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• Page 2 <br /> Mr Mark Johnson <br /> March 17, 2017 <br /> Hayden Property: The current house is approximately 2000 feet north of the proposed gravel <br /> mining area The domestic and irrigation wells(Permit#628& 15990-R-R)are north of the onsite <br /> pond, approximately 200 feet away from the proposed mining area The existing pond acts as a <br /> buffer form dewatering activities and is a significant distance away from the proposed gravel mining <br /> area. <br /> The Weakland Property. is approximately 2000 feet northeast of the proposed site. There are two <br /> wells onsite,one is a deep well approximately 550 feet deep and the other is 50 feet(Permits <br /> #247465&247465-A). The wells are a significant distance away from mining and is buffered from <br /> the dewatering area by the North La Poudre Pit <br /> Windsor Reservoir&Serfer Reservoir: The Windsor Reservoir and Serfer Reservoir are both lined <br /> and will be unaffected during mining <br /> Dewatering: <br /> The North La Poudre Mine which has been dewatered to bedrock in 2013 and 2014 with no negative <br /> impacts to the surrounding well owners. The approximate dewatering rate was 350 gallons per minute <br /> which will remain the same during dewatering of the Lee Amendment. Below is a brief description of the <br /> calculation used to determine the drawdown due to mining, <br /> The radial well equation was used to determine the drawdown surrounding the mine. <br /> Using a well pumping rate of 380 gallons per minute(50 acre-feet per month) and an effective sump radius <br /> (area used to pull the water down and set the trash pump in)of 250 feet the drawdown at 1,600 feet is zero <br /> (existing water levels are met, 13 feet above bedrock or 7 feet below grade). Therefore a dewatering rate of <br /> 380 gallons per minute will have very little drawdown effect on the surrounding well users <br /> Onsite Monitoring: <br /> There are three wells that will be continuously monitored as shown in the attached figure. Currently the <br /> water levels are as follows during recent observation. Monitoring Well East is 4.5 feet below grade and <br /> Monitoring Well West is 7.5 feet below grade <br /> Mitigation Measures <br /> Proposed activities on the Site have very limited potential to result in significant off-site groundwater impacts <br /> to the local groundwater levels and therefore mitigation should not be required but in the event the operator <br /> has to mitigate they have the ability to drill wells deeper,truck in water or provide irrigation water should it <br /> be needed. <br /> Conclusion <br /> The potential for reduction in groundwater in the surrounding properties that will affect the well is limited <br /> The applicant will continue to monitor the groundwater levels in the wells <br />