What began as an otherwise nondescript Thursday afternoon in mid-February 2018 in a municipality near Washington, D.C., ended with an unexpected catastrophe that area officials were not prepared to handle alone. A 20-inch cast iron pressurized sewer main ruptured at a Maryland wastewater treatment plant, with the end result being a substantial health and environmental crisis that required immediate attention.
The Washington Suburban Sanitary Commission (WSSC) and Maryland Department of Environment (MDE) were notified and called in, as were emergency maintenance crews employed by the wastewater treatment plant and Ross Contracting, Incorporated. Everyone quickly agreed that this was a much larger issue than they could repair on their own. This was going to be a serious multiday project that would require outside help and heavy machinery.
They relied on a manufacturer of pumps and related equipment that also provides engineering expertise for construction dewatering, bypass and emergency operations.
“When we arrived, there was no equipment on-site, but once we were advised of the situation we immediately knew we had to react and get control of the situation,” said Howard Brown, a representative of the pump manufacturer. “With the help of both Ross Contracting and the municipality itself, we determined the flow of the treatment plant was 12 million gallons per day (mgd) based on the existing conditions. We mobilized four dry-prime pumps with 1,200 lineal feet of 8-inch quick connect pipe, which allowed us to route the wastewater into a nearby overflow/retention lagoon. Everything was installed by 11 p.m., and the immediate issues were under control.”
This was a major victory by anyone’s standards, but Brown knew the solution was only temporary. The wastewater continued flowing and, within a day, the retention/overflow lagoon was already getting close to maximum capacity. The team deployed five additional 6-inch dry-priming pumps to move the contents of the first overflow lagoon into a second one, increasing the holding capacity of the sewer. While this was another essential milestone, it was also another short-term solution. The good news was that it allowed the teams to take the first step forward in the overall restoration process.
Before anything could be repaired, the existing sewer lines needed to be inspected to allow the team to understand the extent of damage that occurred in the line. The engineers, along with the team of city employees and the contractor concluded that the construction of a 30 mgd bypass was needed to allow for the required inspection and, ultimately, repair of the existing sewer line.
The decision was made to begin the construction of the bypass immediately. Pumps and pipe would need to be installed, diverting the sewage from the influent pump station to the grit facility.
The next morning, the massive multiday undertaking began. Six 12-inch dry-prime pumps and three discharge lines (each measuring 2,000 lineal feet) were mobilized at the site. A forklift, two skid steers and two fusion machines were also brought in. Light towers were set up to ensure the safety of the workers, who routinely worked long hours, often deep into the night.
“The entire system took six long days to set up, and then the bypass began,” Brown said. “As much as we would have liked to have done it more quickly, you simply cannot rush the pipe fusion process, which creates an exceptionally durable bond (making them much less susceptible to leaking). In our line of work, particularly in a job as big and complex as this one was, it is vital that everything works as it is supposed to. We also had to make sure we were always in compliance with the government’s guidelines, eliminating spills or sewage leakage and ensuring that our team was working safely.”
All three of the discharge lines/pipes were installed above ground. Because this part of the process was trenchless, it allowed the team to complete the project in a shorter time frame. From beginning to end, the crews operated the pumps around the clock, monitored the system and fueled the equipment being used to perform the bypass.
The project lasted about 30 days without disruption.
Pump technicians were assigned two important tasks. First, they conducted hourly checks, allowing them to promptly spot any irregularities. Second, they were charged with quickly and efficiently repairing mechanical issues and releasing the occasional clog. In addition to installing the 16 dry-prime pumps with sound enclosures used to pump the sewage and the 8,000 lineal feet of pipe and hose, Brown says it took thousands of man-hours to install, operate and, once complete, tear down the project.
The opportunity to play an instrumental role in restoring systems like this one is what motivates Brown to do his job each day.
“It is such a fantastic feeling when everyone tells you how grateful they are to you and your team for solving what was a very serious problem—and hearing about how they couldn’t believe how well our trenchless bypass system worked,” Brown said.