Diving deep: The unseen work that keeps sewers and wastewater systems flowing

In Ohio, a municipality was gearing up to perform assessments on its sanitary collection system.

As with most sewer assessments, the municipality wanted to establish realistic goals, budgets and schedules for its Capacity, Management, Operation and Maintenance (CMOM) program.

Upon inspections, the municipality realized it needed a better eye on one of its 96-inch concrete sewer mains.

Project requirements

The municipality chose Bulldog Diving LLC., to conduct the large sewer assessment. The job quickly proved to be intensive. It required a visual inspection by safely lowering a technician into the sewer main, through a manhole entryway that ranged up to 14 feet high.

Once inside, divers would need to gather core samples from the eight-foot diameter line. Job specifications required a six-inch core sample, which proved an additional challenge due to the structural rebar in the sewer line.

Bulldog Diving

Lowering men 14 feet into the sewer to take core samples was no easy task. In fact, the work would take long enough to require the diving team to wear enclosed operating helmets (positive air masks) with fresh air supply.

The intricacy of the job was part of the reason this diving team was chosen.

Bram Williams, founder and president of the company, went to dive school before working in Maine and New Orleans as a commercial diver for the inshore industrial market.

“It started down in New Orleans,” said Williams. “It’s an incredibly heavy industrial area as far as diving. So, you get a little bit of everything along the Mississippi. We did chemical plants, sugar plants, powerplants, papermills – any of the large water users.”

After moving around some more, Williams founded the company under a different name in 1991. The company now employs about 25 to 30 employees.

“There’s not a lot of companies that are interested in working in a sewer,” Williams said.

Williams stated that the company also does work in live sewers. The company gained recognition, and even had clients on the East Coast reach out for help saying that they couldn’t find any other divers that were willing to do work in a sewer.

Williams’ team is called out for situations that municipalities cannot handle themselves.

Diving in: 96-inch sewer main in Ohio

Back in Ohio, at the 96-inch sewer main site, the diving team prepared to go in.

“I think the company that hired us had done an assessment of thousands of miles of sewer lines,” Williams said. “Then they took the worst ones, and they hired a team to go in there physically to get some sampling done.”

Once lowered in, the dive team would be required to take multiple tests and samples of the system.

The first being a spike test, where a team member would take a stainless-steel spike and smack it into the wall of the system with a 5-pound hammer. The team would then measure how far the spike went into the wall to determine the degradation of the concrete. They did the test five times upstream and five times downstream of the manhole, requiring the divers to traverse roughly 100 feet in each direction.

“Once we got the spike test done, it all had to be recorded and ID’d,” Williams said.

Next up for the team was retrieving core samples. Divers had to take one core sample upstream and one core sample downstream just above the observed water line.

“They wanted it 3x6, so 3-inch diameter and 6-inches long,” Williams said. “There were times we couldn’t get one that long, maybe 4- or 5-inches, sometimes they were longer, but it would be in that range.”

Like the spike test, the core samples had to be recorded. Everything from size to location of the sample. The samples were then placed into a sealed bag. Once the core samples were pulled the team filled the holes with no shrink grout.

Following the core samples the team were required to do a graph test.

“We take a battery-powered hammer drill and basically chisel off a 2-inch square of concrete that we capture into a glass jar and label,” Williams said.

Outside of those tasks, the team also completed a visual inspection of the pipe itself. The divers noted highway wire showing, cracks in the pipe and visible water coming through.

Back on land: Analyzing samples and relaying observations

Once the team completed patchwork on sample sites, recorded data and finished their visual inspection, they headed back to the surface.

The marked samples and data were then sent out for analysis so the municipality could determine the next steps.

“We’re a small company, but we have the ability to do complicated jobs,” Williams said. “We often get calls to do jobs that either other dive companies wouldn’t do or failed at doing.”

Williams' more than 40 years of industry experience, along with the company’s skilled team, made this project feasible.

“We don’t shy away from jobs like that,” Williams said. “We figure out how to do them first before we accept them. Once we figure out how to do it with a high rate of success we will accept the job.”