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t03 April 2002 <br /> AGE-NC Project No. 97-0333 <br /> ' Page 8 of 12 <br /> 3.3. MULTI-LEVEL WELL INSTALLATION AND DEVELOPMENT <br /> Each multi-level well will be single-completed as ground water monitoring wells utilizing 1.7-inch <br /> ' diameter polyethylene(outer)tubing. The inner tubing consists of multiple %2-inch diameter teflon <br /> tubes partitioned into separate chambers; a stainless steel, 0.02-inch screen will be wrapped around <br /> each perforated area of the tubing. Additional multi-level design information is contained in <br /> ' Appendix B. <br /> Based on review of lithologic and analytical data derived the previous CPT investigation (Figures <br /> ' 3 and 4),AGE proposes multi-level screen intervals between 15 and 25 feet bsg,50 and 55 feet bsg, <br /> 70 and 75 feet bsg, 95 and 100 feet bsg, 130 and 135 feet bsg and 170 to 175 feet bsg;however,the <br /> proposed screen depths may vary based on the lithologic findings from each continuous core. <br /> ' After deploying the multi-level well casing in the hollow stem boring, a filter pack material <br /> consisting of pre-washed#212 Lonestar sand will be added through the augers to approximately two <br /> feet above each screened interval.A bentonite seal(pell plug-coded bentonite pellets)will be placed <br /> between filter pack intervals to minimize the potential for cross contamination into the screened <br /> ' section of the well. The bentonite seal will be formed by pouring bentonite pellets into the annulus <br /> and allowing them to settle on the filter pack. The remaining annular space above the uppermost <br /> screen interval and bentonite seal will be filled to the ground surface with portland cement grout.The <br /> ' grout mixture will consist of Type I/II portland neat cement and not more than 6 gallons of water per <br /> 94-pound sack of cement. The grout will be placed by pumping through tremmie pipe. A grouting <br /> inspection will be scheduled with PHS-EHD personnel. A proposed well construction diagram is <br /> depicted in Figure 5. <br /> ' 3.4. GROUND WATER SAMPLE COLLECTION AND ANALYSIS <br /> Ground water monitoring and sampling activities for each newly installed multi-levelground water <br /> monitoring well will be conducted on a quarterly basis until PHS-EHD notification or approval to <br /> do otherwise. Ground water monitoring activities will include recording depth to ground water <br /> measurements and collection of ground water samples. Ground water sample collection procedures <br /> ' are described in Section 4.5. <br /> ' Ground water samples will be analyzed by a DHS-certified laboratory for the following constituents: <br /> • TPH-g by EPA Methods 5030/8015M; <br /> • BTEX and MTBE by EPA Method 8020;. <br /> • Methanol, ethanol, EDB, 1,2-DCA, TBA, DIPE, ETBE, TAME, MTBE, PCE and TCE by <br /> 1 Advanced GeoEnvironmental,Inc. <br /> t <br />