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March 2. 2007 <br />Page 3 <br /> <br />Looking North at the Excavation <br />, <br />J,. <br />A' <br /> <br />As a result of the shallow water table, i.e., approximately I I feet deep, it was necessary to dewater <br />the excavation during the repair of the pipeline. Three 500 barrel frac tanks were brought to the site <br />to collect the water since it was believed that this water would likely be contaminated by the released <br />gasoline. Approximately 1,200 barrels of dater were collected in the frac tanks. <br />One of the water samples we collected had a dissolved benzene concentration above the hazardous <br />waste threshold of 0.5 mg/L. Therefore, we treated the water in each of the frac tanks using the <br />sparging equipment on our pilot testing trailer. Sparging consists of injecting air into the bottom of <br />the frac tanks using PVC piping as shown below. <br />After the water was treated, additional water samples were collected and analyzed. These data <br />indicate the dissolved benzene concentration had been successfully lowered to below the hazardous <br />waste concentration. The water was later transported to the Arvada Treatment Center, LLC for <br />disposal. The manifests for the water shipments are attached.