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1 Consent Decree Exhibit C 2.0 Site Description and History 2.1 SITE DESCRIPTION The City of Everett Landfill/Tire Fire Site (Site), located west of the downtown Everett business district, is approximately 70 acres in size, of which approximately 66 acres have been landfilled. The landfill is generally bounded by 361h Street to the north, Burlington Northern Santa Fe (BNSF) railroad tracks (spur "turkey" track and mainline) to the west, and two BNSF tracks to the east. The junction of the BNSF west turkey track and the westernmost eastern track forms the southerly point of the triangular Site. On both the western and eastern sides of the landfill, the Site boundary is defined as the innermost edge of ballast for the BNSF tracks. The Site therefore includes some portion of BNSF right-of-way in these areas. Category I wetlands and the Snohomish River are east of both the landfill and the BNSF spur lines. The old Simpson mill site is located south and southeast of the landfill. See Figure 2-1, Vicinity Map, and Figure 2-2, Site Map. Various portions of the landfill Site were historically used for landfill purposes from approximately 1917 to 1974. Originally, waste was placed on the northern portion of the Site in the low-lying lands within the Snohomish River floodplain, between the western and eastern railroad tracks. Because the ballasts of the railroad tracks were in place prior to the placement of refuse, the Site is bounded by the innermost tracks. Therefore, the Site is bounded on the east and west side by the ballast of the tracks closest to the landfill: the ballast of the easternmost western track (turkey track) and the ballast of the westernmost eastern track. The Site is defined on the north by the current property boundary. Land west of the turkey track as well as land east of the innermost eastern track is not considered part of the Landfill/Tire Fire Site. The thickest part of the landfill refuse, at 30 to 35 feet thick, is located within the center portion of the landfill. The thickest areas of refuse also correspond with former drainages or "ravines" — as described by former landfill operators. Elsewhere on the Site, the average refuse ranges from 10 to 30 feet. Along the eastern edge of the Site, boring and well logs document over 20 feet of wood debris, including wood chips, sawdust, and logs. This material is reportedly demolition wood debris and other waste from former mills located in the proximity of the Site. Soils directly beneath the refuse on the eastern two-thirds of the Site are characterized by recent alluvium, which is also referred to as the aquitard layer. These alluvial soils are comprised of peat at the surface, and underlain and interbedded by soft silt and clay soils. The deposits are five to 40 feet thick and generally exhibit low shear strength and high compressibility. The aquitard layer separates the shallow (leachate) aquifer from the deep aquifer and is considered a significant barrier to vertical flow between the two aquifers where it is present. Hydraulic conductivity testing of the aquitard material has indicated low permeability characteristics. The refuse on the western third of the Site is underlain by transitional beds and shallower glacial soils. The transitional beds consist predominantly of thinly bedded stiff to hard clay and silt with some fine sand and sand interbeds and occasional coarser -grained sands and fine gravel layers. This geologic unit has generally horizontal contacts with the surrounding strata and is FINAL - March 2001 2-1 Everett Landfill Tire Fire Site Cleanup Action Plan 1