ARCHIVED REPORTS_MONITORING WELL INSTALLATION REPORT - SITE ASSESSMENT WORK PLAN

Home Browse Search

' Historical Background: River Iver City Petroleum and Connell Motor LIR Truck tPage 6 of 13 samples collected between 45 feet and 65 feet bsg, at decreasing concentrations with increasing depth. In addition, 1,2-Dichlorobenzene was detected at concentrations less than 68 gg/kg in the soil samples analyzed. • The most intensely hydrocarbon-impacted soil was encountered in the area west of the truck bay building,in borings P26 and P27. Soil contamination between depths of 10 feet bsg and 55 feet contained the highest hydrocarbon concentrations encountered. Moderate concentrations of TPH(1,000 mg/kg)and low concentrations(>10 mg/kg)were detected in the remaining boring samples at depths between 20 and 55 feet bsg. ' • The lateral extent of impacted soil,between 35 feet and 55 feet bsg,was limited toward the west by soil boring P28 and the lateral extent of impacted soil between 30 feet and 45 feet bsg was limited to the south by soil boring M 1. ' • A ground water sample collected at the southern most end of the site contained TPH-d and toluene at concentrations of 110 micrograms per liter (µg/1) and 0.81 µg/1, respectively. There was an UST site located directly south, that was closed by the RWQCB, which may ' be a potential source of the TPH-d impacted ground water. ! • December 2000 - Additional Site Assessment ' In order to define the lateral and vertical extent of soil contamination and determine if ground water had been impacted by the unauthorized release(s)of solvents,AGE advanced four CPT soil borings P30 to P33 to depths ranging from 80 to 100 feet below surface grade(bsg)in December 2000;grab ' water and soil samples were collected from selected depths. Based on the CPT data, generally, fine-grained soil was penetrated in the soil borings, however several sand intervals were locally encountered in two of the four CPT borings. Sand was encountered at depths between 25 and 30 feet bsg in CPT P30 and at depths of 30 and 35 feet bsg ' in CPT P31. Sand and gravel were encountered at a depth of 30 feet bsg. Sand,locally cemented or consolidated,was encountered at a depth of 80 feet bsg in three CPT soil borings,P30,P32 and P33. The deeper sand unit encountered in borings P32 and P33 was well indurated and caused CPT-data ' probing refusal at the two referenced locations. Variable lithology including silty sand, silt and clayey silt to silty clay was encountered over most other depths. ' Based on the data from CPT soil borings P30 through P33, supplemented with subsequent soil borings MW-1 through MW-6, stratigraphic cross section A-A'was constructed,which depicts the general lithology north to south across the suspected release area. ! Fourteen soil samples collected from the CPT soil borings were analyzed for TPH-g,TPH-d,BTEX, • and fuel additives including MTBE and VOCs.TPH-g,TPH-d and TPH-ss were detected in the soil Advanced GeoEnvironmental,Inc. i