The shallow aquifers that underlie the Grand Strand of South Carolina average approximately 60 to 400 ft thick and have variable productivity with some wells producing little water and others producing several hundred gal/min. These aquifers are separated from the underlying Black Creek aquifer by a 200 ft to 300 ft thick clay confining unit. The shallow aquifers are recharged by local rainfall and discharge primarily into the Atlantic Ocean, the Intracoastal Waterway, and other surface waters. In the North Myrtle Beach area a vertical difference in potentiometric levels of < 1 ft was observed within the shallow aquifers in 1983. However, the difference in potentiometric levels between the shallow aquifers and the Black Creek aquifer was probably from 25 ft to > 50 ft. The quality of groundwater is also variable. Calcium and bicarbonate are generally the predominant ions in solution as a result of the dissolution of calcite in the aquifer sediments. Concentrations of chloride may be high in the vicinity of the salty surface waters. Concentrations of iron range from 5 to 35,000 micrograms/L, but generally < 2,000 micrograms/L. (Author 's abstract)
