Pipeline relining is part of the San Diego County Water Authority’s multi-billion dollar CapitalImprovement Program which was initiated in 1989 to plan and implement projects to meet the region’s future waterneeds. The relining program is addressing signs of deterioration detected in some sections of the existing aqueduct.The urgency for relining was made apparent by recent catastrophic pipeline failures in May 2006 and October 2008.Relining was identified as a faster, more cost-effective alternative to cut and cover replacement of the entirepipeline. In addition, it significantly reduces the impact of construction on local communities through which theaqueduct is routed. The general construction method involves lining the existing prestressed concrete cylinder pipe(PCCP) with steel liner sections that are welded together. The resulting annular space between the PCCP and steelliner is filled with cellular grout and a cement mortar lining is applied to the surface of the new steel liners. Thismethod is estimated to extend the service life of the aqueduct by 50 to 75 years.This paper will provide background information on the Water Authority aqueduct and the driving forces behind theinitiation of the relining program. In addition, it will address prestressed concrete cylinder pipe (PCCP), corrosionissues, construction methods, design and scheduling considerations, project delivery methods, challenges faced andlessons learned. It will also discuss the future of the relining program.
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