The project involved of the construction of approximately 900 feet of a 48-inch tall by 72-inch wide reinforced concrete stormwater box culvert and outlet and also included relocation of existing utilities along the proposed alignment. The culvert tied into existing stormwater structures at the intersection of Talbot Street and Waverly Street in Cambridge, Massachusetts and daylighted at an outfall structure within the Charles River. The 900-foot excavation was divided into seven (7) excavation areas that were completed simultaneously.
LRT designed and installed the dewatering systems and water treatment systems for the project. Specifically, wellpoints and sumps were installed along the culvert excavations and within a sheeted cofferdam within the Charles River. Two (2) deep wells were used to dewater the jacking and receiving pits on either side of Memorial Drive. A total of four (4) water treatment systems were staged along the project route with treatment capacities of between 200 and 400 gallons per minute (gpm). The water treatment system(s) discharged treated water back to four different outfalls along Charles River in accordance with a NPDES Remediation General Permit (RGP). The primary contaminants of concern included total suspended solids (TSS) and total metals.