PFAS discovery and utility conflicts delay OC San’s $55m interceptor rehab
Orange County Sanitation District, California · Meeting date: June 3, 2026 · Published: June 14, 2026
The Orange County Sanitation District has approved a contingency increase for construction services on its Gisler-Red Hill Interceptor project after unanticipated groundwater treatment for PFAS and unmapped fiber optic cables added nearly seven months to the schedule.
Key points
- CDM Smith received a $296,000 contingency increase for construction support services after the project experienced a 207-day time impact.
- Groundwater dewatering required emergency carbon treatment after PFAS levels spiked to 70 parts per trillion during construction.
- The $55 million rehabilitation project, which involves CIPP lining of gravity lines and dual force mains, is currently 85% complete.
Full report
Unexpected groundwater contamination and unmapped utility installations have added over 200 days of delays to the Orange County Sanitation District’s (OC San) $55 million Gisler-Red Hill Interceptor and Baker Force Main Rehabilitation project.
During a June 3, 2026 meeting, the OC San Operations Committee approved a $296,000 contingency increase for CDM Smith, the project's design and construction services consultant. The additional funding was required after a 207-day schedule delay exhausted the firm's original contract time and led to a surge in submittals and requests for information (RFIs) that more than doubled initial estimates.
Project management supervisor Daniel Barakoff indicated that the $44 million construction phase—which involves installing cured-in-place pipe (CIPP) liners in gravity and pressurized force mains in Costa Mesa and Irvine—faced major underground hurdles. After the project was designed and bid, a utility company installed fiber optic cables that directly conflicted with the planned access pits for the force mains.
Further complicating the excavation, contractors encountered per- and polyfluoroalkyl substances (PFAS) during access pit dewatering. While groundwater testing during the design phase showed PFAS levels between 30 and 40 parts per trillion (ppt), concentrations during construction reached the 70 ppt threshold. This required the district to deploy carbon treatment to filter the groundwater before discharging it into its own sewer system.
A staff member noted that the contamination's exact source remains uncertain, though committee members speculated it could be linked to a nearby former Army base. Because OC San is not a defendant in major ongoing PFAS class-action settlements, the district currently bears the cost of mitigating the contaminated groundwater encountered during its infrastructure projects.
The project's timeline was also hampered by wet weather and high wastewater transfers from the Irvine Ranch Water District, which forced OC San to halt the contractor's work to manage flow capacity. Despite the setbacks, Barakoff confirmed the rehabilitation project is now 85% complete, with the final completion date expected to be finalized shortly.
This summary was generated by AI based on the source document and may contain errors.
Source: OPERATIONS COMMITTEE, Orange County Sanitation District