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Mr Harlan Knoll 5 July 24, 1992 For the selected borings that will be completed as wells, Canonie proposes placing polyvinyl chloride IPVC) casing with sand filter pack and surface seal for all ground water monitoring/vapor extraction wells proposed in this document. PVC blank casing coupled to PVC screen will be used to complete the wells. Because all proposed wells are also planned for remediation activities, a 0.020 inch slot size will be used to provide sufficient flow capacity for both ground water and vapor extraction. In addition, because the subsurface grain size is considered to be primarily sand, a No. 3 Monterey type sand for equivalent) will be used for the filter pack. The top of the sand filter pack will extend to a depth of one foot above the top of the screen. A one to two foot bentonite seal will be placed immediately above the sand filter pack. An expansive cement-bentonite grout will then be placed from the top of the bentonite seal to approximately one foot below ground surface The top of the well casing will be completed approximately six inches below ground with the threads intact to allow the well to be adapted to a remediation system and for vacuum testing of vapor wells. A locking diaphragm expansion cap will be affixed to the piezometer to discourage unauthorized access to the well. A well monument with a bolted lid will be set around the well casing with neat cement, slightly elevated above the surrounding ground surface to prevent ponding of water. This will leave the well casing extended approximately six inches above the cement-bentonite grout inside the monument. This extension provides a small reservoir to collect water that may inadvertently enter the monument. A typical well construction detail is shown on Figure 3. The measuring point elevation for each monitoring well will be surveyed and tied Into a locally accepted datum. In the event that wells are completed for ground water monitoring, the wells will be developed by aggressively applying a vented surge block to each well continuously for 30 minutes. This should effectively develop the surrounding formation Into the filter pack After surging has been completed, five to ten casing volumes of water will be extracted from each well to remove sediment which was generated during surging. This extraction will also serve to purge the well in preparation for sampling, which will be completed following well development Water samples will be collected with either a disposable PVC or Teflon'''' bailer. Water samples will be collected in triplicate in 40- milliliter volatile organic analysis (VOA) bottles and one-liter plastic containers. Sample labeling, handling, and chain of custody procedures will conform to those described previously for soil sampling. During ground water extraction, notes will be maintained concerning drawdown to give an approximation of aquifer conductivity. This data can be used in conjunction with a future aquifer test to provide design data for any required remediation system. All extracted water will be placed in 55-gallon drums for temporary storage on-site. PL191-6341REPORTSILOCKEFOR RPT IJUIV 22. 19921 CanonleEnvironmental