07/15/2004 Env Bd Packet - Laserfiche WebLink

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• • 12. Physical impacts on water resources. Will the project involve the physical or hydrologic alteration — dredging, filling, stream diversion, outfall structure, diking, and impoundment of any surface waters such as a lake, pond, wetland, stream or drainage ditch? IEI Yes 0 No If yes, identify water resource affected and give the DNR Protected Waters Inventory number(s) if the water resources affected are on the PWI: #10P . Describe alternatives considered and proposed mitigation measures to minimize impacts. Protected water #10P is Wards Lake, defined by the ordinary high water level (OHWL) of 883.7. Wetlands with cattails and other wetland vegetation can be found along the edges of the water. The wetland delineation shows that the wetland edge and the OHWL are nearly identical, varying in some places by up to 15 feet horizontally. A wetland delineation and wetland permit application narrative can be found in Exhibit D. The proposed project includes a 300 foot bridge to span a wetland/lake area to connect to an upland island. The bridge would consist of two bridge sections of 150 feet each. The preliminary design has one pier in the center of the bridge, in the lake (below the ordinary high water level). This central pier will have an approximate footprint of 100 square feet. The plan is to construct the bridge abutments, on each end of the bridge, outside of delineated wetlands. Fill for bridge approaches then would be entirely outside the wetland boundaries. This would need to be examined as the design of the bridge progresses beyond a preliminary stage. Alternative accesses to the proposed bridge have been discussed. One alternative is creating an earthen bridge by filling below the OHWL to provide access to the property. Although the least expensive, this alternative was not considered a desired alternative because of impacts to the lake and wetlands. A second alternative is a "flatter" bridge design. Flat bridge designs require more piers. The original design reviewed by the DNR for bridge permit approval showed five piers. Although approved, the design was later revised to show one pier after finding a bridge company that could design a bridge effectively with one pier. The location shown requires a 300 foot span bridge using one pier. Additional piers would require additional fill and construction dewatering. Regarding the location of the bridge access, the wetland /lake spans approximately 500 feet to the west and to the south to the nearest high ground. A bridge from either of these directions would require additional piers and corresponding fill and construction dewatering. The stormwater management plan has been designed to minimize impacts of runoff. Proper construction is extremely important in ensuring the successful operation of the stormwater management plan. The following recommendations will be incorporated in the final plans and specifications. • A "preservation area" has been incorporated into the stormwater plan. This area is located on the north side of the island. Because it is downhill from the building sites, Environmental Assessment Worksheet Page 8 Pheasant Hills 12`h Addition