More than 24 hours after the sewage began flowing in the St. Lawrence River, city officials say the work is going about as well as expected.

Mayor Denis Coderre entered the construction site on Thursday so he could see firsthand what is being done, a move that city hall opposition party Projet Montreal dismissed as a publicity stunt.

The mayor wore protective clothing, a mask and had to make sure his hepatitis and tetanus vaccines were up to date before being lowered 35 meters into the sewage interceptor.

“It's black you don’t see anything, that’s why we have a light. There's some smell, we had a foot of water and some… other things in there,” he said.

Work on schedule and going well

Construction crews entered the underground interceptor around noon on Wednesday and Coderre followed about a half hour later as the 30 km of sewage lines leading to it were drained and dried out.

By nightfall they had already managed to remove one of the rotting support beams and begin its replacement. It's work they will have to repeat over and over again until the collector is secure and no longer in danger of collapsing and destroying Montreal's water treatment plant.

Richard Fontaine, who oversees waste water management for Montreal, said work is going well.

"I got the first call back, not a pretty sight. So we're doing what we should be doing," said Fontaine.

He says while the tunnel itself is in good shape, he saw a lot of rotting wood and steel around the supports. There were also some pieces that were detached, and could have made their way to the water treatment plant, which could cause bigger problems.

As Coderre was underground, the new prime minister opened the door to helping with the cost of this repair and future ones. Justin Trudeau spoke of his plan to give cities $20 billion over 10 years for green infrastructure projects and specifically mentioned the Montreal interceptor.

But his critics say the mayor had no business going doing what he did.

"Everytime there's a crisis, Mr. Coderre's answer is 'Let me put myself in front of a [camera]," said Guillaume Lavoie, a Projet Montreal councillor.

Collecting larger waste

Booms are catching some of the larger items coming out of sewage drains, but a stinky froth can be spotted in several locations.

Montreal has hired Urgences Marine to collect what it can.

"If there's big residues, big parts, pieces, you know, we pick that up," said Richard Kobel.

Water samples are being taken every two days at every dumping station, but it takes 24 hours to process the results.

The first results should be available in 72 hours.

Protests continue

For the second night in a row, a small group of protesters blocked access to the Mercier Bridge to show their opposition to Montreal's planned dumping of raw sewage. The protest started late Wednesday night and the bridge was re-opened several hours later.

Protesters said they were hoping to gather 200 people in order to shut down the entire bridge, but only two dozen opponents showed up

Projet Montreal leader Luc Ferrandez was not at the protest, but was one of many voicing his opposition to the entire project.

"The mayor has decided he would rule this with authority not with listening," said Ferrandez.

Coderre reiterated that as disgusting as dumping 8 billion litres of untreated sewage can be, the city's only other option was a catastrophic failure of the water treatment centre.

"Nobody is pleased with that situation but we have to do it and it's to enhance our own structure for the treatment," said Coderre.

The work will continue 24 hours a day until it's done.