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Iq r •s k%j KLEINfELDER • The PVC pipe and end caps are steam-cleaned prior to installation. E • The annular space between the screen and the wall sof the boring is backfilled with the appropriate clean Lone Star Industries 0/30 or 2112;'Monterey sand to approximately 2 feet above the top of the perforated sections. Based on soil logs or. a sieve test, modifications may be made regarding the size of sand to be used. Installation of the 0130 ' sand may require that the sand be tremmied, using clean water. In this event, a sample of the tremie water is collected, unless the source is known to be clean. E • A 3- to 5-foot bentonite plug is placed above the sand pack to provide a seal against surface water infiltration. 1 • The remaining annular space is filled to the surface with tremmied cement/bentonite grout to the surface. �E if + The wells are secured in a locking stovepipe. The` well heads may be enclosed in a cement utility box set flush to the ground surface located in a traffic area. i ErI A-3.2 Monitoring Well Development and Sam lin The wells are developed to reduce the effects of drilling on the formation and to increase the effective hydraulic radius of the well. Monitoring wells are generally developed 24 to 48 hours after installation to allow the grout to set. Each well is first sampled with a clear acrylic bailer to visually inspect for hydrocarbon layer or sheen. If no product layer or sheen is observed onlithe water, the well is developed by Surging, pumping, or bailing. Surging along the screened interval of the well is performed to draw the sediment from the formation into the filter pack and the well and to set the sand pack. The sediment laden water is purged from the well at a rate'4 of between 0.75 to 10 gallons per minute (gpm) depending on recharge rate and casing sized Development continues until the discharge runs relatively clear of fines. Approximately 5 to 10 well volumes are generally removed from each monitoring well. Discharge water is stored in 55-gallon drums and left on site for later discharge or disposal by the client, depending on laboratory results. Ei After the wells are developed, the aquifer is allowed to equilibrate for at least 24 to 48 hours. The wells can then be purged and sampled. Purging and sampling may be accomplished with Teflon bladder pumps and/or bailers. During the purging�bf the wells, field parameters (pH, conductivity, and temperature) are monitored. Samples are]collected after the field parameters have stabilized (normally requiring the removal of three to five well volumes). Water sampling containers are supplied and prepared by the laboratory. These sample containers are immediately sealed after sample collection and placed in an'?iced cooler. At the end of the day, the water samples are delivered under chain-of-custody to an analytical laboratory certified by the state for the planned chemical analysis. , f 20-4659-01 TO1/2011 R1442 " Page A-4 2001,Kleinfelder,Inc. iI November 28,2001 j ��