Agenda - Council Work Session - 09/13/2022

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Figure 5 — Drawdown in Observation Well 8 840 E 835 c0 c 00 830 c w 825 a) J L C 820 > 815 Drawdown in Observation Well 8 -2400 feet from pumping well (Well 7) October 19, 2019 CO CO CO CO CO CO CO O CO CO CO CO CO CO O O N- O co O O CO 00 O COT- CO O CO CO 0 T- O CO O CO O M O O O O 71- 71-Lf) Li) Li) O O T- T N N 00 00 Li) Lf) Li) O LID O O O T- T- T- T N N 00 M M OD Li) Lf) Li) O O .. CO.. .. .. .. .. .. .. .. .. .. .. .. .. O co 00 00 O O f` Lf) In M M O) O) N- N- N- Ln LO O 00 7tN N N 0 0 0 00 00 00 O O O 7t,( N M T- L00000MNNN OOOLOCOMNNN,-,-,-OOOLO00Lf) NNN OOOLf)00 .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. f` 00 00 00 O d) O O O T- r T- N N 00 00 00 ,r O O O O LO LO O O O N- N- N- 00 00 00 d) d) O) O) d) O N Time During the course of Well 7 pumping, Well 8 at a distance of 2,400 feet observed approximately 6 to 9 feet of d rawdown . The Theis equation predicts a cone of depression approximately 2,448 feet from pumping well 7. Theis Equation for the City of Ramsey Time = 0.5 days Theis W(u) Function 0.752 unitless Drawdown = 6 ft Transmissivity = 11493 gpd/ft Pumping Rate = 800 gpm Theis u variable = 0.390 unitless r2 = 4Ttu 4S Storativity = 0.0002 unitless Radius rounded for map 2400 ft These results indicate that a single well pumping at current well field spacing does not induce mutual well interference. This 6-foot cone of depression is depicted on Figure 11. However, complexities arise as present-day conditions see the use of 3 to 5 concurrent wells, and a 2040 demand increasing up to a projected 500% daily maximum demand. In order to model these scenarios and their resulting cone of depressions a groundwater model was developed. FEASIBILITY STUDY RAMSY 154354 Page 22