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Groundwater Monitoring Well Installation The boring will be converted to a groundwater monitoring well by installing 24nch diameter, flush-threaded, Schedule 40 PVC casing with 0.020-inch factory-slotted screen. Approxi- mately 15 feet of screen will be placed in the bottom of the boring. A grade of sand appropriate to the screen size will be placed in the annular space across the entire screened interval, and will extend approximately 2 feet above the top of the screen for the well. A bentonite seal will extend from the sand pack to the well box. The well casing will be topped with a locking cap . The well head will be contained in a water-tight traffic rated and flush mounted well box. The boring logs will show well construction details. The wells will be developed after completion. The development procedure for each well will consist of pumping or bailing water from the well until the water is visibly clear, the well goes dry, or until a maximum of ten casing volumes have been removed. The newly installed wells will be surveyed by a California State Licensed Surveyor. The well casings will be surveyed to the nearest 0. 01 feet in elevation and to the nearest 0. 1 feet in northings and castings to a known benchmark. Groundwater Sampling Procedures The sampling procedure for each well consists first of measuring the water level and checking for the presence of separate-phase hydrocarbons (SPIT), using either an electronic indicator and a clear Teflon® bailer or an oil-water interface probe. After purging, water levels are allowed to partially recover. Groundwater samples are collected using a Teflon bailer, placed into appropriate EPA-approved containers, labeled, logged onto chain-of-custody documents, and transported on ice to a California State-certified laboratory. Laboratory Procedures Selected soil and groundwater samples collected will be analyzed for the presence of total petroleum hydrocarbons calculated as gasoline, total petroleum hydrocarbons calculated as diesel, benzene, toluene, ethylbenzene, and xylenes, and methyl tertiary butyl ether (MtBE) using modified EPA Methods 8015 and 8020. The highest reported detection (if any) of MtBE will be confirmed by EPA Method 8260. Soil Cuttings and Rinsate Water Soil cuttings generated during drilling operations will be temporarily stored onsite and covered with plastic sheeting pending characterization and disposal. Soil cuttings will be removed by Chevron' s disposal contractor to an appropriate disposal facility. Water generated during steam cleaning will be temporarily stored in DOT-approved 55-gallon drums pending transport by Chevron' s disposal contractor to an appropriate disposal or treatment 70007-044-01/Vlplm A - 2 11/03/98