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1 <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br />The borehole lithologic logs and monitoring well completion diagrams are attached in <br />Appendix B. <br />2.3 Monitoring Well Installation <br />Monitoring wells were installed in each of the five boreholes. Each of the wells was <br />constructed of two-inch inside diameter Schedule 40 PVC, and the stick up above <br />ground is protected with a locking, steel protective casing. Each well screen is 10 feet <br />long and factory-slotted with 0.020 inch slots. A sand filter pack consisting of 20/40 <br />silica sand surrounds the screen to approximately one to two feet above the top of the <br />slots. An annular seal of hydrated bentonite chips was placed on top of the sand pack in <br />each of the wells. Because most of the wells are shallow, the bentonite chips were <br />brought to within about one foot of ground surface. Only well, MW-3AS, was grouted <br />above the bentonite annular seal. The steel protective casing is installed in a concrete <br />pad, and concrete was poured around the casing to the top of the bentonite seal. A <br />permanent datum for water level measurements was cut in the top of the PVC casing <br />and marked. The well numbers are painted on the protective casings. The borehole <br />logs in Appendix B also schematically depict the well completions. <br />Table 2: Well Completion Information <br /> <br /> <br />1 <br />Well No. Date of <br />Installation Ground <br />Elevation <br />(approx.) Screened <br />Interval <br />(bgs) Top of <br />Sand Pack <br />(bgs) Top of <br />Bentonite <br />Seal <br />b s Casing <br />Stickup <br />(ags) Water <br />Levels <br />after <br />Dnllin ' Water <br />Levels <br />on <br />2/2/00' <br />MW-1AS 1/13/00 5019' 9.3'-19.3' 8.0' 1' 2.5' 14.80' 12.91' <br />MW-2AS 1/13/00 5015' 7.7'-17.7' 6.3 1' 2.6' 12.20' 12.25' <br />MW-3AS 1/13/00 5027' 20.5'-30.5' 18.0' 15' 2.5' 26.74' 27.42' <br />M1N-4AS 1/19/00 5017' 7.2'-17.2' 6.2' 1' 2.4' 10.87' 10.71' <br />fMN-5AS 1/19/1x) 5020' 13.0'-23.0' 11.3' 1' 2.5' 16.22' 16.04' <br /> Note: gound elevation is approximated from the site topographic map <br />' bgs -below ground surface <br /> ags -above ground surface <br /> -all water level measurements are from the top of the two-inch casing. <br />' Upon completion of the wells, each well was developed. Development consisted <br /> withdrawing a number of well volumes of groundwater with a bailer until the chemical <br /> parameters pH and specific conductance (conductivity) stabilized and the water began to <br />' clear. The bailer was also used to surge the well to keep fines in suspension so they <br /> could be removed. Well development records are contained in the field notebook. <br /> 2.4 Groundwater Sampling <br /> Groundwater samples were collected from each well and analyzed for an extensive suite <br />' of pesticides and herbicides. Groundwater sample collection procedures consisted of: <br />• Measuring water level and total depth of the well with a cleaned electronic water <br />' level probe. <br />• Calculating the volume of water in the well. <br />Removing a minimum of three well volumes using dedicated, disposable, high <br />' density polyethylene (HDPE) bailers and cord. <br />' 22314-0001: 02/21/00 rJ <br />