02/28/2001 Env Bd Packet - Laserfiche WebLink

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1. Construction of temporary sediment basins in the locations proposed for stormwater ponds, and development of these basins for permanent use following construction. 2. Silt fence installed at the construction limits prior to the initiation of earth work and maintained until all exposed soil is stabilized. 3. Installation of a rock construction entrance. 4. Periodic cleaning of adjacent city streets. 5. Energy dissipation, such as rip -rap, installed at storm sewer outfalls. 6. Use of cover crops, sod, and landscaping to stabilize exposed surface soils after final grading. All erosion control plans will be reviewed by the City of Lino Lakes. Because the above BMPs will be implemented, the potential for adverse affects from construction- related sediment and erosion on water quality will be minimized to the extent practical. 18. Water Quality - Surface Water Runoff: a. Compare the quantity and quality of site runoff before and after the project. Describe methods to be used to manage and / or treat runoff. The existing site soil regime is of naturally high infiltration media. Drainage calculations for the predevelopment 100 -year flood event computed a total site runoff of only 1.54 cfs. Post - development runoff rates will be maintained at the pre - development rates by the addition of two ponds and a bioretention basin. One pond, located on the northeast corner of the site, will capture water from the roofs of the SuperTarget and the three major retail buildings west of Apollo Drive. This pond will also collect water from the parking areas and drive isles in this area. The pond will have a National Urban Runoff Program (NURP) volume of 5.26 acre -feet and a wet storage capacity of 6.12 acre -feet. It will discharge to the bio- retention basin at a maximum rate of 2.88 cubic feet per second. The other pond, centrally located on the southern property boundary, will capture runoff from Apollo Drive and the parking lot area west of Apollo Drive. This pond will have an NURP volume of 1.64 acre -feet and a wet storage capacity of 2.12 acre -feet. It will discharge to the bio- retention basin at a maximum rate of 10.32 cubic feet per second. The bio- retention basin, located in the southeastern corner of the site, is an existing wetland. The basin development will include 40 vertical infiltration tubes, a berm, landscaping, and a 6 inch diameter pipe discharging to the I35W Right of Way. The basin will have a dry storage volume of 4.7 acre - feet, and a peak discharge of 1.72 cubic feet per second. b. Identify the route(s) and receiving water bodies for runoff from the site. Estimate the impact of the runoff on the quality of the receiving waters. (If the PARSONS TRANSPORTATION GROUP Barton•Aschman • De Leuw, Cattier, • Steinman Page 11 Town Center Development Draft-Draft EAW....February 1, 2001