12/18/2013 Env Bd Packet - Laserfiche WebLink

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ITEM 17 WATER QUALITY: SURFACE WATER RUNOFF • • • Break up impervious surfaces to allow opportunities for infiltration; • Use ecological stormwater management techniques, such as vegetated swales, infiltration systems, and biofilter wetlands; • Provide energy dissipation and outfall stabilization; and • Establish and maintain vegetated buffers around aquatic resources. 16.4 Provide construction oversight to ensure designed sediment and erosion control measures are being implemented. 16.5 Implement the Conservation Design Framework (CDF, Figure 10 -3). which is designed to help mitigate erosion and sedimentation caused by surface water runoff. Components of the CDF that help mitigate erosion and sedimentation include conservation of natural open spaces, buffering, and an ecological stormwater management system. Mitigation Strategies The City will: 17.1 Work with project proposers to establish a regional stormwater management system within the Conservation Design Framework (CDF, see Figure 10 -3) that consists of vegetated swales, wet prairies, and wetlands oriented in series to effectively retard runoff rates, reduce stormwater volume, and enhance water quality. 17.2 Work with project proposers to disperse collection, conveyance, and management of stormwater runoff as much as possible throughout the AUAR site through the use of bio- swales, rain gardens, and infiltration areas. 17.3 Require stormwater management systems to be developed in accordance with Rice Creek Watershed District Rules. 17.4 Require project proposers to design stormwater management areas (SMAs) to support native vegetation and maintain runoff rates at or below pre - development conditions. 17.5 Require project proposers to design stormwater management systems that can achieve proposed conditions runoff volumes that are no less than 80% and no greater than 150% of existing conditions runoff volumes. 17.6 Encourage project proposers to use techniques that produce no net increases in total phosphorus content of proposed conditions runoff relative to existing conditions runoff. 17.7 Require project proposers to provide detailed topographic information with a contour interval of 1 -foot and drain tile mapping.