C.4.1 Background and Previous Investigations

This case study summarizes the investigation of a 400-acre, former sugarcane field and a ½-acre pesticide mixing area located within the field. The area was being developed for residential and commercial use. The primary COCs were arsenic, PCP, dioxins (associated with past use of PCP), and triazine herbicides, each used in the past for weed control. A detailed discussion of the sugarcane field investigation is provided in the report East Kapolei Affordable Housing Project Kapolei, Oahu, Hawaii, Final Site Assessment Report (TTEMI 2007). A summary of the pesticide mixing area investigation is provided in the report Site Investigation Report and Environmental Hazard Evaluation, East Kapolei II Pesticide Mixing and Loading Site (ESTC 2007, 2010).

DU and ISM (ISM, referred to as “multiincrement sampling” or “MIS” in the reports) investigation approaches were used to investigate the site. The pesticide mixing area, where heavy pesticide contamination had been previously identified, was investigated separately from the field area. This approach allowed the field area to be cleared for development early in the process. Except as noted, 30- to 50-increment ISM samples were collected from DUs and subsampled in the laboratory for preparation of aliquots and analysis.