Project engineer discusses Talkeetna wastewater upgrades

After years of compliance issues, a plan is in the works to upgrade Talkeetna’s wastewater treatment plant.

On Thursday, representatives from HDL Engineering Consultants and the Mat-Su Borough came to Talkeetna to discuss the upgrade plans with area residents.

Talkeetna’s wastewater treatment system has had numerous compliance issues in recent years, and the Mat-Su Borough has recently reached a settlement with the Alaska Department of Environmental Conservation about a plan to get the system back up to par.

Chris Bowman, the project engineer from HDL Engineering, says the system’s current problems are a result of overloading in the summer.

“Talkeetna has grown quite a bit in the summer.  Summertime flows are overwhelming the system, and, the way it’s set up right now, the existing lagoons just can’t handle the influx of summer tourists.”

Before construction begins on the upgrades, sludge that has built up in the lagoons will be removed later this spring and transported to Point Mackenzie.  Removing the sludge will mean there is more volume available for additional wastewater.

Part of the upgrade plan is to build chambers that will catch a lot of the solids that enter the treatment plant, preventing sludge buildup in the future.  Chris Bowman says it works similar to a septic tank.

“Wastewater comes into the first chamber, and the easily settleable stuff will come out in that first chamber….The second chamber should be mostly clear, but it will still have some stuff in it that can settle out prior to being discharged into the wastewater lagoon.”

Once the wastewater gets into the lagoon, the treatment process begins.

Currently, the Talkeetna sewer lagoon relies mostly on natural processes to treat wastewater before discharging it into the Talkeetna River. Since that method has not been able to keep up with increased flows, Chris Bowman says steps will need to be added to bring the system back into compliance with state regulations.

“The problem right now is coliform—so bacteria—and dissolved oxygen.  What we’ll be doing with this project is disinfecting the wastewater by injecting chlorine and re-aerating it to meet our dissolved oxygen requirements.”

Bowman says the chlorine that is used to treat the wastewater will be completely removed before the water is discharged into the river.

The upgrades are being designed to handle Talkeetna’s wastewater treatment demands based on a twenty-year projection of population growth and increased tourism.  Part of planning for the future of the system means preparing for the Talkeetna River to flood.  Chris Bowman says the system is classified as critical infrastructure, meaning it has to be built above the 500-year flood plain.

“Right now, the…lagoons are protected from that 500 year flood.  Everything that we’re constructing as part of this project will also be at or above that 500-year flood protection elevation.”

The current timeline is to have a bid for the upgrades this summer, with the actual construction being completed this fall.  Because the borough’s permit doesn’t allow discharging of wastewater after October, actually turning the new chlorination and aeration system on will likely have to wait until next year.