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14 May 1999 <br /> AGE-NC Project No 97-0343 <br /> Page 4 of 6 <br /> be covered with Teflon sheets,capped and sealed with tape Each preserved sample sleeve will be <br /> labeled with the boring location,depth,time and date Appropriately sealed and labeled samples will <br /> be placed on ice in a chilled container and transported under chain-of-custody to a DHS-certified <br /> laboratory <br /> Soils encountered xn the borings will be visually classi£ed by an AGE geologist in accordance with <br /> the Unified Soil Classification Systema (USCS) Additionally, soil samples with be field-screened <br /> for the presence of volatile organic compounds using an organic vapor meter equipped with a photo- <br /> ionization detector(PID) precalibrated to isobutylene <br /> 3 3 SOIL BORING ABANDONMENT <br /> Borings not completed as wells will be permanently sealed to prevent vertical migration of <br /> contaminants Soil bonngs will be abandoned by backfilling with portland cement from the total <br /> depth to surface grade A tremnue pipe will be used for backfilling borings exceeding 25 feet in <br /> depth or where ground water is present in the boring <br /> 3 4 MONITORING WELL COMPLETION <br /> Following completion of drilling a pilot bonng northeast of the former UST cluster area, a 2-inch <br /> diameter Schedule 40 PVC 0 010-inch slotted well screen and casing will be installed A 20-foot <br /> section of well screen will be installed,extending approximately 15 feet below and S feet above the <br /> top of the ground water table The filter pack material, consisting of pre-washed #2116 Lonestar <br /> sand,will them be added extending from the bottom of the borehole to approximately two feet above <br /> the screened interval Following placement of the filter pack, the well will be surged to assist in <br /> settling the filter pack Additional sand will be added if settling of the filter pack occurs <br /> A nominal two to three-foot bentonite seal will be placed above the filter pack to minimize the � <br /> Potential of grout Penetration into the screened section of the well The bentonite seal will be formed <br /> by pouring bentonite chips into the annulus and allowing them to settle on the filter pack Bentomte �r <br /> chips will be hydrated using five gallons of water The bentoiute chips will be allowed to hydrate <br /> for a minimum of 20 minutes prior to grouting The annular space above the bentonite seal will be <br /> grouted up to approximately 35 5 feet bsg <br /> Approximately 0 5 feet of filter pack sand will be placed on the grout,and a second screened interval <br /> will be installed from approximately 35 to 15 feet bsg, with blank casing extending OW to the <br /> ground surface A sand filter pack will the be installed as described above up to a depth of <br /> approximately 13 feet bsg A 1 to 2-foot bentonite seal will be placed over the filter pack as <br /> AdmWed GeoEnvironmentat,Inc <br />