Laserfiche WebLink
d Harding Lawson Associates <br /> ' were collected at the capillary fringe area immediately atop the <br /> shallow ground-water zone. No detectable concentrations of gaso- <br /> line hydrocarbons were found in any off-site soil samples. <br /> i.; <br /> Concentrations above detection limits but lower than 100 ppm were <br /> found at P-6 and P-8. <br /> The primary mechanism of hydrocarbon transport to areas <br /> adjacent to the source appears to be along the lower portion of <br /> the capillary fringe. Hydrocarbons are transported laterally <br /> ! � r <br /> across the site through this fringe zone and deposited in the <br /> 1 <br /> soils as both the ground-water zone and this fringe area experi- <br /> ence seasonal fluctuations. l <br /> ,,. A "zero line" for hydrocarbon contamination in soil is <br /> shown on Plate 1. This line represents a "not detected" (ND) s <br /> f <br /> boundary based on soil analyses with results of ND.. A line <br /> defining an area in which delectable concentrations of hydro- <br /> carbons have been found is also shown on Plate 1. This area s <br /> :r f� f <br /> extends from the tank backfill east-northeast towards Buthmann <br /> Avenue.. This is also. the general direction of ground--water <br /> f <br /> 4 <br /> movement. <br /> a F� <br /> i <br /> 4 3. Ground Wa er <br /> The main sources of gasoline hydrocarbons are believed <br /> tohave been the 10,000-gallon unleaded gasoline tank andthe dry <br /> r well (plate 1) . With the decommissioning of the 10,000-gallon <br /> f d <br /> tank, the major source of gasoline hydrocarbons was removed. The <br /> dry well is used as a wash-down sink for the site; thus,<:.'any 9 <br /> gasoline spilled on the asphalt would have been washed towards <br /> c <br /> �, 14 <br />