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KLEINFELDER <br />B-3.2 Monitoring Well Development <br />The wells are developed to reduce the effects of drilling on the formation and to increase the <br />effective hydraulic radius of the well. <br />Monitoring wells are generally developed 24 to 48 hours after installation to allow the grout to <br />set. Each well is first sampled with a clear acrylic bailer to visually inspect for hydrocarbon <br />layer or sheen. If no product layer of sheen is observed on the water, the well is developed by <br />surging, pumping, or bailing. Surging along the screened interval of the well is performed to <br />draw the sediment from the formation into the filter pack and the well and to set the sand pack. <br />The sediment -laden water is purged from the well at a rate of between 0.75 to 10 gallons per <br />minute (gpm) depending on recharge rate and casing size. Development continues until the <br />discharge runs relatively clear of fines. Approximately 5 to 10 well volumes generally are <br />removed from each monitoring well. Discharge water is stored in 55 -gallon drums and left on <br />site for later discharge or disposal by the client, depending on laboratory results. <br />B-3.3 Equipment Decontamination <br />To reduce the potential for cross -contamination between wells, developing equipment is washed <br />in a trisodium phosphate or lab grade detergent solution and rinsed in distilled water or steam <br />cleaned prior to use in the next monitoring well. <br />B-3.4 Well Survey <br />The locations of soil borings and monitoring wells and the elevation of the top of the PVC <br />casings will be surveyed and tied into permanent markers, if readily available. Survey accuracy <br />is 0.1 foot for the "x" and "y" coordinates and 0.01 foot for the "z" coordinate. The depth to <br />static groundwater is measured from a set location at the top of the PVC casing. The depth of <br />water is then subtracted from the elevation of the top of the well casing to provide a groundwater <br />elevation for each monitoring well location. <br />B-4.1 Water Level Measurements <br />Water level measurements are made in the wells prior to purging and sampling the wells. <br />Measurement protocol is as follows: <br />1. The wells are opened and allowed to equilibrate with the atmosphere. <br />2. The water level probe is decontaminated in a trisodium phosphate wash, followed by a <br />distilled water rinse, prior to use in each well. <br />20-3978-OI.W36/2017P117 Page B-4 <br />© 1997, Kleinfelder, Inc. September 5, 1997 <br />