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2. Comments about concerns that the water quality of the groundwater pumped from the <br />A2 sandstone could potentially be changed before the water is reinjected back into the A2 <br />sandstone. Commenters expressed concern about the potential for changes in water quality from <br />the following three ways: A) the storage tanks that will be used to store the groundwater on the <br />ground surface before it is reinjected, B) bacteria, and C) increase in dissolved oxygen content of <br />the groundwater that could result in the mobilization of uranium when the groundwater is <br />reinjected back into the A2 sandstone. <br />A. Concerns related to potential changes in water quality resulting from previous <br />use and improper cleaning of the storage tanks that will be used to store the A2 sandstone <br />groundwater. Commenters expressed concern that the storage tanks may have been previously <br />used to store hazardous materials that could contaminate the groundwater while it is being stored <br />in the tanks, if the tanks are not properly cleaned. Other concerns related to the storage tanks <br />include the adequacy of the standard operating procedures Powertech is proposing to use for tank <br />cleaning, formation of rust inside the tanks, the growth of algae during storage, and changes in <br />temperature of the stored groundwater. <br />EPA Response: <br />To demonstrate that the water quality of the stored groundwater is not degraded before it <br />is reinjected, the UIC Class V Final Permit requires that the permittee collect composite samples <br />of the stored groundwater from the storage tanks. The samples will be analyzed for Total <br />Coliforms; Total Metals for the arsenic, barium, cadmium, chromium, lead, mercury, selenium, <br />and silver; Volatile Organic Compounds; Semi-volatile Organic Compounds; and Total <br />Petroleum Hydrocarbons. The analytical results will be submitted to the EPA for review to <br />verify that the stored groundwater is not degraded before authorizing injection. <br />Powertech provided EPA with standard operating procedures (SOPs) for the cleaning and <br />inspection of the storage tanks before the tanks are brought on the site where the aquifer-pump <br />test will be conducted. This information is included in the Administrative Record for the Final <br />Permit. Although the contract between Rain for Rent, the company supplying the storage tanks <br />to Powertech, and Powertech includes a clause stating that the storage tanks may have contained <br />hazardous waste in the past, most of the tank use is for the storage of clean water or groundwater <br />from dewatering of construction sites. Rain for Rent has agreed to provide Powertech with tanks <br />that were not used to store hazardous materials during the last use event, if available. <br />To verify that the storage tanks will not contaminate the A2 sandstone groundwater <br />during storage, the Colorado Division of Reclamation, Mining, and Safety is requiring that <br />Powertech verify cleaning SOPs have been followed, provide information about the substances <br />the tanks were previously used to store, including at least the most recent tank use event, and <br />analytical results of storage tank rinseate samples. The rinseate samples will be analyzed for <br />total metals for the eight RCRA metals (arsenic, barium, cadmium, chromium, lead, mercury, <br />selenium, and silver), volatile organic compounds, semi-volatile organic compounds, and total <br />petroleum hydrocarbons. The UIC Class V Final Permit will require that Powertech provide <br />EPA with written documentation that these Colorado Division of Reclamation, Mining, and <br />Safety requirements have been fulfilled. <br />Page 4 of 24