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0 Appendix A: Site Background Information Page 2 of 3 PREVIOUS SITE ASSESSMENT On 02 and 03 June 2009, nine soil borings (B1 through B9) were advanced on site, to depths between approximately 10 feet and 20 feet below surface grade(bsg). Discrete soil samples were collected at regular intervals from each soil boring, and grab ground water samples were collected at total depth from borings B3 and B6. Total petroleum hydrocarbons quantified as diesel (TPH-d) were reported in thirteen of twenty-one soil samples at a maximum concentration of 5,900 mg/kg. TPH-d were also reported in grab ground water samples collected from borings B3 and B6, at 28% and 98%, which is approximately equivalent to 280,000,000 micrograms per liter(Ng/1)and 980,000,000 pg/l. Free-phase petroleum was observed in both grab ground watersamples.Analytical results of soil and grab ground water samples are summarized in Tables Al and A2. Field procedures and sample results are outlined in the AGE-prepared Preliminary Investigation and Evaluation Report, dated 12 August 2009. Between 28 December and 30 December 2009, six soil probe borings (B10 through B15) and four ground water monitoring wells (MW-1 through MW-4) were advanced on site to depths between approximately 30 feet and 50 feet bsg. Discrete soil samples were collected at regular intervals from each soil boring, and grab ground water samples were collected at depths between 30 feet and 34 feet bsg from borings B10 through B15.TPH-d were reported in three of twenty-three soil samples collected, at a maximum concentration of 350 mg/kg. Additionally, TPH-d were reported in grab ground water samples collected from boring 610 and B13 at a maximum concentration of 11,000 pg/l. Analytical results of soil and grab ground water samples are summarized in Tables Al and A2. Field procedures and sample results are outlined in the AGE-prepared Additional Site Assessment Report, dated 05 March 2010. Between 12 July and 16 July 2010, approximately 257 tons of hydrocarbon-impacted soil was excavated from two separate areas (excavation Area A and excavation Area B), utilizing a backhoe (Figure 2). • On 12 July 2010, an area of approximately 318 square feet was excavated to depths between 4 feet and 8 feet bsg in excavation Area B, located south of the truck wash and building. • Between 13 July and 16 July 2010, an area of approximately 873 square feet was excavated to depths between approximately 4 feet and 6 feet bsg in excavation Area A, located under the fueling canopy. A 4-foot by 10-foot portion of the center island,which forms part of the footing for the fueling canopy,was left in place during excavation. Prior to beginning excavation in Area A, the fuel lines supplying the dispensers were shut off and product was diverted to a temporary dispenser set up near the above ground diesel storage tank. During excavation, all three sets of Advanced GeoEnvironmental,Inc.