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i <br />' 19 November 1999 <br /> . AGE-NC Project No 99-0657 <br /> iPage 8 of 10 <br />' 4 3 IN-SITU GROUND WATER SAMPLING PROCEDURES <br /> For the collection of grab ground water samples, soil probe borings will be advanced to the top of <br /> the ground water table as identified by collection of a saturated soil sample Once ground water has <br /> been encountered, a Geoprobe push-driven water sampling device will be advanced two to three feet <br /> into the water-bearing zone Grab ground water samples will be collected using a Geoprobe water <br />' sampling assembly fitted with a pre-cleaned one-inch 0 01 slotted temporary well screen Each <br /> ground water sample will be extracted by lowering a polyethylene bailer through the hollow center <br /> of the push rods into the screen section Samples for TPH-g,BTEX, and fuel oxygenate analyses will <br />' be collected into I aboratory-supplied, 40-m1 VOA vials containing 0 5-ml of hydrochloric acid as <br /> sample preservative Samples for TPH-d analysis will be collected into Iaboratory-supplied, 1 liter <br /> amber bottles The labeled sample containers will be placed in a chilled container under ice and <br />' transported under chain-of-custody to a DHS-certified laboratory <br /> 4 4 MONITORING WELL INSTALLATION PROCEDURES <br />' <br /> Proposed monitoring well borings will be completed using hollow-stem auger drilling techniques <br /> Relatively undisturbed soil samples will be collected at five-foot intervals in each of the borings <br /> lie using a California modified split-spoon sampler fitted with 2-inch diameter, 6-inch long brass <br /> sleeves Soil sample handling will be consistent with the procedures presented in Section 4 2 <br />' Following completion of drilling the boring, a 2-inch diameter Schedule 40 PVC 0 010-inch slotted <br /> well screen and casing will be installed Twenty feet of screen will be installed in each well, <br />' extending approximately 15 feet below and 5 feet above the top of the ground water table <br /> The well casing, filter pack and sealing materials will be placed into the borehole through the interior <br />' of the hollow-stem augers After installing the well casing, filter pack material consisting of pre- <br /> washed 42112 Lonestar sand will be added from the bottom of the borehole to approximately two <br /> feet above the screened interval Following placement of the filter pack, the well will be surged to <br />' assist in settling the filter pack Additional sand will be added if settling occurs <br /> A nominal two-foot bentonite seal will be placed above the filter pack to minimize potential for <br />' grout penetration into the screened section of the well The bentonite seal will be formed by pouring <br /> bentonite chips into the annular space between the auger and the well casing and allowing them to <br /> settle on the filter pack Bentonite chips will be hydrated using five gallons of water The bentonite <br />' chips will be allowed to hydrate for a minimum of one-half hour prior to grouting <br />' The remaining annular space above the bentonite seal will be filled to the ground surface with a <br /> cement grout The grout mixture will consist of type 1/11 portland neat cement and not more than 6 <br /> gallons of water per 94-pound sack of cement The grout will be placed by pumping through tremmie <br /> AdrancedGeoEnrironmental,Inc <br /> 1 <br />