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High-rises in Manhattan’s Battery Park City are ahead of the curve in residential water treatment and reuse.
By Don Talend
When one thinks of New York City, words that come to mind include big,grand, and fabulous. These adjectives might not be the first ones to come to mind when describing the onsite wastewater treatment and recycling systems in multiple new high-rises in Lower Manhattan’s sustainable Battery Park City development, but these systems at least represent a bold approach to onsite water treatment. The first-ever installation of onsite wastewater treatment and recycling systems in residential high-rises is a bold undertaking because the projects met site-specific environmental regulations prior to the development of the Leadership in Energy and Environmental Design (LEED) rating system. The first residential high-rise constructed on the site also earned the state’s first-ever tax credit for sustainable construction.
Battery Park City was sustainability-focused before sustainability was cool. The city’s longest-running development project was actually launched in the late 1960s, when it was envisioned as a city-within-a-city constructed on landfill (including a significant amount of construction waste from the nearby World Trade Center). The development stalled for years, due largely to the city’s financial problems in the 1970s. It would take nearly 20 years for the first apartment building to be completed, and by the end of the ’90s, a mini-city began to take shape more or less according to the original vision. With enough retail and commercial services having sprung up in Battery Park City, the development was ripe for large-scale residential settlement by more families.
However, the development is on state-owned land leased to developers by the state, which mandates sustainable construction on the site. At the arrival of the current decade, the Battery Park City Authority followed former Governor George Pataki’s vision for sustainable construction and developed its own Residential Environmental Guidelines. In terms of high-rise residential construction, Battery Park City was speculative as both an investment and for purposes of sustainability. High-rise residential construction, and sustainable at that, had never been tried before at that location.
Regulations Preceded LEED
The Battery Park City Authority sought to make the development into a model of sustainable living where human health and comfort and environmental stewardship would be addressed concurrently. In the process, the authority planned to make Battery Park City a model of sustainability and use the project to take a leadership position in the sustainable development arena. The authority issued a request for proposals requiring adherence to its new site-specific environmental requirements and the addressing of enhanced indoor air quality, water conservation and purification, energy efficiency, recycling construction waste, the use of recycled building materials, and commissioning to ensure building performance. The Albanese Organization, a Garden City, NY–based developer, was eventually awarded the bid.
“At the time, LEED had not been formally issued as a formal set of guidelines,” notes Marty Dettling, vice president of construction for the Albanese, which built the three high-rise residential towers on the site. “The rating system was not formally issued; it was issued for comments by the US Green Building Council and it was in the very early stages of development, and there were a lot of aspects that did not apply to this type of development. LEED was originally written for low-density commercial settings and this was a high-density residential setting, so a lot of the credits did not make sense for what we were trying to do, and we had difficulty assimilating them.”
Section 5, “Water Conservation and Site Management,” of the Hugh L. Carey Battery Park City Authority Residential Environmental Guidelines states the intent to reduce potable water use as well as wastewater outflow. One of the ultimate aims of the guidelines is to reduce the burden on New York City’s sewer system. Section 5.3, “Innovative Intent: Water Technologies,” specifies that technologies should be used to “minimize the impact on New York City’s sewer system and reduce the use of potable water by treating and reclaiming water from lavatories, toilets, showers, sinks, laundry, and dishwashing facilities.”
According to this section of the guidelines, technologies should be utilized to “treat all wastewater and reuse to maximum extent possible with an on-site Reclaimed Water Treatment System; use ecology-based treatment processes (i.e., ultrafiltration), as opposed to a chemical treatment system, for reclaimed water treatment; use reclaimed water for toilet flushing, cooling tower make-up, irrigation, laundry (to the extent allowed), building and sidewalk maintenance management uses (in all cases, if applicable and properly treated); and use best efforts to minimize use of chemicals in the maintenance of cooling towers.”
To meet these requirements, developers are charged with providing appropriate water recovery, treatment, and delivery infrastructure. Providing this infrastructure has several cost implications: increased plumbing infrastructure initial costs, savings on water and sewage costs, decreased demand on infrastructure, and availability of water during drought conditions. Developers do derive an economic benefit from bearing higher costs of onsite water treatment and other sustainability features, however. Recognizing that sustainable building can create a significant cost burden, the state had approved the New York State Green Building Tax Credit before any of the high-rises were built.
Compact, Ecological System
The first residential high-rise to be built in Battery Park City, the Solaire, was a 27-story, 293-unit building. The Solaire would use the onsite treatment system, stormwater reuse for irrigation of two green roofs and nearby landscapes, and water-saving fixtures and strategies on the interior. Given the Battery Park City Authority’s environmental guidelines, the developer awarded the bid would be entering uncharted territory in terms of incorporating an onsite water treatment and reuse system. Such systems are typically used on suburban or rural sites that do not have access to a municipal sewer system, unlike Battery Park City.
Dettling notes that not only had such an onsite water treatment and reuse system never been tried on an urban residential high-rise, but the Albanese Organization also had no experience with a blackwater treatment system. “It was a requirement of the Battery Park City guidelines and we had concerns,” he says. The Albanese Organization would get plenty of help in designing and installing the system, however. The developer worked with the Hillsboro, NJ–based Applied Water Management Group division of American Water to design a treatment system that utilized ultrafiltration (UF) technology. Planning meetings with the state Department of Environmental Conservation and the city’s Department of Health and Department of Buildings also made system implementation easier, says Dettling. “Since there were no official codes written, we set parameters based on the project that we all could be comfortable with and we worked toward those parameters,” he says. “We got basically a staged approval process where they first gave us a design approval and a construction approval and then an operational approval.”
Ed Clerico of Applied Water Management Group studied the water treatment and reuse specifications and recommended installing an immersed UF membrane type of treatment system, due to the ecology-based treatment requirements in the environmental guidelines as well as the need for a small system footprint and high output. An alternative, an external pressure membrane type of system, would have required a separate filtering area unlike the immersed membrane type, which processes the effluent inside the bioreactor by drawing it from the outside in using a vacuum. The latter type required less space and less energy.
The Solaire’s water treatment system was constructed in the basement of the building and consists of multiple concrete tanks. First, large solids are separated from the effluent in a primary treatment compartment. The next stage in the GE ZeeWeed treatment system uses UF membranes that purify the wastewater with bacteria inside a bioreactor. The bioreactor has two chambers for growing different types of bacteria: an anoxic chamber, which does not use an air addition, and an aerated aerobic chamber.
Membrane modules are combined into cassettes, which can be added to expand system capacity along with wastewater volume. The membranes are hollow, string-like fibers with significant surface area and billions of microscopic pores ranging from 0.04 to 0.1 micron that trap material such as suspended solids, pathogens, and some viruses.
Low-pressure pumps slowly draw the effluent through the cassettes from the outside in. The materials to be filtered out are easily trapped on the membranes due to the addition of coagulant, and bacteria trapped within the membranes break them down.
The membranes are freed of particulate matter through aeration at the bottom of the bioreactor and occasional backpulsing of the effluent. “The membrane behaves as much like a natural living organism as you can have it behave,” notes Clerico. “It’s processing water molecules all the time through a vacuum. If the outer area begins to clog, the vacuum shuts off and it goes into a relaxed mode where the outer layer sheds what was clogging it, and then the vacuum comes back on. Periodically, it’s backpulsed and you actually reverse water and pump a little water back in the opposite direction, forcing clean water out through the membrane just to rejuvenate it and keep it clean. It pumps water through like a living organism would, but then it has to stop and pump water back to clear itself and then pump water through again.”
After the membranes filter the effluent, it is further treated by ultraviolet light and ozone to kill any remaining pathogens and remove color and odor. The treated water is then stored in tanks for toilet flushing in the restrooms and for recharging the building’s cooling tower. Some of the water is also used for irrigating plants at an adjacent park, notes Dettling. “There’s also a pipe that goes out and feeds Battery Park City’s Teardrop Park that’s in between the buildings,” he says. “There is a reverse-osmosis system where they feed this water and mix it with some potable water to get the right mix to irrigate the park.” Dettling adds that the reverse osmosis process removes salts that remain in the treated water and make it suitable for irrigation.
In order to reduce maintenance requirements, a programmable-logic controller was installed with the system to track flow rates and oxygen levels in the system for performance monitoring. Most of the monitoring takes place remotely and a remote alarm alerts the maintenance staff to problems. Regular onsite system maintenance consists of only about four hours a week.
Dettling says that the Albanese Organization’s first experience with onsite water treatment for a residential high-rise building was high profile due to the fact that large concentrations of people use the Solaire’s restrooms, which are serviced by the treated and recycled water. “We’ve learned at each step of the way that you have to keep an eye on what the effect of the effluent that is produced from the system is on its intended use, like for the toilets or for the cooling tower,” he says. “You want to keep an eye on that so that you can make proper adjustments to that water quality. You want to make sure that you are taking water-quality samples so you know what’s going on and making minor adjustments as you go to account for differences in water quality that we’re not typically used to. You don’t just turn on the system and forget it; you have to monitor it and give it some guidance.”
A Model of Sustainability
The Solaire, which was completed in June 2003, serves as a model of sustainable construction, including water conservation and purification, in both the city and state. The combination of onsite water treatment and reuse, stormwater reuse, and water-saving strategies and devices on the building interior yielded a roughly 50% savings on potable water use compared with a conventionally built similar structure. After the building’s completion, the New York City Water Board unveiled a Comprehensive Water Reuse Program that reduces rates by 25% for buildings that have onsite water treatment and reuse systems.
In 2004, the Solaire became the first residential tower in the United States to achieve a LEED Gold rating. In February 2006, the EPA’s highest-ranking official in the region, Alan J. Steinberg, toured the Solaire and praised its attractiveness to residents along with its sustainability. “With every flick of the light switch and swoosh down the drain, the Solaire’s design has empowered residents to live in an environmentally responsible way,” said Steinberg. “From the drafting table right on through to its current operation, the Solaire stands as a model for sustainable development and outstanding energy management. The design and day-to-day operation of this building prove that innovation and energy conservation are key building blocks for accelerating environmental protection while maintaining our economic competitiveness.”
The ultimate measure of the project’s success is the fact that the building achieved full occupancy within six months of its opening at rents averaging 4% to 5% higher than in comparable buildings. Two more nearly identical high-rises, the Verdesian and the Visionaire, are being built and use the same water treatment and reuse system. The Verdesian, a 26-story, 250-unit high-rise that opened in 2006, actually shares the Solaire’s system via a pipe that is connected to both buildings. The Visionaire, a structure that is scheduled for completion in 2008 with 250 units that are larger than those in both the Solaire and Verdesian, uses its own dedicated immersed UF membrane treatment system. Battery Park City’s third residential high-rise is on track for LEED Platinum certification.
Don Talend of Write Results in West Dundee, IL, is a writer and business-to-business communications consultant.
OW - September/October 2007 |
