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<br /> <br />October 4, 2005 <br />Ms. Valois Shea <br />USEPA Region 8, BP-W-GW <br />99918x^ Street, Suite 300 <br />Denver, Colorado 80202-2466 <br />RE: Groundwater Recharge Sites -USEPA Injection Well Requirements <br />Dear Ms. Shea: <br />The following information is being submitted so that a determination can be made by the USEPA as to the <br />status of the proposed groundwater return activities and the required or recommended monitoring activities for <br />such. In previous conversations, you had indicated that a permit and monitoring may not be required for the <br />proposed activities. Please review the following information and de±ermine if a USEPA permit is required. A <br />Groundwater Samplin_r, and Analysis Plan (SAP) was developed to address conditions imposed by the State of <br />Colorado, Deparirnent of Minerals & Geology (DMG). We have attached the proposed SP.P for your reference <br />as it includes site maps, a description of the proposed activities on the Site and a typical detail of the proposed <br />"wells". AdditienaFinformatior: about the proposed activities follows: <br />Business Tvoe: Gravel/sand extraction (Refer SAP for more detail) <br />Infection Well Tvpe: Refer to the S:AP atCachment for drawing detail <br />Drinking Water Wells: QriE or more drinking water wel~s'are located within % mile of each: These recharge <br />site locations were selected to protect the volumetric production of these wells and Therefore are necessarily <br />adjacent to the domestic wells. <br />aeration: The area of active gravel mining will be dewatered during mining. The dewatering water will <br />enter the pit excavation and be directed to a sump via a drainage Swale. The water collected in the sump(s) will <br />be either pumped directly to the recharge sites or to the silt ponds. If the water is pumped to a silt pond then it <br />will subsequently either infiltrate naturally, be discharged from the site as surface water, or could be pumped to <br />a recharge area. <br />Infection Procedure: The dewatering water will be discharged into the top of the perforated stand pipe and <br />will not be pressurized. The water will radiate out of the pipe, through the gravel pack and natural sands and <br />reenter the groundwater table that is below the bottom of the stand pipe. <br />In'eJ cfate: The injectate is the groundwater dewatering volume. It is our estimate that the injectate will be <br />of the same general water quality as the local groundwater due to a lack of known degrading sources resulting <br />from the mining, Local mounding of the water table is expected as the recharge wells are being used to protect <br />the volumetric production of the local shallow alluvial wells. <br />Abandonment: The stand pipes will be pulled from each area after they are no longer required for the gravel <br />extraction operation and the area will be backfilled with native soils. <br />i <br />451 ^AK STREET, SUITE 209 ~ P.O. BOX 600 ~ FREDERICK, CO H0530 ~ (3031 033-1 41 6 ~ (3~3) 833-28 SO -FAX <br />