WRRCSR No. 7.3:85 Spatial and Temporal Distribution of Contaminated Basal Water in Southern and Central O'ahu Aquifers

Abstract

In recent years, several pesticide-related contaminants have been detected in the basal waters of southern and central O'ahu aquifers. Dibromochloropropane (DBCP) and ethylene dibromide (EDB), two soil fumigants which were previously used by pineapple growers in southern and central O'ahu, have been discovered in several wells in the area. A third contaminant, trichloropropane (TCP), which is an impurity of the soil fumigant DD, has also been detected in a number of wells. DBCP, EDB, and TCP are of particular concern to state public health officials due to the known and possible unknown health effects associated with these compounds. This is especially true for the Pearl Harbor Aquifer, which is the major potable water source for Honolulu. Thus, it is imperative to have an understanding of the extent and movement of the contamination.

The locations of the contaminated well sites appear to be correlated with the areas of past and present pineapple cultivation when the ambient groundwater flow pattern is taken into consideration. In addition, several significant pipeline leaks of petroleum products (aviation fuels) in the vicinity may have contributed to the EDB contamination. An analysis of the temporal variation of contamination in selected wells indicates no significant fluctuation in contaminant levels over a one-year study period from 1 September 1983 to 1 September 1984.