Sweetwater Authority awards $1.5 million PFAS design contract to Carollo Engineers

Sweetwater Authority awards $1.5 million PFAS design contract to Carollo EngineersThe California agency selected Carollo to develop a preliminary design report for PFAS treatment at the Perdue Water Treatment Plant, utilizing funds from a 3M class-action settlement.

Carollo Engineers won the $1.5 million contract to produce a PFAS Preliminary Design Report and conduct pilot testing.

The project is fully funded by a $3.7 million settlement payment received from 3M.

Staff negotiated the fee down from an initial $1.93 million by incorporating a desktop study to shorten the pilot testing timeline.

The board also awarded a $2.89 million construction contract to HPS Mechanical for a reservoir aeration system.

The Governing Board of Sweetwater Authority approved a contract with Carollo Engineers to perform a study and develop a Preliminary Design Report for per- and polyfluoroalkyl substances (PFAS) mitigation. The contract, with a not-to-exceed amount of $1.5 million, focuses on developing treatment strategies for the Perdue Water Treatment Plant. Director of Engineering and Operations Xochil Aranda explained that the project is a critical step to meet EPA Maximum Contaminant Levels (MCLs) expected to take effect in 2029. Testing conducted by the authority in October 2024 at the Perdue facility detected PFOA and PFOS concentrations above the future federal limits, as well as PFHxS and PFOA levels exceeding California's notification levels. The authority received five proposals for the project. Following interviews with four shortlisted firms—Carollo, CDM Smith, Hazen and Sawyer, and Trussell—staff recommended Carollo based on technical scoring. Aranda highlighted the firm's experience with over 70 PFAS projects and their in-house pilot test capabilities. The firm’s portfolio includes significant mitigation initiatives, such as designing a nanofiltration facility for the Florida Keys Aqueduct Authority and deploying novel suspended ion exchange technology for Tampa’s water supply. While Carollo initially proposed a fee of $1.93 million, staff negotiated a revised scope to achieve cost efficiencies. The updated approach includes a desktop study to identify recommended treatment media early in the process, which allows for a shorter pilot testing duration. This adjustment reduced the total fee to $1.5 million. The scope includes the desktop study, pilot testing, and the delivery of a preliminary design report by August 2026. The project will be funded entirely through a $3.7 million settlement the authority received from 3M regarding PFAS contamination. After allocating funds for this contract and previous work by owner’s representative Tetra Tech, approximately $1.84 million will remain in the authority's PFAS mitigation reserve. During the discussion, Director Cox noted that the proposal focused on commercially available technologies such as granular activated carbon (GAC), ion exchange, and reverse osmosis. She expressed an interest in ensuring the consultant also assesses emerging technologies, provided they are proven and regulatory-compliant. In a separate infrastructure decision, the board awarded a $2.89 million construction contract to HPS Mechanical for the Sweetwater Reservoir Aeration and Destratification System Project. The project is designed to address oxygen depletion and nutrient release in the reservoir, which cause treatment challenges. The authority secured a $1.53 million WaterSMART grant from the Bureau of Reclamation to support the work.