Wrangell is one of nine Alaska communities operating under old federal permit waivers from costly secondary treatment for its sewage water discharge, and officials expect the upcoming permit reissuance will require the community to disinfect its wastewater before piping it into Zimovia Strait.
“Everyone says the same thing … disinfection is coming,” Tom Wetor, the borough’s Public Works director, said last Friday. “It’s been reiterated to us multiple times.”
Construction and installation of a disinfection system could cost around $2 million, said Randy Bates, director of the Water Division at the Alaska Department of Environmental Conservation.
“For us, a couple million dollars is a big deal,” Wetor said.
In addition to construction costs, a disinfection system, whether adding chlorine to the wastewater or using ultraviolent light to kill bacteria, would add operating expenses.
“Each one has pros and cons,” Wetor said.
The borough is waiting on federal and state decisions on the sewage treatment permit reissuance before spending money on system designs and choosing the best option. The state expects the U.S. Environmental Protection Agency to issue its draft permits for Wrangell and Sitka this month, Bates said last Friday. Those decisions would set a pattern for other communities in Alaska, he explained.
“Disinfection is incredibly effective,” Bates said, though he noted it’s frustrating “anytime we have a reissuance of a permit” that adds costs in the community.
“We’re trying to find avenues of funding” to help communities pay for the upgrades, he said. That could include low-interest state loans.
EPA permit waivers from secondary treatment under the 1977 Clean Water Act go back years in Alaska, Bates told a legislative committee in April. Of the 45 remaining waivers nationwide, nine are in Alaska, he said.
The federal agency “has not taken a look (at these waivers) in a number of years,” Bates told the Senate Finance Committee. “It’s long overdue.”
Standards to obtain a waiver include removing some of the bacteria that consumes oxygen out of the water, removing solids, controlling toxins and monitoring discharge water. And a community must meet state water quality standards at the edge of its mixing — dilution — zone in deeper waters.
In coordination with the EPA permit for each community, the state will review its accompanying discharge permit for the mixing zone. Success for the state and the communities would be reissuance of the federal permits and disinfecting the discharge to meet state water quality requirements, Bates said.
The Wrangell sewage treatment plant, uphill of City Park, removes solids from the wastewater stream and introduces “biological activity” in its aeration ponds, essentially good bacteria eating the bad bacteria, Wetor explained.
The plant, which is about 20 years old, does a good job of removing fecal coliform and other bacteria, he said, though it’s not as complete as full secondary treatment. The discharge is tested monthly, and last month’s results showed 75% of harmful bacteria removed with primary treatment and aeration, Wetor said. It generally ranges between 40% and 90%, depending on water volumes and other factors.
The EPA waivers allow communities to discharge into marine waters without building and operating larger and more complex treatment plants to clean up wastewater to significantly higher standards than primary treatment and disinfection.
Secondary treatment plants can run into the high tens of millions of dollars or more, even for smaller communities. In addition to Wrangell, municipalities with EPA waivers are Ketchikan, Petersburg, Sitka, Pelican, Haines, Skagway, Whittier and Anchorage.
Adding disinfection to the Ketchikan borough system could cost $15 million, not counting operations and maintenance, Bates told the committee.
The discharge pipe from Wrangell’s sewage treatment plant extends about 1,700 feet — one-third of a mile — into deeper water in Zimovia Strait, near City Park and Heritage Harbor, Wetor said. The treatment plant handles all of the wastewater that flows into the borough-operated system from about 6 Mile to the north end of the island.
Reader Comments(0)