AgdaPkt 2009-07-13 clsd and jnt - Laserfiche WebLink

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REPORT 6.1H Page 1 To the Honor.able Nla'yor and City C.ounc.n From' the C'i' Man" er July 13, 2009 SUBJECT Award of Contract -Sewer Force Main Replacement Project RECOMMENDATION Approve, by motion, the contract documents and award the contract for the Sewer Force Main Replacement Project (from Pump Station NO.12 to Pump Station No.10) to the lowest responsible bidder, Peak Engineering, Inc. of Oakland for their responsive and responsible low bid of $414,635.11 and authorize the City Manager to increase the contract amount up to 10% if necessary. BACKGROUND This project is prioritized for completion because of the deteriorated condition of a section of the existing 12-inch diameter asbestos cement pipe. During the recent replacement of an air release valve on the pipe near the intersection of Shell Parkway and Davit Lane, Public Works Services staff noted leaking joints. When the pipe was opened to repair the leaks, staff discovered that the existing pipe wall thickness at the crown of the pipe had thinned to approximately 0.25 inch. Normal wall thickness is approximately 1.25 inches. Engineering staff attributes the excessive deterioration of the pipe wall to the action of corrosive gases trapped in the pipe. The significantly deteriorated condition of the pipe compromises the reliability of the sewer force main. If the force main fails, the sanitary sewer will overflow creating a public health hazard. The continued reliability of this section is critical to the operation of the sewer system. A failed pipe would req uire Public Works Services staff to perform repair work under very disadvantageous conditions. Public Works Services staff would be required to divert the flows generated by five other pump stations located upstream from Pump Station NO.12 until repairs were made. Additionally, without the force main operational, the sewer system loses the capability of conveying wastewater in this area. The project consists of approximately 2,400 linear feet of 12-inch polyvinyl chloride (PVC) pipeline that will replace asbestos cement pipe along Shell Parkway and Davit Lane, from Sewer Pump Station NO.12 to Sewer Pump Station No.1 0, in Redwood Shores. The new force main will be constructed using traditional open cut method. The contractor will resurface roadway areas, from curb to curb, that are disturbed or othelWise affected during the work to replace the pipeline segment. This project will restore the reliability and improve the overall functionality of the sewer collection system in Redwood Shores.