Construction is complete on the Llano Trunk Rehabilitation Phase 1 project, city staff told the Board of Public Utilities. Supervising engineer Richela Maeda said the work rehabilitated a 66-inch trunk sewer that runs from the Laguna treatment plant north of Todd Road for about 8,100 linear feet and included inspection and rehabilitation of 15 manholes.

Maeda said the project required bypassing roughly two-thirds of the city’s wastewater flow — about 16 million gallons per day — around the work area. The bypass system used three parallel 18‑inch temporary pipes and six on‑site pumps for redundancy; about 25 truck deliveries were needed to bring fusionable bypass pipe to the site. The team used cured‑in‑place pipe (CIPP) lining as a trenchless method because the host pipe lies 25 to 30 feet deep and the area has a high groundwater table.

The city estimated initial total costs at about $21 million, including roughly $14.7 million for construction, a 15% construction contingency and an approximately $1 million expense for California tiger salamander mitigation credits. Maeda said final payments and invoices are still being completed but that the final cost “will be closer to $18,500,000.” She told the board design–build proved successful for this complex, environmentally constrained project because contractor input early in design helped meet permitting and schedule requirements.

Board members praised the team for delivering the large project under the initial estimate. Vice Chair Arnoni asked whether the city would shift more projects to design–build if savings recur; Maeda said procurement choices will depend on project complexity and the advantages of having the contractor involved early.

Board member DeWitt asked about mitigation-credit pricing; Maeda said credits are about $280,000 per acre and that a typical 3:1 mitigation ratio can make effective mitigation costs roughly $840,000–$900,000 per acre depending on disturbance. In public comment, Michael Hilbert questioned the claim that the project came in $1.5 million under estimate, noting the existence of a $2.2 million contingency and asking about the age and remaining life of the pipe. Maeda replied that the rehabilitated section was installed in the 1960s and had reached the end of its useful life.

Board member Wright emphasized the operational risk if the deep trunk pipe failed, noting the difficulty of excavating 30 feet to repair a collapsed trunk that conveys the system’s largest flows. Maeda said lessons learned include involving bypass subcontractors earlier in design and providing staff buffers when removing bypass systems to reduce interruptions.

No formal action was required for the briefing; the board concluded the item after questions and public comment.