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10062 Flanders Court NE – Blaine, MN 55449 – (763) 780-0450 fax (763) 205-2341 <br /> <br />Z:\PROJ\120211E - 2017 Storm Improvements\0060\Memo-092217-council (Award).doc <br /> <br /> <br /> <br />Memo <br /> <br /> <br /> <br />TO: Mayor Keis & Members of the City Council <br /> <br />FROM: Lee Elfering, City Engineer <br /> <br />DATE: September 22, 2017 <br /> <br />RE: Miscellaneous Storm Sewer Improvements <br /> Recommendation for Award <br /> <br /> <br />Late this summer Public Works crews encountered a sink hole near a storm structure on <br />County Road B2, upon further inspection of the street structures it was determined that <br />one full structure replacement and one full ring and casting replacement was needed <br />along the roadway. The structure replacement will invo lve the removal of a large 2’ by <br />6’ structure and installation of two smaller 2’ x 3’ structures to maintain the same inlet <br />capacity. <br /> <br />With the need to have a pipe contractor in to complete the work on County Road B2 we <br />choose to get pricing on two other storm utility projects at the same time. A sink hole <br />has formed around a storm structure located north of Gervais Creek and 50 feet west of <br />Country Drive. The structure is near the bottom of the roadway embankment <br />approximately 18 feet below the road surface. Upon review of the structure the base <br />slab and bottom section of the manhole have failed causing the sink hole. The work <br />proposed includes salvaging of the top manhole sections, replacement of the base slab <br />and bottom section, reinstallation of salvaged sections and filling of the hole to pre- <br />existing grade. <br /> <br />A third storm improvement bid was the installation of a structure and pipe off the end of <br />Boss Road. Currently there is a curb depression that allows water to drain from the <br />street into the infiltration pond to the north of the cul-de-sac. Although the grade is not <br />excessively steep there have been continuing issues with erosion of the spillway and <br />efforts to address the erosion have not been successful. It is proposed to install a <br />shallow structure and pipe outlet to the pond to eliminate the erosion problem. <br /> <br />Two of the four Contractors contacted submitted quotes to complete the work and the <br />results are summarized below: <br />