ARCHIVED REPORTS_XR0005597 - Laserfiche WebLink

Home Browse Search

C,eologccal reamcs Inc Page 2 GW Monitoring Report Ted Peters -AST Project No 7012 July 31, 2002 from each of thirteen (13) boreholes Of these, ten soil and ten groundwater samples were analyzed for BTEX, TPH-G, TEPH-D and MTBE In addition, five soil and five ' groundwater samples were also analyzed for gasoline oxygenates (MTBE, TAME, TBA, DIPE and ETBE), 1,2 DCA, and EDB utilizing EPA Method 8260B The Geoprobe effort resulted in the completion of the lateral definition of the soil plume ' Gasoline range hydrocarbons detected in soils on the western portion of the site are anomalous and not consistent with the two known sources of petroleum fuels at the facility Diesel range petroleum hydrocarbons and gasoline oxygenates were not detected in any of the groundwater samples from the probe locations Based on the Geoprobe effort, GTI proposed two new monitoring wells one shallow well to be placed in the vicinity of the highest level of detected gasoline contaminants in the ' west portion of the site, and one deep well to be placed in the central portion of the site near the presumed source area of the diesel In his December 26, 2000, correspondence, Mr Joseph Mello of the Regional Water Quality Control Board (RWQCB) denied the deep well and requested a second shallow well in the southwest portion of the site On March 21, 2001, GTI supervised the installation of two new monitoring wells, MW-7 & MW-8 Groundwater monitoring events were conducted on March 29 and August 8, 2001, which included the new wells GTI documented the installation of the wells and the subsequent monitoring event in our "Soil & Groundwater Investigation" report dated April 20, 2001 The August 2001 monitoring event was documented in GTI's "Groundwater Monitoring — Yd Quarter 2001" report dated September 19, 2001 Both reports were submitted to the RWQCB-CVR and the SJC PHS/EHD ' The CRWQCB-CVR issued Monitoring and Reporting Program (MRP) Order No 5-01-868 for the site on October 3, 2001 The MRP requires that quarterly monitoring reports be submitted to the RWQCB-CVR This report details the completion of the second quarter 2002 monitoring event performed on June 19, 2002, and is intended to satisfy the ' requirements of the MRP 2.0 GROUNDWATER MONITORING 2.1 Site Hydrology ' Site-specific groundwater gradients and bearings were calculated from the depth to water measurements taken during the event Two separate gradients were calculated for the three wells in the former UST location (MW-1, MW-2 and MW-3) and five wells in the former AST location (MW-4, MW-5, MW-6, MW-7 and MW-8) Table 1 in Appendix A is a summary of water level elevations, gradient slopes and bearings and Table 4 includes well construction details Figure 2 is a groundwater gradient map for the site Historical ' groundwater direction and slope data are summarized in Figure 3 Groundwater Gradient Rose Diagram The average groundwater elevation of the AST wells was 13 13 feet above mean sea level The direction and gradient of groundwater for the June 2002 monitoring event was N5 I°W at 0 006 ft/ft As indicated in Figure 3, a northwest direction was calculated for the fourth consecutive event since wells MW-7 and MW-8 were installed in March 2001 These data 1