CHAPTER 72 - STORMWATER MANAGEMENT ORDINANCE

Transcription

1 CHAPTER 72 - STORMWATER MANAGEMENT ORDINANCE PURPOSE AND GENERAL OBJECTIVES DEFINITIONS EXEMPTIONS APPLICATION STORMWATER MANAGEMENT REQUIREMENTS WATERSHED OVERLAY DISTRICTS STORMWATER MANAGEMENT FACILITIES ENFORCEMENT FEES ESTABLISHED PURPOSE AND GENERAL OBJECTIVES. (a) (b) Purpose. 1. It is the purpose of this chapter to establish policies to comprehensively manage and control quality and quantity of stormwater runoff in a safe and economical manner in developing areas for the purpose of promoting the health, safety and general welfare of the population, and for the protection of property. 2. It is also the intent of this chapter to provide for stormwater storage within the city where detention/retention basin facilities have been determined to be beneficial in reducing the peak runoff to subservient lands. 3. Requirements shall be established by this chapter in an effort to manage stormwater runoff. Except as exempted in this chapter, a stormwater management plan, as set forth herein, will be required as part of proposed improvement projects. General Objectives. 1. To integrate Stormwater Management Plans in the Cedar Rapids Metropolitan Area with other communities. 2. To encourage innovative and economic solutions which provide for multipurpose use of stormwater management facilities. 3. To identify the roles and shared responsibilities of all participants in urban stormwater management, including regular maintenance of stormwater management facilities. 4. To implement a program addressing both individual development sites and a watershed (drainage area) approach to the planning and construction of stormwater management facilities. 5. To develop stormwater management standards to minimize soil erosion, sedimentation, and to enhance water quality as well as mimic or improve existing conditions. 6. To reduce the adverse impacts on existing developed areas by the implementation of stormwater management practices on development sites. 7. To systematically reduce the existing level of stormwater inundation in areas currently experiencing flooding, in a manner consistent with the overall goals and objectives for stormwater management set forth in this chapter. 8. To adopt engineering methods and techniques for estimating stormwater runoff which can be updated as technology improves, and to systematically monitor the effectiveness of the stormwater management program. Page 1 of

2 DEFINITIONS. (a) Wherever used in this chapter and printed with an initial capital letter, the terms listed below will have the meanings indicated. Words using the present tense shall include the future; the singular shall include the plural; the plural shall include the singular; the masculine gender shall include the feminine. The term "shall" is always mandatory, and the term "may" is permissive. 1. Capacity of a Stormwater Facility. The maximum volume or rate of conveyance available in a stormwater management facility, including freeboard, to store or convey stormwater without damage to public or private property. 2. Channel Protection Volume. Provide 24 hours of extended detention of runoff from the 1-year 24-hr duration storm event to reduce bank-full flows and protect downstream channels from erosive velocities and unstable conditions. 3. City. The City of Cedar Rapids, Iowa. 4. City Council. The City Council of the City of Cedar Rapids, Iowa. 5. City Engineer. That position as established by Section 5.09 of the Cedar Rapids Municipal Code. 6. Civil Engineer. A professional engineer licensed in the state of Iowa to practice in the field of civil works. 7. Comprehensive Plan. The plan or series of plans prepared by the city or by the Linn County Regional Planning Commission to guide the development and redevelopment of the city and the surrounding area. Such a comprehensive plan may include a Major Street Plan, Land Use Policy Plan, Open Space Plan, and other applicable plans available through the Department of Development. 8. Control Structure. Part of a stormwater management facility designed to regulate the stormwater runoff release rate. 9. Core Area. That portion of the City defined in Sec F. 10. Design Standards Manual. This includes the Design Standards as approved by the City Council in conjunction with the Stormwater Management Manual or other approved standards by the City Engineer. 11. Detention Basin. A stormwater management facility designed, constructed or modified to provide short term storage of stormwater runoff, which reduces the peak outflow to a rate less than the peak inflow. 12. Development. Is either Land Disturbing Activities or Substantial Improvements. 13. Drainage Area. An area of land contributing to stormwater runoff. 14. Extreme Flood Volume. Provides peak discharge control of the 100-year storm event such that the post-development peak rate does not exceed the downstream conveyance capacity and/or cause overbank flooding in local urban watersheds. 15. Floodway. The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designed height. 16. Forest Preserve. An area of forest set aside and preserved for the purpose of protecting the trees and area from encroachment. 17. Impervious Surface. Any surface that cannot be effectively (easily) penetrated by water, thereby resulting in runoff. Examples: Pavement (asphalt, concrete, etc), buildings/structures, driveways/roadways, parking lots and sidewalks. 18. Land Disturbing Activities. Any activity that alters greater than 10,000 SF of area by clearing, grading, excavating, filling, or removal of vegetation, paving, buildings or exposing earthen material on a site. 19. Licensed Professional. May be any individual that is licensed (architect, engineer, surveyor, environmental, other) and competent in the area reviewing. 20. Nonsingle Family Lots. Is a lot that has multiple single family dwellings on one lot. For Page 2 of

3 example a duplex on one lot would be nonsingle family. A zero lot line subdivision with duplexs straddling the property line would still be classified as single family. 21. Ordinance. The portion of the City Municipal Code entitled "Stormwater Management Ordinance." 22. Overflow System. The path taken by stormwater runoff as a result of flows which exceed the capacity of the underground drainage system. This path may include streets, channels, drainage ways, or areas of sheet flows, and be located on public property or private property within an easement. 23. Pervious Surface. Any surface that allows water to filter into the ground, which enables natural groundwater to recharge, helps with filtration of pollutants, and reduces erosion and flooding. 24. Precipitation Water. Water received on earth from clouds in the form of rain, hail, sleet or snow 25. Recharge Volume. A fraction of the water quality volume of stormwater that is returned/recharged to the ground water. 26. Retention Basin. A stormwater management facility designed, constructed or modified to provide long-term storage of stormwater runoff, which reduces the peak outflow during a specific rainfall event. This facility is typically designed to maintain a specific water elevation. 27. Site. A lot, parcel, or tract of land, or portion thereof, where development is occurring, or has occurred, and may, or may not, require additional permits. 28. Storm Sewer System. Facilities for the conveyance of stormwater runoff, typically a series of conduits and appurtenances, to accommodate frequent storms not generating large peak discharges. These facilities usually include conduits, street gutters, and small swales. 29. Stormwater Best Management Practice (BMP). A technique, process, activity, or structural control that is used to manage the quality and quantity of stormwater runoff. BMPs include simple nonstructural methods, such as good housekeeping and preventative maintenance. BMPs may also include structural modifications, such as the installation of bioretention measures. BMPs can also function as treatment controls. 30. Stormwater Management Plan. A site plan, certified by a Civil Engineer, including materials, construction phasing, grading activities, and methods used for mitigation of increased stormwater runoff from the site under the requirements set forth in the Design Standards Manual. 31. Stormwater Runoff. The flow of water resulting from precipitation upon a surface area, not absorbed by the soil or plant material. 32. Stormwater Runoff Release Rate. The amount of stormwater runoff discharged from dominant to subservient land. 33. Stormwater Management Facilities. Any facility that detains, retains, infiltrates, evapotransports, or transports stormwater for a given site. 34. Stormwater Management Manual. Guidelines for stormwater controls deemed suitable to meet the goals of the United States Environmental Protection Agency's National Pollutant Discharge Elimination System Program when properly designed constructed and maintained. For a copy go to following link or you may request a printed copy from City Public Works. 35. Substantial Improvements. Any repair, reconstruction, or improvement of a structure, the cost of which equals or exceed fifty percent (65%) of the market value of the structure either (a) before the improvement or repair is started or (b) if the structure has been damaged, and is being restored, before the damage occurred. 36. Surface Waterways. A body of water as shown in the USGS National Hydrography Dataset (NHD). The NHD is a digital vector dataset about the nation s surface water. More information may be found at Page 3 of

4 37. Water Quality Volume Wqv. Runoff generated from the one inch rain. Wqv (cubic feet of water) = Site Area (sf) * 1 rainfall / 12 inches per foot. 38. Wetland. Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas. (40 CFR 232.2(r)). (Section 404 of the Clean Water Act ) Wetlands, regulated by the U.S. Army Corps of Engineers (Corps) under Section 404, must exhibit all three characteristics: hydrology, hydrophytes, and hydric soils (US ACOE 1987) EXEMPTIONS. (a) The following may be exempt from the requirements of this chapter: 1. Agricultural use of land; 2. Emergencies posing an immediate danger to life or property, or substantial flood or fire hazards or other natural disasters; 3. Forest Preserve. 4. Where Core Areas are defined in Zoning Ordinance (Ch. 32). 5. Local Public Streets 6. Areas deemed appropriate by the City Engineer APPLICATION. (a) The requirements of this chapter shall apply to all land disturbing activity and substantial improvement within the city STORMWATER MANAGEMENT REQUIREMENTS. (a) Recharge Volume 3/10 - inch of precipitation over the entire site shall be infiltrated to ground water or harvested for use on site. (b) Quality Volume 7/10 inch of precipitation in addition to the recharge volume over the entire site shall be detained/released over a 24 hours period. (c) Quantity Volume Shall have sufficient detention volume so that the runoff from the developed site will not exceed the existing, pre-developed peak runoff from a two year frequency storm. (d) For purposes of obtaining approval of a Stormwater Management Plan, a plan for the site meeting the requirements established in the Design Standards Manual shall be submitted to the City Engineer for review and approval. All design criteria and plan details shall be in conformance with the Design Standards. (e) Construction of stormwater management practices shall be in conformance with the approved Stormwater Management Plan for the site. (f) The Stormwater Management Plan, including on-site storm water management practices, shall be reviewed and approved by the City Engineer prior to the issuance of foundation permits, or building permits for the site. The improvements shall be constructed prior to the Page 4 of

5 issuance of final certificates of occupancy. The requirements of this paragraph may be deferred at the discretion of the City Engineer. (g) For sites on which privately owned and maintained stormwater management and/or conveyance practices are located, the property owner shall be responsible for the following: 1. All future grading, repairs, and maintenance. 2. Maintenance of the management practice shall ensure the practice is operational as per the approved plan on record with the City. 3. The property owner shall provide certification by a Licensed Civil Engineer verifying every 5 years that it complies with the approved plan. The minimum stormwater detention volume and the maximum theoretical stormwater release rate, as required in subsection a., b. and c. are in conformance with the approved design. If deemed necessary by the City Engineer this certification may be required more often if a site has issues that may not allow it to comply with the approved plan on file with the City. (h) The property owner shall place no fill material, or erect any buildings, obstructions, or other improvements on the area reserved for stormwater management purposes, unless approved otherwise by the City Engineer. (i) The property owner shall dedicate to the City of Cedar Rapids, by instrument or final platting, any property on which public stormwater management practices will be located. Ingress-egress easements for maintenance of public facilities shall be provided prior to final site approval. (j) The City Engineer may inspect the site(s) at any time to determine compliance with these regulations. (k) Except as provided in this chapter, no person shall engage in construction of stormwater management facilities, unless a Stormwater Management Plan has been reviewed and approved by the City Engineer. (l) Required Stream Buffer The planting of foreign or invasive species, including intrusive native varieties, in buffer areas shall be prohibited. (a) 50 from center line of surface waterway as defined by USGS National Hydrography Dataset at (b) 10 from edge of designated floodway (c) Shall be designated as an easement or unbuildable outlet on plat (d) Shall have no structures in easement area (e) At the discretion of the City Engineer some of the above items may be modified. (m) Wetland Buffer Privately owned outlet shall be 150 feet from line of delineation and shall be unbuildable. The planting of foreign or invasive species, including intrusive native varieties, in wetland or buffer areas shall be prohibited. (a) Shall be from depending on wetland quality and criteria as outlined in the Cedar Rapids Stormwater Management Manual wetland section. (b) Shall be designated as an easement or unbuildable outlet on plat (c) Shall have no structures in Easement area (d) At the discretion of the City Engineer some of the above items may be modified WATERSHED OVERLAY DISTRICTS. (a) Any development in the Districts in item (b) will need to comply with the special requirements unless approved otherwise by the City Engineer (b) 303D impaired for Thermal Shock 1. Any new development will need to infiltrate (recharge) first 1 or rainfall over site 2. Ensure stormwater runoff does not have a thermal impact to stream Page 5 of

6 STORMWATER MANAGEMENT FACILITY. (a) Ownership of stormwater facilities 1. Stormwater facilities intended to serve single family residential development shall be publicly owned and maintained, unless approved otherwise by the City Engineer. 2. Stormwater wet basins intended to serve single family residential development shall be privately owned and maintained, unless approved otherwise by the City Engineer. 3. Nonsingle family lots shall comply with one of the following, as approved by the City Engineer: a. Privately owned, on-site detention basin. b. Tributary to a privately owned detention basin. In some watersheds, on-site stormwater detention may be waived, at the discretion of the City Engineer. At the discretion of the City Engineer, if a detention basin serves non-single family zoning districts and can provide stormwater attenuation for a substantial drainage area, the facilities may be publicly owned and maintained. (b) Any facility that City will be assuming maintenance responsibility will require the following: 1. A letter from developer requesting the City take over maintenance responsibilities a. This can only be done once the facilities is not being used as a sediment/erosion control practice for the site 2. City will do a final inspection to ensure the facility complies with the approved plans on file with the City. a. If corrections are needed they will be given to developer. b. Once corrections are made a reinspection will occur. If all items are corrected next step will be implemented. 3. Once facility is acceptable to City a letter will be sent to developer confirming the City has taken over maintenance of the facility. (c) Credits for Stormwater Best Management Practices credits shall be given based on approved policies in the City of Cedar Rapids Stormwater Management Manual (see Fair Manual Section), most recent edition. 1. Credits for infiltration Best Management Practice against Detention Volume a. Volume of stormwater infiltrated will be subtracted from required detention volume. IE infiltrate volume = 3000 CF Required Detention Volume = 20,000 CF, Actual Detention Volume needed 20,000 3,000 = 17,000 CF 2. Stormwater Utility fee reduction a. Only considered for stormwater management in excess of minimum Requirement ENFORCEMENT. (a) Upon determination that a site is not in compliance with these regulations, the City Engineer may issue, an order to comply. The order shall describe the problem and specify a date whereby the work must be completed, and indicate the penalties to be assessed for further noncompliance. Page 6 of

7 (b) Violation of any provision of this chapter may be enforced by civil action including an action for injunctive relief. (c) In any civil enforcement action, administrative or judicial, the city shall be entitled to recover its attorneys' fees and costs from a person who is determined by a court of competent jurisdiction to have violated this chapter. (d) Violation of any provision of this chapter may also be enforced as a municipal infraction within the meaning of Iowa Code , pursuant to Chapter 1, General Provisions of the Cedar Rapids Municipal Code FEES ESTABLISHED. The City Council may establish fees by resolution for the review and processing of documents necessitated by this chapter. When such fees are established a submittal shall not be considered unless the appropriate fee has been submitted to the City Engineer. Page 7 of