Agenda - Council - 10/27/2026 - Laserfiche WebLink

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A single well also creates a radius of influence drawing down adjacent water levels. The zone of influence for a single well was observed and modeled to be approximately two to three thousand feet, meaning that a single well pumping at approximately 800 feet will not cause a significant drawdown in another well. When multiple wells are being utilized such as under heavy day demand or under 2040 conditions the modeled and observed drawdown in nearby wells sees a substantial drop in static water levels from that of a single well pumping. Modeled drawdown during present heavy day conditions depict 30-40 feet of drawdown approximately 1,500 feet around the wellfield. After pumping stops, the aquifer will recharge to static levels within one or two days. In general, it appears new well sites should be spaced at least 1,500 to 2,000 feet away from existing wells to ensure a pumping scheme that gives the aquifer sufficient time to recharge. Future well sites should attempt to balance the City's current economics, well spacing, and take into account the underlying geology. The City of Ramsey should continue to utilize the current source water aquifer for both a water quantity and a water quality standpoint. The source water aquifer is underneath protective "confining" units that appear to inhibit the influence of new water from brining contaminants to the City's wells and will likely produce consistent water quality unlikely unconfined sources such as surface water that may have a highly variable water quality. Additional considerations for well Sites should take into account the thickness of the two hydrogeologic units that make up the source water aquifer The Tunnel City aquifer is not as prolific an aquifer as the Wonewoc aquifer, meaning that the Wonewoc aquifer is a more economical source of water. Figure 15 in Appendix D depicts three potential well sites taking into account these issues. Well Site Area A has Tunnel City aquifer thickness ranging from 100 to 150 feet and Wonewoc thickness ranging from 45 to 60 feet. Well Site Area B has Tunnel City aquifer thickness rangingfrom 0 to 80 feet and Wonewoc thickness ranging from 35 to 100 feet. Well Site Area C has Tunnel City aquifer thickness rangingfrom 90 to 100 feet and Wonewoc thickness ranging from 15 to 35 feet. All of these sites have potential for potable water sources, but a test well will need to be installed to confirm their viability. As opportunities to investigate these well sites present themselves the City should consider these as potential well sites. The following bullets summarize key takeaways from this text; • It is SEH's opinion there is a 95% to 99% certainty that the Tunnel City-Wonewoc aquifer will continue to produce potable water in sufficient quantities to meet present and foreseeable future demands. • The City of Ramsey should plan additional well sites to ensure static water levels remain sufficiently above top of aquifers to meet MnDNR thresholds. • New well sites should be spaced at least 1,500 to 2,000 feet away from existing wells to ensure a pumping scheme that gives the aquifer sufficient time to recharge. • The City of Ramsey should continue to utilize the current source water aquifer for both a water quantity and a water quality standpoint. • The source water aquifer is underneath protective "confining" units that appear to inhibit the influence of new water from bringing contaminants to the City's wells and will likely produce consistent water quality unlike unconfined sources such as surface water that may have a highly variable water quality. • Additional well sites should take into account the thickness of the two hydrogeologic units that makeup the Tunnel City-Wonewoc aquifer. The Tunnel City aquifer is not as prolific an aquifer as the Wonewoc aquifer, meaning the Wonewoc aquifer is a more economical source of water. • Figure 15 in Appendix D identifies three potential municipal well site areas, called out as Potential Well Siting Areas A, B and C, which will be explored in detail during preparation of the Well Siting Study. In summary; o Well Site Area A has Tunnel City aquifer thickness ranging from 100 to 150 feet and Wonewoc thickness ranging from 45 to 60 feet. O Well Site Area B has Tunnel City aquifer thickness ranging from 0 to 80 feet and Wonewoc thickness ranging from 35 to 100 feet. O Well Site Area C has Tunnel City aquifer thickness ranging from 90 to 100 feet and Wonewoc thickness ranging from 15 to 35 feet. o All these sites have potential for potable water sources, but a test well will need to be installed to confirm their viability. As opportunities to investigate these well sites present themselves, the City should consider these as potential well sites. Other potential well site locations will be explored as part of the Well Siting Assessment, including on city -owned properties as identified in Figure 10 (page 88), as well as on properties closer to the water treatment plant since such locations may be