Builders' Message: Contra Costa County Admin Building and Jail Demo & Redevelopment (ADR) - March 2023

Since our last Builders' Message update, we’ve been busy completing the entire building demo scope, constructing the new building pad, etc.

March 6, 2023

Project Updates

The Contra Costa County Administration Building and Jail Demo & Redevelopment (ADR) is a $62 million project consisting of the abatement and demo of one 5-story office building built in the early 1950s, one 12-story office building built in the late 1950s, and an old jail originally built in 1903 in the commercial area of downtown Martinez, CA.

The last jail section to be demolished. There was no rebar in the granite wall block, so the excavator just used its arm to push the block to the ground.  After demo, the block was categorized and paletized, then shipped to a storage yard.  Half of the block will be repurposed on-site to create retaining walls in the plaza area. The other half of the block will be cut into 5”x5” pavers and repurposed as a walking surface throughout the plaza.

Since our last update, we’ve been busy completing the entire building demo scope, constructing the new building pad, and finishing new foundations, underslab utilities, and pouring the slab on grade.  Webcor Concrete is currently working on the vertical sequence of architectural concrete from levels 1 to 2 and has begun forming the first elevated deck.

Due to the height and proximity to the busy area around the county court buildings, demolition of the 12-story, 180-foot-tall steel building was one of this project's biggest risks.  Our demolition partner, FERMA, proposed utilizing a high-reach excavator and pneumatic processor to demolish the tower--an approach that was one of the determining factors in awarding our team this project during the pursuit phase.

In August, the team completed building abatement, cut and capped all utilities, and removed the construction hoist in preparation for tower demo. When FERMA's high-reach excavator reached 180 feet to cut the first piece of steel, however, it became clear that the pneumatic processor's shear lacked the strength to make any cuts at that height.

A photo from when we started tower demo and realized the high-reach excavator could not cut the structural steel.

After a week of trying to resolve the issue, the team decided to demo the top five floors using the “floor by floor” method, then use the high-reach excavator to take down the remainder of the building.  The “floor by floor” demo method required us to reinstall the hoist and hoist multiple Bobcats to the top floors.  We used the Bobcats to break up the concrete decks, then a torch crew cut structural steel beam, then a hoisting crew hoisted each beam section down to the ground level for further processing and off-haul.  It was a high-risk, tedious, and time-consuming process that we ultimately performed without any injuries. However, it did add 23 days to our overall construction schedule.

The crane moves demo equipment to level 10 for the “floor by floor” demo method that was utilized to remove the top portion of the tower.

Once the building was brought down to the eighth floor, we were able to utilize the high-reach excavator to demo the remainder of the tower.

Upon completion of building demo in October, the existing underground basement was abandoned by placing 6,000 cubic yards of fill to create the building pad for the new administration building.  Since the project delays pushed the foundation sequence into the winter months, we decided to build the top portion of the building pad out of class 2 AB, providing a solid surface for winter foundation work.

We utilized base rock to abandon and fill the top portion of the existing basement and build the building pad.
The completed north half of the building pad right before it was turned over to Webcor Concrete for foundation work.
Mat slab progress showing electrical rough-in at the transformer room.

Webcor Concrete mobilized in November and started foundation work in December.  The pad survived the rainy winter weather, and Webcor Concrete finished the foundations at the end of January. Currently, Webcor Concrete is finishing up their vertical sequence from levels 1 to 2, where the majority of architecturally colored concrete walls will be poured.      

“From a concrete perspective, the architectural colored concrete is the toughest part of this project," Superintendent, Concrete Dan Deane says.

Level 1 to 2 vertical concrete progress looking North toward the main lobby

Level 1 to 2 vertical concrete progress looking South toward the main electric room

At the end of the day, the architectural concrete will be what draws everyone’s attention to this building.  The quality will have to be top-notch. In this scenario, quality trumps schedule because you only get one shot at pouring an architectural wall. The consequences of missing something because we rushed the architectural concrete work could be disastrous for the project.  We’re fortunate to have Webcor Concrete out here because they pay close attention to detail, plan the work extremely well, and execute without cutting corners. The concrete for the 3-story, 65,000-square-foot structure is expected to top out in April. We're looking forward to Webcor Drywall’s mobilization at the end of March and expect to reach TCO in April 2024.

Looking North toward one of the main architectural colored concrete walls getting stripped the day after being poured.