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Groton Water Treatment Plant upgrade more than halfway complete

Groton — When the original Groton Utilities Water Treatment Plant was built, operators used candlelight to measure the cloudiness of water in a vial, and water regulations fit on a single page.

Now, at a time when lasers count every particle and regulations have increased, a project to upgrade the plant and its aging infrastructure is more than halfway completed.

The $54 million project, which received a $15 million state grant, includes constructing a new nearly 20,000-square-foot building for treating and processing water and two new above-ground storage tanks, while repurposing elements of the 1939 facility, according to Groton Utilities. R.H. White Construction Co. of Massachusetts is the general contractor on the project.

During a tour of the plant, Rick Stevens, manager for Groton Utilities in the water and wastewater division; Senior Water Treatment Operator Mike Hedman, the design team leader; City of Groton Mayor Keith Hedrick, who also is chairman of the Groton Utilities Commission; and Daniel Bouges, Groton Utilities' manager of communications and community outreach, showed The Day the work so far and went over the history of the facility and the new upgrades.

Stevens said the upgrades to the plant, which are expected to be completed next year, incorporate measures for redundancy, resiliency and energy and water conservation, as well as new technology for processing and treating water.

"It's amazing, the technology to make a glass of water," Hedrick said during the tour.

New uses

Rather than just demolishing the existing plant and building a new "cookie-cutter" one, Groton Utilities is repurposing elements of the existing plant. An old settling basin will become a chemical pump room; filtration spaces in the existing plant will turn into locker rooms, an electrical room and a space for secondary filtration of manganese; and an old switch gear room will serve as a training/conference room, among other features that the GU representatives pointed out during the tour.

As part of the project, another building, a 1909 pumping station, was retrofitted into a public health laboratory.  

The water treatment plant project includes upgraded mechanical and electrical systems.

Hedman showed how the water treatment plant had been added on to over the years with new units since 1939 and original filters were decommissioned.    

While the plant was improved and uses the best available technology, the upgrade project calls for implementing more advanced technology in an integrated manner, Stevens said.

Hedman pointed out the new switch gear room, and the old switch gear room where the equipment had become outdated, requiring utility officials to go on eBay to find replacement parts if anything broke.

Paul Hyatt, work leader, compared charts from the 1939 control room to the computer system now used in the current control room. While some of the current computer system is automated, the upgrade project will go a step further and include a fully automated system that still will require maintenance, but a different kind, he said. Under the new system, operators will be able to better pinpoint any issues, monitor trends and more easily control pressure levels.

Treatment, filtration

Just as the existing plant was considered state-of-the-art when it was built, the new plant is designed with advanced technology to better remove "emergent contaminants," such as manganese and algae by-products that currently aren't regulated as primary contaminants, Stevens said. He said the existing plant is fully compliant with existing regulations, but officials wanted to prepare for what could be coming down the pike.

"We're regulatory compliant now but in the future if the regulations became more stringent, then we'd be better prepared to meet the health standards," Stevens said.

At the new water processing and treatment facility under construction, they showed the new dissolved air flotation, or DAF, units that remove organic matter from source water.

Water enters the units from tanks called saturators that create microbubbles in the water, Hedman said. The bubbles expand when atmospheric pressure is reached and attach to organic matter in the unit, causing the matter to float up and form a foamy layer on the surface. An automated "mechanical arm" running on a rail then pushes off the top layer, leaving behind clear water on the bottom that can be moved to the next step of filtration.

Stevens said the new technology allows for more process control and is more energy-efficient. One of the advantages is that it more efficiently removes algae from the water while avoiding the potential of splitting the cell wall. Some types of algae can release byproducts, some of which are considered emergent contaminants, when their cell wall is split.

The facility also contains new deep-bed Granular Activated Charcoal filters to improve taste and odor and remove organic materials, Stevens said. The filters will more efficiently remove synthetic organic chemicals from products such as Teflon and Scotchgard, considered to be emergent contaminants, he said.

Groton Utilities also is adding secondary filtration measures to better remove manganese, and is upgrading its corrosion control treatment, he said.

While the existing plant is fully meeting current regulations, the project also calls for better removing byproducts from disinfection, which will make Groton Utilities prepared if regulations become more strict in the future, Stevens said. In addition to the new treatment plant, the utility is installing enhanced systems in the tanks of its distribution system that improve the removal of byproducts from disinfection by 40 percent. Groton Utilities has added the new systems to tanks at Bailey Hill and Walker Hill and will be doing modifications to other tanks "one at a time," as needed, he said.

"When this water treatment plant is put online, with the state of the technology that we're using, the advanced technology that we're using, we will be able to meet technical requirements that have not even been written yet, into the future," Hedrick said, "so this will be a state-of-the-art plant that will meet regulations for the next 50 to 75 years or more. That's how forward-thinking this plant is, and a lot of that is due to the employee input."

Hedrick said the contributions of employees, who provided original ideas for the design and capabilities of the water treatment plant prior to the engineers becoming involved, can't be overstated.

The employees toured other plants to gather ideas on new technology, went to training seminars, and consulted with experts, Stevens said. "This project, the ideas, came from the individuals that are doing the job as certified operators for the state of Connecticut," he said.

The project also was a long time in the making, with Groton Utilities conducting a pilot study in 2008 with a small version of the DAF unit inside a trailer, Hedman said.

The upgraded plant is designed to be as green as possible, Hedman said, with features such as variable frequency drive pumps that allow operators to control the pump's output, depending on the need, rather than simply having one that operates on a set level and only switches on and off. Stevens said the equipment not only saves energy, but also allows operators to dial in the chemical treatment.

Another example is the use of a static mixer, a pipe with veins inside of it so that as the water travels through, it is swirled and uses no energy, rather than using an energy-intensive mixer with a motor, Hedman said.

Stevens said the plant was built for resiliency, from cladding around the structure to make it more energy-efficient and storm-hardened, to redundant features, including two emergency generators and backup equipment.

Two new concrete, one-million-gallon, above-ground water storage tanks will make the plant more resilient and provide more water capacity for firefighting, they said.

In addition to the water treatment plant project, Groton Utilities recently built a new 2.2-million-gallon capacity Walker Hill water storage tank, which includes the system to better remove disinfection byproducts and also increases storage by 40 percent, according to Bouges and Stevens. The tank is in service, with just some minor work at the site remaining.

Stevens said the water treatment plant upgrade project received the $15 million state grant and a 20-year, low-interest federal loan administered by the state for the rest of the project cost, both because of the current plant's aging infrastructure and because Groton Utilities is a regional provider. The plant, which stands next to Poquonnock Reservoir, the terminal reservoir at the bottom of a cascade of reservoirs in the watershed, serves customers in the City of Groton, Town of Groton, Ledyard along the Route 117 and Route 12 corridors, and Montville and the Mohegan Tribe, and has an interconnection with Aquarion's Mystic division to supply water as needed.

Bouges said the state grant's conditions included the requirement that Groton Utilities create interconnections with Southeastern Connecticut Water Authority through Ledyard's water system and an interconnection to Norwich Public Utilities, also through Ledyard's water system, that can be used in emergencies, which adds resilience to water systems in southeastern Connecticut.

"We are the recipients of the good planning from 1939, from the original plant, and now we're going to go into the next millennium for excellent water quality for the public, and it's a mark of dedication and loyalty to the people of Groton," Chief Plant Operator Joe Nasiatka said.


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