3815_PGSF WMVD Pkg 2_Vol 4-2_03.03.2026_BXWA_Certified

ASPECT CONSULTING 28 FINAL PROJECT NO. AS190583A-08  MAY 21, 2025  In 2.5 years of operation, the SVE system had been effective in reducing xylene concentrations in soil located above the water table in the excavation area.  Further operation of the SVE system was not warranted since vapor-phase VOC concentrations generated by the system were no longer detectable.  Residual xylene-contaminated soil may be concentrated on the north side of the tank excavation area, beneath the adjacent tank pad.  The downgradient extent of xylene and ethylbenzene in groundwater was defined within approximately 100 feet of the excavation area, and the contamination was not impacting downgradient receptors. Additional groundwater monitoring would be required to demonstrate conclusively that natural attenuation of residual xylene is occurring.  More aggressive remedial measures for the xylene release would require removal of operating infrastructure, the cost of which was not warranted because the plume was contained and appeared to be attenuating naturally. Scott Paper Company submitted to Ecology the Landau reports regarding the UST No. 29 release identification and independent cleanup activities. In August 1994, Scott notified Ecology of plans to shut down the SVE system and requested Ecology authorization to do so (Scott Paper, 1994). Ecology responded that the cleanup was an independent action taken by Scott Paper and thus made no determination on sufficiency of the cleanup (Ecology, 1994a). In 2002, Ecology listed the Facilities Leaking Underground Storage Tank (LUST) ID No. 1627 as inactive. 3.1.6 Independent Soil Cleanup in Bunker C Fuel Oil AST Area (1995) Under the terms of Regulatory Order DE 93-AQI064 for Scott Paper’s cogeneration boiler, the mill needed to convert from Bunker C fuel oil to diesel as a backup fuel source. At the time of the conversion in 1995, two ASTs remained in the Bunker C fuel oil AST farm on the north side of the distribution warehouse: one 1,596,000-gallon Bunker C fuel- oil tank and one 211,000-gallon caustic-soda tank (which historically also contained oil). These ASTs were identified as being part of REC 2 in the Phase 1 ESA (AECOM, 2011). The tank farm area had an earthen surface enclosed by a tall concrete wall. Shallow soil samples collected at that time “show oil contamination next to the tank, which decreases rapidly when moving away from it” (Scott Paper, 1995a). Prior to decommissioning and removal of the Bunker C fuel-oil and caustic-soda ASTs, surface soil from around the standing tanks was excavated and disposed of at Associated Sand and Gravel13 , an off-Site facility in Everett licensed for the handling of soil containing Bunker C fuel oil. Visual inspection indicated that the oil contamination had been removed, and none of the soil removed contained elevated pH (Scott Paper, 1995b). CH2M Hill reportedly was to collect soil samples following soil removal within the tank farm area, but a report documenting such activities has not been found. A 1997 letter to Ecology (K-C, 1997a), following removal of the ASTs, concluded, based on hydrocarbon 13 Subsequently CEMEX and then Cadman.