11-08-1999 Council Packet - Laserfiche WebLink

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Introduction This report addresses the proposed Highway 12 Bypass Lift Station and the rehabilitation of the Femdale area lift stations. It is proposed that the lift stations be bid as one construction project in order to generate greater contractor interest and to obtain competitive prices. Highway 12 Bypass Lift Station The existing sanitary sewer collection system in this area is at capacity. Improvements are required to serve the Orono Middle School which is expected to be operational by July 1, 2000. The sanitary sewer system is schedule to be upgraded in 2006 in conjunction with the Highway 12 realignment project. The bypass lift station would provide relief to the gravity sewer by pumping flow in excess of the gravity sewer capacity directly into the Maple Plain Interceptor Forcemain. The proposed location is near Washington Scientific on the south side of Highway 12 as shown on the attached location and site maps. It is estimated that a pumping capacity of 200 gallons per minute (gpm) is required to provide adequate relief to the gravity sewer. After permanent sanitary sewer improvements are constructed at a future date, the bypass lift station would no longer be required and could be removed or abandoned in-place. Femdale Area Lift Stations Lift Stations 1 through 5 are located in the Femdale Road West / Highway 15 area as shown on the attached location and site maps. The lift stations in this area that date to 1980. The system layout and lift station constmction represent the lowest initial cost facilities that were evaluated at that time. Lift Station No. 1 is a concrete duplex grinder pump station. Lift Station No. 1 is in need of minor repairs to the concrete structure, and mechanical / electrical rehabilitation. Lift Station No. 1 pumps through a short 4-inch forcemain connected to the Highway 15 Interceptor Forcemain. Lift Stations 2 through 5 are “steel can” duplex grinder pump stations, which were protected by epoxy coatings and cathodic protection systems. The epoxy coatings and cathodic protection have failed due to age, and the organic soils in this area may have accelerated the deterioration of these structures. Lift Stations 2, 3, and 4 have required emergency repairs due to mst-through. Through the 1990’s, there has been a history of operational problems with Lift Stations 2,3, and 4. In the spring, the lift stations run near continuously and produce frequent high level alarms. There is significant inflow and infiltration of groundwater into the sewer system. Lift Stations 2, 3, and 4 pump through a common 2-inch forcemain to a gravity sewer which flows to Lift Station No. 1. Significant encrustation and deposits are present in the 2-inch forcemain. The