Agenda - Council - 03/09/2021 - Laserfiche WebLink

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5.1.5.2 Figure 4 — Well 5 Drawdown and Recharge 860 840 820 c 800 w 780 w > 760 J *; 740 c0 720 Well 5 Drawdown and Recharge May3-May5th 700 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 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 N M Ln 0 N M LO O N N LO N • LO N O N M 0 N- M • 0 0 N M Ln O N M Ln O N N Lf) .. CO.. .. .. .. .. .. .. .. .. .. CO.. . . .. .. . .. .. .. .. .. .. .. .. .. . .. .. . .. .. .. . .. . .. .. .. Cr .. .. O 00 (0 N O N Ln r d) CD 4 0 00 ( M O) N 0) N 00 (0 N N CrO (0 4 0 O) Ln M O) f— 4 N 00 CO M f` LO O t M o ONO t N Ln M N O M N O Ln N N- L0 ,- 0 t 0) 0 Ln M Ln • O t 0) O Ln ON LC) N .. .. . . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. . .. .. . .. .. .. . Cr.. .. . .. .. .. .. .. .. .. .. O O M Ln O 00 00 O N M Ln O ti 00 O O N M O M CCO 00 00 O N M LO ti 00 O O N M O M 4 NNNN NNNN Time At the start of this period, Well 5 water levels were recovering to static at approximately 23 feet below ground surface. Pumping commenced at 15:15 on May 3rd and continued for the next 18 hours. Initial drawdown or instantaneous drawdown is depicted by the step increase in drawdown from 16:51 to 18:27. Water levels over this period fell 80 feet. Water levels over the following 18 hours decreased another 40 feet. The well ceased pumping at 10:30 on May 3rd and recharge to the aquifer took 17 hours to return to static water levels. Current well pumping and rates of recharge appear good with the aquifer being able to recharge water to static in a relatively low period of time. \NJ' Drawdown and Available Head Water levels from the source water aquifer, the Tunnel City-Wonewoc Aquifer, are much higher than the topographic elevation of the top of bedrock. This scenario is known as a confined aquifer, where the potentiometric surface, or water head, is higher than the topographic location of the aquifer. Presently, water quantity throughout the region is good and there are no regulations actively being enforced on pumping levels within a well. Well interference and long-term groundwater trends through pumping/drawdown is conducted on a case by case basis by the Minnesota DNR if a problem arises. Typically, it is not a good idea to drawdown water levels in a confined aquifer below the top of bedrock as it can introduce oxygen into the formation. Additionally, water levels should stay sufficiently above the specifications of the water pump design. FEASIBILITY STUDY RAMSY 154354 Page 19