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860 <br />840 <br />R 820 <br />c 800 <br />a)i • 780 <br />w <br />, 760 <br />d <br />J <br />m 740 <br />720 <br />700 <br />Figure 4 — Well 5 Drawdown and Recharge <br />Well 5 <br />Drawdown and Recharge <br />May 3 - May 5th <br />i <br />0 0 0 0 0 0 0 0 0 0 0 0000000000000000000000000000000000 <br />O O N CO LO O N CO Lo O N N V Lfl ,- N V L0 ,- N V V O N- CO V O— CO V O O N CO LO O N CO LO O N N V lf] <br />O 6 (O N O I, <br />▪ M 6II M N O O N �I,- O 0 co O O L M O 0 N O O M <br />0 7 CO,- OM04▪ 0 7 D O M O co N O� N r uo r 0).7r co 0 co co r�� 0 7 co OLo co Ncn 7 N .O <br />O O M V L['! CO 40 6 O N M cf'i N O O N M O M V co O 66 O,_ N M CO I- N O O N M O M V <br />r � — — � —— N- N N N N r r ,_ N- N- x- N N N N <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 />5.1.5.z vvell urawaown and Avallanle rieaa <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 RAMSY 154354 <br />Page 19 <br />