Orange County NC Website
Browse       Search
27 <br /> 1 Slide #17 <br /> ARM , <br /> Public Supply Well Testing <br /> • Drawdown testing for yield \�s <br /> • 24-hourtestingto determine sustainable yield vt <br /> rad <br /> COMM <br /> 43.2717 <br /> . � 1 <br /> i <br /> - , <br /> -632717 <br /> ';- 832717 <br /> J r � <br /> 103.2717 <br /> 2 <br /> 3 C.J. Corvette said drawdown testing involves 24-hour continuous pumping to certify <br /> 4 yield, contrasting with private wells' one-hour "airlift yield" estimates. He said he just completed <br /> 5 this type of test, and water levels and flow rates are monitored throughout. He explained that <br /> 6 steady state is achieved when the water level fall is 0.1 feet per hour or less. <br /> 7 Vice-Chair Hamilton asked if the time of year impacts the drawdown. <br /> 8 C.J. Corvette said it can, but he explained that crystalline rock aquifers draw from distant <br /> 9 recharge regions, making them less susceptible to seasonal variations than shallow wells. He <br /> 10 noted that human demand, particularly lawn irrigation, typically has a more immediate impact <br /> 11 than weather changes. <br /> 12 Wesley Poole, Orange County Water Resources Coordinator, said Orange County <br /> 13 monitors 13 wells every two months with hourly data collection uploaded to USGS. <br /> 14 C.J. Corvette was glad to hear about this data collection and said it helps assess aquifer <br /> 15 resilience. <br /> 16 Cy Stober said Orange County also monitors surface waters. He said there are USGS <br /> 17 gauge stations on the Eno River, and as part of the nutrient monitoring program with the Upper <br /> 18 Neuse River Basin Association, there are numerous points of collection. He said this data helps <br /> 19 paint a picture of groundwater and surface waters. <br /> 20 C.J. Corvette said there are a lot of assumptions. He said he has drilled wells that have <br /> 21 great water, but had contaminants close by that resulted in the well-being unusable. He <br /> 22 explained that one of the biggest assumptions is the sameness of the rock (homogeneity) <br /> 23 between nearby formations. He said there is variation that occurs naturally. He said North <br /> 24 Carolina has some of the most complex geologic features of any of the states he's studied, and <br /> 25 each county is unique, because there is such variation and difference. He said geologists must <br /> 26 try to classify differences as the same. <br /> 27 Chair Bedford asked about the length of time for community well tests, recalling that he <br /> 28 said a well is supposed to be run for 12 hours. <br />