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SAMPLING <br />Glass sample bottles were ordered from Environmental Sampling Supply (ESS). <br />The bottle pre-cleaning was certified compliant with USEPA OSWER Directive <br />#9240.0-05A. <br />Monitor Well COV23 was drilled in 2008 October. The well flowed until being <br />sealed and then flowed for sampling in 2008 and 2009. A flowing 12 hour <br />constant head test was performed on 2008 November 17 with a calculated <br />hydraulic conductivity of 0.1 ft/day. <br />The well was sampled for tritium on 2009 September 21 to determine if drilling <br />fluids had been purged from the well. Drilling fluids are usually mixed with <br />surface water which generally has higher tritium concentrations and would not <br />be representative of formation water. The sample was collected from the <br />wellhead in two 1 liter glass bottles with Teflon septa tops by Mr. Chris Miller <br />of Miller Water Sampling. The <1.0 TU tritium result showed that drilling fluids <br />had been purged from the well. <br />The well was sampled for all three isotopes on 2009 November 4 by Mr. Chris <br />Miller of Miller Water Sampling. The sample was collected from the wellhead in <br />eleven pre-cleaned 1 liter glass bottles with Teflon septa tops. All samples <br />were taken of raw water before any treatment. <br />The Yampa River was sampled on 2009 November 4 by Mr. Chris Miller of Miller <br />Water Sampling. Eleven 1 liter glass bottles with Teflon septa tops were filled. <br />ANALYSES <br />The samples for tritium analyses were sent to Isotech Laboratories <br />(Champaign, Illinois). The samples were analyzed with low sensitivity (+/-1 <br />Tritium Units, TU). <br />The samples for carbon 14 analyses were also sent to Isotech. The Yampa <br />River and Monitor Well COV23 samples were analyzed with sensitivities of +/- <br />0.3 to 0.5 percent of modern carbon (90 to 150 years). <br />The chlorine 36 samples were prepared by Dr. Glen Snyder of Rice University <br />(Houston, Texas). The prepared samples were analyzed by Primelab at Purdue <br />University (West Lafayette, Indiana). The chlorine ratio was plotted using the <br />chlorine 36 half-life of 301,000 years to calculate a minimum apparent age <br />(Figure 7). <br />Unanalyzed samples were archived at the author's office in Steamboat Springs, <br />Colorado. These provided back up for samples damaged in shipment and/or <br />further analyses. <br />12