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Enviro ctics <br /> 16 <br /> An Earth Systems Company <br /> Ground-water levels vary seasonally; levels decline during summer and early fall when atmospheric <br /> conditions enhance evaporation and plants transpire substantial quantities of water and rise during winter <br /> and early spring when plants are dormant. <br /> The decadal hydrograph from observation well NC-126 in Orange County indicates a seasonal range of <br /> water-level change of about 4-6 ft,with the upper and lower whiskers indicating a 12-ft range in water levels <br /> over the past 62 years; thus, the average saturated thickness of the regolith can vary by 4 to 12 ft. Year-to- <br /> year variations, however, usually are small; on an annual basis, ground-water storage in the study area <br /> probably is relatively stable. <br /> 39 <br /> AL <br /> 32 <br /> LL 34 <br /> o � <br /> 38 <br /> 3 <br /> g <br /> 40 <br /> 42 <br /> 44 <br /> 46 —well dry at <br /> 463 feet <br /> 48 <br /> 1981 1982 1983 1994 1985 1996 1987 1988 1989 19% <br /> 35 <br /> B. <br /> 37 <br /> ti <br /> h <br /> a 39 UPPER WHISKER <br /> � TSTN PERCENTILE <br /> 0 <br /> 41 - MEDIAN <br /> 20 PERCENTILE <br /> 1 <br /> 43 LOWER WHISKER <br /> tme <br /> u <br /> a <br /> 3 45 <br /> 47 <br /> JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. <br /> Groundwater available in storage can be estimated using the formulas: <br /> Groundwater Available in Storage = 0.2 x Change in Water Table <br /> 9https://pubs.usgs.gov/wri/2000/4286/wri20004286.pdf <br /> Envirotactics, LLC Page 15 of 22 Hydrogeologic Desktop Study <br /> (732) 449-0077 Project No.6704 <br />