ARCHIVED REPORTS_XR0011077 - Laserfiche WebLink

Home Browse Search

i Stockton with instructions to test for BTEX (EPA 8020, ) & TPH-G (EPA 8015M, ) using San Joaquin County specified detection limits . The results of laboratory analyses of those samples are summarized on TABLES III & IV, the laboratory worksheets are included as EXHIBITS F & G. On August 9, 1995, Del-Tech Geotechnical Support Services, deveoped, purged, measured water depths, and sampled the three monitoring wells as directed by Wm J Hunter & Associates The water table was measured at an average depth of 7 95 ' bgl Preserved water samples were transported under chain of custody to FGL Environmental laboratory with instructions to test for BTEX (EPA 8020, ) & TPH-G (EPA 8015M ) Details of that work, including field protocol, are included as EXHIBIT E The results of the laboratory analyses of those samples are summarized on TABLE V, copies of the laboratory sheets are included as EXHIBIT H Custody chains & laboratory QA/QC are included as EXHIBIT I On October 5, Wong Engineering, licensed surveyors, determined the wellhead elevations and surface coordinates of the three monitoring wells, a copy of that survey is attached as EXHIBIT J DISCUSSION OF RESULTS OF ABOVE WORK Soil contamination was not encountered above 11 ' in any of the soil borings/wells placed during this work. Benzene was measured in MW-1 at 11 ' (1 8 mg/kg, ) & 16 ' ( 003 mg/kg) ; and in SB-1 at 11 ' (1 7 mg/kg, ) & 16 ' ( 004 mg/kg ) Ethylbenzene was measured in MW-1 at 11 , (2 2 mg/kg, ) in MW-3 at 111 (1 3 mg/kg, ) and in SB-1 at 111 (4 9 mg/kg, ) & 161 ( .068 mg/kg ) Toluene was detected in MW-1 at 111 (4 7 mg/kg, ) & at 16 ' ( 008 mg/kg; ) in SB-1 at 111 (19 0 mg/kg, ) & at 16 ' (0 14 mg/kg, ) and in SB-3 at 1116" ( 004 mg/kg ) Xylene was measured in MW-1 at 11' (11 0 mg/kg, ) & at 16 ' ( 007 mg/kg, ) in MW-3 at 11 ' (22 .0 mg/kg, ) and in SB-1 at 11' (34 0 mg/kg, ) & at 16 ' (0 34 mg/kg ) TPH as gasoline was measured in MW-1 at 11' (120 mg/kg, ) in MW-2 at 11 ' (30 0 mg/kg, ) in MW-3 at 11 ' (440 mg/kg, ) and in SB-1 at 111 (1800 mg/kg, ) & at 16 ' (200 mg/kg ) Those results are summarized on TABLES III & IV PLATE XIX shows the estimated limits of the soil plume based on levels of benzene & TPH-G As mentioned earlier, the water table was measured at an average depth of 7 .95 ' bgl, (1 50 ' msl datum ) Using that data, and wellhead elevations as determined by the survey, a groundwater . gradient map was constructed, (PLATE XIII, ) which indicates a 9