Orange County NC Website
27 <br /> Slide #17 <br /> ARM <br /> PPUEO PFfvuPCF mreGFraEWT.P[ <br /> Public Supply Well Testing <br /> • Drawdown testing for yield <br /> • 24-hourtestingto determine sustainable yield �, s► <br /> WPM <br /> CUM,.PW <br /> 43.2717 <br /> 1 <br /> 63.2717 <br /> A. <br /> 83.2717 <br /> u� <br /> 103.2717 <br /> C.J. Corvette said drawdown testing involves 24-hour continuous pumping to certify yield, <br /> contrasting with private wells'one-hour"airlift yield"estimates. He said he just completed this type <br /> of test, and water levels and flow rates are monitored throughout. He explained that steady state <br /> is achieved when the water level fall is 0.1 feet per hour or less. <br /> Vice-Chair Hamilton asked if the time of year impacts the drawdown. <br /> C.J. Corvette said it can, but he explained that crystalline rock aquifers draw from distant <br /> recharge regions, making them less susceptible to seasonal variations than shallow wells. He <br /> noted that human demand, particularly lawn irrigation, typically has a more immediate impact than <br /> weather changes. <br /> Wesley Poole, Orange County Water Resources Coordinator, said Orange County <br /> monitors 13 wells every two months with hourly data collection uploaded to USGS. <br /> C.J. Corvette was glad to hear about this data collection and said it helps assess aquifer <br /> resilience. <br /> Cy Stober said Orange County also monitors surface waters. He said there are USGS <br /> gauge stations on the Eno River, and as part of the nutrient monitoring program with the Upper <br /> Neuse River Basin Association, there are numerous points of collection. He said this data helps <br /> paint a picture of groundwater and surface waters. <br /> C.J. Corvette said there are a lot of assumptions. He said he has drilled wells that have <br /> great water, but had contaminants close by that resulted in the well-being unusable. He explained <br /> that one of the biggest assumptions is the sameness of the rock (homogeneity) between nearby <br /> formations. He said there is variation that occurs naturally. He said North Carolina has some of <br /> the most complex geologic features of any of the states he's studied, and each county is unique, <br /> because there is such variation and difference. He said geologists must try to classify differences <br /> as the same. <br /> Chair Bedford asked about the length of time for community well tests, recalling that he <br /> said a well is supposed to be run for 12 hours. <br />