Project Description

A two-mile sewer tunnel that was built in 1954 runs deep inside the ocean-facing cliffs in South Laguna, CA. The tunnel houses a sewer line that conveys one million gallons of wastewater a day by gravity flow to the Coastal Treatment Plant in Aliso Canyon. The volume of wastewater carried by the line is approximately 25% of the District’s daily load. The tunnel was undersized, deteriorating, and unsafe, posing risks of injury to workers and risks of damaging or breaking the sewer line itself, potentially causing a sewage spill onto the beaches along the two-mile coast.

OPC acquired upgraded easements, new easements, access rights, and fee interests from 214 beach-front property owners along the 2-mile length of existing sewer tunnel. Our program management capabilities for this large parcel project were enhanced by OPC’s SharePoint project management site.

The District allowed OPC’s phased program with stepped-up levels of effort consistent with the values of the property rights to be acquired and impacts to the land. OPC was able to contain condemnation proceedings to a handful of residents who were fundamentally opposed to the project – which was a $20 million litigation expense savings from the original services cost estimates.

Photo: The Tunnel Stabilization & Sewer Pipeline Replacement Project site is shown with a rendering of the replacement pipeline.