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] Work Plan - - - Cmepas Car Wash November 17, 1998 Page -3- All soil samples collected for laboratory analysis will be retained, undisturbed, in the brass liners. The liners will be sealed at the ends with Teflon tape, capped, wrapped with duct tape, and labeled. The samples will be stored in a cooler chilled with Blue Ice and delivered within 24 hours of collection, under chain-of-custody procedures, to GeoAnalytical Laboratories in Modesto, California. Three soil samples from the vadose zone of each borehole will be selected for chemical analysis. One of the soil =l samples will be from the capillary fringe. The soil cuttings from the borings and steam cleaning effluent will be placed in 55-gallon drums, sealed, labeled, and left on site pending laboratory analyses. Disposal of hazardous materials, if any, will be the responsibility of the property owner. ' I -- 3A MONITOR WELL CONSTRUCTION The three monitor wells (MW-9, MW- 10, and MW-11 ) will be constructed with 2-inch O.D ., Schedule 40, flush-threaded, machine-slotted PVC screen (slot size 0 .020) extending from a depth of approximately 25 feet to 45 feet bgs. A flush-threaded PVC bottom cap will be placed at the bottom of _ the screen. Blank PVC casing will be installed above the screen to the ground surface. The well casing � ! will be steam-cleaned on site prior to use. No glue or solvents will be used in the construction of the wells. A sand pack of #3 Monterey sand will be placed in the annular space to approximately one foot above J the screen. Approximately two feet of bentonite pellets will be placed above the sand to form a protective seal. The bentonite will be hydrated using potable water. A seal of neat cement will be poured in the annulus from the bentonite seal to the ground surface and a locking, traffic box will be installed at the ground surface. The proposed well design is shown in Figure 3, Appendix A. 3.5 MONITOR WELL SURVEYING, DEVELOPMENT, AND SAMPLING Condor' s licensed land surveyor will determine the location and elevation of the well collars following the installation of the monitor wells. The well collars will be surveyed with a vertical accuracy of 0.01 foot and horizontal accuracy of 1 .0 foot. The measuring point for water-level measurements will be marked on each well collar. The groundwater gradient will be estimated using the survey information and the depth to water measurement in each well. The wells will be gauged during periods of low and - ! high tide to evaluate tidal influences on the groundwater gradient. At least 48 hours following construction, the monitor wells will be developed by surging and bailing the groundwater in each well until the discIrarge water is free of sediment (clear to the unaided eye). The monitor wells will be purged until the temperature, electrical conductivity and pH of the water has stabilized. All well-development equipment will be cleaned prior to use in each well by washing in a solution of laboratory-grade, non-phosphate detergent and hydrocarbon-free water, and double rinsing with hydrocarbon-free water. The purge water discharged from the wells during development will be placed in 55-gallon drums, sealed, labeled, and left on site to await disposal pending results of laboratory analysis. too? CONDOR J