Universities and the water profession have long collaborated to bring innovative and effective treatment technologies to the field.

But it’s not often that the two institutions share the same site and work together to deliver clean water to both municipal and campus users.

That’s the case at a new zero-discharge water treatment plant that serves students and staff at the University of New Hampshire and the 15,000 residents of the town of Durham.

“About 55% of our consumption is at the university, though that population is seasonal,” says Matthew O’Keefe, former director of the school’s Department of Energy and Utilities, who recently moved on to another position. “The remainder is in the town.”

Ownership of the raw water sources and the distribution system is shared as well.

The plant is operated under a contract with Woodard & Curran, which designed and built the facility in a partnership with Waterline Industries. The project won the Silver Engineering & Excellence Award from the New Hampshire chapter of the American Council of Engineering Cos. It also earned a New England Silver Award from the Design-Build Institute of America, and a Bronze Engineering Excellence Award from the ACEC of Massachusetts.

A NECESSARY CHANGE

For years Durham drew raw water from the Oyster River and treated it at the Arthur Rollins Water Treatment Plant, built in 1935. That plant’s age and condition as well as the university’s zeal for sustainability prompted construction of the new facility, which is only the latest in a series of measures in the community and the school to make the infrastructure more resilient.

The new plant continues to draw source water from the Oyster but supplements it with higher-quality water from the Lamprey River south of the town. In a unique setup, Lamprey River water is also used to recharge and store water in the aquifer through basins at Spruce Hole. In turn, the Spruce Hole well can provide water when the river flow is below specific thresholds.

It’s a way for the university and the community to help protect water resources and the environment, while still supplying source water during drought. Once at the plant, the water undergoes a series of carefully selected treatment processes. First, water from the different sources is blended. Online analyzers (Hach and Chemtrac) monitor flow, pressure and the changing raw water quality of the different streams.

In the chemical pretreatment stage, polyaluminum chloride promotes coagulation. Sodium hydroxide is added for pH control and, if needed, potassium permanganate can be added to help remove naturally occurring manganese. The flocculation-coagulation step follows; the speed of mixers (SPX Flow) is closely controlled to keep the floc together.

Flowmeters help plant operators direct the water to three separate process trains. The design ensures complete redundancy in case one train, or one basin or piece of equipment, requires maintenance or emergency repairs. “Process and equipment redundancy and flexibility are critical in both water and wastewater treatment operations,” explains Rob Little, national practice leader for drinking water with Woodard & Curran. 

SETTLING OUT

Water exiting the mix and flocculation stage is directed to one of three clarification basins, where inclined plate settlers (Meurer Research), allow solids to collect on the plates and slide off into collection troughs at the basin bottom. Clarified water flows over weirs to the filters.

“The plate settlers are very efficient, and provide a much greater surface area for settling in a much smaller overall footprint than conventional clarifier basins,” says Little.

The four filters (Leopold) consist of 36-inch-deep beds of anthracite and 10 inches of fine sand. Extra filter depth is available in case granular activated carbon needs to be added in the future to deal with emerging contaminants. Sodium hydroxide can be added for additional pH control; blended phosphate protects against corrosion in the piping.

Chlorine is added for disinfection and fluoride for dental health. The flow is then pumped to the distribution system, a portion of which is owned and maintained by the town, and the remainder by the university. A state-of-the-art SCADA system (GE iFIX) controls the plant, allowing it to operate remotely while regulating and monitoring the incoming raw water streams and effluent water quality. 

CAREFUL VIGILANCE

The plant is staffed with two full-time operators and one part-time specialist, notes Joe Geary, area operations manager with Woodard & Curran. Mike Sullivan is plant manager, John Ciaburri is water treatment plant operator and Glenn Sutson serves as the specialist on site about two days a week.

Geary explains that the three raw water sources make it necessary to constantly and carefully monitor incoming water quality: “We wanted a plant that was as robust as it could possibly be, able to treat widely varying water quality and flow rates,” says Geary.

“The quality of the Lamprey is good, though variable. The Oyster is not as good and also variable, and the water from Spruce Hole is pretty clean. The main challenge was having a process that could anticipate and adjust to changing quality based on the three sources.”

The plant uses streaming current detectors (Chemtrac) to optimize pH and alkalinity adjustment and coagulant addition. “The detectors read out the electrical charge in the water, and that serves as a guide to enable the staff to adjust coagulants accordingly,” Geary says.

In addition, the staff monitors water flowing into the distribution system. That’s because a separate groundwater well that the town of Durham owns feeds directly into the water mains serving the town, providing about 30% of the flow. “We get samples of that water every day and test it in our plant laboratory,” says Geary. The testing assures proper water quality throughout the system.

HERE AND GONE

Seasonal consumption is another feature of the Durham-UNH system. Unlike most public systems, demand drops in summer because the university is on break. “We get reductions in water usage when the students are on winter and spring breaks, as well,” Geary says.

The plant staff also operates and maintains the various smaller water treatment systems on the campus: membranes, softeners and UV systems used in labs and various university buildings. With this range of responsibilities, communication among all parties is critical. Geary says his firm, along with town and university representatives, meets face-to-face every two weeks to discuss operations and address any issues.

The filters are air-scoured and backwashed every four days on average. Backwash water, along with solids settled out in the treatment process, are directed to one of three residuals-handling lagoons on the plant site. One design challenge involved the desire of the university and the town for zero discharge: no liquid discharge to any receiving streams or groundwater. “We were able to achieve that goal with a very innovative and unique design,” says Little.

The solids lagoons are the key. Clear liquid including supernatant above the settled solids, as well as rainwater and snowmelt on the surface, are regularly decanted from the lagoons. The residuals lagoons have a sand underdrain that collects filtrate from below, promoting more rapid drying of the lagoon contents. The decant and filtrate are returned to the head of the treatment process. Dried solids are trucked to a disposal site. The goal is to remove water and achieve the driest possible material so that the university is not paying to haul water weight.

The plant has a 10% limit on the incoming flow that emanates from the lagoon system recycle, but the actual amount is well below that. “It varies in concentration, but it’s really a very small portion of the overall flow,” says Little.

LOOKING FORWARD

The new water plant is the latest example of the forward-looking approach the university takes on climate change and the concept of resiliency and sustainability. The campus heating facility reduces emissions by using landfill gas instead of natural gas as its fuel. “We produce hot water, steam and chilled water,” says O’Keefe. In fact, the campus is powered entirely by renewable energy.

The measures are being noticed. UNH is just one of 10 in the United States to hold STARS (Sustainability Tracking Assessment and Ranking System) Platinum Award status from the Association for the Advancement of Sustainability in Higher Education. The school also incorporates sustainability into all departmental course offerings

“We were one of the early adapters of climate policy,” says O’Keefe. “Our administration has been a strong supporter of this approach.” Security is one challenge. “This is critical infrastructure. We’re compliant with security needs today, but we need to be protected against future IT risks,” he says.

Contaminants are another issue. “Planning, design and construction of our plant was a 10-year process,” O’Keefe explains. “Now there are contaminants, like PFAS, that not everybody knew about at the time.” He suggests that designs today need to be flexible and easily adaptable to future considerations. “This plant accomplishes that. These are things you are going to have to deal with in the future. It’s a learning process, for sure.”