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Technical Memorandum <br /> TO: Debbie Taege and Alan Sugino, The Boeing Company <br /> FROM: Piper Roelen, PE, CHMM, and Jered Newcomb, EIT <br /> DATE: October 1, 2020 <br /> RE: Downgradient Plume Interim Action, Phase 2 <br /> EGW192 Relocation Work Plan <br /> Powder Mill Gulch <br /> Boeing Everett Plant, Washington <br /> Project No. 0025175.120.021 <br /> Introduction <br /> This technical memorandum presents a work plan to relocate extraction well EGW192, which is <br /> associated with the Powder Mill Gulch (PMG) Downgradient Plume Interim Action (IA) groundwater <br /> extraction and treatment (GET) system. The IA has been implemented in two phases: Phase 1 of the IA <br /> is located south of Seaway Boulevard on property owned by The Boeing Company (Boeing), and Phase <br /> 2 of the IA is located north of Seaway Boulevard on City of Everett (City) property. Extraction well <br /> EGW192 is located in the Phase 2 area of the PMG site (Site; Figure 1). The IA is being conducted <br /> under Agreed Order (AO) No. DE 96HS-N274 (Order; Washington State Department of Ecology <br /> [Ecology] 1997) and subsequent amendments (specifically Amendment No. 5; Ecology 2011) between <br /> Boeing and Ecology. <br /> Relocation of extraction well EGW192 will be performed as authorized by Ecology (Ecology 2020) in <br /> order to continue achieving the Phase 2 IA interim action objective (IAO). As identified in the AO and <br /> the Phase 2 IA work plan (LAI 2013), the IAO of Phase 2 "is to reduce to the maximum extent <br /> practicable, migration of chlorinated solvent contaminated groundwater to the surface waters of <br /> Powder Mill Creek (PMC), north of Seaway Boulevard." <br /> Background <br /> The following provides a summary of pertinent background information related to the GET system and <br /> operation of extraction well EGW192. <br /> GET System <br /> In 2012, Phase 1 of the GET system was constructed on Boeing's property (south of Seaway <br /> Boulevard), consisting of three groundwater extraction wells, a groundwater treatment system, and <br /> treated groundwater piping and an outfall to the City sanitary sewer system (discharge authorized <br /> under a City Industrial Discharge Permit).The GET system began operating in November 2012. <br /> In 2015, Phase 2 of the GET system was constructed on the City's Lot 9 property (north of Seaway <br /> Boulevard), consisting of seven additional extraction wells (including extraction well EGW192), and <br /> LANDAU <br /> ASSOCIATES 130 2nd Avenue South • Edmonds,Washington 98020 • (425)778-0907 <br />