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' Laboratory results indicated that concentrations of petroleum hydrocarbons were detected in the <br /> soil samples collected from beneath the northern and central USTs Concentrations of petroleum <br /> hydrocarbons included 9,9UU milligrams per kilogram (mg/kg) I EPH beneath the northern weed <br /> ' oil UST and 18 mg/kg NPH from beneath the central gasoline UST Petroleum hydrocarbons <br /> were not detected in the soil sample collected from beneath the southern weed oil UST <br /> ' 1 2 2 Preliminary Investigation and Evaluation <br /> On October 12, 1999, Ramage Environmental published Preliminary Investigation and Evaluation <br /> Report, which documented the results of soil and groundwater-grab samples collected from five <br /> (5) Geoprobe® soil borings (Figure 2) One boring (SB-1) drilled through the northern end of the <br /> former UST excavation was continuously cored to a depth of 43 feet Groundwater levels <br /> measured in each of the soil borings ranged from 18 7 to 21 0 feet bgs <br /> ' Six soil samples from SB-1, five sal samples from SB-2, SB-3, SB-4 and SB-5, and groundwater- <br /> grab samples from all five borings were analyzed for Total Petroleum Hydrocarbons (TPH)-as- <br /> diesel by modified EPA Method 8015, for TPH-as-gasoline, BTEX, methyl tertiary butyl ether <br /> (MTBE), di-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether <br /> (TAME) and tertiary butanol (TBA) by EPA Method 8260B The sod sample collected at 15 feet <br /> bgs from SB-1 was also analyzed for total lead by EPA Method 6010 <br /> ' The highest concentrations of diesel and gasoline hydrocarbons in sod and groundwater were <br /> detected in samples collected from SB-1, located within the former UST excavation In the soil <br /> ' sample collected at 18 feet bgs from SB-1, TPH-as-diesel was detected at a maximum <br /> concentration of 18,000 mg/kg, and TPH-as-gasoline was detected at 1,900 mg/kg Vertically, the <br /> extent of impacted soil beneath the former USTs was defined to a depth of between 35 and 43 <br /> ' feet bgs Laterally, the vertical extent of impacted soil appears to be concentrated between 15 <br /> and 25 feet bgs, within the capillary fringe and zone of groundwater table fluctuation Total lead <br /> was not detected in the soil sample analyzed These sal sample analytical results are <br /> summarized in Table 1 <br /> ko1 <br /> 5 <br />