Conco Pumps, Crews Help Resurrect California “Lifeline” 2006
From Concretepumping
Since project start in January of 2002, Conco Pumping & Belting, Inc., Concord, CA, has utilized most of its 100+-piece fleet to complete the northbound portion of the new $1.4 billion Benicia-Martinez Bridge in central California. The bridge has been designated by Caltrans as a “lifeline” structure, because of its location along transportation corridors crucial to both emergency relief and economic revitalization. As construction progresses past the four-year mark, Conco Vice President of Operations Mike Cusack says his pumps and crews will place approximately 185,000 cubic yards into the bridge, which is scheduled for completion in late 2007.
Conco Pumping is no stranger to the Benicia-Martinez Bridge site. Throughout the mid-90s, the pumper worked with general contractor Kiewit Pacific Co., Vancouver, WA, to widen the existing four-lane bridge from 67 to 77 feet in order to accommodate three mixed-flow lanes of northbound and southbound traffic. Conco was also commissioned to help with the seismic retrofitting of the existing bridge under general contractor FCI Constructors, Grand Junction, CO, which wrapped up in June 2000.
Kiewit Pacific Co., one of the largest construction and mining organizations in North America, barely gave the pumper a chance to catch their breath. The general contractor rang in the new millennium with a contract to erect an entirely new bridge to accommodate all northbound traffic traveling on Interstate 680 across the Carquinez Straight, connecting the City of Benicia in Solano County and the City of Martinez in Contra Costa County. The new 8,790-foot long bridge will be aligned east and parallel to the existing Benicia-Martinez Bridge and a Union Pacific Railroad Bridge.
Conco has been involved in all phases of construction for the bridge’s substructure. As of January 2006, the pumper had filled every one of a total 99 cast in drill hole (CIDH) piles in the water to accommodate 12 of the 64-foot wide, 68-foot long, 15-foot deep pier footings. Several of Conco’s boom pump fleet were transported by barge to complete tremie pours through up to 300 feet of line into the depths of the straight. Kiewit Pacific Co. supplied ready mix to all of the marine-based pours from their own batch plant on the south side of the project in Martinez, CA. Kiewit truck mixers were barged to the pour sites separately from the pumps.
Construction of the 12 bridge footings stretching across the straight has been broken into two stages. Stage one is executed on dry land at the Mare Island Precast Facility 10 miles north of the bridge. Conco’s Schwing boom pumps have the necessary output and reach to place over 600 cubic yards into each of the 1700-ton footings. Upon completion, each footing is floated up river into place and supported on eight to nine piles.
“At the precast site we weren’t looking for any outstanding reach; just maneuverability around the yard and consistent, reliable output,” says Cusack. RMC Pacific, now Cemex, one of the largest ready-mix suppliers in the world, delivers to the precast yard, as well as portions of land-based pours on the north and south ends of the project.
The second stage of footing construction requires several high-output marine-based pours. Approximately 2,000 cubic yards of concrete is installed directly above the precast portion of each footing. These pours require consistent performance from Conco’s S 58 SX truck-mounted concrete pump with 187-foot, 4-section Overhead Roll & Foldä boom. Conco’s 58-meter boom pump is equipped with Schwing’s Generation III 2525-H6 pump kit, with maximum output to 213 cubic yards per hour at 22 strokes per minute and 1169 psi on the concrete.
“On Stage Two footings, we’re typically pouring about 80 cubic yards every hour,” says Cusack. “That’s not a tall order for a concrete pump, but between pumping and clean-up it’s 30 hours of non-stop operation. And we are out on a barge which means reliability is highly prized. Our Schwings have never let us down.” Kiewit’s ready mix crews follow the same procedure during footing pours as on the tremie pours, taxiing trucks to the pour site via barges.
To erect the piers themselves, crews utilize a slip form system, pouring approximately 400 cubic yards at a time, reconfiguring the forms and repeating the process twice more. Upon completion, the Benecia-Martinez Bridge’s 17 total marine and land-based piers will consist of 61,200 cubic yards of concrete.
“The 52-meter and our S 58 SX have been popular requests since the pier construction started,” says Cusack. “The extensive long boom reach is important as we get up near the top of the pier tables. The outriggers supply the stability that’s so important when we’ve got the boom stretched to its farthest and we’re out in the middle of the straight. All of those factors provide huge piece of mind on a project of this magnitude.”
As of January, the pumper had also completed 268 of a total 335 cast-in-place pours on the bridge’s segmental superstructure. These segmental pours require a 10-sack Carolina lightweight mix design.
Currently, over 90,000 vehicles cross the Benecia-Martinez Bridge each day. By erecting the new northern portion, the California Department of Transportation (Caltrans), hope to alleviate existing and projected traffic congestion, reduce accident rates and facilitate the regional movement of freight. The new bridge will carry five lanes of northbound traffic, be over 83 feet wide and accommodate bicyclists, pedestrians, and future light-rail transit.
Also included in overall project specifications is the construction of new 17-booth toll plaza and Administration Building south of Carquinez Strait in Contra Costa County, the reconstruction of the 1-680/I-780 in Solano County, and I/680/Marina Vista Interchanges to accommodate the bridge toll plaza.
