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Maine's aging wastewater systems are adapting to new challenges

Gravity is a friend of wastewater treatment plants, which is why the plants are typically located at low elevations, often along Maine's extensive coastline.

Placing them in lower areas makes it easier to collect wastewater from uphill sinks and toilets. And if you place them near waterways, you can easily send filtered and disinfected water or wastewater back into our rivers, reservoirs and harbors.

Many wastewater plants in Maine and across the country were built after the passage of the Clean Water Act in 1972, so some are now 50 years old. They need modernization, not only because of their age but also because of the threat of climate change. Flooding in coastal areas now occurs regularly during storms and high tides.

“Flooding can damage or destroy pumps, blowers and electronics stored in basements,” said Robert Lalli, manager of the Wiscasset Wastewater Treatment Plant. “And when saltwater enters wastewater aeration tanks, it can disrupt the microbiology needed to break down wastewater and other dangerous compounds. Untreated wastewater can then overflow into waterways, harming wildlife and those who make their living from fishing.”

It may also endanger Maine's drinking water sources.

With the help of $40 million in federal funding, Maine communities are finding new ways to deal with threats to their wastewater facilities.

The most common approach is to raise tanks and buildings and make other structural improvements to protect facilities from sea level rise. This occurs along the entire coast of the state, from Kittery to Eastport.

In Machias, for example, a new pumping station will ensure the plant remains operational during heavy rains, which will help prevent sewage overflows like those that caused mussel closures on the Machias River.

“Increasingly severe storms are working against us,” said Mike Riley, the combined sewer overflow response coordinator for the state Department of Environmental Protection. “But the new pumping station, which we hope will be operational by the end of this year, will significantly reduce, if not eliminate, overflows.”

The nearly $3.6 million project was funded largely by a DEP grant.

Machias also plans to install a combination of levees (vertical or near-vertical walls) and berms (raised and sloping banks) that will protect the facility and downtown streets while creating a scenic river walkway. This project is in the design and approval phase, said Dr. Tora Johnson, who runs a GIS lab at the Sunrise County Economic Council based in Machias.

Portland, meanwhile, is installing four underground tanks that will hold millions of gallons of rainwater and wastewater and prevent the plant from backing up – and dumping untreated wastewater into the nearby Back Cove tidal basin.

“These pollution control efforts have been in the works for some time,” said Bill Boornazian, Portland’s water resources manager. “But the need is growing due to sea level rise and regular flooding.”

“The biggest challenge of climate change is the heavy rainfall in winter when the ground is frozen,” Boornazian added. They make the ground “like asphalt,” he said, noting that the new tanks would improve drainage and reduce flooding on city streets.

Portland is expected to begin using the new tanks in December, said Brad Roland, senior project engineer with the city's public works department. He said the project, which began before the pandemic, will cost about $42 million.

The Ogunquit Sewer District Power Plant sits on a long, sandy peninsula between the Ogunquit River and the ocean. At this scenic and sensitive location, a second story will be added to a garage to create more office space and the existing tank walls will be made taller, according to Philip Pickering, the sewer district's manager. The electrical equipment and generator at a nearby pumping station will also be increased.

A chart from the 2012 report “Assessing Sea Level Rise, Storm Surge and Flooding Risks at the Ogunquit Wastewater Treatment Facility.” Courtesy of the Ogunquit Sewer District.

But it's only a temporary solution. A 2012 study concluded that there was “no practical solution” that would allow the site to host a wastewater treatment plant beyond 2052 due to “increased risk from sea level rise, flooding and coastal erosion.” .

Ogunquit is raising money to move the facility about two miles west of its current location. The move, expected to occur between 2040 and 2055, is estimated to cost $30 million.

Facing a similar dilemma, Wiscasset officials hope to relocate the city's facility once a suitable location is found. The current location on the Sheepscot River is “the lowest point in Wiscasset,” Lalli said.

“There was salt water coming through our gates and into our tanks,” he said. “A seawall is impractical. If we just moved forward three or four blocks we would be fine.”

If officials find a site near the current location, it will cost about $35 million. If the new site is further away and requires additional pipelaying and pumping stations, the cost could rise to at least $45 million, according to Lalli.

Lynda DeWitt

Longtime editor and author Lynda DeWitt has written about natural history for many organizations, including the National Geographic Society, Discovery Communications, Scholastic Productions, and Smithsonian's National Academies of Sciences. She is the author of “What Will the Weather Be?” and divides her time between Maine and Maryland.

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