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Monitor Well Installation Work Plan Pilkington North America,Inc. July 16,2001 Page-3- of screen and casing, depth intervals of the screen, blank casing, sand pack, bentonite seals and surface seals,and the quantities of materials added to the annular spaces. 4.3 MONITOR WELL DESIGN Each well site will be hand-augered to four feet bgs before drilling to lessen potential for intercepting utilities. The monitor wells will be drilled using 8-inch O.D., continuous-flight, hollow-stem augers. The augers will be steam cleaned before each boring is drilled. Each well will be drilled to approximately 10 feet below the water table with a total maximum depth expected to be approximately 20 feet bgs. The monitor wells will be constructed with 2-inch O.D., Schedule 40, flush-threaded, machine-slotted PVC screen (slot size 0.020) extending from approximately two feet above the water table to a depth of ten feet below the water table. 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. 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 two(2)feet above the screen. Approximately three (3) 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 well monument with crash posts will be installed at the ground surface. A cap and padlock will be installed on the well monument. A diagram of the proposed monitor well construction is shown in Figure 3,Appendix A. 4.4 MONITOR WELL SURVEYING A survey will be conducted to determine the location and relative elevation of the well collars following the installation of the monitor wells. The monitor wells will be surveyed to the same reference used in surveying the existing monitor and recovery wells at the site to provide a common reference for all the 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. Ground surface elevation at each well will be recorded to the nearest 0.1 foot by measuring down from the measuring point. 4.5 MONITOR WELL DEVELOPMENT At least 48 hours following construction, the monitor wells will be developed by surging and bailing the groundwater in each well until the discharge water is relatively free of sediment and clear. The wells will be purged until the temperature,electrical conductivity and pH of the water has stabilized. The volume of water purged from each well during development will be recorded. All development water will be discharged to the ground surface near the wells. 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 de-ionized water, and double rinsing with de-ionized water. 4.6 INITIAL WATER QUALITY SAMPLING Groundwater samples will be collected at least 48 hours following development of the monitor wells to allow the static water level to recover from development activities. Prior to sample collection, the static water level in each well will be measured to the nearest 0.01-foot with a battery-operated, water level meter. The monitor wells will be purged using a clean, disposable bailer until the temperature, electrical