Laserfiche WebLink
1 <br />' 6 REMAINING RESIDUAL PETROLEUM HYDROCARBONS <br /> IN SOIL <br />' Based on the results of soil samples collected from beneath the former USTs (tanks T1 <br /> through T10) and from soil borings, residual petroleum hydrocarbons at the site have been <br /> delineated The former gasoline tank cavity was excavated to approximately 13 feet bgs <br /> The former product lines were excavated to approximately 3 feet bgs The former waste- <br /> oil tank cavities were excavated from 6 to 9 feet bgs <br /> The total mass of benzene and TOG remaining were not calculated The mass of benzene <br /> was not calculated due to the relatively low concentrations of benzene In soil samples <br />' collected beneath the site Benzene concentrations ranged from below laboratory detection <br /> limits to 5 4 ppm (sample collected beneath the USTs) The TOG mass was not calculated <br /> because the carbon range for TOG overlaps with the carbon range of the TPHG and <br /> TPHD Based on the laboratory analytical methods, the carbon range for TPHG using <br /> USEPA Method 8015 ranges from Cs to C12, the carbon range for TPHD using <br /> USEPA Method 8015 ranges from C12 to C16 and the carbon range for TOG using <br /> USEPA Method 5520 B and F (gravimetric) ranges from C6 to C32 In addition, TOG <br /> represents the heavier, less mobile, mass of petroleum hydrocarbons The total mass for <br /> TPHG and TPHD were calculated as described below <br />' 6.1 Petroleum Hydrocarbons Removed <br /> During excavation and overexcavation activities of the former gasoline USTs and product <br />' lines, approximately 150 cy of soil were removed and disposed of at a Class lI landfill The <br /> total pounds of petroleum hydrocarbons removed have been estimated using an average <br /> concentration of 600 ppm and assuming a bulk density for soil of 122 pounds per cubic foot <br /> (lb/ft) for silty sediment The average concentration used was obtained from analytical <br /> results of soil samples collected from samples beneath the former USTs and former product <br /> Imes Analytical results are presented in Table 7 <br /> 1 Petroleum hydrocarbons as gasoline removed = 600 milligrams per kilograms <br /> (mg/kg) x 1 x 10-6 kg/mg x 122 lb/ft3 x 150 cy x 27 ft3/cy <br /> -296 lbs of petroleum hydrocarbons as TPHG removed <br /> SA('\N\PJ0\0805'4)8051420 4QS-9 rVrz 1 Rev 0 3112/97 <br /> 20805-142 004 6-1 <br />