ARCHIVED REPORTS_PHASE II ENVIRONMENTAL SITE ASSESSMENT

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WGIR, • Sou chw est, I[inte. 12.10 Vehicle and Tire Storage The old vehicles and rubber tire stockpiles documented in the Phase I ESA were no longer present at the time of the Phase II. Detections of TPH-d, TPH-mo, O&G, zinc, acetone, MEK and naphthalene in the soil at the eastern end of the site may be attributable to maintenance and/or storage of old vehicles, stockpiling and other historical site activities. Further investigation of soil and groundwater conditions in the eastern portion of the site is recommended. 12.11 Adjacent Petroleum Terminal Significant TPH-g contamination was detected in the groundwater sample from the northwest site comer adjacent to the ST Services Terminal site. This may be indicative of an offsite source of dissolved TPH-g or it may indicate an onsite source, possibly motor block stockpiling which has occurred in this area. It is recommended that further investigation into groundwater conditions in this area be conducted, including research into potential off-site sources. • 13.0 RECOMMENDATIONS It is recommended that further assessment of the site be undertaken in order to provide more complete characterization of the nature and extent of the contamination identified in this Phase II ESA. Further assessment should be designed to provide sufficient data to develop a remedial action plan for the site. It is recommended that groundwater monitoring wells be installed and monitored to provide reliable, reproducible and verifiable data regarding groundwater conditions at the site. Data should be generated to confirm contaminant concentrations and distribution in the groundwater and determine groundwater flow direction and gradient so that the behavior of dissolved contaminants can be reasonably predicted. The preliminary groundwater data provided by this Phase II ESA supports the need for permanent monitoring wells on the site. Additional borings should be undertaken and soil sampling at a variety of depths should be conducted to provide additional information regarding the vertical and lateral distribution of the identified contaminants of concern in the underlying soils across the site. Particular attention should be paid to the areas near the hazardous materials sump where access was restricted during this investigation, to the AST and former UST area, to the equipment wash • area and maintenance shop, the South Ditch banks and to all other areas identified in this 704. PRI.05 33 July 21, 2008