issued until the City has received written confirmation from the developer that the modification has been incorporated into the stormwater runoff control plan and will be incorporated into the actual development.
5. 
The City shall promptly notify the applicant of the City's decision on a plan. Failure of the City to act on any plans submitted within seventy-five (75) days after they have been properly filed should be deemed to constitute approval of the plans. Any approved plan shall be issued, dated, and bear the manual signature of the City Administrator.
E. 
Submission Requirements.
1. 
All plans and specifications submitted for review and/or approval shall be prepared by or under the direct supervision of a registered professional engineer licensed in the State of Missouri and shall meet the minimum standards and requirements of the City and other applicable authorities. Each of the plan, profile and special drawing sheets for a project shall bear a legible stamp of the professional engineer in charge.
2. 
In order to facilitate review of plans, all projects shall be submitted with a letter of transmittal which shall include the name of the project, name and address of the owner or developer, name, address and telephone number of the engineer, and clarification as to the purpose of submittal.
[R.O. 2008 § 420.070; R.O. 2004 § 520.070; Ord. No. 787 § 1, 12-16-1993; Ord. No. 1172 § 4, 8-4-2008]
A. 
The stormwater runoff control permit and associated stormwater runoff control plan shall be subject to all provisions of this Chapter relating to enforcement, violations and penalties. In addition, a corporate surety bond conditioned upon carrying out all and every part of approved plans for at least the sum estimated to be the full costs of carrying out such plans or a cash escrow upon the same conditions and in the same amount shall be furnished by City whenever such costs exceed five hundred dollars ($500.00). The bond or escrow shall be released upon proper completion of all of the requirements of such approved plans.
B. 
Enforcement. This Chapter shall be enforced by the City Administrator with the assistance and cooperation of other officials, including the City Engineer. If the City Administrator finds that any of the provisions of this Chapter are being violated, he/she shall notify in writing the person responsible for such violation, indicating the nature of the violation and ordering the action necessary to correct it. He/she shall take any other action authorized by law to ensure compliance with or to prevent violation of the provisions of this Chapter.
C. 
Violations And Penalties.
1. 
Violations of this Chapter shall include, but are not limited to, the following:
a. 
Any activity of proceeding not in accordance with the procedures, requirements, standards or other provisions of this Chapter.
b. 
No owner, or agent of the owner, of any land located within a subdivision of the City of Pevely shall knowingly or with intent to defraud, transfer, sell, agree to sell or negotiate to sell that land by reference to or by other use of a plat of any purported subdivision of the land before the final subdivision plat has been approved by the Planning and Zoning Commission and Board of Aldermen in accordance with this Chapter and recorded by the Recorder of Deeds of the County.
c. 
Failure to obtain the approvals and permits required by this Chapter and to comply with their terms and conditions.
2. 
Those chargeable, singly or jointly, with violations of this Chapter shall include, but are not limited to, the following:
a. 
Those who commit, assist in or otherwise participate in a violation.
b. 
The owner or other persons who maintain the building, premises, property or other place where the violation has been committed or exists.
c. 
The developer, agent, architect, contractor or any other person who performs work or enters into a contract for work in violation of this Chapter.
3. 
Penalties shall be in accordance with the general penalty in Chapter 100, Article III, of the Code.