Environmental Site Investigation of Former Waialua Sugar Mill
Based on historical operations at the Waialua Sugar Mill facility, the suspect contaminant sources generally included former underground and aboveground fuel storage tank systems, pesticide mixing and loading activities, vehicle maintenance activities, electrical transformer storage, former sugarcane processing operations, and a commercial vehicle towing baseyard.
Under the State of Hawaii Department of Health Voluntary Response Program (VRP), ETC investigated the extent of soil and groundwater contamination for metals (arsenic, cadmium, lead, mercury, thallium, vanadium, zinc); herbicides/pesticides; dioxins/furans; polychlorinated biphenyls (PCBs); total petroleum hydrocarbons as diesel/gas/oil (TPH-D, TPH-G, TPH-O); methyl tertiary-butyl ether /benzene /toluene /ethylbenzene /xylenes (MBTEX); dimethyl phthalate; polynuclear aromatic hydrocarbons (PAHs); and halogenated volatile organic compounds (HVOCs). In order to assess the potential impacts, the site was divided into 27 surface and/or subsurface decision units. Discrete and multi-incremental soil samples were collected from these 27 decision units. Monitoring wells were also installed and sampled using low-flow methodology to assess potential impacts to the underlying groundwater. Approximately 80 discrete soil samples, multi-incremental soil samples, and groundwater samples were collected and analyzed. In addition, ETC also conducted personal, perimeter, and work area air monitoring, during all aspects of the project to protect the workers and surrounding public.
Deliverables for the project included a Phase I Environmental Site Assessment (ESA), conceptual site model, and general and detailed site investigation plans. Specifically, a Site Investigation Report and Environmental Hazard Evaluation (SI-EHE) was prepared to document site investigation activities, compare data to applicable DOH Environmental Action Levels (EALs), and evaluate/discuss all potential environmental hazards associated with the site. A Remedial Alternatives Analysis (RAA) evaluated four potential remedial alternatives, which were then compared to nine evaluation criteria. Upon completion of the RAA, a Draft Remedial Action Memorandum (Draft RAM) was created to summarize findings and activities performed to date. A Public Participation Plan was also developed to solicit input from members of the affected public regarding the planned work to be completed on portions of the site to mitigate environmental hazards. A Public Meeting was then held and comments obtained through the public participation program were used to create a Final RAM and develop a Remedial Action Work Plan.
Prior to implementation of the selected remedial action, an interim Environmental Hazard Management Plan (EHMP) was prepared for use by the site contractor. Construction activities for the implementation of the selected remedial action were monitored to ensure adequate controls were maintained to minimize or eliminate airborne contaminant hazards. Following completion of construction, a Remedial Action Report was completed to document the implementation of the final remedy and a final EHMP for managing the remaining environmental hazards on-site was prepared. In December 2018, the DOH issued a Letter of Completion, subject to the terms and conditions of an Environmental Covenant Agreement, the final EHMP, and the completion of a Groundwater Monitoring Program.
