Wastewater Treatment & Disposal

Nestled between Waialua and Haleʻiwa on Oʻahu’s North Shore, the Paʻalaʻa Kai Wastewater Treatment Plant (WWTP) plays a vital role in safeguarding the health and environment of the Paʻalaʻa Kai community. Established in 1980, the facility provides secondary treatment using the activated sludge process, a method that mirrors natural biological breakdown to remove contaminants from wastewater.

The Paʻalaʻa Kai WWTP is designed to treat an average of 144,000 gallons of wastewater per day, with the capacity to handle peak flows up to 648,000 gallons per day. Currently, the plant treats approximately 72,779 gallons daily, reflecting its efficiency and resilience in managing community needs.

After treatment, the cleaned wastewater (effluent) is safely discharged through 10 onsite injection wells, in accordance with federal and state environmental regulations. Residual solids, a byproduct of the treatment process, are transported to the Honouliuli Wastewater Treatment Plant for further processing and final disposal.

The facility operates under the Underground Injection Control (UIC) Permit No. UO-1258, issued by the state of Hawaiʻi and renewed September 28, 2022. This permit authorizes the City and County of Honolulu to use its injection well system while adhering to strict standards for effluent quality, monitoring, and environmental protection. The current permit is valid through September 27, 2027.