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Wright Environmental Services, Inc. <br />Final well design will be adjusted in the field to site specific subsurface conditions observed in the <br />borehole, and well screens or slots will be placed so as not to interconnect two possible aquifers or <br />uncontaminated vadose zone strata. Screens will extend a nominal length (up to 5 feet) above first <br />encountered unconfined groundwater for floating product detection where needed. A 1-2 foot thick <br />bentonite seal will be placed on top of the sandpack. A cement grout annular seal which extends to the <br />surface will be placed by tremie line from the bottom to top of the remaining annular space above the <br />bentonite. Sealing can be modified as regulatory input requires. <br />6. The top of the well casing will be locked to prevent contamination and tampering. An above - <br />grade or at -grade well completion will depend upon well location. At -grade completions require <br />traffic rated boxed set in concrete or cement grout just above grade. Above -grade completion will <br />require a 6 -inch diameter locking, steel protective "stovepipe' casing and a Christy, or equivalent, <br />traffic box and concrete pad and surface poles or barriers to mark the location. <br />Monitoring Well Development <br />1. Wells will be developed until the water is free of fine grained sediments and/or until field <br />measurements of pH, and electrical conductivity have stabilized. Approximately 3 to 10 well volumes <br />of water will be removed during development of the well. The actual number of volumes withdrawn <br />for development is well dependent and based on the field judgment. Duration of development will <br />be specific for each well and site aquifer conditions and continue until the water clears and sand <br />content is minimal or ceases. <br />Measurements of aquifer parameters may be taken to observe for aquifer conditions. Notes of well <br />development will be kept including quantity of water removed, turbidity, and sand yield and well <br />recharge. <br />2. Only precleaned equipment will be inserted into the well during development, and will be <br />decontaminated by washing or steam cleaning after its use. Development water will be collected and <br />stored in in drums. <br />Monitoring Well Sampling <br />1. Depth to groundwater will be measured to the nearest 0.01 foot, and the well checked for <br />presence of separate phase product. If present, the apparent thickness of the product will be <br />measured. The well will not be sampled if separate phase product is present. <br />2. The standing well volume calculated, and usually between 3 to 10 well volumes will be <br />purged from the well prior to sampling depending on well performance and yield (USEPA (1985) <br />sampling guidance indicates that the number of purge volumes are related to aquifer strata and <br />specific for each well). <br />Measurements of aquifer parameters (conductivity, temperature and the pH) of the water will be taken <br />until parameters have stabilized to indicate that aquifer water is entering the well over at least two <br />purge volumes. The sampler will keep field notes for each well sampled. That field log will record <br />sampling measurements and observations. Aquifer parameters which will be measured are; pH, <br />temperature and electrical conductivity. Aquifer water is assumed to be entering the well when these <br />parameters are measured within a 10% range of the previous measurements. The sample will be <br />collected when the well recovers to within 80% of the original depth to water measurement. <br />Wes Sampling Protocols last rev. 2/96 Page <br />