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�. 1.90 16 December 1999 AGE-NC Project No. 95-0184 Page 5 of 6 A nominal two foot bentonite seal will be placed above the filter pack to minimize the potential of grout penetration into the screened section of the well. The bentonite seal will be formed by pouring bentonite chips into the annulus and allowing them to settle on the filter pack. Bentonite chips will be hydrated for a minimum of twenty minutes using five gallons of water. Following hydration of bentonite chips,the remaining annular space will be filled to near the ground surface with neat cement. A traffic-rated well box will be installed over the well, flush with the surrounding surface. The monitoring well construction diagram is illustrated as Figure 3. Grouting procedures will be inspected by PHS-EHD personnel. Following completion of the monitoring well,the well casing elevation and location will be surveyed relative to the existing wells at the site. � h 4.3. DUAL-COMPLETED WELL INSTALLATION �"4 �t �qw V The dual-completed monitoring/extraction well will be installed in a similar manner as the monitoring well. The lower screened interval will be installed from 45 to 25 feet bsg with the filter pack installed from 45 to 24 feet bsg. A bentonite plug will be installed from 24 to 20 feet bsg to separate the screened intervals. A second screened interval will be installed from 20 to 10 feet bsg in a similar manner. The upper 7 feet of annular space will be filled to near the ground surface with a cement grout. The proposed dual-completed well construction is illustrated in Figure 4. 4.4. EQUIPMENT DECONTAMINATION All sampling tools used for sample collection will be thoroughly rinsed with clean water after being washed with a solution of Alconox. All down-hole drilling and sampling equipment will be pressure washed prior to starting each boring. 4.5. SOIL VAPOR EXTRACTION/IN--SITU AIR SPARGING PILOT TEST For performance of an SVE/IAS pilot test, a compressor-driven unit will be used to inject air into the subsurface using MW-2. MW-1 may alternately be used, based upon field observations. The induced pressure at monitoring points, sparging rate (discharge rate), vapor concentrations at monitoring points, depth to ground water in surrounding wells and dissolved oxygen will be measured throughout the IAS pilot test. } h \5k A portable internal combustion system will be set-up on-site and operated for a period of 8 to 10 Advanced GeoEnvironmental,Inc.