WATER QUALITY STUDIES OF A SHALLOW AQUIFER ON ST. CATHERINE'S ISLAND, GEORGIA

St. Catherine's Island is a barrier island located off the central Georgia coast. The core of the island is composed of well-sorted, permeable Pleistocene sands, which are fringed by lower-lying Holocene sands. The Pleistocene sands contain a shallow, unconfined aquifer with water table depths ranging from 5 to 15 feet. An open, unlined dump exists in these Pleistocene sands in the northwest corner of the island. The dump has received waste (household garbage, appliances, and automobiles) for more than 20 years. Diesel fuel was previously stored on site for use in igniting the waste. A more expansive junkyard (automobiles, batteries, motor oil drums, assorted metal objects) exists on the Pleistocene sands to the south of the dump. A total of 9 shallow monitoring wells were installed in the vicinity of the dump and junkyard. Water samples from these wells were analyzed for the presence of organic hydrocarbons (benzene, toluene, ethylbenzene, xylene, diesel fuel, motor oil, and total petroleum hydrocarbons – analytical methods 602 and OA2) and for a suite of 66 other elements (ICPMS analytical method). Water table elevations were established in the area of the dump to determine the direction of ground water flow. An additional 12 shallow monitoring wells were installed across the island and sampled for the same 66 elements to further define water quality in the shallow aquifer. Analyses showed no presence of any organic hydrocarbons in ground water in the vicinity of the dump or junkyard. However, two wells within the junkyard indicated elevated levels of copper, zinc, and lead within the ground water. Decaying automobiles are the likely source for these metals. This is the first extensive study of ground water quality on St. Catherine's Island.