Kīhei Effluent Reuse System

Construction of the Core System required careful phasing and scheduling to avoid disruptions to ongoing operations at the Kīhei Wastewater Reclamation Facility (WWRF), which remained fully functional throughout the project. Key facility components integrated into the reuse system included the effluent pump station — featuring dual 1,500 gallons-per-minute pumps — and a 1.8-million-gallon effluent storage basin.

The existing storage basin was rehabilitated with a polypropylene liner and a floating membrane cover system. These upgrades protect the high-quality R-1 effluent from environmental contaminants and minimize algae growth by shielding the water from sunlight and debris.

New infrastructure developed under the Core System was designed to align with existing systems while allowing for future expansion. These enhancements included a 1.0-million-gallon reinforced concrete reservoir with an aluminum geodesic dome roof, as well as an 18-inch ductile iron pipeline connecting the reservoir to the treatment facility. The dome roof eliminated the need for internal columns and footings, resulting in cost savings that were reinvested in a high-performance tank lining system.

Advanced monitoring and control features were also installed, including remote pressure, flow, and level sensors connected to the Kīhei WWRF via solar-powered radio transmitters. This setup enables reliable, off-grid communication between the reservoir and the facility's Supervisory Control and Data Acquisition (SCADA) system for efficient operation and real-time monitoring.

To ensure continued service to key users—including Monsanto Corporation’s seed corn operations and the Elleair Golf Course - the Core System was brought online before final completion. Strong coordination among system users, the County of Maui, and the Contractor (Hawaiian Dredging Construction Company) enabled uninterrupted service during construction. The project was completed over a 12-month period at a total construction cost of $3.2 million, with substantial completion achieved in April 1998.

Growing community interest in reclaimed water use — combined with surplus funds remaining from the Core System — led the County of Maui to expand the effluent distribution network. The Kīhei Effluent Reuse Distribution System, Phase I, was launched during the construction of the Core System. Planning, design, and bidding for Phase I were completed before the Core System’s construction concluded. A key objective was to finish the distribution system in time to support irrigation needs for the new playfields at the soon-to-be-completed Kihei Community Center.

This phase of the project extended the effluent transmission line makai from the Kīhei Wastewater Reclamation Facility (WWRF), across Piilani Highway, and then north along the planned North-South Collector Road corridor to the Kīhei Community Center. The installation included approximately 6,200 linear feet of 12-inch and 1,700 linear feet of 18-inch ductile iron pipe.

The Phase I Distribution System delivers reclaimed water to several key community facilities, including the Kīhei Community Center, Kīhei Elementary School, Lokelani Intermediate School, the Haggai Institute, and the Piilani Commercial Center. To enhance safety, the system also includes specially designated fire hydrants painted purple in accordance with Hawaii Department of Health (DOH) standards, providing an additional tool for combating frequent brushfires in the area.

The total construction cost for Phase I was $682,000, with work completed in just 8 months. Substantial completion was achieved in December 1998. The project contractor was Goodfellow Brothers, Inc.

As the lead engineering consultant, Fukunaga & Associates, Inc. (FAINC) collaborated with the County of Maui from the early stages of the Kīhei Effluent Reuse System, overseeing planning, system design, and providing support during construction. One of the key challenges was shifting public and user perception — presenting treated effluent not as waste, but as a valuable, reusable resource. Maintaining the high quality of the R-1 effluent throughout the storage and distribution network was critical for gaining user trust and ensuring reliable, low-maintenance operations.

The system’s flexibility was enhanced through the integration of covered storage and a pressurized distribution network, which enabled users to access reclaimed water directly, without requiring additional booster pumps. A major design priority was optimizing the use of existing infrastructure at the Kīhei Wastewater Reclamation Facility (WWRF) without compromising the performance of the newly developed reuse system. This included testing and verifying pump performance for both transitional and final operating conditions. Retrofitting the existing effluent storage basin with a membrane liner and floating cover significantly improved water quality preservation.

Construction phasing and coordination were also essential to ensure continuous service to existing users while avoiding operational disruptions at the WWRF. Subconsultants MK Engineers, Ltd. and Shigemura, Lau, Sakanashi and Higuchi, Inc. (SLSH) supported the project by providing electrical and structural engineering services, respectively. MK Engineers collaborated with County staff and equipment vendors to implement a solar-powered reservoir level monitoring system. This system, connected via radio telemetry, linked directly to the County’s SCADA system to automate pump and valve operations for clients such as Elleair Golf Course and Monsanto Corporation. SLSH optimized the storage reservoir design by recommending an aluminum geodesic dome cover, which eliminated the need for internal columns and reduced overall project costs.

The Kīhei Effluent Reuse System successfully delivers a sustainable solution for water conservation on Maui’s dry south shore. By providing a reliable supply of high-quality reclaimed water, the system reduces the community’s reliance on potable water for irrigation and supports critical functions such as agriculture, recreation, and fire protection. Key beneficiaries include local parks, landscaped areas, the Elleair Golf Course, and Monsanto Corporation’s agricultural operations, which produce seed corn for global distribution.

Today, the Kīhei Wastewater Reclamation Facility recycles approximately 40 to 50 percent of its daily flow — between 1.6 and 2.0 million gallons — while the remainder is disposed of through onsite injection wells. As community acceptance and demand for reclaimed water continue to grow, the long-term vision is for the facility to reuse 100 percent of its effluent, making it a model of sustainability for wastewater management in Hawaii.