ARCHIVED REPORTS XR0009905 - Laserfiche WebLink

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iti Ali Results of Groundwater Pumping Tests - 152 East 1 Ith Street, Tracy Page 4 In connection with investigations of a release of hydrocarbon fuels at the Beacon station, a total of rune ground water monitoring wells have been installed on and around that property The locations of these wells are also shown on Figure 2 where they are designated as ULT 1 through ULT 9 The Ultramar monitoring wells were installed subsequent to installation of new tanks at the Beacon Station in October 1986 Components of fuel hydrocarbons were detected in the pit excavated to accomplish the tank replacement project and the pit was over- excavated to remove approximately 1,155 tons of affected soil which was disposed off-site at a permitted facility Some 52,000 gallons of affected groundwater was pumped from the excavation and similarly disposed by shipment off-site for treatment at a permitted facility The over-excavated pit, which was backfilled with clean material, had plan dimensions of 42ft by 40ft and was 15ft deep Its location is indicated on Figure 2 The round of groundwater sampling that was performed by The San Joaquin Company Inc in July 1993 included recovery and analysis of samples from all of the wells installed for both the Navarra property at 152 East 11th Street and for the Beacon Station at 153 East I 1 th Street Data Compilation For convenience of reference, depths to the water table measured on July 8th 1993 and the results of analyses of all soil and groundwater samples that have been recovered from borings and wells installed for both the 152 and 153 East Street sites have been compiled in Tables 1, 2 and 3 respectively The available logs of the wells installed for both the 152and 153 East l lth Street sites are presented in Appendix A Interpretation of Area of Subsurface Affected by Release of Gasoline As has been described in earlier reports related to the 152 East I Ith Street property, the geotechnical and geochemical data obtained from the several phases of investigation conducted separately for both the 152 and 153 East lith Street properties have been synthesized and used as the basis for an interpretation of the lateral and vertical extent to which the subsurface has been affected by hydrocarbons released at the 152 East Street site This interpretation is presented in the form of the plan view on Figure 3 and the longitudinal and cross sections on Figures 4, 5 and 6 The groundwater-table contours shown on Figure 3 reflect the data gathered on July 8th 1993 and are similar, except for minor seasonal variations, to those that can be constructed from data gathered at other times iIt is important to understand that the interpretations shown on Figures 3, 4, 5 and 6 are not intended to precisely define the exact boundaries of hydrocarbon fuel components