Hilo Landfill Leachate Treatability Study

Dr. Roger Babcock, WRRC/Civil Engineering, UH Manoa


ERM-West, Inc. Hawaii


6/20/2008 - 8/31/2009


This project is a subcontract to collaborate with ERM on a landfill leachate study. Hawaii County is considering an expansion of the existing Hilo municipal landfill. The current landfill has no underliner system, and therefore precipitation that infiltrates through the waste pile discharges to the underlying aquifer system. A newly constructed landfill cell at the site, in compliance with State and Federal regulations, would include an underliner system to allow collection and removal of infiltrating water (leachate). Due to the high precipitation rates in the Hilo area, a substantial volume of leachate is anticipated to be generated. The leachate is likely to be impacted by dissolved metals and organic compounds.

Several alternatives are available for leachate management, and fall into two broad categories: 1) on-site treatment and discharge and 2) transport to a local wastewater treatment facility for treatment and discharge. On-site treatment and discharge may prove to be the most cost-effective approach, especially if the leachate contains relatively low concentrations of contaminant compounds. The proposed work will evaluate on-site leachate treatment technologies in advance of more formal landfill design efforts that have not yet been initiated. The results of this study are intended to provide guidance to the selection of leachate management technologies and future design efforts.


This research will be a collaboration involving personnel and other resources from ERM Inc. and the University of Hawaii. The scope of work to be conducted by UH is as follows:

1. Leachate characterization.

Leachate collected from the current waste pile will be characterized for various chemical constituents including: Biochemical oxygen demand (BOD5), chemical oxygen demand, total organic carbon, total nitrogen, total phosphorus, pH, alkalinity, and total dissolved solids.

2. Technology screening and treatability studies.

A suite of proven and innovative technologies will be screened for inclusion in treatability tests. Approximately 3-4 of the most promising technologies will be selected for a more detailed evaluation using a formal technology screening process. Possible technology to be screened include: wetlands treatment, biological oxidation and membrane filtration (among others). For one or more of the candidate technologies selected through the screening process, treatability studies with actual leachate will he conducted to determine treatment efficiencies and general design parameters.

3. Alternatives analysis and final report

Upon completion of the technology screening process and focused treatability studies, UH will work with ERM on conducting an Alternatives Analysis based on the Feasibility Study Guidance developed by the US. EPA's CERCLA (Superfund) program. A comparative analysis of technologies will consider treatment effectiveness, implementability and cost. The findings of this Alternatives Analysis will he presented in a Final Report, to include results of the technology screening and treatability study work.