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STATEMENT OF WORK MONITORING WELL INSTALLATION All Pure Chemical Facility 26700 South Banta Road Tracy, California Two monitoring wells will be installed and developed within the Northern California Railroad property adjacent to the All Pure Chemical Facility located in Tracy, California. This work is estimated to commence in May, 1999. Prior to mobilization to the site by the drilling subcontractor, the new well locations will be marked by IT Corporation (IT). The drilling subcontractor will forward well construction permits in IT possession to San Joaquin County Environmental Health Division. All drilling, construction, and development will be performed in accordance with California DWR Well Drilling Standards. For monitoring well installation, the boreholes will be sampled at five-foot intervals, starting at the ground surface, using an 18-inch California Modified Split-Spoon Sampler or equivalent. The contractor will provide brass tubes with caps for the sample collection. An IT-provided geologist will be on site with the drillers to log the soil. Adequate time will be provided by the drilling subcontractor for the IT geologist to lithologically log the soil. Construction of the two monitoring wells will be performed with an 8-inch diameter hollow-stem auger rig (HSA). The well materials will be placed through the auger as it is removed. The well casing will be constructed of 2-inch diameter Schedule 40 PVC with threaded joints and end caps, and 0.020-inch factory cut slot screen. The wells will be approximately 25-feet deep and will be screened at an estimated depth of 15 to 25 feet. A 2/16 or equivalent filter pack will be placed from the bottom of the well up to 3 feet above the screen interval. The well will then be surged to set the filter pack. A 2 to 3 foot seal of bentonite pellets will be placed above the filter pack. If formation water is not present, potable water will be added along with the pellets for hydration. The seal will be allowed to hydrate at least 1 hour prior to grouting. A 3% to 5% bentonite cement grout mixure will then be tremmied into the annular space to the surface. After the grout has settled, the hole will be topped off with grout. All downhole materials must be steam cleaned prior to use and between boreholes.