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Enviro ctics <br /> An Earth Systems Company <br /> Table 3. Statistical summary of selected well characteristics for inventoried wells in Orange County,N.C. <br /> Quartiles for all wells Num- <br /> Well Aver- 5th 95th bar <br /> characteristic age Mini- percen- First First Median Third Ninth percen- Maxi- of <br /> mum tile dectile quartile quartile dectile tile mum [yells <br /> Yield' 17.6 0.1 1.5 2 5 10 20 40 60 240 630 <br /> (gallons per minute) <br /> Yield per foot .119 .0001 .0049 .0094 .024 .062 .143 .311 .417 1.297 625 <br /> (gallons per minute <br /> per foot of total well <br /> depth) <br /> Depth(feet) 208.0 24 73 85 125 180 250 365 420 805 625 <br /> Casing(feet) 53.6 4 21 24 37 49.5 64 86 103.5 148 600 <br /> Water level 26.6 0 l0 15 20 25 30 40 40 88 534 <br /> (feet below land <br /> surface) <br /> Saturated thickness of 27.0 0 0 0 7 22 41 61 74 126 512 <br /> regolith(feet) <br /> 'Unadjusted for differences in depth and diaracier. <br /> The typical well in Orange County has an average depth of 208 feet, an average casing length of 53.6 feet, a <br /> static water level of 26.6 feet, a yield of 17.6 gallons per minute, and a well casing diameter of 6.25 inches. <br /> The yield per foot of total well depth is inversely proportional to the depth of the well, indicating that the <br /> amount of additional water obtained by drilling deeper continuously decreases. <br /> This is consistent with the observation that in a regolith-crystalline bedrock aquifer system, fractures are <br /> most numerous and have the largest openings nearthe top of the bedrock.As depth increases,the pressure <br /> of the overlying material, or lithostatic pressure, holds these fractures closed, and the total porosity of the <br /> bedrock can be less than 1 percent.The base of the ground-water system is indistinct because the fractures <br /> tend to decrease in size and number with increasing depth. <br /> 0.25 I 25 <br /> 5 <br /> z= <br /> 0.20 20 <br /> �a <br /> ll¢.4 b Z <br /> d� � <br /> CD 0.15 Yield 15 i <br /> J J y <br /> CD F Z <br /> U'O � <br /> �� Q <br /> CD 0.10 10 �^ <br /> pp <br /> O 2 <br /> a Yield per fact <br /> 0.05 5 <br /> 0 0 <br /> 0 200 400 600 800 1,000 <br /> TOTAL WELL DEPTH,IN FEET BELOW LAND SURFACE <br /> Envirotactics, LLC Page 13 of 22 Hydrogeologic Desktop Study <br /> (732) 449-0077 Project No.6704 <br />