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SECTIONTHREE Scope of work <br /> The purge volume will be calculated as follows: <br /> • Square of Radius of Tubing (ft`) * Length of Tubing (ft) * (rc) = Volume of Tubing (ft') <br /> • Volume of Tubing (ft') * 28.3 1-/ft' = Volume of Tubing (L) <br /> • Volume of Tubing (L) * 3 Tubing Volume = Desired Purge Volume (L) <br /> • Desired Purge Volume (L)/ Purge Rate in L/min (2 L/min maximum) = Purge Time (min) <br /> Radius of Tubing = 1/8-inch = 0.0104 foot <br /> • 0.0104 (ft'` radius) * 50 (ft tubing length) * 3.14 = 0.017 (ft) = Volume of Tubing <br /> (W) <br /> • 0.017 (ft) * 28.3 L/ft3= 0.481 L= Volume of Tubing (L) <br /> • 0.481 L * 3 Tubina Volumes = 1.43 L Desired Purge Volume <br /> • 1.43 L (/) 2 L/min * 60 sec/min = 42.9 Second Purge Time <br /> A 42.9-second purge time is used for 50 feet of 1/4-inch-diameter tubing at a flow rate of <br /> 2 L/min. <br /> Tedlar bags will be stored in a cooler along with chain-of-custody (sunlight exposure will be <br /> limited) until the sample is analyzed. <br /> Soil gas samples will be analyzed for VOCs by EPA's Toxic Organic Compounds in Ambient <br /> Air (TO 15) by Direct Inject. This test method analyzes for 36 target analytes from the 8260 <br /> compound list. The analytes that have been detected in the soil and groundwater at the Dow <br /> facility are on the TO-15 analyte list. Samples will be analyzed by Air Toxics Ltd. of Folsom, <br /> California on a 72-hour turnaround time. <br /> Following soil gas sampling, each borehole will be backfilled with neat cement grout. <br /> V:\Dow\CeIoIex\SOII Gas WP\Soil Gas WP.doc 3-2 <br />