Ch9.§5-1 · City of Nowthen public records

### PURPOSE: A. Land development projects and associated increases in impervious cover alter the hydrologic response of local watersheds and increase stormwater runoff rates and volumes, flooding, stream channel erosion, and sediment transport and deposition; B. Stormwater runoff contributes to increased quantities of water-borne pollutants; and, C. Stormwater runoff, soil erosion and nonpoint source pollution can be controlled and minimized through the regulation of stormwater runoff from development sites. It is determined that the regulation of stormwater runoff discharges from land development projects and other construction activities in order to control and minimize increases in stormwater runoff rates and volumes, soil erosion, stream channel erosion, and nonpoint source pollution associated with stormwater runoff is in the public interest and will prevent threats to public health and safety. D. The purpose of this Section is to establish minimum stormwater management requirements and controls to protect and safeguard the general health, safety, and welfare of the public and environment in the watersheds within the City of Nowthen through the following objectives: 1\. Minimize increases in stormwater runoff from any development in order to reduce flooding, siltation, increases in stream temperature, and streambank erosion and maintain the integrity of stream channels.   2\. Minimize increases in nonpoint source pollution caused by stormwater runoff from development which would otherwise degrade local water quality. 3\. Minimize the total annual volume of surface water runoff which flows from any specific site during and following development to not exceed the pre- development hydrologic regime to the maximum extent practicable. 4\. Reduce stormwater runoff rates and volumes, soil erosion and nonpoint source pollution, wherever possible, through stormwater management controls and to ensure that these management controls are properly maintained and pose no threat to public safety. E. This Section is not intended to interfere with, abrogate, or annul any other ordinance, rule or regulation, stature, or other provision of law. The requirements of this Section should be considered minimum requirements, and where any provision of this Section imposes restrictions different from those imposed by any other ordinance, rule or regulation, or other provision of law, whichever provisions are more restrictive or impose higher protective standards for human health or the environment shall be considered to take precedence. (Ordinance #16, adopted April 13, 2010) 9-5-2: DEFINITIONS: For the purposes of this section, the following terms shall mean: Accelerated Erosion: Erosion caused by development activities that exceeds the natural processes by which the surface of the land is worn away by the action of water, wind, or chemical action. Applicant: A property owner or agent of a property owner who has filed an application for a stormwater management permit. Building: Any structure, either temporary or permanent, having walls and a roof, designed for the shelter of any person, animal, or property, and occupying more than 100 square feet of area. BMP Manual: The manual titled Protecting Water Quality in Urban Areas (Best management Practices for Minnesota) prepared by the Minnesota Pollution Control Agency, Division of Water Quality, Latest Edition. Channel: A natural or artificial watercourse with a definite bed and banks that conducts continuously or periodically flowing water. Dedication: The deliberate appropriation of property by its owner for general public use.   Detention: The temporary storage of storm runoff in a stormwater management practice with the goals of controlling peak discharge rates and providing gravity settling of pollutants. Detention Facility: A detention basin or alternative structure designed for the purpose of temporary storage of stream flow or surface runoff and gradual release of stored water at controlled rates. Developer: A person who undertakes land disturbance activities. Drainage Easement: A legal right granted by a landowner to a grantee allowing the use of private land for stormwater management purposes. Fee in Lieu: A payment of money in place of meeting all or part of the storm water performance standards required by this Section. Grading, Drainage, and Erosion Control Plan: A set of plans prepared by or under the direction of a licensed professional engineer that depicts existing and proposed grading, temporary and permanent drainage facilities, and indicates the specific measures and sequencing to be used to control sediment and erosion on a development site before, during and after construction. Hotspot: An area where land use or activities generate highly contaminated runoff, with concentrations of pollutants in excess of those typically found in stormwater. Hydrologic Soil Group (HSG): A Natural Resource Conservation Service classification system in which soils are categorized into four runoff potential groups. The groups range from A soils, with high permeability and little runoff production, to D soils, which have low permeability rates and produce much more runoff. Impervious Cover: Those surfaces that cannot effectively infiltrate rainfall (e.g., building rooftops, pavement, sidewalks, driveways, etc). Industrial Stormwater Permit: An National Pollutant Discharge Elimination System permit issued to a commercial industry or group of industries which regulates the pollutant levels associated with industrial stormwater discharges or specifies on-site pollution control strategies. Infiltration: The process of percolating stormwater into the subsoil. Infiltration Facility: means any structure or device designed to infiltrate retained water to the subsurface. These facilities may be above grade or below grade. Jurisdictional Wetland: means an area that is inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support a prevalence of   vegetation typically adapted for life in saturated soil conditions, commonly known as hydrophytic vegetation. Land Disturbance Activity: Any activity which changes the volume or peak flow discharge rate of rainfall runoff from the land surface. This may include the grading, digging, cutting, scraping, or excavating of soil, placement of fill materials, paving, construction, substantial removal of vegetation,, or any activity which bares soil or rock or involves the diversion or piping of any natural or man-made watercourse. Landowner: The legal or beneficial owner of land, including those holding the right to purchase or lease the land, or any other person holding proprietary rights in the land. Maintenance Agreement: A legally recorded document that acts as a property deed restriction, and which provides for long-term maintenance of storm water management practices. Nonpoint Source Pollution: Pollution from any source other than from any discernible, confined, and discrete conveyances, and shall include, but not be limited to, pollutants from agricultural, silvicultural, mining, construction, subsurface disposal and urban runoff sources. National Pollutant Discharge Elimination System (NPDES) Storm Water Discharge Permit: A permit issued by EPA (or by a State under authority delegated pursuant to 33 USC ' 1342(b)) that authorizes the discharge of pollutants to waters of the United States, whether the permit is applicable on an individual, group, or general area-wide basis. Offset Fee: A monetary compensation paid to a local government for failure to meet pollutant load reduction targets. Off-Site Facility: A stormwater management measure located outside the subject property boundary described in the permit application for land development activity. On-Site Facility: A stormwater management measure located within the subject property boundary described in the permit application for land development activity. Recharge: The replenishment of underground water reserves. Redevelopment: Any construction activity where, prior to the start of construction, the areas to be disturbed have 15 percent or more of impervious surface. (Ordinance 2015- 04, adopted September 8, 2015) Site Development Permit: The permit issued by the municipality for which the purpose is construction or alteration of ground.   Stop Work Order: An order issued which requires that all construction activity on a site be stopped. Stormwater Management: The use of structural or non-structural practices that are designed to reduce storm water runoff pollutant loads, discharge volumes, peak flow discharge rates and detrimental changes in stream temperature that affect water quality and habitat. Stormwater Management Plan: The hydrologic analysis report and drainage area map(s) that provides the pre-development and post-development hydrologic site conditions. Stormwater Retrofit: A stormwater management practice designed for an existing development site that previously had either no stormwater management practice in place or a practice inadequate to meet the stormwater management requirements of the site. Stormwater Runoff: Means flow on the surface of the ground, resulting from precipitation. Stormwater Treatment Practices (STPs): means measures, either structural or nonstructural, that are determined to be the most effective, practical means of preventing or reducing point source or nonpoint source pollution inputs to stormwater runoff and water bodies. SWPPP: The Stormwater Pollution Prevention Plan required by the NPDES permit. Water Quality Volume (WQv): The storage needed to capture and treat 90% of the average annual stormwater runoff volume. Numerically (WQv) will vary as a function of long term rainfall statistical data. Watercourse: A permanent or intermittent stream or other body of water, either natural or man-made, which gathers or carries surface water. (Ordinance #16, adopted April 13, 2010) 9-5-3: PERMITS: No land owner or land operator shall receive any of the building, grading or other land development permits required for land disturbance activities without first meeting the requirements of this Section prior to commencing the proposed activity. The permit application must be accompanied by the following in order that the permit application be considered: a Grading, Drainage, and Erosion Control Plan, a Stormwater Management Plan, and a permit review escrow as established in Section 1-2-2 of the City Code. A. This Section shall be applicable to all site development permit applications, unless eligible for an exemption or granted a waiver by the City of Nowthen   under the specifications of this Section. The Section also applies to land development activities that are smaller than the minimum applicability criteria if such activities are part of a larger common plan of development that meets the following applicability criteria, even though multiple separate and distinct land development activities may take place at different times on different schedules. In addition, all plans must also be reviewed by local environmental protection officials to ensure that established water quality standards will be maintained during and after development of the site and that post construction runoff levels are consistent with any local and regional watershed plans. B. To prevent the adverse impacts of stormwater runoff, the City of Nowthen has developed a set of performance standards that must be met at new development and redevelopment sites. These standards apply to any construction activity disturbing one (1) acre or more of land or creating ten thousand (10,000) square feet of new or fully reconstructed impervious surface unless eligible for an exemption or granted a waiver. (Ordinance 2015-04, adopted September 8, 2015) C. No site development permit is required for the following activities, except as required in Section 9-4-3.A for disturbances of ten thousand 10,000 square feet or more: 1\. Additions or modifications to existing single family structures 2\. Developments that do not disturb more than one (1) acre of land provided they are not part of a larger common development plan. 3\. Repairs to any stormwater treatment practice deemed necessary by City Engineer or any emergency activity which is immediately necessary for the protection of life, property or natural resources. D. When a development plan is submitted that qualifies as a redevelopment project as defined in Section 9-5-2 of this Section, decisions on permitting and on-site stormwater requirements shall be governed by special stormwater sizing criteria found in the current Engineering Manual. These criteria are dependent on the amount of impervious area created by the redevelopment and its impact on water quality. Final authorization of all redevelopment projects will be determined after a review by the City of Nowthen. E. The applicant shall file with the City of Nowthen a security as outlined in Section 9-4-3.E of this Chapter. F. The permit application shall follow the review and approval procedure outlined in Section 9-4-3.F of this Chapter.   G. Permits issued under this section shall be valid from the date of issuance through the date the City of Nowthen notifies the permit holder that the site has passed the final inspection as required under the permit. (Ordinance #16, adopted April 13, 2010) 9-5-4: WAIVERS: Every applicant shall provide for stormwater management as required by this Section, unless a written request is filed to waive this requirement. Requests to waive the stormwater management requirements shall be submitted to the City of Nowthen for approval: A. The minimum requirements for stormwater management may be waived in whole or in part upon written request of the applicant, provided that at least one of the following conditions applies: 1\. It can be demonstrated that the proposed development is not likely to impair attainment of the objectives of this Section. 2\. Alternative minimum requirements for on-site management of stormwater discharges have been established in a stormwater management plan that has been approved by the City of Nowthen and the implementation of the plan is required by local ordinance. 3\. Provisions are made to manage stormwater by an off-site facility. The off- site facility is required to be in place, to be designed and adequately sized to provide a level of stormwater control that is equal to or greater than that which would be afforded by on-site practices and there is a legally obligated entity responsible for long-term operation and maintenance of the stormwater practice. 4\. The City of Nowthen finds that meeting the minimum on-site management requirements is not feasible due to the natural or existing physical characteristics of a site. a. Onsite non-structural practices will be used that reduce: 1\) The generation of stormwater from the site, 2\) The size and cost of stormwater storage and 3\) The pollutants generated at the site. These non-structural practices are explained in detail in the current BMP Manual and the amount of credit available for using such practices shall be determined by the City of Nowthen. B. In instances where one of the conditions above applies, the City of Nowthen may grant a waiver from strict compliance with these stormwater management   provisions, as long as acceptable mitigation measures are provided. However, to be eligible for a waiver, the applicant must demonstrate to the satisfaction of the City of Nowthen that the waiver will not result in the following impacts to downstream waterways: 1\. Deterioration of existing culverts and other structures; 2\. Degradation of biological functions or habitat; 3\. Accelerated streambank or streambed erosion or siltation; 4\. Increased threat of flood damage to public health, life, property. C. Where compliance with minimum requirements for stormwater management is waived, the applicant will satisfy the minimum requirements by meeting one of the mitigation measures selected by the City of Nowthen authority. Mitigation measures may include, but are not limited to, the following: 1\. The purchase and donation of privately owned lands, or the grant of an easement to be dedicated for preservation and/or reforestation. These lands should be located adjacent to the stream corridor in order to provide permanent buffer areas to protect water quality and aquatic habitat, 2\. The creation of a stormwater management facility or other drainage improvements on previously developed properties, public or private, that currently lack stormwater management facilities designed and constructed in accordance with the purposes and standards of this Section. 3\. Monetary contributions (Fee-in-Lieu) to fund stormwater management activities such as research and studies (e.g., regional wetland delineation studies, stream monitoring studies for water quality and macroinvertebrates, stream flow monitoring, threatened and endangered species studies, hydrologic studies, and monitoring of stormwater management practices.) a. Fee-in-Lieu of Stormwater Management Practices. 1\) Where the City of Nowthen waives all or part of the minimum stormwater management requirements, or where the waiver is based on the provision of adequate stormwater facilities provided downstream of the proposed development, the applicant shall be required to pay a fee in an amount as determined by the City of Nowthen. 2\) When an applicant obtains a waiver of the required stormwater management, the monetary contribution required   shall be in accordance the adopted fee schedule. Nowthen is storm water authority established by the City of Nowthen, and based on the cubic feet of storage required for stormwater management of the development in question. All of the monetary contributions shall be credited to an appropriate capital improvements program project, and shall be made by the developer prior to the issuance of any building permit for the development. b. Dedication of land: In lieu of a monetary contribution, an applicant may obtain a waiver of the required stormwater management by entering into an agreement with the City of Nowthen for the granting of an easement or the dedication of land by the applicant, to be used for the construction of an off-site stormwater management facility. The agreement shall be entered into by the applicant and the City of Nowthen prior to the recording of plats or, if no record plat is required, prior to the issuance of the building permit. (Ordinance #16, adopted April 13, 2010) 9-5-5: STORMWATER MANAGEMENT PLAN: The plan shall include a stormwater drainage report and where storm sewer structures and pipe are present or proposed, storm sewer capacity calculations. The plan shall conform to the most recent version of the Engineering Manual requirements. A. The stormwater drainage report shall include: 1\. A title page, table of contents, written summary of items critical to the review of the entire report, computer printouts of the hydrologic analysis stormwater model, and drainage area maps. 2\. When storm sewer is proposed or present storm sewer sizing and spread calculations shall accompany the stormwater drainage report. Separate drainage area maps are required depicting the area draining to each storm sewer structure. B. The Grading, Drainage, and Erosion Control Plan shall incorporate all stormwater facilities (i.e. ponds, infiltration basins, storm sewer, etc.) as shown in the Stormwater Management Plan. C. Modifications to the plan: 1\. Major amendments of the Stormwater Management Plan shall be submitted to the City of Nowthen and shall be processed and approved, or disapproved, in the same manner as the original plans.   2\. Field modifications of a minor nature may be authorized by the City Engineer by written authorization to the permitee. (Ordinance #16, adopted April 13, 2010)

Ch.9 § 5-1

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