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CDOT greening of river contained, will be filtered
16-May-14 – On a river known for its various shades of green, it may not be obvious but construction of the Chicago Riverwalk has turned pockets of the river light green. Fine particles of sand and cement are responsible for the milky green water. The particles are from demolition of concrete near where the new Riverwalk is being constructed. The image above shows construction east of Clark Street. The water is contained between the old river wall and steel sheets that have been pounded into the riverbed in recent months. As the area is filled with new concrete, the water will be pumped through filters to remove the particles, according to Riverwalk construction manager Oswaldo Chaves. “The new steel sheet pile wall and turbidity curtain are in place to make sure this water does not migrate into the river,” said Chaves on Thursday. “We have an erosion control plan in place to make [sure] the water is contained within our site.”
(Above) A surveyor at lower right studies the Riverwalk construction site between Dearborn and Clark Streets. (Click on images to view larger versions.) Caisson drilling delayed by debris Debris at the bottom of the river has delayed installation of the first of the caissons. Chicago Department of Transportation had expected to begin drilling the first caisson on the east side of the Clark Street Bridge this week with the caisson-drilling machine that was delivered to the site. “The contractor encountered debris in the river bottom that would have prevented the steel casing from being installed,” Chaves reported on Friday. “Divers will be working in the river to remove some of the debris to clear the way for the casing.” The steel cylinders – 75 feet deep, six feet in diameter, and open at each end – will be pounded into the riverbed. After the soil is drilled out, rebar will be lowered into each caisson, which will then be filled with concrete. The rebar, used to reinforce the concrete, will be in the form of a steel cage running the full height of the caisson. Meanwhile, installation of walls of steel sheet pile, along with the “H pile” steel beams, should be complete from State Street west to LaSalle Street by May 23, according to Chaves. The sheet pile will form the outer wall of the Riverwalk.
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