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' Former Manna Pro Site page 5 Quarterly Groundwater Monitoiing Repoit &Monitoring Well Construction Pi oject No 2072 June 2, 2000 2 1.3 Monitoring Well Construction After drilling was completed, the drilling mud was displaced with clean water The mud was temporally stored in 55 gallon DOT approved steel drums The monitoring well was constructed by inserting 2 0 inch diameter, schedule 40 PVC casing with flush threaded points into the boring Attached to the bottom of the blank casing was a slotted casing section with a pre-packed filter pack of#3 sand The screened interval consists of 0 020 inch perforated schedule 40 PVC pipe extending from total depth and upward a distance of 5 feet The filter pack ' surrounded the perforations and extends two feet above the screened interval The well was then "surged in" with a surge block An annular seal was ' constructed by installing sufficient bentonite to form a 4 foot thick seal The granular bentonite was hydrated by the water which had been used for the mud displacement The remaining annulus was the filled by a tremae pipe with neat ' cement grout The well was secured with a water tight locking cap encased within a traffic safe well box The following table summarizes the construction details of this well Well No TD Screen Interval Seal Slot Size MW-11 97' 1 97' - 92' 90'- 86' 0 020" After the monitoring well (as well as other wells associated with the remedial pilot test) were constructed, the vertical and lateral position was determined by ' a licensed surveyor The elevations were tied to sea level based on a nearby City of Stockton bench mark ' 2 2 Monitoring Well Development After construction, the well was developed on April 25, 2000 by Del-Tech ' Geotechnical Services of Oakdale, CA The well was opened and the water level and the total depth were sounded by lowering an electronically actuated air / water interface detector suspended from a polyethylene measuring tape ' calibrated to the nearest 0 01 foot (see groundwater monitoring data sheets in Appendix B) The well was then developed by pumping with a submersible pump and bailing with an electrically actuated stainless steel bailer A minimum of 10 casing volumes of water were purged to assure that representative formation water was entering the well 2.3 Waste Disposal After developing the monitoring well, the soil cuttings, drilling mud, and purge ' water were disposed of by licensed hazardous waste haulers The purge water and drilling mud were collected by American Valley Waste Oil Co and the soil 2937 Veneman Ave ,#B240 Geo-Phase Environmental Inc Phone (209) 569-0293 Modesto, CA 95356 Fax (209) 569-0293 I