Understanding the Castle Hayne Aquifer - BIPAC

Understanding the Castle Hayne Aquifer• The aquifer is a wedge-shaped limestone layer whichcontains and transmits tremendous quantities ofhigh-quality groundwater.• The Castle Hayne Aquifer is approximately 300 feet thickin the area around the PCS Phosphate facility but thinsout as it moves west.• The groundwater typically flows in aquifers at rates ofabout one inch to one foot per day.• Recharge of the groundwater comes from rainfall on theland surface. (Note: One inch of rainfall over one squaremile of land produces about 17 million gallons of water.)• The land around the Castle Hayne Aquifer exceeds 5,000square miles, and it usually receives about 40 inches ofrainfall each year which means that a tremendous amountof rainfall is annually available for recharge of the aquifer.• It has been estimated that over 280 million gallons of waterper day recharge the Castle Hayne Aquifer.• PCS Phosphate, through a series of 200 wells locatedon the plant site and throughout Beaufort County, monitorsthe quality and quantity of water on a regular basis.• The North Carolina Division of Water Resources (NCDWR)must issue a permit for the withdrawal of waterfrom the Castle Hayne Aquifer.• Permits are required for ground water users of morethan 100,000 gallons per day.• Since depressurization began in 1965, no significantchanges have been observed in the quality of watercoming from the aquifer.Helping Nature ProvidePCS Phosphate Company, Inc.Aurora Division1530 NC Highway 306 SouthAurora, NC 27806CASTLE HAYNE AQUIFERAND PCS PHOSPHATE

“The Castle Hayne Aquifer is a tremendous resource for the citizens of the region.It is being naturally recharged at a rate at least equal to the present rate ofpumping. I truly believe that if we manage it properly, it will supply the citizensof the region with abundant and high-quality water for a long time.”— Dr. Spruill, Associate Professor of Hydrogeology, ECUPCS Phosphate and the Castle Hayne AquiferGroundwater PermittingMonitoring the Castle Hayne AquiferGroundwater plays an important role in PCS Phosphate’s dailymining operations. Due to its significance, the company employs ateam of people whose primary job consists of monitoring, recording,and reporting on the wells and groundwater surrounding the mineand plant operations. This data is reported to the North CarolinaDepartment of Environment and Natural Resources – Division ofWater Resources (NCDWR).The PCS Phosphate mine is located over the Castle HayneAquifer. To prevent the groundwater from flooding the mine pit,it is necessary to depressurize the aquifer. Depressurization isaccomplished by installing a series of wells approximately 700 feetapart surrounding the perimeter of the mine. Each well pumps anaverage of about 3,000 gallons of water per minute.In the late 1960s, NCDWR established the state’s first capacityuse area. Capacity Use Area No. 1 was formed to protect thegroundwater resources of the east-central coastal plain of NorthCarolina in direct response to what was then Texas Gulf SulfurCompany, now PCS Phosphate’s mining operation near Aurora,North Carolina. The formation of Capacity Use Area No. 1 hasserved the resource well as additional users have accessed theCastle Hayne’s groundwater. These users include aquaculture,agriculture, turf grass producers, golf course irrigation, aggregatemining, and public water supplies.Currently, the NCDWR regulates the amount of water that is pumped by allpermitted users. While PCS draws approximately 65 million gallons of waterper day from the aquifer, the current permit allows for withdrawals up to 78million gallons per day. PCS Phosphate compiles a groundwater report ona monthly basis and provides the information to the NCDWR.Where does the water go afterit is pumped from the aquifer?A portion of the water pumped from the aquifer by PCS is sent to the plantsite and used in a variety of plant operations. Water not needed for plantoperations flows, in its natural state, to the Pamlico River. Currently, PCSPhosphate has a contract with Eagle Water Company which allows Eagleto sell the water to public and/or private water systems as well as othercustomers within North Carolina.How does depressurization of themine area affect my personal well?Pumping of any well produces a cone-shaped depression on the “watertable” or “pressure surface.” Pumping at PCS Phosphate produces a “coneof depression” which extends outward approximately 20 miles from thecenter of the mine. Deep wells that are located in close proximity of thecone of depression may experience problems due to a slight drop in thewater level. PCS Phosphate has conducted detailed evaluations on theeffect of the cone of depression and consistently mitigates its impact toprivate drinking water wells.For more than 40 years, PCS Phosphate has monitored the quantity andquality of the Castle Hayne Aquifer through its network of approximately200 wells located along the plant site and throughout Beaufort County.Water levels stabilized shortly after pumping started and have remainedconsistent since depressurizationbegan in 1965. During this time,there has been no significantchange in the water quality.PCS Phosphate operates sixpublic water systems that utilizethe Castle Hayne Aquifer andsupply water for drinking, cookingand other general purposes onthe plant site. These public watersystems meet the drinking waterstandards which are set by the U.S.Environmental Protection Agency.In addition, the aquifer provideswater to area municipalities thatsupply Belhaven, Chocowinity,Washington and other townsacross eastern North Carolina.They too are testing the waterquality and have experienced nonotable changes.Dr. Richard K. Spruill, Associate Professor of Hydrogeology in theDepartment of Geological Sciences at East Carolina University is anexpert in groundwater research and notes that the Castle Hayne Aquiferis one of the most studied aquifers in the nation.