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1 <br /> r <br /> EXECUTIVE SUMMARY <br /> ' The objective of this investigation was to evaluate the lateral and vertical extent of any impacted <br /> soil and/or groundwater associated with the former USTs To achieve the project objective, soil <br /> and groundwater-grab samples were collected for laboratory analysis from five sod borings Due <br /> to the depth and distribution of petroleum hydrocarbons in soil and groundwater beneath the <br /> site, the approved scope of work was modified in the field with approval from PHS/EHD The <br /> scope of work was modified to include five soil borings instead of 11, to a depth of up to 43 feet <br /> ' instead of 25 feet <br /> On July 12, 1999 and August 19, 1999, soil and groundwater-grab samples were collected from <br /> five locations using a Geoprobe One boring (SB-1) was continuously cored to a depth of 43 <br /> feet Sods observed in the five soil borings consisted of alternating sand and gravel sequences, <br /> interrupted by finer-grained silt and clay intervals Groundwater levels measured in each of the <br /> soil borings ranged from 18 7 to 21 feet bgs Groundwater does not appear to be confined and <br /> recharge was found to be moderately strong <br /> Six soil samples from SB-1, five soil samples from SB-2, SB-3, S134 and S13-5, and <br /> groundwater-grab samples from all five borings were analyzed for Total Petroleum <br /> Hydrocarbons (TPH)-as-diesel by modified EPA Method 8015, for TPH-as-gasoline, BTEX, <br /> methyl tertiary butyl ether(MTBE), di-isopropyl ether (DIPS), ethyl tertiary butyl ether (ETBE), <br /> ' tertiary amyl methyl ether(TAME) and tertiary butanol (TBA) by EPA Method 8260B The soil <br /> sample collected at 15 feet bgs from SB-1 was also analyzed for total lead by EPA Method 6010 <br /> Based on the results of the laboratory analyses, soil and groundwater beneath the site has been <br /> impacted by diesel and gasoline hydrocarbons The highest concentrations of diesel and <br /> gasoline hydrocarbons were detected in samples collected from SB-1, located within the former <br /> UST excavation In the sod sample collected at 18 feet bgs from SB-1, TPH-as-diesel was <br /> detected at a maximum concentration of 18,000 milligrams per kilogram (mg/kg) TPH-as- <br /> gasoline was detected at 1,900 mg/kg Vertically, the extent of impacted sod beneath the former <br /> ' USTs is defined to a depth of between 35 and 43 feet bgs Laterally, the vertical extent of <br /> impacted sod is concentrated between 15 and 25 feet bgs, within the capillary fringe and zone of <br /> groundwater table fluctuation <br /> ' Concentrations of diesel and gasoline hydrocarbons were detected in the groundwater-grab <br /> samples collected at each of the five soil boring locations The highest concentrations were <br /> detected in the groundwater-grab sample collected from SB-1, located within the former UST <br /> excavation This sample contained 2,700,000 micrograms per liter(µg11) of TPH-as-diesel, <br /> 29,000 µg/l of TPH-as-gasoline, 68 µg/l of benzene, 7 5 µg/l of toluene, 130 µg11 of <br /> ethylbenzene, 210 µg11 of xylenes, and fi 5 µg11 of tertiary butanol MTBE, DIPE, ETBE and <br /> TAME were not detected in any of the groundwater-grab samples <br /> Based on the results of this investigation, Ramage Environmental recommends the following <br /> course of corrective action <br /> 1 Install three on-site groundwater monitoring wells at the site These three wells should be <br /> monitored and sampled on a quarterly basis for a period of at least one year <br /> 2 Conduct a survey of water wells within a 2,000-foot radius of the site <br /> • 4 <br /> r <br /> {r <br /> ,j <br />