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Lil • <br /> Forms <br /> A member of the Pilkinglm Gmup <br /> ord Co. <br /> April 9,1993 500 East Louise <br /> P.O. Box 128 <br /> Lathrop, California 95330 <br /> Tel. 209-858-5151 <br /> Ms. Wendy Cohen Fnx 209-ase 2024 <br /> California Regional Water Quality Control Board <br /> Central Valley Region :. j <br /> 3443 Routier Road, Suite A <br /> Sacramento, CA 95827-3098P'= <br /> APR 1 , <br /> WNVIRONM€ !T 41'93 <br /> Re: Libbey-Owens-Ford Co. '.j 01�g47-/=1 <br /> Lathrop, California I fif W CES <br /> Monitoring Well - Work Plan <br /> Quarterly Monitoring Well Results <br /> Dear Ms. Cohen: <br /> By this letter, the Libbey-Owens-Ford Co. (LOF) is responding to Regional Water Quality <br /> Control Board (RWQCB) correspondence dated March 15,1993 and enclosing the quarterly <br /> groundwater monitoring results for the period of January thru March, 1993. The March 15 <br /> correspondence requested LOF to submit a work plan for the installation of an additional <br /> monitoring well. After reviewing previously reported data as well as the enclosed data, LOF <br /> believes that the installation of an additional monitoring well is not warranted. <br /> The issue appears to be whether groundwater monitoring and sampling of the existing monitoring <br /> wells adequately characterize the groundwater in the area of the May 3,1992 fuel oil release. <br /> The RWQCB has expressed concern that a monitoring well does not exist directly downgradient <br /> of the fuel oil release area. The groundwater gradient at this site has in the past and continues <br /> to demonstrate slight changes in directional flow. LOF believes however, that existing <br /> monitoring wells (MW-4 and MW-92-2) adequately encompasses the downgradient flow of the <br /> groundwater at the site. The following information from the enclosed "Quarterly Groundwater <br /> Sampling Report First Quarter 1993" report prepared for LOF by Condor Earth Technologies <br /> will help clarify the changing groundwater gradient conditions. <br /> The groundwater gradient was estimated using the survey information and the depth to water <br /> measurement in each well. The water levels in the monitor wells were measured to the nearest <br /> 0.01 feet with a standard battery-operated, flat-tape, water-level meter. Measurements were <br /> taken before purging and before sampling. The following table shows the well collar relative <br /> elevations, depth to groundwater measurements and groundwater relative elevations for July 17, <br /> 1992, November 10, 1992 and March 4, 1993 for each monitor well. The groundwater gradient <br /> for the latest sampling on March 4, 1993 was calculated using the elevations and groundwater <br /> measurements from MW-3, MW-92-1 and MW-92-2. Interpolation of the data collected from <br /> these wells indicated that the groundwater gradient was to the north-east at .0022 (.22'/1001). <br /> The estimated gradient is shown on Figure 2. <br /> PILKINGTON q���0 <br />