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Rml Quarter 1995 status Report 2 . Golden Grain Company, Manteca Bean Facility,229 Moffat Blvd, Manteca,CA April 6, 1995 The water table elevations recorded on February 16, 1995, 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 2 85 feet since the November 18, 1994, monitoring event The groundwater movement beneath the site flows generally to the north at an average gradient of 0 003 foot per foot (ft/ft) The gradient at the southern portion of the site is slightly greater than that for the northern portion 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 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 February 16, 1995, 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 February 1995, dissolved TPH-g and benzene was detected in wells MW-1, MW-2, MWA, MW-5, and MW-7 The dissolved TPH-g and benzene concentrations detected in groundwater samples from MW-1, MW-2, and MW-4 were significantly lower than the results from the sampling performed on November 18, 1994 Concentrations of TPH-g and benzene detected in groundwater samples from MW-5 and MW-7 were within the range reported In previous quarters TREATMENT SYSTEM OPERATION AND MAINTENANCE During this quarter, the soil treatment system was operational for 87 days and the groundwater treatment system was operational for 73 days The soil treatment system currently extracts vapor phase hydrocarbons from wells MW-1, MW-2, MW-3 and MW-4 The groundwater treatment system extracts groundwater from well RWA During the quarter, 13 site visits were made to perform system operation and maintenance work Work performed during each maintenance event included taking flame-ionization detector (FID) measurements of catalytic oxidizer vapor influent and effluent • 0 checking and recording the catalytic oxidizer operational data 0102RO15 202 1=9GROUNDWATER TECHNOLOGY, INC