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31 March 2008 AGE-NC Project No. 98-0500 Page 8 of 10 A two foot interval of bentonite chips(transition seal)will be placed above the upper portion of the filter pack. Portland cement will be utilized to grout from the annular seal to surface grade. Each air sparging well will be single-completed utilizing 2-inch diameter well casing.All wells will be installed utilizing schedule 40 polyvinylchloride(PVC)0.010-inch slotted well screen and blank well casing. Based on geologic conditions, a 5-foot length of well screen is anticipated for installation of the IAS well. A IAS well construction diagram is depicted in Appendix B. After installing each well casing, a filter pack material consisting of pre-washed#2/16 or#3 sand for the IAS well,that will be added over the screened interval to approximately two feet above the screened interval. The IAS well casing will be surged to settle the sand pack for a minimum of ten minutes;additional sand will be installed,if necessary. A nominal two-foot bentonite transition seal (bentonite pellets)will be placed above the filter pack to minimize the potential for grout penetration into the screened section of the well.The bentonite seal will be formed by pouring bentonite pellets into the annulus and allowing them to settle on the filter pack.The bentonite pellets will be hydrated using approximately five gallons of tap water and allowed to hydrate for a minimum of approximately one-half hour prior to grouting. The remaining annular space will be filled to the ground surface with a cement grout. The grout mixture will consist of Type I/H Portland neat cement and not more than 6 gallons of water per 94-pound sack of cement. The grout will be placed by pumping through tremmie pipe. Soil samples required to complete the site assessment, will be analyzed by a CDPH-certified laboratory for the following constituents: • Total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d, respectively) in accordance with EPA Method 8015 Modified; • Volatile aromatics(benzene,toluene,ethyl benzene and xylenes(BTEX)and in accordance with EPA Method 8020; and • Fuel oxygenates including methyl tert-butyl ether(MTBE),tertiary-butyl alcohol(TBA),di- isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE) and tertiary-amyl methyl ether (TAME),1,2-Dichloroethane(1,2-DCA),ethylene dibromide(EBD)by EPA Method 8260. Laboratory reports for soil analysis, testing methods, laboratory quality assurance/quality control (QA/QC) reports, and sample chain of custody documentation will be presented in a report with findings and recommendations. Advanced GeoEnvironmental,Inc.