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32 <br /> 1 Slide #25 <br /> Commissioner Questions <br /> . How do the types of rocks matter for water supply to wells? <br /> • Typseof rock matters to a great degree, but that is part of the whole for each site. <br /> Rack types vary from site to site and some rock types may be better in one <br /> region due to local deformations as opposed to other regions where they remain <br /> minimally altered. <br /> ■ Can any portion of our county be predictable or not for water <br /> supply aquifer? <br /> • Yes and no. Every well is different.We can use the information at our disposal to <br /> reduce the risk or randomness in dritling, but there will always be risk. <br /> ■ Can wells be tested ahead of approval for zoning change or <br /> building? <br /> • Yes, and they should be.This work can be completed prior to any development <br /> on a property. No development work should be undertaken without ensuring that <br /> well water(or another water source) can sustain the development. <br /> 2 <br /> 3 Chair Bedford said there are community members who have opposed developments <br /> 4 because of the type of rock and the thought that it would lead to other wells in the area being <br /> 5 depleted. <br /> 6 C.J. Cornette said a community well is different than 40 wells that don't have a timer on <br /> 7 them or requirements for maximum use or review from the state. He reiterated that there are <br /> 8 more protections for sustainable drawdowns than with a private well. <br /> 9 Chair Bedford asked what the diabase rock specifically has to do with that. <br /> 10 C.J. Cornette said a diabase dike comes in and cuts through the middle of a type of <br /> 11 rock. He said this creates a channel that water could flow through, but is also a means for water <br /> 12 to be pulled out. In certain geologies, the dikes are more important to target than the other types <br /> 13 of rock because the other types of rock don't have as conducive water flow. However, any well <br /> 14 runs the risk of drawing down another well if it's close enough. He explained that the utilities and <br /> 15 professionals involved in a project will advise if a well is likely to interfere with something else. <br /> 16 Cy Stober asked for clarification on the relationship between the distance between wells <br /> 17 and the likelihood of influence. <br /> 18 C.J. Cornette said, generally speaking, the closer two wells are to each other, they more <br /> 19 influence they will have on one another. <br /> 20 Commissioner Carter asked if neighboring wells are factored into the testing for a new <br /> 21 well. <br /> 22 C.J. Cornette said there are no state requirements to test beyond a 100 ft. radius. <br /> 23 Vice-Chair Hamilton about the impact over time when a well is located close to the <br /> 24 headwaters of a stream. <br /> 25 C.J. Cornette referenced the depiction in chart#1: <br /> 26 <br />