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Environ ctics <br /> 16 <br /> An Earth Systems Company <br /> 3.0 CONCLUSIONS <br /> Envirotactics, LLC (Envirotactics) prepared this Hydrogeologic Desktop Study based on the documents <br /> reviewed in connection with the community well at 3531 NC 54 W (Orange County, PIN 9749422010) in <br /> Chapel Hill, NC 27516 (the Site): <br /> • North Carolina Department of Environmental and Natural Resources (NCDENR) 2011 letter pertaining <br /> to Wastewater Treatment System <br /> • NCDENR 2024 Pump Test Data <br /> • United States Geological Survey (USGS) 2001 Investigation of Ground-Water Availability and Quality <br /> in Orange County, North Carolina (WRIR 00-4286) <br /> • USGS 1996 Ground-Water Recharge to the Regolith-Fractured Crystalline Rock Aquifer System, <br /> Orange County, North Carolina (WRIR96-4220) <br /> The documents reviewed confirmed that groundwater modeling may be used for the Site to estimate the <br /> impact of the Site's supply well's pumping on the neighboring supply wells. A Conceptual Site Model (CSM) <br /> will be created using the above documents. <br /> Simple groundwater modeling will be performed using the NC DEQ tools12: <br /> • Distance Drawdown Analysis: If we have drawdown measurements at various distances from a <br /> pumping center and want to estimate the transmissivity and storage coefficient of an aquifer. <br /> • Reverse Distance Drawdown Analysis: If we know the transmissivity and storage coefficient of an <br /> aquifer and need to estimate how groundwater levels will respond with distance from the pumping <br /> center after some time has elapsed. <br /> • Time Drawdown Analysis: If we have drawdown measurements from one well over time at some <br /> distance from a pumping center and want to estimate the transmissivity and storage coefficient of <br /> an aquifer. <br /> • Reverse Time Drawdown Analysis: If we know the transmissivity and storage coefficient of an <br /> aquifer and need to estimate how groundwater levels will respond over time in a well at some <br /> distance from the pumping center. <br /> • Simple Finite Difference Model: If we estimate groundwater level drawdowns associated with a <br /> pumping center overtime (non-steady state solutions). <br /> If the simple finite difference modeling is going to be required for the site, we recommend to move forward <br /> to either: <br /> • Install additional monitoring wells on site, in the bedrock, in order to be able to obtain triangulation to <br /> estimate bedrock flow direction or <br /> 12https://www.deq.nc.gov/about/divisions/water-resources/groundwater-resources/groundwater-management- <br /> data-tools-technical-reports <br /> Envirotactics, LLC Page 21 of 22 Hydrogeologic Desktop Study <br /> (732) 449-0077 Project No.6704 <br />