King County Brightwater Conveyance DEIS

King County, Washington

HWA performed 18 deep geotechnical borings in support of new influent and effluent sewer lines for the new Brightwater Treatment Plant, and worked with the King County team to develop the DEIS.

HWA provided geotechnical information and analyses for several of the potential alignments and co-authored the Geology/Soils portions of the Draft Environmental Impact Statement (DEIS).

Key issues included deep shaft construction, tunneling methods, impacts to adjacent structures, impacts to groundwater and spoils disposal. HWA worked closely with both the EIS team, King County and the University of Washington Seattle Area Geologica Mapping Program to complete this project. HWA was underbudget.