Agenda - Public Works Committee - 06/17/2014

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Sec 117.384-410 Revised June 5, 2014 to include 2013 Construction Stormwater Permit, 2013 MS4 Permit requirements and 2012 LRRWMO Third Generation Plan [deletion;,, additions] (9) rain water harvesting (c) Other practices. Other traditional stormwater BMPs mav be approved on a site by site basis to achieve the Goals of water quality and quantity, and rate control. These practices shall conform to the standards outlined in the resources referenced above. (d) All stormwater runoff shall be pre-treated prior to discharge to anv surface water. (e) Maintenance plan. A plan shall be established to maintain all temporary and permanent BMPs in a working and efficient condition. This mav include removal of invasive species, sediment, debris, or anv other foreign or obstructive obiect or condition that prevents the BMPs from performing as desianed. (f) Exemption. The mill and overlay or rehabilitation of a public roadway that does not create additional impervious surfaces; and sidewalk or trail proiects are exempt from these stormwater requirements. These proiects mav be subiect to other regulations. At a minimum these facilities must conform to the most current technoloav as reflected in the current version of the Minnesota Pollution Control Aaencv's publication, "Protecting Water Quality in Urban Areas" and the current requirements found in the same aaencv's NPDES permits for stormwater associated with construction activities. (Code 1978, § 9.27.12; Ord. No. 06-32, § 1, 11-28-2006) Sec. 117-394. - Minimum protection for natural wetlands. (a) Runoff must not be discharged directly into wetlands without appropriate quality (i.e., treated) and quantity runoff control, depending on the individual wetland's vegetation sensitivity. See the current version of the Minnesota Pollution Control Agency's publication, "Storm -Water and Wetlands: Planning and Evaluation Guidelines for Addressing Potential Impacts of Urban Storm -Water and Snow -Melt Runoff on Wetlands" for guidance. The minimum level of treatment required for discharge to wetlands is to meet the NURP Guidelines as follows: • A permanent pool ("dead storage") volume below the principal spillway (normal outlet) which shall be areater than or equal to the runoff from a 2.5 inch storm over the entire contributing area assuming full development. It shall have an annual removal efficiency of 60% total phosphorus and 90% total suspended solids. • A permanent pool average depth (basin volume/ basin area) which shall be >3 feet, with a maximum depth of 10 feet. • Pond outlets shall have skimmers, submeraed outlets or other devices that extend a minimum of 6 inches below the water surface and minimize velocities of water passing under the skimmer to less than 0.5 feet per second for rainfall events having a 99% frequency (1 year storm event). (b) Wetlands must not be drained or filled, wholly or partially, unless replaced by either restoring or creating wetland areas of at least equal public value. Compensating for the impact by replacing or providing substitute wetland resources or environments with those of at least equal public value. Compensation, including the replacement ratio and quality of replacement should be consistent with the requirements outlined in Ramsey, Minnesota, Code of Ordinances Page 10