The Gowanus CSO project is for the construction of an 8-million-gallon Combined Sewage Overflow (CSO) tank adjacent to the head of the Gowanus Canal in Brooklyn NY.   The Work under this Contract includes demolition of existing slabs and foundations, and construction of all below grade structures for the CSO tank measuring 410’ by 146’ by almost 60’ deep.  Work includes slurry wall construction to a depth of 200’ around the perimeter of the tank, approximately 1.2 million pounds of steel bracing, mass excavation of over 91,000 cy of soil and placement of over 30,000 cy of concrete for the CSO structure.  Other work includes jet grout columns for water cutoffs and ground improvement, installation of rigid inclusions and over 1,000 tension piles.  Ancillary work includes the installation of a 42” convenance pipe and manholes with steel sheeting support of excavation, construction of influent and outfall structures which required a cofferdam in the canal and a bypass pump system.