ARCHIVED REPORTS_PHASE II ENVIRONMENTAL SITE ASSESSMENT

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WGIK • Sounthwesit, ]frac. reference levels. This further indicates there has been significant impact to shallow soils from Learner's metal recycling operations. PCBs detected in many of the one-foot soil samples,particularly in the western part of the site (see Figure 3), can be attributed to historical site practices which resulted in materials containing PCBs to be handled on site, potentially resulting in innumerable unidentified PCB releases. The one-foot sample from B-7, taken near the remedial excavation for the August 2007 PCB release, contained a detectable PCB concentration. However, it is unknown whether this detection is associated with the recent release or related to past usage of the site. The detection of PCBs in this area is consistent with historical site usage. The shallow soil samples from B-3 and B-4, located in areas mapped as former motor block stockpiles, contained elevated TPH-mo and petroleum O&G levels, as did many of the other one-foot soil samples (see Figure 4). Since motor blocks are only one of many potential sources of these contaminants and stockpiles are continually relocated, this is consistent with site usage. • The referenced Spill Prevention Control and Countermeasure Plan (SPCCP) by Kleinfelder identified the following materials in use on the Learner site: TPH-d containing naphthalene; unleaded TPH-g containing xylenes, MTBE, toluene, 1,2,4-trimethyl benzene, benzene, ethyl benzene and n-hexane; hydraulic oil; engine oil; automatic transmission fluid; hydra-tranz containing zinc compounds; and multipurpose grease with molybdenum disulfide. Elevated TPH-d, THP-mo, O&G and/or zinc detected in the one- and three-foot samples from B-8, near the hazardous materials storage area and associated sump, may be attributable to spills of substances commonly used on site and poor housekeeping practices in this area. However, due to subsurface restrictions, sampling was not conducted as near to the sump as desirable, possibly leading to failure to detect more extensive impact in this area. DTSC records show violations by Learner relating to the storage of waste oil, absorbent material containing oil and grease and spent activated charcoal in the hazardous materials storage area. The highest TPH-d concentration was detected in the one-foot sample from B-9, located near the diesel and gasoline ASTs and former diesel and gasoline UST area, identifying the fueling practices in this area as a potential source of diesel contamination. This sample also had the highest TPH-mo and O&G concentrations and an elevated zinc concentration suggesting • vehicle maintenance that may occur in conjunction with fueling as a potential source. This is 704. PRL05 25 July 21, 2008