A crane hoists material Thursday onto the banks of the Kennebec River in Augusta for a pipeline installation project being conducted across the tidal waterway for the Greater Augusta Utility District. Andy Molloy/Kennebec Journal

AUGUSTA — Since 2016, any sewage coming from the east side of the Kennebec River to the Greater Augusta Utility District’s treatment plant on the west side passes under the river through a lone 20-inch pipe installed in 1962.

That pipe became the only way to move wastewater from the east side of Augusta across the river for treatment after a smaller, 8-inch pipe, placed at the same time as the still-functioning one 60 years ago, was discovered to have a leak while it was being cleaned in 2016.

Right now, as part of a more than $8 million project, crews are working to dig an underwater trench across the riverbed where two new, 16-inch pipes — one for wastewater, one for drinking water — will be installed underground. The pipes will provide redundancy to the water system and ease officials’ concerns by adding a second pipe to handle sewage from the east side, in addition to the 1962 pipe.

“Right now we only have one operational sewer line, the 20-inch, 1962 cast iron pipe. When that 8-inch line failed, it kicked off this whole thing,” Andy Begin, assistant general manager of the Greater Augusta Utility District, said. “We’re surviving on the hope the other one doesn’t break.”

If the lone existing pipe were to fail, district officials said they won’t have any way to move wastewater from the east, where 20%-30% of its flow comes from, to the west side of the Kennebec. So, it would pollute the capital region’s landmark river instead of being treated.

Crews have from Sept. 17 to Nov. 30 to finish their work in the river, according to the permit for the work. The project could not get underway until after sturgeon would be in the river to spawn.

An excavator and crane, working from barges, will dig the underwater trench, carefully scooping up the river bottom and, without taking it out of the water, place it next to the trench so most of it can be reused to fill the trench back in once new, high-density polyethylene pipe has been set at the bottom. The operators of the heavy equipment doing the digging will be guided by global positioning systems to ensure they don’t get off course.

It will be the first time a district project has required crossing the river with new pipe underground since the old cast iron pipe was installed there in 1962.

The approximately 750-foot-long river crossing portion of a larger, $8.16 million water and sewer infrastructure project is expected to cost nearly $2.3 million.

When it’s done, a future phase of the project will, with the two new pipes in use, resurface the inside of the remaining 1962 wastewater pipe, extending its life.

The water line to be added as part of the project will provide redundancy to the drinking water system, connecting the east and west side systems with an additional water line.

And the old 8-inch pipe will be repurposed, and used as a sleeve for a regional fiber optic communications line running under the river which Begin said will be used by the state, county and city, and may also include use by private entities to house communications infrastructure.

Begin said the old, cast iron pipe has a lifespan of 20 to 75 years and the new pipe is expected to last between 75 and 100 years.

Funding for the entire, $8.16 million project comes from multiple sources.

About $2.4 million was borrowed by the district to do the work. A rate increase in July — a 10% hike in water rates and about 30% increase in sewer rates — was meant to help pay for the project. Begin noted the 30% jump in sewer rates came on the heels of, in 2019, a 29% decrease in sewer rates.

Contractors assemble sections Thursday for barges to cross the Kennebec River in Augusta to install pipelines to cross the tidal waterway that intersects Augusta. Andy Molloy/Kennebec Journal

The rest of the project will be funded by grants and loans that will be forgiven, Begin said. They include $3 million in federal American Rescue Plan Act funds passed on through Kennebec County, and grants from the Maine Drinking Water Program, Northern Border Regional Commission, and the state Clean Water Revolving Loan Fund.

The project has been in the permitting process for two years. That process involved having divers go into the river, which at its deepest point in the crossing is about 20 feet deep, to check for endangered animal and plant life there.

The river is expected to remain open to travel by boats other than for one day. That’s the day, Begin said, workers will bring the new pipe, which will be fused together onshore, out across the river. The new pipe will float, but will be filled with water to sink it down into the trench, where it will be buried. Temporary poles will be placed in the river, every 100 to 150 feet, to help hold the pipe in place before it is sunk and buried under six to seven feet of soil.

Begin said some sediment is likely to escape the worksite, but he anticipated a loss of less than 10% of the materials they take out of the trench. He noted preventing sediment from leaving the site is made more challenging by both the current and tidal flow of the river.

The project site is about 60 feet north of the existing two pipes.

District officials had hoped to bring the new sewer line under the river by horizontal drilling, but efforts to do so in 2018 failed because the material under the river — including rock and cobble — was too loose and collapsed onto itself.

The remaining phases of the project, after the river crossing itself, will include bringing the pipes under train tracks and the Kennebec River Rail Trail on the west side; installing new pipes on the east side of the river, replacing outdated pipes in the Hospital Street area and connecting the new water line to the utility district’s treatment plant on Jackson Avenue; and connecting the new fiber communications lines. It is expected to be completed by December 2023.