WRRCSR No. 7.5:85 Drilling Program and Pesticide Analysis of Core Samples from Pineapple Fields in Central O'ahu

Abstract

As part of the ongoing research of the WRRC Subsurface Water Quality Project, a drilling program was begun in October 1985 to collect soil and saprolite core samples from sites located in central O‘ahu pineapple fields. Samples were analyzed for concentrations of fumigant pesticides used in pineapple cultivation. These included EDB (ethylene dibromide), DBCP (dibromochloropropane), and TCP (trichloropropane) which originated in the pesticide Shell DD applied over 30 years ago. Results from the analyses are expected to provide current information on the subsurface movement of these toxic organic compounds. Thus far, pesticide analyses have been completed for five test boreholes in Dole fields (D-4201A, D-4201B, D-4213B, D-4111W, D-4101), in which residual pesticides have been detected in the first three. None were detected in boreholes D-4111W and D-4101. Additional core samples were collected and preserved intact from the same boreholes for physical, hydraulic, and mineralogical measurements to be performed at a later time. These intact or "undisturbed" core samples can be used to characterize and relate the structural and mineralogical properties of the samples and to determine the importance of such properties on the deep percolation of water and the associated transport of residual pesticides.