2010-07-21_GENERAL DOCUMENTS - M1977004

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3 HOM1lAK.E PITCH RECLAMATION PROJECT Colorado Department of Natural Resources Division of Reclamation, Mining and Safety 1313 Sherman Street Room 215 Denver, CO. 80203 1/Attn: Mr. Robert Oswald ?M-1977-Ooh Alan D. Cox Project Manager 16 July 2010 RECEIVED JUL 212010 Division of Raolamation, Mining & Safety V411E: Response to DRMS Comments on the 2009 Annual Reclamation Plan - Pitch Reclamation Project Dear Bob: Homestake has prepared this letter in response to your questions included in the May 7, 2010 email regarding the Pitch Reclamation Project, 2009 Annual Reclamation Report. Your questions focused on trends in water levels in the P-wells at the site. The specific questions in the email are restated below. "The piezometer data show that some of the levels are staying constant, and some are rising a little. P-7 and P-8 in particular have come up since 20012002. P-7 is behind the adit plug. Is P-7 rising due to rising levels underground generally?" "Is P-8 east of the workings, on, or near the fault? Is this also a reflection of the same phenomenon: rising water in the workings?" "Do you see increased flow from the fault into the NPL?" To aid in answering your questions, we have included a map (Figure 1) of the site showing locations of the piezometers in the Pinnacle Adit vicinity and piezometer water levels from 1995 through 2009 (Figure 2 attached). Piezometers located within the Pinnacle workings include P-4 and P-5. P-9 is located downgradient of the Pinnacle workings and also monitors water levels within the workings. Piezometers located upgradient of the Pinnacle workings (and Pinnacle Adit plug) include P-7, P-8, and P-10; these piezometers are not within the workings. Piezometers that monitor water levels in the workings (P-4, P-5, and P-9) have very similar water levels since 1997 (Figure 2). Spring and summertime water levels may vary from year to year due to the magnitude and timing of snowmelt and rainfall; however, water levels during low-flow conditions since 1997 (i.e., over-the-winter) have consistently been between 10,391 to 10,397 ft-amsl. Water levels during low-flow conditions should be considered when assessing trends and indicate that there is no increasing trend for the Pinnacle workings. Based on the available data since 1997, we believe that the water level in the workings has essentially reached steady state. Piezometer P-7 is designed to monitor bedrock water levels upgradient of in the Pinnacle Adit plug. As shown on Figure 2, the water levels in P-7 are approximately 10 to 15 feet below the level in the Pinnacle workings and follow the same seasonal water level patterns as the piezometers that are within the workings, suggesting that P-7 is somewhat hydraulically connected to with the workings. The slightly lower water level could be due to the complex geology and hydrogeology at the Pitch site. Groundwater is compartmentalized, as documented P.O. Box 98 / HIGHWAY 605, GRANTS, NM 87020 TEE: (505) 287-4456 FAX: (505) 287-9289 0