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p sr sv •� :' ,. -r i as �F "'k" �1a,,y - .,y. ' , KEI-P91-0202.R5 October 16, 1991 Page 4 RECENT FIELD ACTIVITIES On August 27, 28, and 29, 1991, three two-inch diameter monitoring wells (designated as MW1, MW2, and MW3 on the attached Site Plan, Figure 1) were installed at the site. The wells were drilled, constructed and completed in accordance with the guidelines of both the Regional Water Quality Control Board (RWQCB) , and the Califor- nia Well Standards ,er Bulletin 74-90. The subsurface materials penetrated and details of the construction of the wells are described in the attached Boring Logs. The monitoring wells were drilled and completed to total depths ranging from 82 to 86 feet below grade. Ground water was encoun- tered at depths ranging from 73 to 75 feet beneath the surface during drilling. soil samples were taken for laboratory analysis and lithologic logging purposes at maximum intervals of 5 feet, at significant changes in lithology, at obvious areas of contamina- tion, and at the soil/ground water interface, beginning at a depth of approximately 4.5 feet below grade and continuing until ground water was encountered. Add-I-zonally, the boring of MW3 was sampled at an approximate spacing of 2.5 foot intervals (to the maximum depth drilled) for detailed lithologic logging purposes. Also, soil samples were obtained below the first encountered ground water at the depths indicated on the attached Boring Logs for lithologic logging purposes cn ly. The undisturbed soil samples were taken by driving a California-modified split-spoon sampler lined with brass liners ahead of the drilling augers. The two-inch diameter brass liners holding the samples were sealed with aluminum foil, plastic caps and tape, placed in plastic zip--lock baggies, and stored in a cooled ice chest for delivery to a certified laboratory. Each well casing was installed with a watertight cap and a padlock. A round, watertight, flush-mounted well cover was cemented in place over each well casing. The surface of each well cover was surveyed by Kier & Wright of Pleasanton, California, to Mean Sea Level (MSL) and to a vertical accuracy of 0.01 feet. The wells were attempted to be developed on September 3, 1991. Prior to development, the wells were checked for depth to the water table using an electronic sounder, and for the presence of free product---(using_an....interface-p.r.obe"-ar paste-to a) . No free product was noted in any of the wells. After recording the manrtor ng"- data, the .wells were developed with a surface pump until the evacuated water was reasonably clear and generally free of suspended sediment. During development, the wells were purged of 37 to 60 gallons. however, field data collected indicates that