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Mr. Ben Langenfeld, P.E. <br />Page 4 of 5 <br />16 March 2021 <br />DRMS appreciates the clarification provided in the February 2021 response to DRMS's <br />preliminary adequacy. The following additional questions pertain to questions 8 and 9 below: <br />8a. To what extent do control structures extend into the overbank? <br />9a. Please state the flood magnitude/flow velocities utilized for sizing the rip rap. <br />9b. Please provide information on the depth of the channel thalweg, both low flow and <br />flood flow for the designed flood magnitude stated above. <br />Exposure of Ground Water and Reclamation Liability <br />DRMS is responsible for ensuring mining activities comply with Colorado statues protecting <br />water resources and water rights. In 2009 the Division of Water Resources updated guidelines <br />for the replacement of depletions from sand and gravel mining. A DRMS letter informing <br />operators of these changes and compliance options is included as part of this review. Two of <br />the four options are described below for your information. Please review the enclosed letter <br />for additional insight. <br />8. It appears groundwater will be exposed in development of the requested expansion <br />area. Ifground water will be exposed please provide DRMS with either of the <br />following items prior to exposing groundwater: <br />o A water court augmentation plan <br />o Bonding estimation and monies to mitigate injurious stream depletions related <br />to mining related exposure ofground water. This should include costs <br />associated with backfzlling of the pit to cover exposed ground water to a depth <br />of two feet above the static ground water level. <br />o If a slurry wall or clay liner will be installed, the applicant must file and <br />Amendment application and receive DRMS approval ofsuch a change. <br />DRMS Response 2021 March <br />DRMSs' conversations with Colorado Division of Water Resources (CDWR), suggests the <br />following as the most appropriate path forward: <br />9. Please demonstrate by mapping the relationships, that the Bun Ranch Pit site <br />(M1980131), either falls within or outside of the Upper Yampa River Augmentation <br />Plan district boundary. Please submit the mapping analysis to DRMS as revised <br />permit pages. <br />10. Pursue as soon as possible a new gravel well permit from CDWR and provide <br />documentation to DRMS that the well is in process of being applied for. <br />By putting the well permit in process Bunn Ranch Pit will have apple time to construct and/or to <br />apply for any extensions needed to complete the well should it be deemed advantageous for future <br />development. This avoids the uncertainty with the 2021 Yampa River appropriation, protects the <br />resource and satisfies the bonding requirements. <br />TR4 Bunn Ranch Pit March 2021 <br />ADQ #2 <br />