A massive water transmission line replacement project was recently completed in upstate New York – one of the most consequential and important infrastructure projects the city has undertaken in a century, according to one mayor.
The John P. Buckley Water Treatment Plant services the city of Troy and portions of Rensselaer, Saratoga and Albany counties and is located just 7 miles from the Tomhannock Reservoir. Flows to the water plant average 20 million gallons a day, with the flow peaking in summer months to approximately 29 million gallons a day. The plant provides safe drinking water to over 120,000 residents in 10 cities, towns and villages.
In Troy, there were two transmission mains that ran in parallel to the reservoir intake: a 30-inch cast-iron main installed in 1906 and a 33-inch riveted steel main installed in 1914. In the 1960s, the water plant was constructed and these two mains were connected to the 60-foot concrete main that feeds into the water plant. They were cleaned and lined with cement in order to increase flow and reduce friction within the pipe. Direct feeds from Troy residents and surrounding communities were also intercepted and became transmission mains to the water plant.
After taking over his post in 2012, Chris Wheland, Troy’s superintendent of public utilities, began to look at the infrastructure of the mains to determine points of critical replacement. “The transmission mains aren’t only critical; the riveted steel main is difficult and time-consuming to repair if breached. We started to acquire easements and property in 2014 for the replacement of the original 30- and 33-inch mains.”
However, Wheland continued, in January 2016 the riveted steel main in the distribution system ruptured and severely impacted the towns of Halfmoon and Waterford, limiting flow and pressure for domestic use and fire protection.
“This one mile of distribution pipe was replaced in 2017. It brought attention to the remaining 6 miles of the riveted steel main on the upstream side of the water plant. Much of this raw water line is under pressures of well over 100 pounds per square inch and was installed the same year as the distribution main that ruptured. It quickly became evident that the raw water lines need to be replaced.”
Since the city was already in the process of acquiring property for replacement and designing the new mains on a different track, new raw water lines were added to the project.
Design work for the project was granted to CDM Smith. Aspects taken into account for the design of the pipes included construction materials such as high-density polyethylene, ductile iron or steel, hydraulic capacities and pressures, increasing flow for future expansion and the inability to take the current lines out of service. After the design was complete, the project was bid on and awarded to Luizzi Brothers Construction.
All materials larger than 16 inches, such as pipes, valves and fittings, were purchased by the city. The contractor coordinated with manufacturers on delivery and installation. The next 18 months were spent on construction, much of which took place on abandoned railroad tracks where underground utilities were absent. The tracks were simply removed.
“The project extended the new mains from a location that we could connect to the water plant’s 60-inch main and remove all previous connections of the 30- and 33-inch mains,” Wheland explained. “There were many road crossings and an area where we had to relocate a 12-inch potable water line for the installation of the two new 36-inch mains. The project terminated in a location where the existing mains were able to be intercepted with the new mains.”
The project encompassed about four miles of dual 36-inch main installation.
“Installation was the easy part. Much of the time and stress was spent on tying in the new mains and keeping flow going to the water plant,” he said.
Wheland described planning for the project as critical and nerve-racking.
“On the termination point to the north, we had to rely on early 1900s valves to shut down so we could properly cut and fit the new mains. This process took many days so that we could make sure we operated the valves in such a way to maximize the shutdown and minimize the chance of breaking a valve.”
In order to convert the 33-inch steel to a 30-inch ductile iron line, the steel main required a welded fitting and was converted to a 30 by 36 reducer into the new mains. At the south termination point, there was a combination of 30-inch, 33-inch, 48-inch and 60-inch fittings tied together to flow to the water plant. All fittings prior to the 60-inch main were eliminated and rebuilt with new mains. This necessitated a 36-inch bypass installed to the backside of a 60-inch linestop to keep flow to the water plant.
After the linestop and bypass were installed, all previous piping was dismantled and a new welded collar to the 60-inch concrete steel collar was installed. This installation extended to a 60-inch by 36-inch wye pipe, with the 36-inch wye pipe connecting to the new 36-inch main. The previous 30-inch cast iron main also had a reducer and wye pipe connected in order to connect to the 60-inch main; however, the cast iron main was connected as a redundant line via a reducer to the new main since it can be easily repaired and will provide for future opportunities.
“The project is currently at 99% complete and all pipe and fittings are connected and operational,” Wheland stated. “There were only five days where flows were critically low but we were able to manage the distribution system by working with our surrounding communities and managing all flows.
“We still have a northern portion to complete and are currently at 30% design. This portion will include about two miles of pipe where the last mile will be tunneled at a depth of 50 feet to tie into the existing rock tunnel. We anticipate this to be out to bid early winter 2023 for a spring start in 2024.” At one point during the process, Troy Mayor Patrick Madden said the project was “one of the most consequential and important infrastructure projects the city has undertaken since the water treatment plant was built over half a century ago.” He expressed confidence that the monumental undertaking would “ensure a reliable flow of water for at least another 250 years.”