Clay Peak Environmental Studies

HECO has performed a variety of environmental services and studies to the development of the landfill. These projects have  included project engineering with an engineering report and public review for implementing a wastewater land application system and a fugitive dust suppression program using industrial wastewaters. Clay Peak Landfill accepts approximately 40,000 gallons per day of industrial wastewaters from local food processors for subsequent disposal. The industrial wastewaters contain high organics that are not amenable for local municipal wastewater treatment. Clay Peak employs pond evaporation, wetting compost, and road dust suppression for disposing of these industrial wastewaters. Clay Peak has chosen to expand its capability of managing industrial wastewaters by incorporating a water reuse program that employs a wastewater land application system and a more formal landfill fugitive dust control program. Wastewaters stored in an evaporative/containment pond will be pumped directly to the land application system or pumped into County water tanker trucks for dust suppression using portable diesel-powered pumps.

Site geotechnical investigation was perfomred to determine whether existing site soils were suitable for land application. Two hydraulic management units (HMUs) consisting of 15-acre and 20-acre sites were found acceptable for wastewater land application. The land application employs multiple ‘big gun’ irrigation spray onto fallow ground with disking immediately following each wastewater application to promote soil water evaporation. Crop growth is not an element of this design, however, soil organics and soil inorganic testing will be periodically evaluated to determine subsequent soil uses (i.e. soil used for final landfill cover or daily landfill cover). The wastewater land application rates with ‘big gun’ sprays are governed by limiting hydraulic loadings to the soils water retention capacity. A more formal dust suppression program will include using industrial wastewaters on landfill roadways not within the landfill cell.

The Wastewater Reuse program requires an operational and maintenance program manual with field and lab monitoring and reporting requirements. Environmental controls have also been incorporated to protect surface and groundwaters.