January 2008, Vol. 20, No.1
The Fifth Paradigm Has Arrived
This fifth paradigm of urbanism, dubbed as such by Vladimir Novotny of Northeastern University and colleagues, features integrated management of urban waters, landscape, and infrastructure and incorporates decentralized approaches to treating, reusing, disposing of, and distributing water. Some urban planners and decision-makers are embracing this approach, learning about and installing decentralized systems.
The Decentralized Concept
Leaving more water in the environment and minimizing hydrological disruption of watersheds, decentralized approaches embrace reuse and reclamation components. They incorporate small-scale technologies for local treatment and closed-loop systems that reuse water for nonpotable uses, such as toilet flushing, irrigation, and cooling. Decentralized systems also feature green infrastructure, which helps address stormwater issues by reducing combined sewer overflows (CSOs) and water pollution exacerbated by runoff, promote smart growth by clustering development and incorporating onsite treatment, and achieve watershed restoration.
Japan, China, Israel, and other nations are applying these approaches and thus minimizing the costs imposed by centralized treatment systems.
“In many cases, they have leap-frogged past siloed centralized systems,” said Valerie Nelson, director of the Coalition for Alternative Wastewater Treatment (Gloucester, Mass.).
In the United States, however, decentralized systems are not as common.
With the passage of the original Clean Water Act, direct federal funding encouraged regional planning and a strong preference for centralized facilities, according to Paul Brown, senior vice president and president of the Public Services Group at CDM (Cambridge, Mass.) and co-editor of Cities of the Future: Towards Integrated Water and Landscape Management, which discusses the fifth paradigm.
“We were not looking at water as a finite supply; our sole purpose was cost-effective wastewater disposal,” Brown said. “And in the course of making that happen, we developed a whole industry around that approach,” that helped get point sources under control.
However, Brown added, “it is fundamental now, going forward, reuse and recycling is going to be a norm — a significant element of a sustainable water supply.”
That’s because aging infrastructure and new development are stretching U.S. water supplies and challenging water quality. In addition to increasingly stringent regulatory requirements, including reducing CSOs and addressing total maximum daily loads, the costs to maintain and expand our current centralized, regional systems are estimated in the billions.
A Growing Trend
Since the Baltimore Charter for Sustainable Water Systems was signed by an international group of professionals and academics on March 15, 2007, at the Water for All Life conference sponsored by the National Onsite Wastewater Recycling Association (Santa Cruz, Calif.), more parties are taking part in the conversation about the future of urban watersheds, and a forum for sharing knowledge and approaches with others is developing and garnering notice in Washington, D.C.
Of note, the U.S. House of Representatives’ Science and Technology Committee is interested in learning about decentralized, closed-loop approaches and held a hearing in October titled Research to Improve Water Use Efficiency and Conservation.
In addition, the National Association of Home Builders (Washington, D.C.) Research Center, in cooperation with the U.S. Department of Energy and U.S. Department of Housing and Urban Development, has identified decentralized wastewater and stormwater technologies as a top research priority. Participants in a May 2006 workshop sponsored by the National Housing Endowment, a philanthropic arm of the homebuilders association, labeled research into the effectiveness of onsite wastewater systems as “extremely important,” and felt that further investigation of operational performance was needed.
While centralized systems imply that water is treated to one standard, a decentralized approach proposes that different systems should apply to different uses. “It’s much more user- and site-specific,” said Ed Clerico, president of Alliance Environmental LLC (Hillsborough, N.J.).
“We’re going back to what farmers used to do with some of these concepts — learning how to capture and reuse water effectively,” said Clerico, who recently completed work on New York City’s Solaire development project, a Battery Park City residential tower that is home to 700.
In rural areas, rain barrels, green roofs, and cisterns have long been used to capture and treat stormwater, Clerico said, noting that in the United States, decentralized approaches for commercial and industrial uses were first driven by a lack of sewer infrastructure or an environmental constraint. It was in the mid-1990s that the green building movement got many thinking about adapting reuse systems for residential use, he said.
Brown also noted that it was the agricultural and rural areas and the agricultural engineering community that, despite the Clean Water Act, remained interested in microscale approaches. Centralized sewers were considered costly or, at times, inappropriate due to the size of some widespread, sparsely populated farming communities.
In many ways, incorporating decentralized approaches is like designing a miniature watershed where wastewater is treated and reused onsite, and in which treatment units recharge groundwater, streamwater, or wetlands.
“Solaire was a huge step forward,” Clerico said. As the first residential tower in the United States to treat and reuse wastewater, the luxury tower features a 95-m3/d (25,000-gal/d) treatment plant in the basement that supplies treated effluent to the building’s toilets, cooling tower, park irrigation system, and a reservoir.
Solids are disposed to the sewer because the city has the available capacity, Clerico said. The system also helps alleviate CSOs because it has removed a substantial amount of its 700 inhabitants’ waste load from the city’s system. And, Solaire has a green roof that reduces runoff.
Solaire “is one of the great examples of how this concept works,” said Glen Daigger, senior vice president and chief technology officer of CH2M Hill (Englewood, Colo.) and vice president of the International Water Association (London). “You can accommodate more people without changing and disrupting service.”
Daigger noted that only between 2% and 4% of the water an individual uses is actually consumed, and in urban areas, each person uses about 570 L/d (150 gal/d) of potable water.
“But by using water multiple times, you can maintain the standard of living without taking as much water out of the environment,” Daigger said.
“All of the factors are there that we need to look at a new paradigm of urban water management,” Daigger said. “The good news is that the technology is there to do it.”
Membranes, and particularly membrane bioreactors, are leading the way due to high efficiency and a high degree of reliability, according to Daigger. “The evolving treatment technology allows the production of reclaimed water and the protection of public health,” he said.
Barriers to Implementation
“There is a continuous realization by regulatory authorities that decentralized approaches are a long-term solution,” Clerico said. However, “regulatory authorities tend to focus on the pitfalls,” such as distribution, management, regrowth in systems, failures of nonpotable water systems, and how the toilets work, he said.
“There was a push for some conservatism in design [of Solaire] because of the unknowns,” Clerico said. These doubts subsided, he noted, because systems performed and problems — such as toilet leakage and homeowners tapping into walls and getting into the nonpotable supply — were addressed.
A second challenge is funding decentralized approaches. For example, in states such as Connecticut, homeowners can access state revolving funds to repair failing septic systems.
However, “the industry hasn’t completely recognized the opportunities, because regulatory and funding mechanisms are set up for centralized approaches,” Clerico said.
A third hurdle may be the industry itself. Decentralized systems “are smaller, it’s harder to make money, so why go in that direction?” Clerico said. Also, the profession is not well-versed in this area because not many civil engineering programs include decentralized approaches in the curriculum, he added.
“The U.S. has certainly been a sleeping giant in the field,” Nelson said, noting that she believes the nation is slow to make the transition because the concept of a decentralized system is more difficult to understand, federal legislation is based on the function of centralized systems, and some state and local ordinances may prevent certain decentralized approaches.
“Frankly, just the introduction of new ideas” has made acceptance a challenge, because onsite systems and decentralized approaches at times present a transition of a public function into private hands, Daigger said. The separation of water and wastewater utilities in many areas is an even “bigger barrier” to acceptance, he added.
Permitting reclamation and reuse installations is a challenge nationwide, in part due to the number of agencies that are involved in permitting these approaches and a lack of national standards, Daigger said. “Even if they were voluntary, national standards would be helpful,” he said.
Finally, “we need to reset our defaults,” Daigger said. If planners did not first look for freshwater sources for new supplies, as is customary, but first asked, “What are the reuse sources?” And if they did not first ask, “What are the discharge standards?” but first thought, “What are the reuse opportunities?” the industry and regulators may be able together to address how many times it makes sense to reuse water for a particular set of circumstances, he said.
“The industry [has been] slow at rethinking the whole model as a possibility,” Clerico said. “But we are entering an era where that is going to change.”
“While we need to ensure that what is happening at the small scale is not damaging the environment,” it is because of several “bad examples” that small-scale approaches — such as package treatment — have a poor reputation, Brown said.
“We need a truce between the proponents of large-scale and small-scale technologies,” Brown said. “We should not eliminate a whole category of solutions because of something that went wrong 25 years ago.”
Package treatment facilities — small-scale wastewater treatment facilities designed for smaller service areas or developments — have been controversial because of their maintenance records. Because homeowner communities often are responsible for such facilities, there have been problems in their operation and maintenance. Some states do not permit package systems. “But in Arizona and New Mexico, that is the way we provide infrastructure,” Brown said.
“One of the biggest problems is managing decentralized systems,” Daigger agreed. “The boundary of what is operated by a public utility and what is operated and maintained at the building level — the question is, who is responsible for maintenance?”
Also, since multiple agencies are involved with the permitting and oversight of water quality facilities, “we need to figure out how to integrate planning and management functions,” Brown said.
However, agencies can come to a decision that allows a decentralized project to go forward. With the Solaire project, many entities weighed in on the design back in 2000, Clerico said. But once the New York State Department of Environmental Conservation reviewed the plans, it determined that there “wasn’t really a lot for them to regulate,” so New York City’s departments of environmental protection and public health did the permitting for reclaiming the wastewater and supplying reused water. The facility is regulated as a water facility, Clerico said.
Making the Transition
With full-scale centralized systems dotting most of the United States, the transition to decentralized systems may seem unlikely.
According to Brown, siting wastewater treatment plants in communities that do not normally have them and would prefer to send their wastewater out is a potential roadblock.
The challenge to the engineering community lies in creating facilities that are “good neighbors,” Brown said, “Why aren’t we asking environmental projects to deliver on a social and economic bottom line?” he proposed.
In New Bedford, Mass., the Tabor Park treatment facility hosts an annual symphony. It is in part a recreational site and open space that actually improved the property values in that community, Brown said. “If people can get married at the site of a WWTP [wastewater treatment plant], then we have done our job,” he said.
What may help to encourage acceptance of decentralized approaches is full-cost pricing. Water and wastewater services are heavily subsidized by government to make them very affordable to the citizenry — downright cheap by most standards — and one of the U.S. Environmental Protection Agency’s Five Pillars of Sustainability is to have these services adopt full-cost pricing in order to pay for continued maintenance and investment in infrastructure.
With decentralized approaches carrying a more attractive sticker price, the economics may help drive the frequency of decentralized installations.
“I do see this becoming a very important part of our infrastructure,” Clerico said. “It makes more sense economically. It allows you to build just what you need when you need it,” he said.
“It’s easier said than done, but sometimes you need a simple goal to get there,” such as only using one-third of the fresh water we use today,” Daigger said. “We have the technology, we do not have to drop the standard of living, and we need to look at reuse and reclamation.”
— Andrea S. Bistany, WE&T