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Figure 4 — Well 5 Drawdown and Recharge <br />860 <br />840 <br />820 <br />c 800 <br />1 • 780 <br />w <br />• 760 <br />a) <br />J <br />+; 740 <br />720 <br />700 <br />O <br />O <br />O <br />O <br />O <br />Well 5 <br />Drawdown and Recharge <br />May3-May5th <br />0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O O O O O O O O O O O O O O O O O O O <br />O N M 03 0 N 0) 10 O CN N 1 N 1 N O 0) • O N— Cr) 0 0 N 0) 10 0 N 0) 10 0 N N 1 <br />00 (0 N O r— 1 r (0 4 O 00 4 0) 0) r— 0) N 00 C0 N I` 1 O (0 4 O 0) Ln 0) 0) I` 4 N 00 (0 0) r N 1 0) O <br />71- Ce) O (0 N O N 10 CO 0 CO N O 10 N l0 0) CO 0 10 CO 1 0 CO O 10 0) N 1 N <br />O 0) 10 c0 00 00 O N 0) Lf) C0 I` 00 O O N M O 0) 4 Lf) c0 00 00 O CN 0) 10 C0 I` 00 O O N 0) O 0) 4 <br />NNNN NNNN <br />Time <br />5.1.5.2 <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 />INPI� Drawdown and Availably Hew.' <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 />