Supplying water for about 9 mill­ion residents and tourists is no small task, but the New York City Department of Environmental Protection (DEP) is constantly stepping up its game to improve water and services. The city’s water supply, which also serves suburban Westchester County, soon will be treated through the world’s largest ultraviolet light disinfection facility when it opens in February 2012.

While the current largest UV facility is a couple hundred million gallons per day, the new Catskill/Delaware UV disinfection facility will have a capacity of more than 2 billion gallons per day. The $1.5 billion facility – in Mount Pleasant, N.Y. – is being constructed by Skanska USA Civil Northeast/ECCO III Enterprises/J.F White joint venture.

The facility will treat water from the Catskill and Delaware systems, which provide 90 percent of New York City’s drinking water. The 250,000-square-foot facility will enable the water quality to meet the U.S. Environmental Protection Agency’s Federal Safe Drinking Water Act.

The city’s water supply is one of the greatest metropolitan supply systems in the world, and it has exceptional quality, the DEP says. The city’s three systems – Catskill, Delaware and Croton – are fed almost exclusively by gravity from upstate storage reservoirs. The facility will include 56 UV units that are each designed to handle 40 million gallons of water per day.

The units consist of stainless steel disinfection chambers designed and manufactured by TrojanUV. Inside the chambers is an array of UV lamps inside quartz sleeves that are immersed in the water flow. Trojan says the units are similar to others it has built, but the Catskill/Delaware units are so large that they include a hatch big enough to allow a person to climb into the unit for maintenance.

“New York City’s water supply has been chlorinated, but there’s been no real treatment, per se,” says Paul Smith, chief of upstate water supply treatment and facilities. “This is the first time we’ve had major water treatment for our supply.” Although the Safe Drinking Water Act requires water filtration, the EPA granted some filter avoidance determinations, which allowed some bodies to provide alternatives to filtration. To satisfy the act’s requirements, the DEP agreed to build the Catskill/Delaware UV plant to supplement its existing chlorination disinfection facilities, which saved the department money over building a new filtration plant for the Catskill and Delaware watershed.

Weighty Water Work

Executive Construction Manager George Schmitt notes that the project’s sheer size makes it unique. “It’s the largest of its kind by a factor of 10,” he says. “It will double the capacity of all the existing UV systems in North America. The city’s water supply is so huge, so that’s why it has to be built that big, and it’s designed for future use and population growth.”

Because the Catskill/Delaware facility will be the largest in the world by a large margin, the equipment had to be custom manufactured. “One of the biggest challenges is that a lot of the equipment is one of a kind,” Schmitt says. “The UV units were custom-made. There was a prototype that was built and validated by the Department of Health, and the energy dissipating valves are the first of their kind, as well.”

Smith notes that the facility will include custom-made, 40 million-gallon-per-day units, whereas the previous larger ones processed about half that amount. Most of the bulbs and controls were made in Canada, he adds. “A lot of the valves are from around the world,” Smith says. “It’s a pretty unique project.”

Eye On The Future

The plant’s Eastview site in Mount Pleasant has been in the city’s hands since the early 1900s, when it founded the Catskill Water Supply System. City officials at that time anticipated that filtration to remove impurities from water would be needed in the future.

“With an eye on any future filtration plants, our forefathers had this site here when they built the Delaware aqueduct,” Smith says. The Eastview site spans acres about 20 miles from New York City.

Easy Flow

Coordinating a team of the four prime contractors and all the subcontractors on such a large project can be a challenge, Smith and Schmitt say, but the job is proceeding smoothly and may finish before schedule and under budget. “I think we have a great group of people working here, with four contractors, the designer and the construction manager,” Schmitt says. “We all have a good rapport with each other, and there are no real major issues to deal with. We’ve been able to solve them fairly quickly and evenly so far.”

The entire project team meets weekly to discuss coordination, and the construction manager – Malcolm Pirnie/CH2M Hill, JV – has staff dedicated to site coordination. “Logistics definitely have been challenging, but we’ve been meeting on a regular basis with all the contractors to make sure it’s well-coordinated,” Smith says. “They’ve all done excellent work, and it’s rare that all the contractors keep up with the general contractor, but on this project, it has been a success.”

Despite challenges related to the project’s size, Schmitt says all the contractors are excited to be working on a milestone project. “A lot of people enjoy that this is a once-in-a-lifetime project, so a lot of people are taking pride in that,” he remarks. “The uniqueness of this project is one of the things I’m really enjoying about it. “We have a state-of-the-art building that’s never been built before with treatment units that have never been built before,” he continues. “We’ll all be proud to make it work in one of the world’s largest and most important water infrastructure systems.”

Superior Safety

Overseeing a team of multiple contractors on such a large project is challenging, but Schmitt notes that the DEP is going to great lengths to ensure safety on the site. The department has a “huge focus” on safety because the projects are so massive, he says.

“There are five persons strictly dedicated to site safety in our construction management office, and the contractors themselves have dedicated safety employees, too,” he says. “Basically, we feel that we want to get people home to their families. Safety matters as much to us as it does to the contractors. A lot of credit goes to them because they’re the ones doing the construction work.”

Eliminating Parasites

According to the Centers for Disease Control and Prevention (CDC), cryptosporidium is a microscopic parasite that can cause diarrheal disease. Humans and many animals can be affected by the parasite. Both the parasite and the disease, cryptosporidiosis, are commonly referred to as crypto.

Protected by an outer shell, cryptosporidium can survive outside the body for long periods of time, and it is very resistant to chlorine disinfection, which is a traditional method of treating water. The parasite can be transmitted in many ways, but water is one of the most common methods of transmission, and cryptosporidium is one of the most frequent causes of waterborne disease.

The symptoms of the disease cryptosporidiosis include stomach pain or cramps, dehydration, nausea, vomiting, fever and weight loss. Symptoms generally begin two to 10 days after infection, and they can last about one to two weeks. “Some people with crypto will have no symptoms at all,” the CDC notes. “While the small intestine is the site most commonly affected, crypto infections could possibly affect other areas of the digestive tract or the respiratory tract.”

The country’s largest documented crypto contamination occurred in 1993 in Milwaukee, when one of the city’s two plants became contaminated. Over the span of two weeks, 403,000 residents reported symptoms, and more than 54 deaths were attributed to the contamination.

That outbreak spurred the federal government to crack down on crypto potential. The EPA’s Interim Enhanced Surface Water Treatment Rule requires filtered surface water systems serving at least 10,000 people to remove at least 99 percent of crypto. The act, which went into effect in 2001, also required systems without filtration to adopt a watershed control program to protect source water.

The Catskill/Delaware UV facility also will protect against gardia, which is a microorganism found in drinking water but is most present in recreational water uses, such as swimming pools. Symptoms of contamination are similar to crypto, and like that parasite, gardia is protected by an outer shell and can live for up to 45 minutes even in a properly chlorinated swimming pool.

Smith notes that New York City hasn’t experienced an outbreak like Milwaukee’s, and that the new facility will prevent any in the future. “It was determined that UV light basically messes up their DNA, so they can no longer reproduce and it will no longer be a virus,” he says.

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VENDOR FOCUS

With about 350 water meters in the New York City water system, Primary Flow Signal (PFS) was a natural choice to provide Venturi flow meters on the Catskill/Delaware Ultraviolet Filtration project. The New York City Department of Environmental Protection demands the highest quality in its projects, and PFS President Bruce Briggs says the company easily meets those demands.

“We have supplied very large Venturi meters to DEP before, so we’ve had a very long track record,” he says. “They’re very, very quality-conscious, because it’s the taxpayers’ money, so they’re not only concerned with performance but [product] life expectancy.”

PFS has more than 700,000 Venturi meters installed and operating in more than 40 countries for meter sizes ranging from half-inch to 180 inches. It also has more than 3,000 laboratory flow calibrations supporting the proven performance of their differential flow meter products.

PFS has been providing quality products worldwide for 29 years, Briggs says. The company supplied two 108-inch and four 144-inch Venturi meters to the Catskill/Delaware UV project, and Briggs notes that the meters have a life expectancy of 100-plus years and a warranty period of 25 years.

“The equipment we’re providing is measuring all of the influent water to the plant,” Briggs says. “The facility is the largest UV treatment facility in the world, and because of the way the plant’s been designed, the ability to accurately determine how much water is moving into the facility is critical to the process.”

PFS became involved during the design and engineering phase of the project, working with DEP’s consulting engineers CDM and Hazen & Sawyer. PFS was awarded the $7 million contract from SEW Construction, a joint venture between Skanska, ECCO III Enterprises and J. F. White Contracting. Briggs says PFS had previously worked with both the engineering firms and the contractors and their successful relationships helped it overcome some scheduling challenges early on.

The meters originally were scheduled to be delivered over three years, but the contractor requested that they be delivered in just 14 months to better coordinate construction. “We had to significantly compact our normal manufacturing schedule, which was a challenge not only because of engineering but raw material procurement and manufacturing,” Briggs says.

But PFS’ commitment to quality prevailed. “When you have a track record where there are never quality problems and there’s a high attention to detail, it makes a big difference,” he states.