Laserfiche WebLink
1 <br /> ARCADIS G ERAG HTY&M I LLER <br /> Previous investigations also indicate that hydrocarbon concentrations in the soil appear to be <br /> limited to the area around the former underground storage tank and dispenser islands, in the <br /> southeast portion of which were removed in 1967 Soils in the vicinity of the product island D- <br /> 4 at location U-D, within the depth interval of 16 5 to 315 feet bgs, were found to have TPHg <br /> concentrations ranging from 2,900 to 1,600 mg/kg with benzene concentrations non-detect <br /> Highest TPHg impacts were observed at U-P (UV-1), beneath the 1967 UST excavation, with <br /> a TPHg concentration of 20,000 mg/kg TPHg at 35 ft bgs Benzene was measured as high as <br />' 99 mg/kg m the same sample Boring U-L, approximately 15 feet southwest of Boring U-P <br /> (LN-1), yielded a TPHg concentration of 19,000 mg/kg at 45 5 ft bgs The same sample had <br />' a benzene concentration of 140 mg/kg Lower levels of TPHg and benzene were found in <br /> boring U-M, located approximately 22 feet southeast of UV-1 TPHg (510 mg/kg) and <br />' benzene (46 mg/kg)were found in the deepest samples collected from boring U-M at 45 5 ft <br /> bgs Approximately 23 feet northeast of U-P (LTV-1), U-K had one detection of TPHg (130 <br /> mg/kg) at 415 ft bgs All other samples from this boring were non-detect for both TPHg and <br /> benzene <br />' 3.4 SITE GROUNDWATER CONDITIONS <br />' Groundwater occurs beneath the Site within medium- to fine-grained deposits <br /> Groundwater at the Site has been consistently observed to flow northeast, since 1994, at an <br />' approximate gradient of 01 to 003 The maximum Site groundwater fluctuation of 218 feet <br /> was measured in well U-2 between 1994 and 1999 The depth to groundwater in Site wells on <br />' February 5, 1999 ranged from 25 45 ft bgs (well U-6) to 26 77 (well U-5) ft bgs The <br /> groundwater table is currently above the screened interval in wells U-1 through U-8 Well <br /> UV-1 is screened above and below the groundwater table <br /> Separate-phase hydrocarbons were observed m Site well UV l on one occasion, <br /> November 3, 1997 In no other instance have separate phase hydrocarbons been detected in <br />' 11 <br />