Location Clayton, CA
Client Contra Costa County, CA
Services Construction Management
Project Value $5 million
The Marsh Creek Bridge project, nestled in the countryside of Mount Diablo State Park near Walnut Creek in Contra Costa County, CA, delivered a new, wider, 100-year-flood-compliant bridge built to current safety standards, all while accommodating 6,000 vehicles per day and minimizing impacts to local stakeholders.
The team achieved the project by conducting what would normally be a two-season project in one construction season. Several Accelerated Bridge Construction (ABC) techniques were used to accomplish this. Four stages of construction and traffic handling were required to build the new roadway section, a retaining wall, bridge, and driveways. A temporary wildlife-proof work area was created by utilizing manmade stream diversion within the creek. The result was a bridge that has a pair of 12-foot lanes, each with an 8-foot shoulder.
Hill provided construction management services during the pre-construction, construction, and post-construction phases for the project. The pre-cast and pre-stressed concrete structure, with a California “bulb-tee” wide flange girder, was completed in less than eight months utilizing ABC techniques. These methods helped the project meet a critical environmental permit deadline for work within Marsh Creek. The project included removing the existing bridge, installing coir block wall creek bank stabilization and soldier pile retaining wall, and relocating an eight-inch water main.
Project challenges included providing safety for the traveling public and accommodating environmental restrictions for work in Marsh Creek, including a critical May 15-to-October 31 work window, and a wide variety of federal, state, and locally protected species. The project management team worked with the contractor, the County, and other key stakeholders to realize the project on time and on budget. An intricate plan was developed to keep traffic moving, protect the creek bed, and maintain a safe and secure work site. To stage the dual cranes and trucks needed for girder installation, the County developed a convenience-focused staging plan that used short, staggered closings lasting no longer than 15 minutes each: a girder was lifted, placed, and inspected, traffic would resume, and then the process was repeated. To create the new bridge’s substructures, a temporary work area within Marsh Creek was created through a man-made stream diversion.
The deadline for completing of all creek work by October 31 required the contractor to work longer shifts (10-12 hours) and weekends throughout the summer months, paying premium time to their workers. The construction management team covered the inspection of these long hours/additional shifts working in a spirit of cooperation to ensure completion by the deadline with no compromise to work quality and safety.
The in-creek work was finished before the October deadline, with all significant bridge components completed in one construction season. By avoiding a costly site winterization process, the project was also maintained within budget and kept costs under control while protecting both the traveling public and creek ecosystem.
The Marsh Creek Bridge Replacement won both APWA’s Transportation Award for Projects Less than $5 Million and ENR California’s Best Project North Award in the Highway/Bridge category.
