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CLEARWATER ' <br /> G R. O U 'P, I N C. <br /> Clearwater implemented the workplan in ' March' 1995_ by. drilling and <br />' sampling three soil borin sand convertin the borin s t <br /> g g . g o t wo-inch-diameter <br /> monitoring wells. - Soil and groundwater samples, were-analyzed for total_ <br /> petroleum -hydrocarbons as gasoline (TPHg) -. and for ' benzene, toluene, <br /> eth lbenzene, and total x lenes BTEX . . <br /> y 'Y { ) <br /> -The results of the investigation are:.presented in Clearwater's'Preliminary Site <br />' Assessment Report, dated ted May 25, 1995.. The following is a summary of .the <br /> findings presented.in that report: <br /> • Subsurface materials 'encountered while drilling,consisted of silt, sand, or <br /> mixtures of the two, with minor amounts --of clay. The -top of a layer. of . <br /> relatively',clean sand, apparently 5-11 feet thick, was encountered at 20-30 <br /> feet below ground surface (bgs) <br /> ' • Groundwater was encountered <br /> at approximately 50 Feet .bgs while drilling <br /> the three,monitoring wells. Static water .levels ranged from 45.87 to'47.26 . <br /> feet bgs; on the basis of these data and surveyed well casing elevations, the <br /> direction ofroundwater flow was s estimated to be northward <br />' • Up -to 2800 parts per million (ppm) TPHg were detected insoil samples <br /> . <br /> . p <br /> • Concentrations of TPHg'in groundwater samples,ranged, from 5,100 parts. <br /> : per billion,(ppb) to .120,000 ppb;'benzene concentrations ranged from <br /> ' g _ 1,300, <br /> Ppb to 18,000'ppb. <br />' The followingrecommendations ' were made in the Preliminary .e iminary Site <br /> Assessment =Report,-' on ' the ' basis of- data obtained. during the . initial . <br /> investigation:` <br /> • Backfill the existing excavations, possibly after excavating to 20-25 feet bgs <br /> in the .large'excavation on the north side of the site <br /> • Pave the'area after backfilling <br /> • Continue evaluation of the site by 'installing additional soil,borings,..a'' <br /> 'monitoring well'through the. center"of the backfilled tank excavation, and <br /> soil vapor extraction wells in the vicinity of the tank excavation <br /> D-105WP 7/95 _ 3 <br />