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KKJ KLEINFELDER A-3 GROUNDWATER WELL INSTALLATION A-3.1 Monitoring Well Construction Construction details for the shallow groundwater monitoring well MW-1 is as follows. o The well casing used was 2-inch inside diameter, flush threaded ,joint, schedule 40 PVC pipe o The wells were constructed in an 8-inch diameter boring. o Well screen sections were perforated with 0.02-inch factory-cut slots. o The well was generally screened from 5 feet above to 15 feet below stabilized first encountered groundwater o The PVC pipe and end caps were steam cleaned prior to installation. o The annular space between the screen and the wall of the boring was backfilled with the clean Lone Star Industries 2112 Monterey sand to approximately 2.5 feet above the top of the perforated sections o An approximately 1 5-foot bentonite plug was placed above the sand pack to provide a seal against surface water infiltration and to reduce the potential for cement grout to infiltrate into the water • o The remaining annular space was filled to the surface with tremmied cement/bentonite grout to the surface o The wells were secured in a below-ground loclung stovepipe The well head was enclosed in a water-tight cement utility box set flush to the ground surface A-3.2 Monitoring Well Development The wells are developed to reduce the effects of drilling on the formation and to increase the effective hydraulic radius of the well The monitoring well was developed over 48 hours after installation to aIlow the grout to set. The well was first sampled with a clean disposable bailer to visually inspect for hydrocarbon layer or sheen No product layer or sheen was observed on the water The well was then developed by surging and bailing with the bailer. Surging along the screened interval of the well was performed to draw the sediment from the formation into the filter pack and the well, and to set the sand pack Development continued until approximately 20 well volumes were removed from the monitoring well Discharge water was stored in a 55-gallon drum and left on site for later discharge or disposal by the site owner, depending on laboratory results A-3.3 Equipment Decontamination To reduce the potential for cross-contamination, developing equipment consisted of a clean disposable bailer A-3.4 Well Survey The location of the monitoring well and the elevation of the top of the PVC casing is usually surveyed and tied into permanent markers, if readily available, for assessing the groundwater FR10-26(1993) Page A-2 24-220172-A00 Copynght 1993 Klemfelder, Inc