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To: Jared Ebert <br />Date: February 14, 2018 <br />Page 9 <br />site) recently, and they have indicated that the ditch leaks very little through this section, <br />indicating that natural siltation has likely sealed up the ditch. The Taylor and Gill ditch is <br />sealed on the west side of the site as it is conveyed through concrete sewer pipe. <br />LRM is in contact with both the Little Cache and Taylor and Gill ditch companies. <br />Agreements have been signed to commit LRM to providing mitigation should ditch <br />losses become excessive (Attachments 10 and 11). <br />The ditches were simulated in the groundwater model. Mine dewatering was projected to <br />increase ditch losses by a few percent for the Little Cache and Taylor and Gill, <br />respectively, during mining. After mining, ditch losses are expected to decrease due to <br />lining of the pits. The results section of the groundwater modeling report provides <br />estimates on the increased losses due to dewatering. Sections 6 and 7 of the revised <br />groundwater report provides a monitoring and mitigation plan to measure for and <br />mitigate excessive ditch losses. <br />Comment 35b <br />Has the Little Cache La Poudre Ditch Company provided LRM with any documentation <br />that they agree with your proposal included in Attachment 10? If so,please provide it. <br />Response 35b <br />LRM is corresponding with the Little Cache La Poudre Ditch Company and is in the <br />process of obtaining fmal agreement. <br />Comment 37a <br />Please submit a groundwater monitoring and impact mitigation plan to DRMS for <br />approval. This plan should include: all historic water level data available for the site <br />wells and immediately surrounding area if available, monthly monitoring of water levels <br />at all existing wells ifpossible, trigger levels for each well based on historic high and low <br />water levels for that well, proposed reporting and mitigation plan when groundwater <br />levels deviate beyond proposed trigger levels to minimize any impact to groundwater <br />levels and especially off-site impacts. Section 9.1 states LRM may mitigate adverse effects <br />to existing wells by supplementing water supplies or deepening wells. Due to the <br />approximately 1,900 feet of Pierre Shale bedrock underlying the area at a depth of 12-30 <br />feet below ground surface (bgs), deepening the existing wells is unlikely to be a <br />successful mitigation solution. <br />Response to DRMS Adequacy Review 3 comments T E L E S T