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08 November 2005 . AGE-NC Project No. 98-0481 Page 3 of 8 In September 1998, AGE initiated a preliminary assessment at the site as directed by the SJCEHD ' for investigation of petroleum impacts to soil reported during the UST removal.A total of seven soil probe borings (B-Ia through 13-1g) were attempted using Geoprobe techniques in the approximate area of the former fuel dispenser island and former waste oil UST. During the investigation ' activities,the Geoprobe encountered refusal in each of the soil probe borings at depths ranging from 8 to 10.5 feet below ground surface (bsg). Only one soil sample was collected, from probe boring B-1 g at a depth of 9.5 feet bsg(B-1-9.5'); there were no reported dctections of BTEX, TPH-d,TPH- g, fuel oxygenating compounds, or total lead in the soil sample (Table 2). The results of AGE's preliminary site assessment work were presented in a letter report to the SJCEHD, dated 04 December 1998; the letter included the recommendation that the preliminary site assessment be continued utilizing hollow-stem auger drilling techniques. ' On 28 January 1999,the preliminary site assessment was continued using a hollow-stern auger drill rig to advance soil borings SB-1 and SB-2. Soil boring SB-1 was advanced to a depth of 31 feet bsg at the former location of the eastern fuel dispenser (Figure 2). The subsequent laboratory analysis reported no detections ofBTEX,TPH-d,TPH-g,or fuel oxygenating compounds in the soil samples collected from soil boring SB-1 at depths of I 1 feet bsg, 26.5 feet bsg, and 31 feet bsg. Total lead was detected only in soil sample SB-I-11',at a concentration of 4.7 mg/kg(Table 2).The soil sample ' . analytical results from soil boring SB-1 indicated that the relatively low levels of petroleum hydrocarbons previously detected at the eastern dispenser location(S-4-FDe)were localized and did not significantly migrated vertically.The laboratory analytical results for soil samples collected from boring SB-1 were attached to the AGE-prepared Additional Site Assessment Work Plan, dated 22 February 2000. Soil boring SB-2 was attempted in the vicinity of the former western fuel dispenser and waste oil UST. However, an active gasoline product line for the operating service station was inadvertently ruptured during advancement of the soil boring; the active product line had not been accurately located on the engineer's "as-built" construction plan. Soil boring SB-2 could not be advanced following the product line rupture. Utilizing a standard 2-inch pipeline diameter, AGE estimated that the rupture of the product line could have resulted in the release of a maximum of 6.9 gallons of gasoline: Total Volume =Length of piping from UST to dispenser X Volume of 2-inch diameter pipe =40 feet x 0.16 gallons/feet = 6.88 gallons The amount of the release could be substantially less if gasoline in the piping between the rupture ' point and the UST flowed back to the UST, leaving only the product in the piping from the rupture point to the dispenser to be released; this scenario would result in a potential release of only . 3.7 gallons (i.e., 23 feet of piping from rupture to dispenser x 0.16 gal/ft= 3.68 gallons). ' Advanced GeoEnvironmental,Inc..