ARCHIVED REPORTS_XR0004884 - Laserfiche WebLink

Home Browse Search

Monitoring Well Installation Report Quik Stop Market No 121 Page 2 Upon removal of the fuel tanks, the pea-gravel in the excavation did not visibly appear to have been impacted by the hydrocarbons Six soil samples collected from the bottom of the excavation (approximately 14 to 15 feet) were reported to be relatively free of detectable TPHg/BTEX compounds These six soil samples were, however, found to contain varying concentrations of methyl-t-butyl-ether (MTBE), ranging from 43 ug/kg to 27,000 ug/kg Two grab water samples collected from the excavation indicated that groundwater beneath the fuel tanks had been impacted with petroleum hydrocarbons Over-excavating the remaining pea- gravel and capillary fringe area was impractical, since further excavation to remove the pea- gravel and some of the native sand would have seriously jeopardized the canopy and could have undermined the stability of the two streets nearby, Union Road and West Louis Avenue, as well as an historical marker, which is located on the northwest corner of Union Road and West Louis Avenue In October 1998, CCI conducted a Soil and Groundwater Investigation at the subject site using a Geoprobe direct push sampling rig A total of twenty-one soil samples and five grab water samples were collected for chemical analysis during the investigation Laboratory analysis of the soil and groundwater samples collected from the site during this investigation revealed only one area (GP-1, on the north side of the site, to contain petroleum hydrocarbons This area was reported to contain the highest levels of petroleum compounds during the fuel tank removal in March 1998 Three monitoring wells were installed at the site in April 1999 and quarterly groundwater monitoring was initiated On January 20, 2000, Compliance & Closure, Inc (CCI) conducted the first quarterly groundwater monitoring at Quik Stop Market No 121 Samples collected from the three on-site wells in January were reported by the laboratory to contain elevated concentrations of methyl tertiary butyl ether (MTBE) The three wells were reported to have MTBE concentrations of 59 micrograms per liter (ug/1) in well MW-2, 21,000 ug/l in well MW-1 and 58,000 ug/l in well MW-3 These samples were analyzed using EPA Test Method 8020 In order to confirm the MTBE concentrations, CCI re-sampled the three wells on February 17, 2000 During the re- sampling of the wells, monitoring well MW-3 had a moderate product odor No odor was noted in the other two wells The three water samples were analyzed using EPA Test Method 8260 The laboratory reported all three wells to have detectable concentrations of MTBE Monitoring well MW-3 was reported to contain the highest MTBE level, at a concentration of 49,000 ug/1 Monitoring wells MW-2 and MW-1 were reported to have detectable concentrations of MTBE, at 3 ug/1 and 11,000 ug/l, respectively Based on the January and February 2000 sample results, the Central Valley Regional Water Quality Control Board (RWQCB) and the San Joaquin County, Public Health Services, Environmental Health Department (County) requested a Work Plan to further define the vertical and lateral extent of the petroleum hydrocarbon plume at the Quik Stop site CCI was aware of