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9 <br />Response to DRMS September 25. 2009 Letter Powertech (USA) Inc. <br />16c. If Powertech provides an acceptable demonstration that injection at <br />ambient pressure will minimize adverse water quality impacts, as <br />discussed in item 11 above, DRMS can require sufficient bond for this <br />type of injection. For this bonding option, Powertech must provide a <br />technical evaluation of how long it would take to complete injection under <br />ambient pressure. <br />Response <br />In theory, the rate at which an aquifer can be produced by pumping and the rate <br />of injection at the same head differential are the same but opposite in sign (i.e., <br />positive or negative). In the case of the Section 33 pumping test, if the <br />production well PW-1 is pumped at 10 gallons per minute for 72 hours, under the <br />same head differential, one should be able to reinject the produced water back <br />into the same well at the same rate over the same period, i.e., 72 hours. <br />In practice, however, there may be other factors such as skin effects that may <br />limit either production from the aquifer or the rate of injection into the aquifer. <br />These factors may act either way, i.e., the rate of injection into the aquifer may <br />be either greater than or less than the rate of production due to pumping. In <br />most situations, the rate of injection is less than the rate of pumping. <br />At the Centennial pumping test location, there is more available head for <br />reinjection under a vacuum than there is available drawdown above the A2 Sand <br />during pumping. As noted in the responses to Items 11 and 14, based on the <br />preliminary estimates of transmissivity and storativity for the A2 Sand, the <br />projected drawdown in the pumping well at the end of 72 hours of pumping at 10 <br />gallons per minute is less than 100 feet. <br />M0 M