Board approves Hazen & Sawyer agreement for Laguna headworks seismic retrofit design

The Santa Rosa Board of Public Utilities voted unanimously to approve a professional services agreement with Hazen & Sawyer for 90% design of a seismic retrofit at the Laguna wastewater treatment plant headworks, funding the contract in an amount not to exceed $443,626.

The board acted after a presentation from Tanya Mokwitz, water reuse engineer for Santa Rosa Water, who described structural deterioration in the headworks superstructure and recommended a phased retrofit. Mokwitz said a full replacement of the headworks was estimated at roughly $300 million (2023 dollars) and therefore not feasible in the near term. Staff evaluated four interim alternatives — superstructure demolition and equipment frame ($12.7 million), a pre-engineered metal canopy ($17 million), a tent canopy ($15.5 million) and carbon fiber wrapping ($3.7 million) — and recommended carbon fiber wrapping of existing columns because it met seismic reliability needs at the lowest near-term cost and would minimize operational disruptions.

Mokwitz told the board the project…