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