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Jared Ebert <br /> July 8, 2019 <br /> Page 5 of 18 <br /> 16. Page G-4, the Potential Mining Impacts section is confusing and hard to follow. Overall, the points <br /> made in this section are unclear. Please revise this section to clarify the statements made. The <br /> Division recommends addressing the impacts from dewatering and slurry wall installation <br /> (mounding and shadowing) by clearly indicating the possible impacts and their associated severity. <br /> If conclusions about the mining impacts are taken from the groundwater study, please make this <br /> clear and cite specifically where within the report these conclusions are addressed. <br /> Please see the revised Exhibit G Sections 2 (b), and Potential Mining Impacts, <br /> 17. Please submit the baseline water level data that has been collected to date. <br /> Baseline water data collected to date is attached for your review. <br /> 18. The applicant indicates under the second bullet on page G-5 that if a subject well has not been put <br /> to beneficial use prior to mining, then they would have no responsibility to provide mitigation for <br /> groundwater impacts. Please remove this sentence as it is incorrect. <br /> The sentence has been removed as requested. An updated Exhibit G is attached for your <br /> review. <br /> 19. The monitoring wells shown on the Exhibit C-4 and C-5 Maps are difficult to locate and are at times <br /> covered up with the label of another feature. Please submit a separate map or figure that shows the <br /> location of the monitoring wells used in the monitoring plan. <br /> A separate inset map depicting the monitoring wells remaining after mining activities has <br /> been added to Exhibit F-2. <br /> 20. Please update this discussion about the groundwater monitoring plan beginning on page G-5 to <br /> indicate the frequency the groundwater monitoring wells will be monitored. <br /> Groundwater monitoring wells will be monitored monthly until mining commences and <br /> quarterly thereafter. This information is reflected in Exhibit G. <br /> 21. The applicant indicated in the mining plan and shows on the Exhibit C maps that the majority of the <br /> site is located within the 100-year floodp►ain and portions of the East Area are located within the <br /> floodway. In the event of a significant flood event (100-year flood), it is likely the proposed mine site <br /> would be captured by the South Platte River. Where mining will occur within 400 feet of the river <br /> channel, a flood analysis and flood control plan must be evaluated and submitted for Division <br /> review and acceptance. Please provide a flood analysis and flood control plan satisfying the <br /> requirements of the Urban Drainage and Flood Control District ("UDFCD") for an expected 100-year <br /> flood event during the life of the operation and after final reclamation for the Tucson South Mine that <br /> includes and/or addresses the following: <br /> a. The flood analysis should quantify the velocity and volume of flows expected on site from a 100- <br /> year flood event, as well as the elevation of the 100-year base flood event and its relation to the <br /> elevation of any proposed spillways and embankments. <br /> Aggregate Industries—WCR,Inc <br /> 1687 Cole Blvd Suite 300 <br /> Golden,CO 80401 <br />