Proven Pipeline Rehabilitation System Using Steel Liners for the San Diego County Water Authority

The San Diego County Water Authority (SDCWA) conveys water to the residents of San Diego County through a system of over 300 miles of pipelines. Pre-stressed concrete cylinder pipe (PCCP) makes up approximately 82 miles of this system. In 1991 SDCWA instituted a 30 year relining program to reinforce all the existing PCCP with steel liners. The program rehabilitates and extends the life of the aging water delivery pipelines and helps ensure a safe and reliable water supply to the region. To date SDCWA has lined more than 30 miles of PCCP and anticipates completing the relining of the remaining 52 miles by 2027. Pipeline relining is typically used on long sections of pipelines and involves installing new steel liners into an existing pipeline. The new liners, which basically serve as new pipelines, are anticipated to last approximately 50 to 75 years. Relining the existing pipelines with steel is a quicker, more cost-effective alternative to excavating, removing, and replacing an entire pipeline and generally takes up to a year to complete. Typical outages are six to eight months. This paper presents the Mission Trails Park to Lake Murray Relining project which involved rehabilitating approximately 3 miles of 69" and 66" PCCP utilizing steel liner plates. This paper will present the methods of manufacturing and collapsing the steel liner to assist in a timely installation of the project in order to meet the critical deadlines established by the agency. The paper will also present the cost benefits of this type of relining versus other alternatives.