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First Quarter 1994 Status Report March 31, 1994 • Golden Gram Company, Manteca Bean Facility, 229 Moffat Blvd , Manteca, CA 2 Leaking Underground Fuel Tank (LOFT} Field Manual published by the State of California Leaking Underground Fuel Tank Task Force dated October 1989 The water table elevations recorded on February 18, 1994 (Attachment 2, Table 1), were used to prepare a potentiometric surface map for the site (Figure 2) Data collected from well MW-3 was not used to prepare the potentiometric surface map because it was inconsistent with previous data and with data from nearby wells The wellheads on wells MW-1 and MW-8, which were damaged during the previous quarter, were repaired during this quarter and their elevations were resurveyed so they could be used on the potentiometric surface map The potentiometric surface elevations measured in the site groundwater monitoring wells increased an average of 1 81 feet since the November 11, 1993, monitoring event The groundwater movement beneath the site flows generally to the north at an average gradient of 0 002 foot per foot (ft/ft) The gradient at the southern portion of the site is greater and exhibits the effects of the groundwater extraction well on the site groundwater GROUNDWATER SAMPLING Groundwater samples were collected from all 14 of the monitoring wells on site according to the Leaking Underground Fuel Tanks (LOFT) guidelines Field data sheets from monitoring well gauging • and sampling work are included in Attachment 3 The samples were submitted under chain-of- custody protocol to GTEL Environmental Laboratories in Concord, California The samples were analyzed for benzene, toluene, ethylbenzene and xylene (BTEX) and for total petroleum hydrocarbons-as-gasoline (TPH-G) using Environmental Protection Agency (EPA) Methods 5030/8015/8020 Historical and recent analytical data from groundwater analyses are summarized in Table 2 The laboratory analyses reports and the chain-of-custody record for the water samples collected on February 18, 1994, are included in Attachment 4 Maps showing reported values of dissolved TPH-G and benzene concentrations are included as Figures 3 and 4, respectively Of the 14 monitoring wells sampled in February 1994, dissolved TPM-G was detected in wells MW-1, MW-2, MW-4, MW-5, and MW-7 The dissolved total hydrocarbon concentrations detected in groundwater samples from these wells were within the same order of magnitude as the previous sampling event on November 11, 1993 Benzene concentrations detected in samples from these wells were also similar to the previous sampling event, with concentrations being slightly higher in MW-1 and slightly lower in MW-4 Concentrations of benzene less than 1 part per billion (ppb) were also detected in groundwater samples collected from wells MW-13 and MW-14 Reportable TPH-G concentrations were not detected in samples from those wells V 55108014 020 GROUNDWATER TECHNOLOGY, INC