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' 29 March 2004 i AGE-NC Project No. 97-0327 ' Page 3 of 12 ' Locally since February 2000,depth to ground water measurements have varied in monitoring wells at the site between 45 feet and 62 feet bsg. Ground water flow direction has slightly varied between south-southwest and south-southeast at gradients of approximately 0.001 ft/ft (Appendix A). 2.3. UNDERGROUND STORAGE TANK REMOVAL ' On 27 July 1998, one 6,000-gallon diesel UST,one 6,000-gallon gasoline UST, one 10,000-gallon gasoline UST and the associated fuel dispensers and product piping were removed from the site and ' replaced with two 12,000-gallon gasoline/diesel USTs.Laboratory analysis of soil samples collected beneath the,former USTs and product piping areas detected total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d, respectively) at concentrations as high as 12,000 milligrams per kilogram (mg/kg). Benzene, toluene, ethylbenzene and xylenes (BTEX compounds) were detected beneath the former UST and product piping areas at concentrations as high as 290 mg/kg;methyl tertiary butyl ether(MTBE)and tert-butanol(TBA)were detected in the ' same areas at concentrations as high as 0.80 mg/kg (Table 1). 2.4. SUBSURFACE INVESTIGATIONS ' The following is a summary of previous site investigations of the unauthorized release of fuel products to the subsurface; boring and monitoring well locations are depicted in Figure 2: • May 1997- Five soil borings (P-1 through P-5)were advanced near the former UST area to ' assess the lateral and vertical extent of petroleum-impacted soil as part of preliminary site assessment; results of the May 1997 investigation were reported in the AGE-prepared Preliminary Site Assessment, dated 06 June 1.997. Xylenes were detected in boring P-4(30 ' feet bsg)at a concentration of 0.026 mg/kg;MTBE was detected from soil samples collected in borings P-3 (25 feet bsg),P-4(30 feet bsg)and P-5 (25 feet bsg) at concentrations as high as 0.28 mg/kg. The laboratory analysis did not detect any other petroleum constituents. Soil ' data analytical results.are summarized in Table 1. • June 1999 - Four additional soil borings (P-6.through P-9) were advanced at the site; the ' results werereported in the AGE-prepared Preliminary Investigation and Evaluation Report, dated 27 September 1999. Laboratory analysis of the 40 foot P-8 soil sample detected significant TPH-g at a concentration of 340 mg/kg, TPH-d at 37 mg/kg and BTEX compounds at concentrations as high as 20 mg/kg; agrab water sample from P-8 detected TPH-g and TPH-d at concentrations of 1,900 micrograms per liter(p,g/l),BTEX compounds as high as 310 µg11 and MTBE at 52 gg/l. Residual BTEX compounds and MTBE were detected from P-6 in the 40 foot soil sample at concentrations as high as 0.0199 mg/kg. Analytical soil and ground water data is summarized in Tables 1 and 2.