The borough has hired an environmental engineering firm to help it decide how best to kill more of the bacteria that rides along in the discharge from the town’s sewage treatment plant before flowing into deep water near town.

The assembly on May 19 approved a $165,000 contract with DOWL, which has worked on several projects in Wrangell over the years, to analyze whether using ultraviolet light or chlorination would be the best system to disinfect the wastewater discharge.

The company’s report is due by Oct 31.

Whatever system the borough decides to add to the treatment plant will be costly. Congress in January appropriated $10 million for the project, but that could fall short of covering the full construction expense.

The plan is to decide on the best system for disinfecting the discharge and then finish final design in 2027, starting construction in late 2027 or early 2028.

“We understand time is of the essence, and the DOWL team is ready to begin work immediately,” the company said in its May 15 proposal to the borough.

Wrangell’s federal wastewater discharge permit, which was approved in November 2024 — along with permits for Haines, Skagway, Sitka, Ketchikan and Petersburg — requires the communities to reduce the levels of bacteria discharged into marine waters.

The six Southeast communities are among about two dozen municipalities in the country granted waivers by the Environmental Protection Agency for a lower level of treatment of their wastewater because the communities discharge into deep marine waters.

The cost of the borough’s contract with DOWL will be covered by a state loan, with the loan program offering to forgive repayment.

DOWL will conduct an engineering analysis of options to add disinfection to the treatment plant to meet the tighter permit standards for bacteria. The analysis will consider construction and operating costs and environmental impacts.

“There are pros and cons no matter which way we go,” Public Works Director Tom Wetor said in January of the disinfection options. A UV system uses a fair amount of electricity, he said, adding that while a chlorine system is cheaper day to day it requires a carefully calibrated mechanical system to add the chemical to the flow.

The borough has until 2030 to meet the new permit requirements. Most likely, the project will include building an addition to the treatment plant to accommodate the additional equipment, Wetor said. The treatment plant is uphill from Zimovia Highway, roughly across from City Park.

The plant’s discharge flows through a pipeline under the highway, extending about 1,700 feet from shore before it dumps into Zimovia Strait at a depth of about 120 feet.