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,l Fourth Quarter 1994 Status Report 2 Golden Grain Company, Manteca Bean Facility, 229 Moffat Blvd, Manteca, CA December 22, 1994 hydrocarbons, if present (attachment 2, table 1) The well gauging was conducted in accordance with the Leaking Underground Fuel Tank (LUFT) Field Manual published by the State of California Leaking Underground Fuel Tank Task Force, dated October 1989 The water table elevations recorded on November 18, 1994, were used to prepare a potentiometric surface map for the site (figure 2) The potentiometric surface elevations measured in the site groundwater monitoring wells Increased an average of 0 86 feet since the August 19, 1994, monitoring event The groundwater movement beneath the site flows generally to the north at an average gradient of 0 0016 foot per foot (ft/ft) The gradient at the southern portion of the site is greater and exhibits the effects of pumping from the groundwater extraction well (RW-1) on the site groundwater GROUNDWATER SAMPLING Groundwater samples were collected from 13 of the 14 monitoring wells on the site in accordance with the LUFT guidelines Monitoring well MW-3 did not contain adequate groundwater to collect a sample Monitoring well MW-9 was sampled on November 22, 1994, because the peristaltic pump normally used to sample the well required repair on November 18 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 total xylenes (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 November 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 13 monitoring wells sampled In August 1994, dissolved TPH-g and benzene was detected in wells MW-1, MW-2, MW-4, MW-5, and MW-7 The dissolved TPH-g and benzene concentrations detected in groundwater samples from these wells were within the same ranges reported in previous sampling events, with the exception of MW-1 MW-1 contained significantly lower concentrations of TPH-G and benzene this quarter This may be attributed to the addition of this well to the soil vapor extraction system TREATMENT SYSTEM OPERATION AND MAINTENANCE During this quarter,the sod and groundwater treatment system was operational for 80 days The system operated as it has for the previous two years until October 11, 1994, when system modifications were initiated During the three weeks between October 11 and November 4, 1994, monitoring wells (MW-1 0102RO44 202 GROUNDWATER TECHNOLOGY, INC