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Page 4 of 6 <br />Varra- Coulson Resource Project <br />Adequacy Review <br />due to the planned dewatering and dry mining operation in combination with the effects of <br />the dewatering of the Durham site. The Division does not agree with the statement on <br />page 4 of the report that the predicted drawdown at 380 feet is 7.65 feet. <br />Plate 4 — Durham Pumping Simulation indicates a current groundwater elevation at MW -4 <br />of 4616 and a current groundwater elevation of 4620 approximately 380 feet south of the <br />southern permit boundary. Plate 5 — Coulson Pumping Simulation indicates a modeled <br />groundwater elevation at MW -4 of 4600 and a modeled groundwater elevation of 4605 <br />approximately 380 feet south of the southern permit boundary. This is a drawdown of 15 <br />to 16feet, not 7.65 feet, which could impact the groundwater wells located near the permit <br />boundary. <br />Additionally, the model does not indicate the historic, pre- Durham dewatering, <br />groundwater elevations and potential effects. Please model the potential effects of the <br />proposed dewatering activity from historic groundwater elevations and reevaluate the <br />results of the model from the Durham to Coulson simulations. <br />Please provided and explain the mitigation measures to be implemented for the potential <br />impacts to the surrounding groundwater wells and trigger points which would put <br />mitigation measures into effect. Typically, a trigger point of a 2 feet change from historic <br />ground water levels is acceptable. <br />20. The Shadow /Mounding Analysis by AWES, LLC dated June 27, 2013 does not accurately <br />predict the potential shadowing and mounding effect of the proposed clay liner at the <br />Varra - Coulson site. The Applicant must define or predict the shadow and mounding effect <br />expected for the Coulson site not Varra Pits 110 and 112. If the analysis determines a <br />shadow or mounding effect will occur offsite impacting a groundwater user, the Applicant <br />must explain all mitigation measures to be implemented and trigger points which would put <br />mitigation measures into effect. Typically, a trigger point of a 2 feet change from historic <br />ground water levels is acceptable. The mitigation measures must include a scenario for the <br />installation of a French drain to direct groundwater around the clay liner and restore <br />groundwater levels to the historic elevation in area of groundwater mounding. <br />21. Please state if the Applicant is pursuing agreements with the existing well owners within <br />600 feet of the site. Please provide signed copies of the agreements if available or provide <br />evidence the appropriate notice was provided to the well owners. <br />6.4.12 Exhibit L - Reclamation Costs <br />22. The Division will estimate the cost to reclaim the site based on the information submitted <br />once the Applicant addresses the concerns noted in this letter. <br />The Division will include costs to comply with the Office of the State Engineers requirement <br />for out -of- priority groundwater depletions. The reclamation plan states a 59.30 acre clay <br />