Assembly holds workshop on water treatment plant

The Wrangell Borough Assembly held a workshop last week, Oct. 20, to discuss the water treatment plant improvement project. This has been an ongoing project for some time now, and the workshop was to make sure new assembly members were up to speed on the current situation, and to share opinions on how it is going so far.

Capital Facilities Director Amber Al-Haddad led much of the initial discussion, providing a history lesson on the project. Plans to renovate and improve Wrangell's water treatment plant began back around 2015 or 2016, she said. The idea, right now, is to replace Wrangell's existing Slow Sand Filtration water treatment system with a Dissolved Air Flotation (DAF) system. The existing plant has been online since 1999, she said, and a DAF system could work better. It was not the best treatment system available, she said, but it was a good option for Wrangell.

"It was identified that DAF probably wasn't going to give us the best results of water treatment systems out there, but it was one we felt like we could afford," Al-Haddad said. "There were two other alternatives that were identified to potentially give us better quality, but it came with millions of dollars more in investment."

The initial estimated cost of this replacement project was a little less than $13 million. However, Al-Haddad said the project has been revised and costs have been shrunk to approximately $9 million. According to the meeting's agenda packet, the roughly $4 million difference came by reducing the footprint of the roughing filter buildings reconstruction, which would house the new DAF and filtration system. The original idea was to construct the building large enough to house a third DAF train and filter sometime in the future, the packet reads. The current project only renovates the building to accommodate two DAF units. These two units will have a combined production of 1.8 million gallons of water a day.

"For people who want to look at this system, there's a lot of YouTube demonstrations of the DAF process," Assembly Member Patty Gilbert said.

It was explained, during the meeting, that in a DAF system a coagulant is added to the water which will attract waste to each other. Air bubbles then lift the waste to the surface of the water for removal.

According to the workshop's agenda packet, the maximum daily water demand for Wrangell was estimated at 1.5 million gallons per day. This is based on 2014 numbers, the packet reads. Projecting forward, Wrangell's maximum daily water demand is estimated at 1.8 million gallons per day. Two DAF trains, the packet reads, could meet this estimated demand with a flow capacity of 1,250 gallons per minute.

Much of the discussion at the meeting revolved around the details of how a DAF system works, the cost of the project, and the needs of the community. Assembly Member David Powell, at several points, stated his main concern was redundancy with the DAF system, and how to keep water flowing to the community if something broke down. He also said he thought it would be a good idea to go in for bigger DAF trains, which could produce 1,000 gpm, but would increase cost by about $400,000. The agenda's packet states that it is unknown if the size of the DAF train increasing would require a larger building footprint.