Agenda - Public Works Committee - 03/20/2012

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18" HDPE pipe south to County Ditch #3. with an invert elevation of 872.0. Installing the pipe at an elevation of 872.0 will continue to allow 3" stonm events to infiltrate into the soil. The estimated cost to install this outlet is $80,795. 156 Lane During large storm events, the wetland in Woodland Green Park ponds water in the backyard of 5220 156 Lane. The area where water ponds was platted with a 75-foot drainage and utility easement, however, this easement has been vacated. The wetland discharges east through an existing storm sewer system to a low area and then north through another storm sewer system to the Rum River. Different sized ponds and outlet configurations were analyzed. One alternative to reduce the high water level of the wetland in Woodland Green Park included constructing a new outlet pipe from the wetland to the low area to the east. This alternative would also require constructing a new outlet at a lower elevation from the low area directly to the Rum River. This would require the approval of the Minnesota Department of Natural Resources and does not appear viable at this time. We recommend filling the backyard of 5220 156 Lane to an elevation equal to the 100 - year high water level. Stormwater would then be contained within Woodland Green Park and would not impact this homeowner. Filling the backyard would require grading in the Woodland Green Park site to create storage to compensate for the lost volume. The estimated cost to complete the grading is $21,175. Sodium Street The house at 16756 Sodium Street has been experiencing water in the basement. One reason for having water in the basement could be caused by the road ditch in front of the house filling and then overflowing toward the house. The water then seeps along the basement wall and eventually into the basement. Another reason for water in the basement could be caused by a high groundwater elevation in the area. We recommend installing a culvert under Sodium Street, regrading the west ditch of Sodium Street, constructing a berm to keep the water in the ditch, and replacing the existing driveway culvert. The ditch would be graded to drain south and a culvert would be installed near the south property line to drain the water to the west. The estimated cost to complete this project is $12,225.