While the issues facing Talkeetna’s sewer lagoon have seen significant improvement over last year, the system remains out of compliance with its state permit.
For each of the last four months, tests conducted for fecal coliform bacteria in the water flowing out of the lagoon have been lower, in some cases more than five times lower, than results from 2015. In two months, May and July, the results meet the requirements of the lagoon’s permit from the Alaska Department of Environmental Conservation. In June and August, tests of the system are out of compliance, though August’s results are not yet official.
This year marks the third summer in which the lagoon has had results out of compliance. This year, the Mat-Su Borough’s Public Works Department has taken a number of steps to bring the system closer to compliance. Starting this spring, borough staff worked to replant the constructed wetlands that wastewater flows through after treatment. The wetlands are designed to provide natural cleaning of the water before it enters the Talkeetna River. Those wetlands were damaged in the 2006 flood.
Terry Dolan, Director of Public Works for the borough, says artificial aeration of the lagoons has been used this summer as well. Gas-powered water pumps circulate the wastewater, which helps oxygen flow. That oxygen flow contributes to the natural process the lagoon uses to breakdown potentially harmful bacteria in the water. Now, Dolan says the plan is to transition to electric air pumps, which he says will be cheaper to run and will require less maintenance from borough staff. The new pump could be installed as soon as next month.
Terry Dolan says another issue that the system faces is infiltration. He says much of Talkeetna’s sewer system is buried below the water table. As a result, small openings in the pipes can lead to groundwater entering the wastewater. Dolan says the pressure differential means that wastewater is not believed to be escaping the system. When the additional water enters, it has to be treated just like what comes from the sinks and toilets in town. That means wastewater is pushed through the system faster than it is designed to. Dolan says the borough has already sealed six manholes where infiltration was easily visible, and that work on twenty more manholes is likely to happen in September. The borough has also purchased equipment that will allow for video monitoring and exploration of the system, which Terry Dolan says has never been completed in the thirty years it has existed.
While that work is proceeding, an assessment funded by the U.S. Department of Agriculture is also underway for the sewer and water system. This comes two years after the most recent state-funded assessment. Dolan says the new study will be able to gauge progress that has been made, and where future work may be needed. If capital improvements are necessary, the assessment will also cover the necessary environmental factors to apply for USDA capital grants.
The USDA study may factor into the resolution of the Department of Environmental Conservation’s notice of violation to the borough as well. DEC officially informed the borough of the sewer lagoon’s permits last year. While negotiations on the ultimate disposition of the violation have been ongoing, the content of those talks has not been made public. After a gap in meetings this summer, Terry Dolan says the borough and DEC met last week to discuss the violation and the steps that have been taken.
Terry Dolan expects the USDA study to be complete by the end of October, which is also the time of year in which the Talkeetna sewer lagoon must stop discharging for the winter. Whatever steps are taken as a result, Dolan says it could be some time before the full results are evident, since the treatment of wastewater in the system takes between eight months and one year.
