The new Wrangell Water Treatment Plant addresses significant challenges with the safety and reliability of the community’s drinking water. The City and Borough of Wrangell’s existing slow sand filtration plant had become ineffective at treating the high turbidity and organic loads from the city's two reservoirs.
To address these raw water quality challenges, we designed the new treatment plant using Dissolved Air Flotation (DAF) technology. DAF is efficient in removing organic materials and color from water when combined with the appropriate coagulants and polymers. The DAF process provides higher efficiency water treatment within a smaller footprint than traditional treatment technologies, an important benefit in cold weather climates where water treatment infrastructure must be located within a heated building.
Our team repurposed existing infrastructure to reduce waste and environmental impacts. This included reconfiguring slow sand filters into chlorine contact tanks, also known as clearwells, converting roughing filters into backwash waste tanks and transforming space dedicated to aging ozone generators into a chlorine generation and storage room.
This project was carried out in a remote Alaskan island community, which posed significant logistical challenges due to harsh weather conditions and limited access. Our team developed a construction sequencing plan that allowed the contractor to build the new water treatment plant facilities while keeping the existing facility operational. We teamed closely with the contractor to overcome logistical challenges associated with barging equipment from Seattle to Wrangell, as well as timing and sequencing impacts on labor. We also coordinated with the owner and contractor to navigate Build America Buy America (BABA) compliance requirements, which were essential to project funding. This close collaboration reduced impacts on the construction schedule while meeting the funding requirements.
The new plant incorporates machine learning for coagulant dosing by leveraging historical data to optimize chemical consumption based on raw water and clarified water quality. This data provides chemical dosing recommendations to operators to enhance water treatment efficiency. This technology is a first in Alaska and is rarely seen in the continental U.S. The project also incorporated advanced process modeling and 3D Building Information Modeling (BIM) technology.
The new Wrangell Water Treatment Plant improves quality, increases treatment capacity and enhances energy efficiency. The plant’s additional water production capacity and improved water quality supports the City’s fishing and tourism industries, two vital influences on the local economy.