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HomeMy WebLinkAboutOrdinance No. 4481 Ordinance - Amendments to Rochester Code of Ordinances Chapter 6-4 Related to Stormwater Management ORDINANCE NO___________ AN ORDINANCE AMENDING SECTIONS 6-4-9, 6-4-10, 6-4-11, AND 6-4-12 OF CHAPTER 6-4 OF TITLE 6 OF THE ROCHESTER CODE OF ORDINANCES RELATING TO STORMWATER DISCHARGES. THE COMMON COUNCIL OF THE CITY OF ROCHESTER ORDAINS: Section 1. Section 6-4-9 of Chapter 6-4 of the Rochester Code is hereby amended to read as follows: Sec. 6-4-9. Stormwater management plan approval standards. The public works director city engineer shall not approve a stormwater management plan which fails to meet the standards set forth in state and federal regulations and other applicable city standards and regulations. Every applicant for a permit to allow land disturbing activities of one acre or greater, including projects that are less than one acre that are part of a larger common plan of development or sale, must meet the requirements of this chapter and the standards set forth in the land development manual Unified Development Code. Section 2. Section 6-4-10 of Chapter 6-4 of the Rochester Code is hereby amended to read as follows: Sec. 6-4-10. Stormwater management plan review. When any land disturbance project or a series of projects will disturb less than one acre of land, the public works director city engineer shall determine if a stormwater management plan is required, and what submittals, if any, are required. Section 3. Section 6-4-11 of Chapter 6-4 of the Rochester Code is hereby amended to read as follows: Sec. 6-4-11. Stormwater management plan submittal requirements. A written application for stormwater management plan approval, along with a proposed stormwater management plan, shall be submitted to the public works director city engineer per the requirements of the land development manual Unified Development Code. Section 4. Section 6-4-12 of Chapter 6-4 of the Rochester Code is hereby amended to read as follows: Sec. 6-4-12. Stormwater management criteria for permanent facilities and BMPs. Stormwater management BMPs are required within a stormwater management plan for: Newnew development and redevelopment projects with land disturbance area of one acre or greater, including projects less than one acre that are part of a larger common plan of development or sale,; redevelopment projects with land disturbance area of one acre or greater and a net increase of new impervious surface area but less than one acre of new or fully reconstructed impervious surface area,; and redevelopment projects where the sum of the new and fully reconstructed impervious surface area equals one or more acres. must include stormwater management BMPs in the stormwater management plan. Permanent stormwater control facilities included as part of the final design for land development and redevelopment shall be addressed in the stormwater management plan and shall meet the following to the maximum extent practicable (MEP): (1) Post-construction stormwater management. Post-construction stormwater management must incorporate any combination of BMPs, with the highest preference given to green infrastructure techniques and practices (e.g., infiltration, evapotranspiration, reuse/harvesting, conservation design, urban forestry, green roofs, etc.), necessary to meet the following conditions on the site of a construction activity to the maximum extent practicable (MEP): that promote volume reduction and retain the water quality volume on-site. Wet sedimentation basins and filtration systems are not volume reduction practices. If infiltration is prohibited, other volume reduction practices, wet sedimentation basins, and/or filtration basins may be considered. a. New development projects. No net increase from pre-project conditions (on an annual average basis) of: 1. Stormwater discharge volume, unless precluded by the stormwater management limitations in subsection (2) of this section. 2. Stormwater discharges of total suspended solids (TSS). 3. Stormwater discharges of total phosphorus (TP). b. Redevelopment projects. A net reduction from pre-project conditions (on an annual average basis) of: 1. Stormwater discharge volume, unless precluded by the stormwater management limitations in subsection (2) of this section. 2. Stormwater discharges of TSS. 3. Stormwater discharges of TP. 2 (2) Water quality volume for new development and redevelopment. For construction activity (excluding linear projects), the water quality volume must be calculated as one (1) inch times the sum of the new and the fully reconstructed impervious surface area. Where the sum of the new and the fully reconstructed impervious area is less than one acre, the water quality volume must be calculated as one (1) inch times the new, i.e. added, impervious surface area. (3) Water quality volume for linear projects. For linear projects, the water quality volume must be calculated as the larger of one (1) inch times the new impervious surface or one-half (0.5) inch times the sum of the new and the fully reconstructed impervious surface. Where the entire water quality volume cannot be treated within the existing right-of-way, a reasonable attempt to obtain additional right-of-way, easement, or other permission to treat the stormwater during the project planning process must be made. Volume reduction practices must be considered first. Volume reduction practices are not required if the practices cannot be provided cost effectively. If additional right-of-way, easements, or other permission cannot be obtained, owners of construction activity must maximize the treatment of the water quality volume prior to discharge from the MS4. (24) Stormwater management limitations prohibitions. Infiltration systems are is prohibited when the infiltration structural stormwater BMP will receive discharge from, or be constructed, in the following areas system would be constructed in areas: a. That receive stormwater runoff the following types of entities regulated under Where industrial facilities are not authorized to infiltrate industrial stormwater under an NPDES/SDS industrial stormwater permit issued by the MPCA: automobile salvage yards; scrap recycling and waste recycling facilities; hazardous waste treatment, storage, or disposal facilities; or air transportation facilities that conduct deicing activities. b. That receive stormwater runoff from Where vehicle fueling and maintenance occur areas, regardless of the amount of new and fully reconstructed impervious area. c. With less than three (3) feet of separation distance from the bottom of the infiltration system to the elevation of the seasonally saturated soils of or the top of bedrock. d. Where high levels of contaminants in soil or groundwater will be mobilized by the infiltrating stormwater. To make this determination, the owners and/or operators of construction activity must complete the Minnesota Pollution Control Agency’s site screening assessment checklist, which is available in the Minnesota Stormwater Manual, or conduct their own assessment. The assessment must be retained with the site plans. e. With predominately Hydrologic Soil Group D (clay) soils. 3 f. Within 1,000 feet up-gradient or 100 feet down gradient of active karst features. g. Where soil infiltration rates are more than 8.3 inches per hour unless soils are amended to slow the infiltration rate below 8.3 inches per hour. h. Within an Emergency Response Area (ERA) of a drinking water supply management area (DWSMA) as defined in Minn. R. pt. 4720.5100, subpt. 13, classified as high or very high vulnerability as defined by the Minnesota Department of Health. i. Within an ERA of a DWSMA classified as moderate vulnerability unless the permittee performs or approves a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater. j. Outside of an ERA within a DWSMA classified as high or very high vulnerability unless the permittee performs or approves a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater. (3) Stormwater management restrictions. Infiltration is restricted, without higher engineering review, sufficient to provide a functioning treatment system and prevent adverse impacts to groundwater, when the infiltration device will be constructed in the following areas: a. With predominately Hydrologic Soil Group D (clay) soils. b. Within 1,000 feet up-gradient, or 100 feet down-gradient of active karst features. c. Within a drinking water supply management area (DWSMA) as defined in Minn. R. pt. 4720.5100, subpt. 13. d. Where soil infiltration rates are more than 8.3 inches per hour. (4) Linear projects. When a lack of right-of-way precludes the installation of volume control practices that meet the conditions for post-construction stormwater management, a reasonable attempt must be made and documented to obtain right-of-way during the project planning process. (5) Off-site water quality treatment. For non-linear projects, where the water quality volume cannot cost effectively be treated on the site of the original construction activity, the owners of the construction activity are required to identify locations where off-site treatment projects can be completed. If the entire water quality volume is not addressed on the site of the original construction activity, the remaining water quality volume must be addressed through off-site treatment and, at a minimum, ensure the requirements of the items below are met: a. The city engineer must ensure off-site treatment project areas are selected in the following order of preference: 4 i. Locations that yield benefits to the same receiving water that receives runoff from the original construction activity. ii. Locations within the same Department of Natural Resource (DNR) catchment area as the original construction activity. iii. Locations in the next adjacent DNR catchment area up-stream. iv. Locations anywhere within the City’s jurisdiction. b. Off-site treatment projects must involve the creation of new structural stormwater BMPs or the retrofit of existing structural stormwater BMPs, or the use of a properly designed regional structural stormwater BMP. c. Off-site treatment projects must involve the creation of new structural stormwater BMPs or the retrofit of existing structural stormwater BMPs, or the use of a properly designed regional structural stormwater BMP. d. Off-site treatment projects must be completed no later than 24 months after the start of the original construction activity. If the city engineer determines more time is needed to complete the treatment project, the reason(s) for the delays and schedule(s) for completing the project must be provided in the annual report. Stormwater management exceptions. The city may allow for lesser volume control on the site of the original construction activity only under the following circumstances: a. The owner and/or operator of a construction activity is precluded from infiltrating stormwater through a designated system due to any of the infiltration-related limitations described in subsection (2) of this section. b. The owner and/or operator of a construction activity implements to the MEP, volume reduction techniques, other than infiltration (e.g., evapotranspiration, reuse/harvesting, conservation design, green roofs, etc.), on the site of the original construction activity that reduces stormwater discharge volume, but may not meet the conditions of post- construction stormwater management in subsection (1) of this section. Section 5. This ordinance shall become effective from and after its publication. 5 PASSED AND ADOPTED BY THE COMMON COUNCIL OF THE CITY OF ROCHESTER, MINNESOTA, THIS __________ DAY OF _______________, 2022. ___________________________________ PRESIDENT OF SAID COMMON COUNCIL ATTEST: __________________________ CITY CLERK APPROVED THIS _____ DAY OF ______________________, 2022. ___________________________________ MAYOR OF SAID CITY (Seal of the City of Rochester, Minnesota) Ord20\\6-4 StormwaterDischarges.docx 6