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NEPA Details


Categorical Exclusion For the Georgetown Wet Weather Treatment Station (GWWTS)

Document Number


Document Type


Project Description

The GWWTS project includes construction of a new wet-weather treatment station (WWTS); conveyance system improvements including approximately 3,000 linear feet of new conveyance pipelines, a new regulator station, and other conveyance system modifications to connect new and existing pipes; and a new outfall structure. The purpose of the project is to reduce the volume and frequency of discharges of untreated combined sewage (sanitary sewage and stormwater) to the Lower Duwamish Waterway. During wet-weather events, flows of combined sewage would be conveyed to the WWTS, where they would be screened, attenuated in an equalization basin, and then treated by ballasted sedimentation and UV disinfection. The flows of treated water would then travel through new conveyance pipelines to a new outfall structure in the Lower Duwamish Waterway.

EPA Region/Headquarters Office


State or Territory


Point of Contact

Alejandro Escobar

Date of Issuance



NEPA Document(s):

King County Categorical Exclusion Signed 05FEB2018.pdf (5 pp, 1,485 K)