WRRCSR No. 03.02.90 Assessment of the Potential for Groundwater Contamination Due to Proposed Urban Development in the Vicinity of the U.S. Navy Waiawa Shaft, Pearl Harbor, Hawaii

Abstract

The concern over groundwater contamination in Hawaii has become most pronounced since the early 1980s with the discovery of various pesticide-related contaminants in the basal groundwaters of several of the state's aquifers. Two soil fumigants previously used by pineapple growers, 1, 2-dibromo-3-chloropropane (DBCP) and 1, 2-dibromoethane or ethylene dibromide (EDB), have been detected in several wells on Oahu and Maui. The compound 1,2,3-trichloropropane (TCP), which is an impurity of another soil fumigant DD, has also been detected in numerous wells on Oahu and Maui. The herbicide atrazine, commonly used by the sugarcane industry, has been found in wells on the islands of Hawaii, Maui, Oahu, and Kauai. In addition, the solvents trichloroethylene (TCE) and tetrachloroethylene (PCE) have been detected in Oahu groundwater samples. Prior to the recent discoveries of pesticides in the state's groundwaters, it was felt that the great depth (hundreds of meters) between the ground surface and the basal waters of the state's aquifers was sufficient to prevent leaching of pesticide residues to the water table. Furthermore, it was believed that any residues which did reach the basal aquifers would become so greatly diluted as to be undetectable. It is now clear, however, that the overlying soil, saprolite, and basalt layers do not completely insulate Hawaii's groundwaters from contamination. Chemicals applied by man at the ground surface can potentially reach the groundwater table.