Water treatment plant project enters final stretch

The calendar change to 2026 not only marked the beginning of a new year but also the start of the final stretch toward completion of the City of Columbia Utilities ' McBaine Water Treatment Plant Improvement Project.

Contractor Bowen Engineering began construction on the project in September 2024. With construction progressing as scheduled, the City is on track to complete the project in August.

The City expects the project to restore the plant's capacity to treat 32 million gallons of water per day. It includes rehabilitation and replacement projects that will enhance the facility's performance and extend its service life.

Here are updates on key elements of the improvement project.

Clarifier Trains

Each of the four clarifier trains has two aspects:

• Primary Basin: A clarifier keeps influent water moving. Heavy solid particles settle, and the clean water on top flows into weirs, which direct the water into the Secondary Basin.
• Secondary Basin: Additional particles settle to the bottom. This process then directs the clean water at the top to filtration.

City Utilities has restored Train 1 with all-new equipment, pumps and weirs and expects it to be fully back in service at the beginning of April. Train 1 is the third of the four trains that the City has restored.

Crews removed all old equipment from the basins to repair the concrete, then rebuilt them from the ground up. They then refitted the primary basins with clarifiers and weirs. Crews also replaced the clarifiers in the secondary basins with baffle curtains. Baffles slow water flow, allowing particles to settle before filtration.

Chemical Building

The City expects the new chemical building to be operational by mid-April. The building will not only store chemicals but also house feed systems for chlorine gas, liquid ammonium sulfate and fluoride.

Other projects at the water treatment plant include:

• Six of the eight filters have been reconstructed. After installing new drains and air-scour pipes, crews installed new sand and anthracite filtration layers.
• The Operations Building has a new HVAC system and ductwork installed. The building will also receive a new electrical control room.
• The aerators - which add air that will remove dissolved gases and oxidize iron from raw water - are onsite. These will help make the clarifier trains more efficient.

For construction updates, residents can follow the City Utilities blog at the BeHeard McBaine Water Treatment Plant Improvement Project page.

For background on the water treatment plant improvement project, visit the City's McBaine Water Treatment Plant Improvement Project page.