2002-07-25_AgendaPacket - Laserfiche WebLink

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`:~ Lj Lake Watershed, is proposed to be treated in one of two alternative ponds under consideration on the Chippewa Middle School property. One alternative location is on the East Side of the property, and would have a surface area of approximately 027 hectares (0.67 acres) and permanent pool storage volume of 2,775 cubic meters (2.25 acre-feet). This pond location would. also accommodate stormwater runoff from the school property. The second alternative location is on the West Side of the property next to Highway 49, and would have a surface area of approximately ~, 0.22 hectares (0.54 acres) and permanent pool storage volume of 2,110 cubic meters (I.71 acre- i`-~ feet). The removal efficiencies for both alternative pond locations meet National Urban Runoff Program (NURP) standards. Both pond alternatives would discharge through the Red Maple r,, Marsh-Blue Water Marsh system to Pleasant Lake. stormwater from the subwatershed between Highway 96 and Tanglewood Drive (Drainage area 3A&B on Figure 7), which lies in the Grass Lake Watershed, is proposed to be treated in an existing stormwater pond located behind the Rainbow Foods Store north of Highway 96. This pond would be enlarged to have a surface area of 0.13 hectares (0.31 acres) and permanent pool storage volume of 1,949 cubic meters (1.58 acre-feet). The existing stormwater pond has removal efficiencies of 76.5% for total suspended solids and 48.0% for total phosphorous. The enlarged pond would have slightly increased removal efficiencies, 77.6% for total suspended solids and 48.7% for total phosphorous. These removal efficiencies, both for the existing and enlarged ponds, do not meet NURP standards of 90% for total suspended solids and 60% for total phosphorous, but with the limited space available, it is not considered feasible to construct a pond large enough to meet full NURP standards. This pond discharges through a series of wetlands to Grass Lake. The subwatershed south of Highway 96 (Drainage area 1 on Figure 7), which is part of the Grass Lake Watershed, would be treated in an existing stormwater pond west of Bridge Street and Highway 49. The berm enclosing this pond would be rebuilt to its original design elevation, resulting in a pond with a surface area of 0.15 hectares (0.37 acres) and a permanent pool storage volume of 1,234 cubic meters (1.00 acre-feet). The removal efficiencies for this pond would meet f National Urban Runoff Program (NURP) standards. This pond discharges through a series of wetlands to Grass Lake. Capacity and water quality requirements for the storm sewer systems are under the authority of the municipalities and the watershed management organizations according to their stormwater management plans. Additional detail regarding storm water tributary areas and specific ponding locations is included in the "Highway 49 Project Development Report (July, 2000)". 18. Water quality: wastewaters a. Describe sources, composition and quantities of all sanitary, municipal and iiul~sstrial wastewater produced or treated at the site. None. ~° b. Describe waste treatment methods or pollution prevention efforts and give estimates of composition after treatment. Identify receiving waters, including major downstream water bodies, and estimate the discharge impact on the quality of receiving waters. If the project involves on-site sewage systems, discuss the suitability of site conditions for such systems. - None. c. If wastes will be discharged into a publicly owned treatment facility, identify the facility, describe any pretreatment provisions and discuss the facility's ability to handle the volume and composition of wastes, identifying any improvements necessary.