7.2. SR 06-21-2010 - Laserfiche WebLink

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City of El -~ River REQUEST FOR ACTION To Item Number Ma or and Ci Council 7.2. Agenda Section Meeting Date Prepared by Administration une 21, 2010 ohn Anderson P.E. Item Description Reviewed by 182nd Avenue Storm Sewer Improvements Lori ohnson, Ci Administrator Reviewed by Action Requested Authorization to proceed with storm sewer improvements at the intersection of 182nd Avenue and 181St Lane. Background/Discussion The street was constructed in 2000 with the first plat of Trott Brook Farms. The native soils in the area are clay and not free draining. The street section was built with a sand layer to provide drainage for the street subgrade. The original construction included drain file in the road section to drain the sand layer. The current storm sewer in the intersection of 182nd Avenue and 181St Lane discharge to a storm treatment pond located northeast of the intersection. This pond flows to the large wetland to the north. The water level in the large wetland is often high enough to back water up into the storm pond and the storm sewer. As a result of the high water levels, the road subgrade becomes saturated. The saturated subgrade places freeze /thaw forces on the existing storm pipes crossing the roadway causing differential movement in the pavement surface. The proposed storm sewer reconfiguration would route the storm sewer inlets on the south side of 182nd Avenue and subgrade drain file to a pond located south and east of the intersection. The normal water level in this pond is lower and will provide a positive drain for the area. The reconfiguration will also eliminate road crossing of the larger concrete pipes around which the differential movement has been observed. Construction will require the proposed storm sewer to cross two existing large gas mains that run east and west. The gas mains were exposed to determine the elevation of the existing pipes and the feasibility of crossing these pipes with the new storm sewer. The proposed plans have been reviewed and meet the crossing criteria of Northern Natural Gas. Financial Impact Quotations for construction were solicited from two contractors to complete the work detailed on the attached plan. The quotes received were as follows: Brenteson Companies - $38,652.36 Northdale Construction - $48,544.10