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i <br /> U <br /> Geological Technics Inc. Page 6 <br /> Additional Site Characterization Work Plan <br /> Project No.723.2 <br /> z December 10,2007 <br /> The detection limits for these compounds are listed below. A Chain of Custody will be <br /> completed for all samples collected and tracked to ensure sample integrity. <br /> Detection Limits: BTEX< TPH-G <br /> Soil /K 3.0 1,000 <br /> 2.2.4 Monitoring Well Installation <br /> The monitoring wells will be constructed using schedule 40 PVC casing with flush threads. <br /> Before installing the bentonite seal the well will be surged with a clean surge block or bailed <br /> with a clean steel bailer to achieve maximum filter pack density. A-granular bentonite <br /> transition-seal-will_be:installed.to a depth of two foot above the top of sand filter packs...-A, <br /> surface seal will be achieved by pumping a neat cement grout (augmented with <-4% , <br /> ,bentonite) through the augers, as they are withdrawn to ensure that an integral grout seal is <br /> achieved. The wells will be secured with locking watertight caps encased in flush mounted <br /> traffic rated well boxes. The proposed construction details of the monitoring wells are <br /> included in the following table, but the actual well construction will be determined in the <br /> field. <br /> Well No. Dia./TD Screen Slot Sand Pack Trans. Grout Seal <br /> Seal <br /> various 2;'/varies 2.5 - 5' long 0.020" #3 sand varies varies <br /> 2.2.5 Well Development <br /> After the well sealing materials have set (>24 hours) the new wells will be developed (using <br /> mechanical surging and pumping methods) until a clear stream of water is obtained. The <br /> wells will be purged and groundwater samples collected after well development. All <br /> development and purge water will be containerized in 55 gallon containers and added to the <br /> water treatment system holding tank currently in use at the site. <br /> 2.2.6 Well Survey <br /> The new monitoring wells will be surveyed in accordance with GeoTracker requirements as <br /> soon as practical after installation by an appropriately licensed company. <br /> 2.2.7 Groundwater Sampling Procedure <br /> The new monitoring wells will be sampled according to approved protocols utilized in the <br /> existing quarterly monitoring schedule. <br /> 2.2.8 Groundwater Laboratory Analyses <br /> The new monitoring wells will be analyzed for the constituents incorporated into the existing <br /> quarterly monitoring schedule. <br /> 3.0 SITE CONCEPTUAL MODEL <br /> I <br /> I <br />