City of Harrisonville, MO
Cass County
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Table of Contents
Table of Contents
[Ord. No. 2772 §1, 5-20-2002]
No development shall increase the quantity or rate of storm water emanating from said land areas) except in accordance with an approved storm water management plan as provided in this Storm Water Management Ordinance. A professional engineer licensed in the State of Missouri shall prepare the storm water management plan. The City Engineer shall issue no permits prior to the approval of the storm water management plan.
[Ord. No. 2772 §1, 5-20-2002]
A. 
Residential Subdivisions.
1. 
Individual lots in a residential subdivision development shall not be considered to be separate land disturbing activities and shall not require individual permits; whereas, the residential 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.
2. 
If individual lots or sections in a residential subdivision are being developed by different property owners, all land disturbing activities related to the residential subdivision shall be covered by the approved storm water management plan for the residential subdivision. Individual lot owners or developers shall be responsible for all activities on that lot and that they will be carried out in accordance with the approved storm water management plan for the residential subdivision.
3. 
Residential subdivisions which were approved 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. 
Residential land disturbing activities involving less than 1 (one) 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 control plan meeting the requirements listed below. This plan does require approval by the City Engineer and does not require preparation or certification by the engineer specified in this Storm Water Management Ordinance.
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 and receiving storm drainage systems including conduits, channels, lakes, 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 or property survey;
e. 
Anticipated starting and completion dates of the various stages of land disturbing activities and the expected date the final stabilization will be completed;
f. 
The location of temporary and permanent vegetative and storm water management control measures.
5. 
Storm water management plans shall contain certification by the persons responsible for the land disturbing activity that the land disturbing activity will be accomplished pursuant to the plan.
6. 
Storm water management plans shall contain certification by the person responsible for the land disturbing activity of the right of the City Engineer to conduct on-site inspections.
C. 
For land disturbing activities disturbing more than one (1) acre residential or any commercial or industrial development, the requirements of Article II shall apply.
[Ord. No. 2772 §1, 5-20-2002]
A. 
A preliminary storm water plan and design report shall accompany all preliminary applications for land development. This preliminary plan shall contain, but not be limited to, the following information and data:
1. 
A site plan of suitable scale and contour interval showing existing topographic information of the land to be developed and adjoining land whose topography may affect the proposed layout or drainage patterns for the development. A general plan of proposed grading contours of the site development shall also be shown as shall all existing culverts, pipe systems, streams, waterways, channels, and the extent of the established floodplains as defined on the current FIRM;
2. 
The location and calculated flow rates of all adjacent storm water management facilities;
3. 
A general discussion of the type and characteristics of soils contained in the development area;
4. 
Hydrologic and hydraulic analysis with a description of the concept considered in the development to manage anticipated storm water runoff including the methods utilized to detain or control storm water runoff generated by the proposed development;
5. 
A preliminary plan of proposed storm water management facilities (detention, conveyance systems, floodplains, erosion control, etc.) including grading, alignments and preliminary engineering calculations;
6. 
A discussion of the possible effects that the proposed development could have on areas adjoining the development.
B. 
The expected timing of flood peaks through the downstream drainage system shall be assessed when planning the use of detention basins.
C. 
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 10- 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 analysis.
D. 
The storm water analysis shall continue downstream of the development to a point where the development contributes ten percent (10%), or less, of the overall watershed. If the storm water management plan indicates that there may be a drainage or flooding problem within this area downstream of the development, the City Engineer may require:
1. 
Water surface profiles plotted for the conditions of pre- and post-development for the 10- and 100-year design storm;
2. 
Elevations of all structures potentially damaged by the 10- and/or 100-year flows;
3. 
Improvement alternatives to mitigate the flooding.
E. 
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.
F. 
All storm water management plans shall contain certification by the person responsible for the land disturbing activity of the right of the City Engineer to conduct on-site inspections.
G. 
The storm water management plan shall not be considered approved without the inclusion of an approval stamp and date and the signature of the City Engineer. The stamp of approval on the plans is solely an acknowledgment of satisfactory compliance with the requirements of these regulations. The approval stamp 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.
H. 
Approved storm water management plans remain valid for five (5) years from the date of an approval. Extensions or renewals of the plan approvals will be granted by the City Engineer upon written request by the person responsible for the land disturbing activity.
I. 
Following the receipt of the preliminary storm water management plan, a review meeting may be conducted. The purpose of this review shall be to jointly agree on the methods proposed to be utilized and the possible effects of the proposed development on existing and future adjacent developments. If any known downstream problems exist, the City Engineer may require additional improvements.
J. 
All preliminary plats of the development shall be consistent with the preliminary storm water plan.
K. 
Upon approval of the preliminary plan, the applicant shall submit a final storm water management plan (as part of the construction plans) to the City Engineer for review and approval.
[Ord. No. 2772 §1, 5-20-2002]
A. 
Following the review and general approval of the preliminary storm water management plan by the City Engineer, a final storm water management plan and design report shall be prepared for each phase of the proposed project as each phase is developed. The submittal of the final plan shall coincide with the application for final approval of the development and shall constitute a refinement of the concepts approved in the preliminary plan. It is important to note that if a project is to be phased, the total area of the project is to be considered in all calculations, and that facilities should be designed for each phase which would be compatible with those of the total development plan. The final storm water management plan shall be prepared and sealed by a registered professional engineer.
B. 
The final storm water management plan for any development shall include, but not be limited to, the following information unless specifically allowed to be excluded by the City Engineer.
1. 
A topographic map of the project site and adjacent areas, of suitable scale and two (2) feet minimum contour intervals, which shall define the location of all existing and proposed storm water management facilities and regulatory floodplains and floodways. Existing storm water facilities within two hundred (200) feet of the property shall be mapped or as approved by the City Engineer;
2. 
The location and flowline elevations of all existing sanitary facilities and the location of any existing sewage treatment facilities which fall within the project limits;
3. 
Detailed determination of runoff anticipated for the entire project site and upstream areas following development. The proposed runoff calculations shall indicate the design size, land uses, hydrologic factors, rates, and volumes for the project subareas and their effects within the overall watershed, including analysis of methods to manage runoff;
4. 
A layout of the proposed storm water management facilities including the location and size of all drainage structures, conduits, channels, detention basins, and analyses regarding the effect that said improvements will have upon the upstream and downstream facilities;
5. 
The slope, type, length, size, flow, headwater and velocity calculations for all existing and proposed storm water management facilities;
6. 
Existing and future conditions hydrographs of inflow and outflow from the watershed including the site along with proposed development conditions hydrographs for any detention basin(s);
7. 
Plot or tabulation of stage-storage volumes with corresponding stage-discharge rates for any proposed detention basin(s);
8. 
Profiles and cross sections of all existing and proposed storm water management facilities showing existing conditions and the proposed changes thereto including, but not limited to, conduits, channels, streets, buildings, sewers, utilities, inlets, manholes, junction boxes, ground grade lines, and the design hydraulic grade lines;
9. 
Permitting applications with supporting data such as NPDES Erosion Control Plans, FEMA Map Revisions or Amendments, COE Section 404 Permits, and MDNR 401 Water Quality Certification and the Dam and Reservoir Safety Program.
C. 
The 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.
D. 
The final storm water management plan shall be reviewed by the City Engineer. If it is determined that the proposed development will provide control of storm water runoff in accordance with the purpose, design criteria, and performance standards of the Storm Water Management Design Manual and these ordinances and will not be detrimental to the public health, safety and general welfare, the City Engineer shall approve the plan or conditionally approve the plan setting forth the conditions thereof.
E. 
Should any storm water management plan involve any storm water management facility or land to be dedicated to public use, the same information shall also be submitted for review and approval to the department having jurisdiction over the land or other appropriate departments or agencies for review and approval. This storm water management plan shall serve as the basis for all subsequent construction.
F. 
The City Engineer shall review the storm water management plan within thirty (30) working days from and after the receipt of all required information.
[Ord. No. 2772 §1, 5-20-2002]
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, existing and proposed easements, utilities, regulatory floodplains, and other information necessary to locate the development site.
2. 
The existing and proposed topography of the development site except for individual lot grading plans in single-family subdivisions. Include available geotechnical data such as soil boring's location and soil/rock depth and classifications.
3. 
Physical alterations of the site, including existing development and proposed development.
4. 
Location, dimensions, elevations and capacities of all existing and proposed storm water management facilities including plan, profiles and construction details.
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 storm water management qualitative 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 lowest floor elevation of any structure is below the 100-year plus one (1) foot flood elevation.
9. 
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. 
Adequate access to all portions of the drainage system and structures.
b. 
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 basins, or sufficient land area for equipment access for maintenance of all storm water management facilities. This distance shall be measured from the top of the bank or toe of the dam, whichever is applicable.
c. 
Restrictions on the 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.
10. 
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 along with a time frame for applying the vegetation.
c. 
Any special requirements related to the landscaping of the drainage system and efforts necessary to preserve the natural aspects of the drainage system.
11. 
Open detention basins visible to the public shall be incorporated into the design as an attractive amenity or focal point in the site design.
12. 
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 MDNR NPDES.
13. 
The storm water management plan shall include all engineering calculations needed to design the system and associated facilities, including hydrologic analysis, pre- and post-development velocities, peak rates of discharge, inlet sites and capacities, and inflow and outflow hydrographs of storm water runoff at all existing and proposed points of discharge from the site.
14. 
Description of site conditions around points of all surface water discharge including vegetation and method of flow conveyance from the land disturbing activity.
15. 
Construction and design details of the storm water management facilities.
[Ord. No. 2772 §1, 5-20-2002]
A. 
The minimum storm water control requirements shall provide measures necessary to accomplish the following:
1. 
Install storm water management facilities to limit the 10- and 100-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 Manual or as approved by the City Engineer.
B. 
The requirements, or portions thereof, of Section 415.150(A) may be waived by the City Engineer if it can be shown by detailed engineering calculations and analysis which are acceptable to the City Engineer that one (1) of the following exists:
1. 
The installation of storm water management facilities would not reduce downstream flood peaks; or
2. 
The City Engineer 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 City.
3. 
The requirements, or portions thereof, of Section 415.150(A) may not be waived if the City Engineer 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 by the applicant along with the preliminary storm water management plan and containing descriptions, engineering analysis, 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 City Engineer will conduct a review of the request for a waiver within a reasonable period of time.
C. 
Discharge velocities shall be reduced to provide a non-erosive velocity.
[Ord. No. 2772 §1, 5-20-2002]
A. 
Storm water management facilities may include both structural and non-structural elements. Design shall be in accordance with the Storm Water Management Design Manual, as amended, or as specified herein. Natural swales and other natural runoff conduits shall be retained where practicable.
B. 
For all storm water management facilities, a hydrologic-hydraulic analysis shall be done showing how the drainage system will perform with and without the development and how the proposed facilities will function. Existing land use data shall be taken from the most recent aerial photography, field checked and updated; future land uses may be obtained from the Community Development Department.
1. 
Storm water detention facilities shall be designed to detain storm water runoff for the development only. Runoff from tributary areas upstream of the facility shall be calculated for future conditions; the detention facility shall be designed to safely pass this flow without detaining it.
2. 
Evaluation of existing storm water management facilities, either upstream or downstream of the site, shall be done assuming fully developed conditions for the watershed.
C. 
Where 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 basins;
2. 
Facilities designed to encourage overland flow, slow velocities of flow, and flow through buffer zones;
3. 
Infiltration channels or basins.
D. 
Where detention 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.
E. 
Storm water management plans can be rejected by the City Engineer 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.
F. 
The storm water management facilities within the City (including both public and private portions) will be designed to the same engineering and technical criteria and standards as outlined in the Storm Water Management Design Manual or as described herein. The City Engineer's review will be the same whether the portion of the system will be under public or private control/ownership.
G. 
Erosion control measures shall be established for any development one (1) acre or larger. Best Management Practices (BMP) shall be utilized to reduce downstream effects of sediment-laden runoff.
H. 
Maintenance of private facilities shall be described in the plans and shall be the responsibility of the owner. Failure of owner to maintain these facilities shall result in the City taking appropriate action to mitigate such maintenance problems.
[Ord. No. 2819 §1, 3-17-2003]
A. 
This Section establishes the criteria for creating a regional storm water facility and the fee in lieu of on-site detention, as required in Section 415.160, and the procedures to determine qualifications to participate in a regional storm water detention basin.
B. 
For the purposes of this Section, the following terms, phrases, words and their derivations shall have the meaning given herein. When not inconsistent with the context, words used in the present tense include the future, words used in the plural include the singular, and words used in the singular include the plural. The word "shall", as used herein, is not merely directory but is considered mandatory.
1. 
On-site detention means storm water storage facilities for and within a development property as computed in accordance with the applicable provisions contained herein and approved by the City Engineer.
2. 
Regional detention means off-site centralized storm water storage facilities planned and designed to accommodate runoff from several developments or sub-watershed drainage areas and with a controlled release rate in accordance with the applicable provisions contained herein and approved by the City Engineer.
C. 
The City Engineer shall have the authority to establish a regional storm water detention facility based on land availability, hydrologic characteristics, topography, development, hazard mitigation, watershed conditions, benefit cost and any other criteria deemed appropriate.
D. 
It shall be the duty of the City Engineer to determine if a proposed development will qualify for participation in a regional detention basin in lieu of constructing on-site detention. Participation shall only be approved/required when it has been determined that allowing non-detained runoff from the proposed development does not have an adverse impact on the watershed. The impact shall be determined by the City Engineer after submittal and approval of the final storm water management plan in accordance with Section 415.130 and as certified by a professional engineer.
E. 
The per acre participation fee shall be established by the total cost of a regional detention basin divided by the total acres of potential developed area in the watershed.
1. 
The total cost of a regional detention basin shall include, but is not be limited to, the following: land acquisition, appraisals, legal costs, other easements, permits, administration, engineering, inspections, surveys, construction and maintenance.
2. 
The City Engineer shall utilize the Comprehensive Plan to determine the potential developed area in a watershed.
3. 
Each year beginning January 1, 2004, the City Engineer shall adjust the participation fee to reflect contemporary pricing and the construction cost shall be adjusted using the construction cost index. Any adjustment to the participation fee, including supporting calculations, shall be filed with the City Clerk.
4. 
The participation fee shall be paid prior to the issuance of building permits.
F. 
The participation fee collected shall be designated for regional storm water detention and shall be used for or applied to the construction and maintenance of a regional detention basin and expenses incidental thereto.
G. 
The decision of the City Engineer regarding participation cannot be appealed to the Board of Zoning Adjustments.
H. 
Request for participation shall be made to the City Engineer on an application form provided by the Public Works Department which shall include the final storm water management plan.
[Ord. No. 2772 §1, 5-20-2002]
A. 
Following are the criteria related to using storm water management facilities for water quality purposes.
1. 
A storm water management plan will be required for the construction of all ponds, lakes or reservoirs.
2. 
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 methods acceptable to the City Engineer.
3. 
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 settable 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.
4. 
Other practices may be acceptable to the City Engineer if they achieve an equivalent removal efficiency of eighty percent (80%) for suspended solids or 0.5 ML/L peak settable solids concentration, whichever is less. The efficiency shall be calculated for disturbed conditions for the 10-year twenty-four (24) hour design storm event.