SITE INFORMATION AND CORRESPONDENCE

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GROUNDWATER ELEVATION DATA WMAW-92-1 .25 llar Tape reading(ft.) Groundwater Relative e Elevation (ft.) (ft.) 7/17/92 11/10/92 3/4/93 7/17/92 11/10/92 3/4/93 13.53 13.94 12.15 37.24 36.83 38.62 13.15 13.12 11.46 36.73 36.76 38.42 5 12.20 12.19 10.56 37.05 37.06 38.69 MW-92-2 49.39 12.65 12.48 10.93 36.74 36.91 38.46 The groundwater gradient on July 17, 1992 and November 10, 1992 was calculated using the elevations and groundwater measurements from MW-3, MW-92-1 and MW-92-2. Interpolation of the data for July 17 indicated that the gradient was to the east at .0034 (.34'/100') and for November 10, was to the north at .0024 (.24'/100'). These gradients are shown on Figure 2. The variation in the groundwater gradient at the LOF site from July to March is not unusual. The slope of the groundwater gradient in the area investigated is slight. Slight gradients can respond noticeably to small influences on the groundwater flow system. Possible influences include seasonal fluctuations, variation in demands on the aquifer, variations in aquifer recharge, and other surface and sub-surface human influences. Despite these slight variations in the direction of groundwater flow, MW-4 and MW-92-2 continue to represent downgradient sampling locations. Therefore, downgradient information is available. Prior groundwater sampling results, including those enclosed with this letter indicate TEPH and BTEX constituents below the reported laboratory detection limit. Based on the information presented, LOF believes that current monitoring well positions adequately measure the downgradient effect. Therefore, LOF believes placement of an additional monitoring well directly north of the fuel oil release area is not warranted. LOF will continue quarterly groundwater monitoring and sampling for three more quarters without the installation of an additional monitoring well. At that time, if no evidence of groundwater contamination is found, LOF will request the discontinuance of groundwater monitoring and request closure of the site. Should you have questions or need additional information, please contact me at (209) 858-6202. Sincerely, 4 `L::