SITE INFORMATION AND CORRESPONDENCE CASE 2

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' 1 KLE/NFELDER 9dgM/Ya.Ye-fl19M Solutb,u. ' well screen is usually not set above the depth of first encountered ground water. Wells are usually not set in areas of suspected significant soil contamination. • The PVC pipe and end caps are steam-cleaned prior to installation. • The annular space between the screen and the wall of the boring is backfilled with ' the appropriate clean Lone Star Industries 0/30 or 2/12 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 0/30 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. A 3- to 5-foot bentonite plug is placed above the sand pack to provide a seal against surface water infiltration. ' • The remaining annular space is filled to the surface with tremmied cement/bentonite grout to the surface. • 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. A-3.2 Monitoring Well Development and Sampling 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 on the 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 of between 0.75 to 10 gallons per minute (gpm) depending on recharge rate and casing size. 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. ' 101486.6/SAC14R02453 Page A-4 July 25,2014 ©2014 Kleinfelder