The Waimea Wastewater Treatment Plant will generate R-1 recycled water for irrigation use.
Kennedy Jenks (KJ) announced today that, along with the County of Kauaʻi (County), they won Best Small Project for their process optimization at the Waimea Wastewater Treatment Plant (WWTP) from the 2022 Outstanding Civil Engineering Achievement (OCEA) Awards held by the American Society of Civil Engineers (ASCE) Hawaii section.
By leveraging WWTP operator input, plant knowledge, and KJ engineering expertise, KJ and the County achieved the goal of generating consistent R-1 quality recycled water for irrigation. This project will help the County to preserve groundwater for potable use and reduce the reliance on injection wells effluent disposal.
Overcoming challenges from COVID-19 restrictions, the team relied on electronic communication and empowered the County Operation and Maintenance staff to conduct much of the testing, analyses, and construction with a minimal $30,000 capital investment. With simple adjustments to treatment processes based on targeted wastewater testing data, the project team was able to:
- Produce reliable recycled water for irrigation, which will preserve groundwater resources
- Optimize existing equipment, which eliminates major construction and construction-related environmental impacts
- Save treatment energy, operational, and chemical costs
“This project is an example of a great collaboration with the County of Kauaʻi, and shows just how impactful small changes can be,” says Mike Joyce, Principal at Kennedy Jenks. “We did what we do best at Kennedy Jenks: we partnered with our client to find a solution, maximizing their investment, and ultimately, leaving a long-lasting impact on the local community that will be able to leverage recycled water in its operations. It’s this kind of focus on sustainability and resource management that can maximize water resources, a challenge Hawaii knows all too well.”
Optimizing existing infrastructure, plant operators provided feedback on process improvements to KJ’s engineering team in interactive workshops, and the team collectively reviewed wastewater testing data to form a course of action. Operators implemented improvements and made adjustments as needed, based on data from ongoing analyses. The process was repeated until the wastewater effluent met the regulatory requirements for R-1 recycled water.
Wastewater testing data revealed too much organic treatment was taking place in the flow equalization basins leaving too little loading for the main treatment process. Using just one of two flow equalization tanks improved the sludge quality and the effluent turbidity. However, after this adjustment, daily turbidity was still inconsistent, calling for additional adjustments.
KJ theorized that the injection of polymer solution into the treatment process required more hydration time, as well as the right type of mixing, for better solids removal. The testing of these process adjustments proved to be extremely effective in reducing turbidity and led the County to purchase a mechanical mixer for the polymer dosing system.
The final adjustments involved bringing reliability to the existing disk filters to meet the regulatory requirement for the filtration of wastewater effluent. The existing disk filters had proven to be problematic since historically they needed cleaning after being online for a short period of time. KJ worked with plant operators to design a chlorine dosing system, which was constructed in-house, to reduce the maintenance efforts of the disk filters.
These simple adjustments to existing processes allowed the Waimea WWTP to achieve consistent R-1 quality effluent, while increasing operator understanding of the plant and its processes.
About Kennedy Jenks
Kennedy Jenks is a leading water and environmental engineering firm that serves public agencies and industrial clients with over 425 employees nationwide. The employee-owned firm delivers innovative design, construction and technology solutions for water, industrial and environmental projects across the United States.
Suzanne Broadbent, Senior Director of Communications