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

Home

Figure 5 — Drawdown in Observation Well 8 840 E 835 ca c 830 a) w To 825 a) J 820 815 Drawdown in Observation Well 8 —2400 feet from pumping well (Well 7) October 19, 2019 CO CO 00 CO CO CO CO COO CO CO O O CO O O I` O O O) CO CO M O O T- co co CO co co co CO O) O O M O CO CO O 71- O O O O O T- T- N N M M ,T ,T O O O O O O O O T- T- T- T- N N M M M M,f 0 0 0 0 0 .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 0000000OOI`LC)OMMT-T-O)O)I`I`N-OOOM,r NNN000000000OOO ,r NM OMMMNNN, OOL0LOMMNNCD NNC OOO10O . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 00. 00 00 O) O) O) O O T- T- T- N N M 0) M,r ,T 0 0 0 0 0 0 CO CO CO I,- N— I's 00 00 O O) O O) O) O) 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