(l to r) Matt Claise, Rick Waterson and John Butts talk with an inspector (far right).
The Sunset Lake Dam Rehabilitation Project in Ashburnham, MA, is now complete, just in time for the cold New England weather to set in.
The $300,000 job, which was started in October 2008, took just two months from start to finish.
A crew of four was on the site daily working on the reconstruction of the dam that stood 7 feet high, 6 feet wide and 50 feet long.
According to New England Infrastructure Project Manager Jason Mauro, the crew went in and demolished the dam.
"We crushed up the concrete with a Doosan 225 excavator and a Cat 315, and the materials were hauled to Powell’s Sand and Gravel in Lancaster, MA," Mauro said. "Then we reconstructed the dam out of concrete. The biggest obstacle on the job was dealing with the water and keeping a dry work zone. We were able to accomplish this through the use of the Portadam and strategic location of sumps pumps."
Mauro said the new dam is 1 foot wider than the original dam and is made out a 4,000-psi, 3/4-inch stone mix.
A key player in the process was Portadam, specializing in the construction of a temporary, portable cofferdam used for construction, rehabilitation, flood protection, and inspection projects in rivers, streams, lakes, reservoirs, and other retaining areas.
According to Portadam CEO Bob Gatta, the system utilizes a steel frame structure, which supports an impermeable fabric liner, forming a wall capable of holding back up to 10 feet of standing or running water.
"By allowing water to be temporarily diverted, areas that were previously hazardous or hidden underwater are dry and easily accessible for work and repair," Gatta said. "Our Portadam team worked in conjunction with New England Infrastructure to ensure the swift progression of the project."
Gatta said divers go into the water with steel forms and nylon-reinforced PVC material during the construction of the Portadam.
"We went from one point of the dam to the bank," Gatta said. "We had 72 linear feet and tied the part of the dam that was good into the bank area so that we could pump out the water that was close to the other side. Then we pushed the water back by building the coffer dam."
Gatta pointed out that historically people used to dump rocks and dirt to make a coffer dam.
"But they can’t do that anymore, so this system has gained great popularity in the last five years," he said.
Gatta said it took three laborers to build the dam – three days to install and it will take two days to remove.
"Everything that goes into the water comes out of the water," Gatta said. "We put it up with socket wrenches and pliers, and the process is one-half the cost of sheet-piling."
Upon the completion of each project, Portadam is completely removed from the site to be reused elsewhere, making it environmentally preferred over sandbags or cumbersome cofferdams.