Santa Ana Regional Interceptor Line

The Project.

To protect the Prado Basin during future 100-year storms, the US Army Corps increased the capacity of Prado Dam, and the discharge capacity into the Santa Ana River increased to 30,000 cf/sec. Consider that amount of water flowing in a river over a buried pipeline that serves the sewage disposal needs of several cities and portions of Riverside and San Bernardino counties. In the case of the Santa Ana Regional Interceptor Line (SARI), erosion raised concern over the possibility of a break when the flow from Prado would be at capacity during a storm event. Due to the exposed sections, a relocation project proposed an alignment along the riverbank adjacent to the Riverside Freeway, providing protection from flows in the river.


County of Orange Sanitation District


Orange County and Riverside County, CA


  • Environmental
  • Geotechnical
  • Geotechnical Testing

Project Fact:

Our client, Tetra Tech, received the ASCE Orange County Branch 2014 Wastewater Conveyance Project of the Year Award. The project is the largest, most expensive flood control project undertaken by the Orange County Flood Control District.

The Leighton Solution.

Working for the lead civil engineering firm, Leighton provided a Phase I Environmental Assessment, Aerial Deposited Lead survey, Geotechnical Data Report (GDR), and a Geotechnical Interpretive Report (GIR) with design information for the pipeline, backfill, tunnel lining, shoring, dewatering, seismic design parameters, and settlement potential.

We also prepared a Geotechnical Baseline Report presenting the baseline conditions for bidding by the contractors and reference during construction.