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Mr. Robert Garcia • • 17 October 2003 Leprino Foods, Inc. 2 locations of subsequent borings are dependent on the groundwater gradients established by water table elevations in the Geoprobe® borings, it is important to get accurate groundwater elevation measurements in the borings. The Work Plan should state how LFC will determine that the groundwater level in the boring is stable. 4. Page 2,Boring Locations. The Work Plan proposes locating the initial two borings downgradient of RW-1 and RW-2, and if no odor is detected, one of the borings would be chosen to be completed as a monitoring well. If diesel odors are detected in the groundwater samples, additional downgradient borings would be completed at a spacing of about 100 feet until no odor is detected in the groundwater. At this point, a monitoring well would be completed. Under this strategy, two somewhat parallel lines of Geoprobe® sample points would be installed until a lack of diesel odor indicates the location of the well. This strategy does not account for the possibility of preferential flow of groundwater under one of the two sampling lines. Therefore, downgradient points should be sampled in both lines until no diesel odor is detected in either line, at which point the monitoring well location can be chosen. 5. Page 3, Soil and Groundwater Screening. The Work Plan proposes taking groundwater samples at the rate of one sample for every 200 feet downgradient of the fence line, or sampling about every other borehole,to provide information on downgradient attenuation. LFC should collect samples from every boring. After determining the location of the monitoring well, individual samples can be selected for analysis to assess the downgradient attenuation. 6. Page 3, Well Construction. The Work Plan proposes completing one boring as a monitoring well. The proposed well would be constructed of one-inch PVC inserted into the two-inch diameter Geoprobe® hole with a 0.5-inch sand pack, and have a five-foot screen with the top of the screen set two feet above the water table. Several of the well hydrographs in the 29 April 2003 annual monitoring report show that the water table has fluctuated from two to three feet since June 1994. It is possible that the monitoring well could become dry if the bottom of the screen is set only three feet below the water table. Therefore, a ten-foot screen should be installed with the top of the screen set two feet above the water table, as proposed By 5 November 2003,please submit a revised work plan that addresses the above comments. If you have any questions,you may contact me at(916) 255-3077 or at djuthg@rb5s.swrcb.ca.gov. A� 4ZA GERALD J. DJUTH,P.E., C.E.G. Associate Engineering Geologist cc: Ms. Lori Duncan, San Joaquin County Environmental Health Services, Stockton Mr. Brendan Shine, HSI GeoTrans, Westminster, Colorado x