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1 <br /> 6,0 DISCUSSION OF RESULTS <br />' 6.1 SOIL ANALYTICAL RESULTS <br />' For purposes of this discussion, soil analytical data have been compared to United States <br /> Environmental Protection Agency (U S EPA) Region IX Preliminary Remediation Goals <br />' (PRGs) for residential and industrial soil direct contact exposure pathways PRGs are <br /> often used as screening level values in order to assess the need for additional site <br />' characterization or remediation As indicated previously, the only organic constituents <br /> detected in the soil samples analyzed were PCE, phenol, TPH-diesel, and total oil and <br /> grease <br />' PCE was detected in the soil sample from 16 0-feet in boring MW-2 at a concentration of <br />' 140 Ag/kg (parts per billion) Additionally, PCE was detected in the 25-foot soil sample <br /> from MW-3 at a concentration of 5 7 µg/kg and in the 30-foot soil sample from MW-4 at <br /> a concentration of 23 µglkg These two samples were collected from dust above the first <br />' encountered groundwater in these two borings All of the concentrations detected are <br /> below the Region IX residential PRG for PCE of 480 gg/kg (0 48 mg/kg) and well below <br />' the Industrial PRG of 1,300 pg/kg (1 3 mg/kg) <br /> Phenol was detected in one soil sample from 10-fet bgs in MW-4 at a concentration of <br />' 0 070 mg/kg This is well below the residential PRG for phenol of 18,000 mg/kg and the <br /> Industrial PRG of 100,000 mg/kg <br /> TPH as diesel was detected in three soil samples, the 16-foot and 30-foot samples from <br /> MW-2 at concentrations of 6 2 mg/kg and 13 mg/kg respectively, and in the 10-foot <br /> sample from MW-4 at a concentration of 17 mg/kg There are currently no Region IX <br /> PRGs established for TPH as diesel However, the concentrations detected are <br />' considered very low <br /> Total oil and grease was detected in one soil sample from 10-feet in boring MW-2 at a <br />' concentration of 220 mg/kg No total oil and grease was detected in the deeper sample <br /> from MW-2 or in any of the other surrounding borings There are currently no Region IX <br />' PRGs established for total oil and grease <br /> With the exception of beryllium, molybdenum, selenium, silver, and thallium, all other <br />' Title 22 metals were detected in one or more borings at varying concentrations With the <br /> . exception of arsenic, none of the metals concentrations detected exceed their respective <br />' Residential or Industrial PRGs Concentrations of arsenic detected ranged from 2 0 <br />' 11 V\Goodwin ProctorTinalReport doc <br />