WESTBROOK — Crews hired by the Portland Water District worked Tuesday to remove landslide debris from the Presumpscot River in preparation for a rainstorm expected Wednesday that could threaten two large water mains buried under the river.

The utility hired Shaw Brothers Construction on an emergency basis. Work began last week and continued over several days to clear a 300-yard path to the river. The crews built a temporary roadway through brush and undergrowth to access the site of the landslide, where about 2 acres of soil, trees and mud slid into the river and temporarily blocked its flow Sept. 16.

The river eventually carved new channels through the debris, but the soil and trees extended from the bank and created islands in the middle of the old river channel.

Meanwhile, the Portland area could receive up to 1 inch of rain between midnight Tuesday and Wednesday afternoon. It’s a much needed soaking during serious drought conditions, but the added runoff means more water will be flowing through the constricted area of the river just above the buried water mains dug about 4 feet below the riverbed. The pipes provide water to fire hydrants and act as a backup water supply for the district, which serves 50,000 customers in 11 greater Portland communities.

The district also has a 60-inch transmission water main and a wastewater outflow pipe nearby in the river. Planners with the water district are concerned that rushing water could expose the structures and that debris pushed by flowing water could damage the pipes.

“As the days went on, we were concerned about heavy flows or debris moving into our infrastructure,” Water District Spokeswoman Michelle Clements said.

Clements did not know how much the work will cost the district, which is funded by ratepayers. “We still have to figure that out. We’re kind of in an emergency mode and we haven’t gotten those details hashed out,” she said.

Westbrook City Manager Jerre Bryant said the water district may find some funding later on to help pay for the emergency work, but that is not assured, either.

“At this point, what they’re doing they’re paying for,” Bryant said. “There may be federal emergency management money … but there is no assurance of that, so they are proceeding on their own with their own money to protect their own assets.”

A crew with Shaw Brothers use an excavator to move debris to open up the channel of the Presumpscot River in Westbrook Tuesday Shawn Patrick Ouellette/Staff Photographer

Sappi Fine Paper, which owns a paper mill upstream, has assisted by controlling dams upstream to minimize flow to the area, but Bryant said there are tributaries to the Presumpscot that have no dam control.

“The next couple days are going to be very, very interesting,” Bryant said. “Given that this is a response by committee, we’re trying to move as quickly but as smartly as possible. You’d look at this situation and think there’s simple answers, but there’s a lot of contradictory information.”

Workers in excavators and dump trucks had already cleared about 700 cubic yards of material from the site on Monday, including several whole trees and their root balls that had slid into the river’s path. They moved more loads of mud, trees and soil throughout Tuesday afternoon. They may end up removing more than a couple thousand cubic yards, or about 200 dump truck loads.

The clay that caused the slide is visually distinct from the soil around it, with a gray hue and soft texture, and a funky, organic smell similar to clam flats. While it’s great for making pottery, it has turned the river a pasty gray and its material properties can make it a nightmare for engineers.

“That clay’s really gooey,” said Chris Crovo, director of Asset Management for the water district, who was helping to oversee some of the work at the riverbank on Tuesday. “It doesn’t hold anything. It turns into soup. A hearty soup.”

The focus of the work is on a short section at the center of the landslide, where the flow of the river was narrowed considerably. The smaller area means that the same volume of water will be pushed to move through a narrower space. As a result, the flow speed increases, and with it, the risks of deeper erosion of the underlying riverbed, Crovo said. To slow the water down, the crews focused on an area of the river bank about 30 yards by 100 yards long, he said.

A crew with Shaw Brothers uses an excavator to move debris to open up a channel of the Presumpscot River in Westbrook on Tuesday. Shawn Patrick Ouellette/Staff Photographer

But what remains unclear is what risks there are, if any, to the area just outside landslide’s edges. Excavating and construction company Les Wilson and Sons lost about an acre of property that had served as a storage yard for large piles of clean fill.

Robert Marvinney, the director of the Maine Geological Survey, said a geological survey and study of the area would be the first step in assessing any risks.

“We want to work with other stakeholders, the city, property holders, et cetera, to see if there’s a way to move forward on studies like those,” Marvinney said.

Chris Wilson, who owns the excavation company, said he is still unsure of whether he will undertake any effort to reclaim the property he lost, which included a small salt and sand shed, several snow plows and a literal heap of clean, useful soil that’s used for construction projects. Much of the material remains above the riverbank in the potentially unstable slide area.

“No one wants this to happen to them,” Wilson said. “No one has time to deal with any of it.”

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