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w�. <br /> LOYAL OAK SAVINGS & LOAN <br /> I xiended Ground Water Investigation <br /> Page 2 <br /> 2.1 Narrative Of Previous Investigations <br /> previous investigations have shown that relatively low level contamination of <br /> ground water has occurred. <br /> MW-1, drilled in the area where the underground tank was removed <br /> of, <br /> fs37 mgil <br /> an <br /> initial concentration of l img/l and 10 months later, a concentration <br /> of total petroleum hydrocarbons (TPH), The soil samples taken at the time of <br /> the well installation shows a maximum level of 4,800 mg/kg of total <br /> hydrocarbon (see Table 1). <br /> Wells MW-2, 3 and 4 were all installed at a later date by Harding & Lawson <br /> Associates. All were sampled initially on January 26, 1989. Monitoring well 2 <br /> (MW-2) shows a substantial increase from the initial sampling to the second <br /> sampling seven months later. MW-3 shows a decrease to a "none detected" <br /> level and MW-4 shows a slight increase in the benzene level. <br /> Wells MW-5, <br /> 6 and 7 were installed in December of 1990 by WHF <br /> Wells S and 6 showed "none detected" levels, and <br /> Environmental Consultants. <br /> MW-7 showed significant levels of BTE&X (Appendix C). <br /> After the pump test and well development, a sampling round was made and all <br /> wells showed "none detected" in February of 1991. A subsequent round was <br /> taken in March of 1991, and this round shows all wells "none detected", except <br /> Well 2. Well 2 has Benzene in it at l.lppb. Ground water gradient has been <br /> measured in several directions over the life of this project. These measurements <br /> show swings from southeast to east to northeast. The Regional Water Quality <br /> Control Board and the San Joaquin County Environmental Health Department <br /> have determined that down gradient is northeast and have asked for a monitor- <br /> ing well to be installed to the northeast. <br /> 3.0 Site Work Plan <br /> This Work Plan will consist of the installation of one (1) additional monitoring <br /> well. The location of the monitoring well will be to the northeast of MW-S, <br /> which is in the down gradient direction (Figure 2). The depth of the monitoring <br /> well will be approximately 40 feet into the first aquifer. Well development and <br /> sampling are discussed below. <br />