Cosmopolitan Engineering Group is responsible for pre-design and final design and construction services for combined sewer overflow control and conveyance facilities for the South Lake Union area in the City of Seattle. These new facilities are part of a $100 million joint project between the City of Seattle and King County to control untreated combined sewer discharges to South Lake Union and Elliot Bay. New facilities include a regulator and diversion structures to divert flows through 72-inch-diameter conveyance pipelines to a 14 1/2-foot-diameter storage tunnel. New facilities must interface with the Lake Union Tunnel, a 72-inch-diameter brick tunnel built in 1894, and the Dexter trunk, an 84-inch-diameter pipeline built in 1912. New pipelines were constructed using tunneling methods. New facilities are located in the Mercer corridor; the most heavily congested in the city.

Shaft construction over 14'-10" diameter Lake Union Tunnel.
Preparation for one of two 72" pipe jacking installations.