Contractor contours central mixed plant

Bouygues Civil Works Florida has mobilized for its Port of Miami tunnel contract with a portable plant bound less by footprint limitations than head room. After configuring equipment to a site below Interstate 395, Montreal-based BMH Systems shipped a portable plant in three modules, stacked to 26 ft., a few feet below the highway. The plant is geared to producing 55- to 80-yd./hour of grout and roller-compacted mixes, delivering them to a site portal—about 900 ft. away—via small, custom cars.

BMH engineers needed to tailor the plant for a very limited area but provide maximum production flexibility for high flowability or RCC mixes. They equipped the operation with a three-compartment, 50-ton aggregate bin; aggregate, cement, bentonite and water weigh hoppers and conveyors or pipes; skip hoist; twin shaft mixer; RCC mix holding hopper; agitating hopper for grout; one 70-ton and two 50-ton cement silos, plus companion bentonite storage; and, control room. The twin shaft mixer charges a conveyor transferring grout or RCC mixes to their holding hoppers. Plant construction began in mid-2010 following a go-ahead from the Florida Department of Transportation to set up production in the I-395 right-of-way.

Bouygues Civil is pumping grout to reinforce twin, 3,900-ft. long, two-lane tunnels; each are built of precast concrete segments forming a structure of 41-ft. outside diameter. RCC will be used for service pavements. Scheduled for 2014 completion, the $607 million project will connect the Port of Miami to Interstate 395 via Watson Island.