SITE INFORMATION AND CORRESPONDENCE

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t W G_ WESTERN GEOLOGIC RESOURCES INC. STANDARD OPERATING PROCEDURES RE:HOLLOW STEM AUGER MONITORING WELL INSTALLATION AND DEVELOPMENT SOPS The boreholes for monitoring wells are drilled using a truck mounted hollow-stem-auger drill rig. The outside diameter (O.D.) of the borehole will be a minimum of two inches larger than the outside diameterwhen installing 4-in well screen.Thehollow stem augerprovides minimal interruption of drilling while permitting soil sampling at desired intervals, Soil samples are collected by hammering a conventional split.barrel sampler containing pre-cleaned 2-in brass sample tubes. A geologist from Western Geologic Resources (WGR) continuously logs each borehole during drilling and constantly checks drill cuttings for odors. The sampler is rinsed between samples and steam-cleaned with all other drilling equipment between borings to prevent cross contamination. Monitoring wells are cased with threaded, factory perforated and blank scheduled 40 PVC.The perforated interval consists of slotted casing generally 0.020-in slot size by 1.5-in long with 42 slots per foot.A PVC cap is fastened to the bottom of the ccasing to assure even distribution of asing with stainless steel screws;no solvents or cements are used.Centering devices may be affixed to the filter material and grout.The well casing is thoroughly washed and steam-cleaned prior to installation. After setting the casing inside the hollow stem,sand or gravel filter material is poured into the annular space to fill from the bottom of the boring to 1 ft. above the perforated interval. A 1 to 2 foot thick bentonite plug is placed above this filter material to prevent grout from infiltrating down into the filter material. Neat cement containing about 5%bentonite is then tremied into the annular space above the bentonite plug to the surface.A lockable PVC cap is placed on each well head. Traffic rated Christy boxes are installed around the well for wells in parking lots and driveways while steel stove pipes are set over wells in landscaped areas. After installation,the wells are thoroughly developed to remove residual drilling materials from the wellbore and to improve well performance by removing ajoy fine material in the filter pack that can Pass from the formation into the well. Well development techniques used include pumping, bai surging,swabbing,jetting,flushing and airlifting. All development water is collected in 55 galling, lon drums for temporary storage and analytic results. The developed water is then disposed of properly according to analytic results. To assure that cross contamination does not occur between wells during drilling and development,all development is steam-cleaned, SOP-3;Oci/88