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5.1.5.2 <br />Figure 4— Well 5 Drawdown and Recharge <br />860 <br />840 <br />820 <br />c 800 <br />▪ c▪ o <br />w 780 <br />w <br />760 <br />J <br />740 <br />ca <br />720 <br />700 <br />Well 5 <br />Drawdown and Recharge <br />May 3 - May 5th <br />O O O O O O O 0 0 O 0 0 0 0 0 0 0 0 0 0 0 0 O 0 0 0 0 O 0 0 0 O 0 0 0 0 0 0 0 O 0 0 O 0 0 <br />O O N M Ln O N M LC) O N N • Lc) N • Ln N O N- CO O x- M • 0 0 N M LO O N M LO O N N LO N— <br />.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. <br />O 00 CO N O r- Li) O� CO 4 O 00 4 M O7 N- M N 00 CO N N— Lf) r O CO 4 O O Ln M Oo I` 4 N 00 CO M f` Ln O <br />O co O co N O N LO CO O CO N O LC) N Ln N— O 7 CO O LC) CO Ln N- O CO O LO CO N LO N <br />.. .. .. .. .. .. .. CO.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . CO.. .. .. .. .. .. .. .. CO.. .. .. .. .. .. .. .. <br />O O M 4 Lid CO 00 00 O r N M Lib CO I` 00 O O N M O M L 6 CO 00 00 O N M Lf7 CO f` 00 O O N M O M 4 <br />NNNN NNNN <br />Time <br />At the start of this period, Well 5 water levels were recovering to static at approximately 23 feet <br />below ground surface. Pumping commenced at 15:15 on May 3rd and continued for the next 18 <br />hours. Initial drawdown or instantaneous drawdown is depicted by the step increase in drawdown <br />from 16:51 to 18:27. Water levels over this period fell 80 feet. Water levels over the following 18 <br />hours decreased another 40 feet. The well ceased pumping at 10:30 on May 3rd and recharge to <br />the aquifer took 17 hours to return to static water levels. <br />Current well pumping and rates of recharge appear good with the aquifer being able to recharge <br />water to static in a relatively low period of time. <br />Well Drawdown and Available Head <br />Water levels from the source water aquifer, the Tunnel City-Wonewoc Aquifer, are much higher <br />than the topographic elevation of the top of bedrock. This scenario is known as a confined <br />aquifer, where the potentiometric surface, or water head, is higher than the topographic location <br />of the aquifer. <br />Presently, water quantity throughout the region is good and there are no regulations actively <br />being enforced on pumping levels within a well. Well interference and long-term groundwater <br />trends through pumping/drawdown is conducted on a case by case basis by the Minnesota DNR <br />if a problem arises. <br />Typically, it is not a good idea to drawdown water levels in a confined aquifer below the top of <br />bedrock as it can introduce oxygen into the formation. Additionally, water levels should stay <br />sufficiently above the specifications of the water pump design. <br />FEASIBILITY STUDY - DRAFT RAMSY 154354 <br />Page 19 <br />