A failed drainage culvert and sinkhole on Springbrook Road near Sherwood Way in unincorporated Walnut Creek will get a $600,000 fix after Contra Costa County Public Works posted a formal call for construction bids on Tuesday, July 14.

The project will replace a deteriorating 36-inch corrugated steel pipe buried beneath the roadway, install 62 linear feet of reinforced concrete pipe and 29 linear feet of cast-in-place box culvert, add new drainage manholes, and repave a section of road. The Board of Supervisors' authorization labels it a storm damage repair project.

Sealed bids are due by 2 p.m. on Tuesday, August 25, with a virtual public opening at that time. A pre-bid meeting is scheduled for Monday, August 10, at 10 a.m.

The Board of Supervisors pre-authorized the contract on July 7 allowing Public Works Director Warren Lai to award up to $690,000 to the lowest responsible bidder once bids come in. The project is funded by 88.53% federal Emergency Relief dollars, with the remaining 11.47% from local road funds.

Henry Hussey, the county's project manager, is listed as the point of contact for contractors.

Two years in the making

Planning began in July 2024, when the county submitted a preliminary environmental study. A CEQA Notice of Exemption was filed in late February 2025, and federal environmental clearance followed in October 2025. The county received federal funds for design work in August 2025, and temporary construction easements were completed and sent to Caltrans for review in May 2026.

In the Board agenda item, Warren Lai wrote that the project is "dependent on seasonal weather" and that advertising and awarding the contract quickly would allow construction to take advantage of favorable conditions.

What residents should expect

The county's project schedule targets construction in summer or fall 2026, with a 40-working-day duration. The project site sits near Acalanes High School and St. Mary's Elementary, at the intersection of Springbrook Road and Sherwood Way.

County filings note that temporary traffic control or road closures, utility relocations, and tree or vegetation trimming will be necessary during construction. Emergency vehicles will have access at all times.

The culvert carries water from neighboring residential properties across the county-maintained roadway. Its failure compromised the road embankment above it.

Residents can reach the project team at 925-313-2338 for questions about the work.