InfraTerra given CWA contract for seismic vulnerability and repair time study

InfraTerra Inc. has been awarded a contract to provide seismic vulnerability assessments and repair time estimates for San Diego County Water Authority pipelines.

A unanimous SDCWA board vote, Jan. 23, authorized the award of a $724,939 contract for InfraTerra to perform the work. The study is expected to be complete during summer 2021.

The CWA has five large-diameter pipelines with prestressed concrete cylinder, reinforced concrete and welded steel pipe. The most recent major seismic vulnerability study on the CWA pipelines was performed in 1993 and provided an estimate of the number of pipe breaks and repair time needed to restore water service in the event of a significant earthquake. The estimated repair time ranged from two to six months.

That study also determined the emergency storage and conveyance facilities which were needed if an earthquake or other event prevented transmittal of Metropolitan Water District of Southern California supply. Those facilities became the CWA’s Emergency Storage Project which is now a reality.

The new study will incorporate repair time estimates based on current earthquake science standards and practices along with updated engineering and pipeline vulnerability assessment methodology. A specialized consulting team will perform a regional study and also conduct site-specific investigations for areas of concern.

The work will include geotechnical drilling and testing at multiple locations, seismic hazard assessment, pipe failure analysis and updates to the repair time estimates for the pipelines between Lake Skinner in Temecula and the Lower Otay Reservoir. InfraTerra will also make recommendations of pipeline retrofit alternatives and material availability improvements if such actions are warranted.

CWA staff issued a request for proposals, Oct.15, and three bids were received by the Nov. 15 deadline. A selection panel consisting of CWA staff from various departments evaluated the written proposals and interviewed representatives from all three firms.

All three companies provided complete and thorough proposals and demonstrated a clear understanding of the scope of work. InfraTerra, which is based in San Francisco, was deemed to be the most qualified of the three firms based on InfraTerra’s extensive experience with seismic vulnerability assessment in California and also Oregon and Washington, understanding of regional seismic matters and water infrastructure, use of advanced techniques for the reassessment, approach to the scope of work, and corporate resources.

The Elsinore Fault crosses MWD infrastructure north of the CWA boundary and also has a portion within the study area. Part of the Rose Canyon Fault is also within the study area boundaries. The San Andreas Fault and the San Jacinto Fault are located outside of the study area but cross MWD infrastructure.