December 2006, Vol. 18, No.12
Climate Change Takes Center Stage
Renowned NASA scientist outlines future scenarios, implications for water managers
Despite the challenges global climate change presents, immediate action can halt its onset and resulting consequences, according to climate scientist James Hansen, the keynote speaker at the Opening General Session of WEFTEC®.06.
“We can still avoid dangerous climate change,” Hansen said.
The Opening General Session kicked off the 79th annual WEFTEC Conference, which was held Oct. 21-25 in Dallas. The session focused on the growing awareness about climate change and its potential effects on the global water community and water quality professionals.
Hansen is the director of the National Aeronautics and Space Administration’s Goddard Institute for Space Studies (New York), a component laboratory of the Goddard Space Flight Center’s (Greenbelt, Md.) Earth Sciences Division.
In his address, Hansen provided an overview of the reasons behind climate change, citing ever-increasing levels of greenhouse gases — mainly carbon dioxide — and how they have led to increasing temperatures over the last few decades.
“There is a strong congruence between the greenhouse gas changes and the climate change,” he said. “Greenhouse gases are now completely outside the range that has existed over the last several hundred thousand years.
“We understand with complete certainty that at least a quarter of the carbon dioxide that we put into the air by burning fossil fuels will stay there for … at least 500 years,” he said.
Hansen also discussed the effects of global climate change, such as the extermination of species. He said that during the last global warming event, which occurred approximately 55 million years ago, global warming increased temperatures by 6ºC. This rise led to the extinction of more than 90% of the planet’s species, according to Hansen.
Another consequence of global climate change, Hansen said, is the disintegration of ice sheets, which causes rising sea levels, and increased frequency of extreme weather events such as floods and droughts.
Despite these imminent problems, Hansen fears that the public is not yet mobilized to fight global warming. In his address, he cited the gap between what scientists know about climate change and what the public and policy-makers understand about climate change as a major obstacle.
He blamed this knowledge gap on the influence of special interest groups, which hold sway over the media and the government, and a false balance presented by the media, which lead people to believe that the science on global climate change is uncertain.
“Because of this confusion, the public has not been very interested [in climate change],” he said.
To combat the effects of global climate change, Hansen advises stabilizing the atmospheric composition by the end of the century and maintaining global warming to an increase of less than 1ºC. By preserving this level, Hansen believes the effects of dangerous, human-made interference, such as extermination of species and ice sheet disintegration, can be avoided.
In his speech, Hansen also encouraged extending the life of existing conventional fossil fuel sources to allow time to develop alternative forms of energy.
“Eventually we’re going to have to go to non-fossil fuel sources,” he said.
He proposes phasing out coal power plants that do not sequester carbon dioxide and only building new power plants that do sequester the gas. Hansen believes that doing so will help keep carbon dioxide levels low enough to sustain a temperature increase of less than 1ºC. He adamantly opposes turning to nontraditional fossil fuels, such as tar sands and shale oil, because they produce tremendous amounts of carbon dioxide.
Despite this bleak outlook, Hansen believes there is still time to halt climate change if efforts begin immediately.
“Humans are now in control of global climate, for better or worse,” he said.
After the keynote address by Hansen, Water Environment Federation (WEF; Alexandria, Va.) President J. Michael Read announced that the WEF Board of Trustees had approved a new climate change resolution on Oct. 20.
The new resolution acknowledges that global temperatures are increasing and will cause significant disruptions in the natural hydrologic cycle throughout the world. These disruptions include increased flooding due to higher precipitation, increased water temperatures, and more frequent wet weather events, rising sea levels, and severe and more frequent drought.
“I believe [climate change] to be the paramount environmental issue of our times,” Read said.
The resolution calls on WEF to serve a leadership role in combating the effects of climate change on the global water environment. To achieve this goal, WEF will collaborate with other technical, science, and water utility organizations to identify practices that reduce greenhouse gas emissions from water and wastewater treatment processes; assist water resource managers in planning for the challenges posed by global climate change; and encourage municipal wastewater treatment agencies, WEF member associations, and other member constituencies to become leaders in diminishing the effects of climate change.
“The resolution supports WEF’s role as a leader within the water quality community by committing the Federation to working with our members, member associations, and others to help reduce the impacts of global climate change and to better prepare for its impacts,” Read said.
Rep. Eddie Bernice Johnson (D–Texas) opened the general session. She currently sits on the House Transportation and Infrastructure Committee and serves as the ranking Democratic member of the Subcommittee on Water Resources and Environment. In her opening remarks, she stressed the important role that water professionals will play in the United States during the next 20 years.
“In our country, all of our infrastructure is getting old, and we will be depending on you [water professionals] very heavily to make recommendations and help us determine where the real priorities are,” Johnson said.
She also acknowledged the various challenges water professionals face, such as climate change, and encouraged professionals to develop innovative solutions to water problems.
“We must not allow our country to become a bottled water nation by necessity,” Johnson said.
Incoming WEF President Mohamed F. Dahab closed the Opening General Session by emphasizing the role WEF plays in the water environment.
“It’s our aspiration to contribute to the protection and enhancement of our water environment, to sustain our society, and ultimately, our existence and values,” Dahab said.
— Michael Bonsiewich, WE&T
A Closer Look at Emerging Compounds
What does the scientific community currently know about compounds of emerging concern (CECs), and what is their effect on water quality? A special session at WEFTEC®.06 was devoted to demystifying CECs, specifically endocrine-disrupting compounds (EDCs). Speakers discussed the sources of EDCs, their effects on wildlife and humans, and the effect wastewater treatment has on these compounds.
What Is The Impact?
CECs originate from both natural and manmade sources. Pesticides, plastics, industrial chemicals, cleaning products, and food packaging are sources of CECs, according to Al Goodman, principal of consulting, engineering, construction, and operations firm Camp Dresser & McKee (Louisville, Ky.). Goodman noted that other sources include the female sex hormones estrone and 17-B estradiol, plants that produce phytoestrogens, and some animals that naturally generate EDCs.
Studies have revealed that aquatic wildlife is affected by the CECs found in lakes, streams, and rivers. But even with research showing the feminization of fish through exposure to these compounds, it’s still difficult to pinpoint the exact CEC or CECs responsible.
“It’s suspected that estrogen and some of the hormonal compounds have had influences on fish and aquatic organisms that spend 100% of [their] life cycle in water,” Goodman said in a preconference interview with Water Environment & Technology (WE&T). “But there’s not been any direct correlation that substantiates that ‘yes, this one [compound] is the problem.’”
The problem, Goodman said, is that the scientific community — while having made significant strides in detecting these trace elements — does not have the technology to analyze them yet.
“We don’t know exactly how these chemicals persist in the environment,” Goodman told WE&T . “They might be picked up by soils, or by sunlight breakdown, or by degradation through bacteria as they migrate into the water environment. We just don’t know all those mechanisms and whether they continue to exist in the same form as when they’re introduced, or whether they change into other compounds. And if they do change, what are those other compounds? Are they better or worse?”
Jessie Denver, a biologist at the City of San Jose (Calif.) Watershed Protection department, spoke about the effects of CECs on wildlife. Studies have revealed that egg sacs form on male fish, and an EPA study showed that female minnows develop the nose characteristic of males following exposure to EDCs, she explained. The antibacterial agent triclosan has been found to bioaccumulate in the tissue of fish and humans, and it degrades into other compounds, Denver said. The herbicide atrazine has been found to cause reproductive abnormalities in frogs, she added.
But drawing the connection from CECs in the environment to humans is not so easy.
“Consider we are what we are and have been living with these compounds for many years now, 50 years or more; and we don’t know what impact there has been, if there has been any impact, on humans,” said Goodman. “And you have to consider a human is much more tolerant than a small organism that [spends] 100% of its time in water. We’re looking at very different types of impact — whether it’s a chronic impact or acute impact — short period of time or long period of time.”
While the presence of CECs is not in question, their existence and persistence in the environment are.
“We need analytical methods and standards to measure them and find out their toxicological significance,” Denver said.
Akin Babatola, laboratory and environmental compliance manager for the City of Santa Cruz (Calif.) and vice chair of the Water Environment Federation (WEF; Alexandria, Va.) Laboratory Practices Committee, discussed the analytical methods and monitoring technologies for CECs. He noted that sample collection methods must be refined.
“We can’t yet test for multiple compounds with one method,” Babatola said, “so it’s a better strategy to look at environmental effects.” And as new chemicals are being created all the time, “you have to have different analytical methods,” he said.
Goodman said the scientific community is “quite a few years” away from determining the effect of CECs exposure on human health.
“We can detect these compounds at lower and lower and much smaller concentrations then we’ve ever been able to do before,” he explained to WE&T. “They’ve been there, we just didn’t have the analytical capability of finding them in these small concentrations.”
Babatola explained that data quality objectives (DQOs) must be established before samples are collected and before measurements are made. Numerous CECs being tested for are commonly found in the field and in laboratory environments, he said. These DQOs must be carried through with the sampling approach, analytical method, and resulting data results so that interpretation of the data does not extend beyond the limitations imposed by the DQOs chosen. In other words, those conducting the sampling must decide what they want to use the collected data for before sampling begins — otherwise researchers may not get the data they originally set out to collect.
Since wastewater treatment plants are responsible for treating just about everything else in the water, what if they ultimately are charged with removing CECs?
“One hundred percent removal [of EDCs] is not possible” through wastewater treatment processes,” said Joe Cleary, principal at environmental engineering and consulting firm Hydroqual (Mahwah, N.J.). “So, the goal should be reduction to levels with no environmental effects.”
Cleary said there are a few possible options for CEC removal. Specializing in activated sludge, Cleary told WE&T about reduction methods based on solids age.
“Some but not all of these compounds are shown to be biodegradable by bacteria,” he explained. Some scientists are finding that the 15- to 20-day range for solids age allows for the biodegradation of some compounds to low levels, Cleary said.
Another option is the advanced oxidation process, which is used on activated sludge to get additional removal. “It uses chemicals like ozone, hydrogen peroxide, sometimes it might have UV with ozone or peroxide,” Cleary said, “and some of the compounds are destroyed that way.” However, he noted, “some of [the compounds] could break down into other byproducts” which may or may not be hazardous. This remains to be determined.
Brandon Koltz, vice president of engineering and consulting firm Symbiont (West Allis, Wis.), agreed that CECs may or may not be able to be fully or partially removed through treatment at wastewater plants. Some CECs may be treatable through compounds-specific processes, he said.
Removal of EDCs is a prime concern, but how can we keep them out of wastewater and the environment in the first place? Session speakers shared several suggestions for pinpointing and controlling the sources of EDCs.
“The sewer system is just one way that this stuff gets into the treatment plants and into a river, but not the only way,” Cleary told WE&T . “It can get in through agricultural runoff — some of these things originate from livestock; various types of animals, even the vet medicine that gets excreted” through animals, he said.
Koltz reiterated that CECs enter the environment via numerous routes, including stormwater, atmospheric deposition, and animal feeding operations. Therefore, controls are needed, he said — ranging from household hazardous waste disposal programs to the reformulation of personal care products.
According to Koltz, improving the management of manure at animal operations — which contains antibiotics, steroids, and hormones — may be helpful as well. “Long storage times may reduce the pharmaceuticals in manure that is ultimately land-applied,” he said.
Is regulation the answer? Denver noted that the European Union has a regulatory framework for the Registration, Evaluation, and Authorization of Chemicals (REACH), which evaluates chemicals for carcinogenicity, endocrine disruption, and persistency and bioaccumulation. But currently, there are no regulations governing EDCs in the United States, Denver said.
In the absence of regulations, Denver said, it might be valuable for the United States to take action at the local level. One option would be to hold pharmaceutical disposal events for communities. Law enforcement could take care of the controlled substances, while the noncontrolled ones could be picked up by the hazardous waste department. This type of event hopefully would prevent citizens and medical professionals from disposing their unused medications in the trash or down the toilet, where they could end up in wastewater and the environment, she said.
Other options include encouraging green chemistry and environmentally preferable purchasing, Denver said. Green chemistry, as defined by EPA on its Web site, involves promoting chemical technologies that reduce or eliminate hazardous substance production during the chemical products’ design, manufacture, or use. These products could be given a “green seal,” Denver said, so consumers could easily identify them for purchase.
— Meghan H. Oliver, WE&T
Organizations Respond Quickly to Evidence of Coliform Reactivation
According to a recent Water Environment Research Foundation (WERF; Alexandria, Va.) study, fecal coliform counts can increase dramatically in anaerobically digested biosolids, but the reason is unclear.
Utility managers, microbiologists, design engineers, policy analysts, and regulators came together to discuss this unexpected phenomenon at a special technical session at WEFTEC®.06 in October.
“Basically, what happens is when you come out of digestion and go into a dewatering device, you have one density of fecal coliform and then, immediately after dewatering, that level increases by one, two, three, or four orders of magnitude,” said Matthew Higgins, associate professor in the Department of Civil and Environmental Engineering at Bucknell University (Lewisburg, Pa.), and a principal investigator for the WERF study.
Because the bacteria cannot reproduce that quickly, researchers have concluded that this phenomenon is due to the reactivation of bacteria. That is, the fecal coliforms were always present in the samples but were invisible to standard culturing methods until dewatering somehow spurred them to function fully.
Higgins described several mechanisms that could account for this nonculturable state. The first theory is that the bacteria could have been injured but not destroyed during digestion and that dewatering enabled them to repair themselves and become active again. The second theory points to the bacteria entering a viable but nonculturable state; this state would be a defense mechanism to the conditions of the digestion process. The third theory, Higgins explained, is that an inhibitor present in the digested solids is removed by the dewatering process.
Whichever of these mechanisms is at play, dewatering, frequently centrifuge dewatering, often triggers the bacteria to reactivate.
Fecal coliform concentrations are an integral part of the U.S. Environmental Protection Agency (EPA) Part 503 regulations that govern biosolids treatment and use. Class B and A biosolids must contain fewer than 2 million colony forming units of fecal coliform per gram of dry solids and less than 1000 CFU/g dry solids, respectively, at the time of use or disposal to comply with the pathogen criteria of the Part 503 regulations.
However, the regulations also include process-based equivalents for Class A and B that require no subsequent testing. In these cases, the observed reactivation and regrowth could push the fecal coliform concentrations above the allowed levels unbeknownst to utilities.
To find out how many nonculturable fecal coliform bacteria are present in digested solids, the researchers used polymerase chain reaction (PCR) testing to count Escherichia coli cells. PCR enumerates bacteria based on copies of DNA present, and E. coli is one of the main fecal coliform detected in culturing methods, Higgins said.
The testing showed that anaerobic thermophilic digestion followed by centrifuge dewatering led to reactivation most consistently and with the greatest magnitude of increase, Higgins said. About 87% of samples dewatered by centrifuge showed reactivation.
However, substantial increases in fecal coliform and E. coli density can occur after any type of dewatering of anaerobically digested biosolids. Such reactivation occurs about 70% of the time, according to WERF’s findings.
At the technical session, Mark Meckes, an EPA microbiologist, stated that much more work needed to be done before any actions were taken. “We still feel that the 503 [regulations] are appropriate and protective,” Meckes said. “There’s a lot more research necessary in this area if we are to discern the public health impacts.” However, he added, that as data comes to light, EPA will make changes to the part 503 rules as needed.
Meckes emphasized that reactivation and regrowth have only been seen in bacterial indicator organisms, not pathogens. Moreover, he said that this issue is strictly a bacterial one. Viruses, protozoa, and other monitored organisms require a living host to multiply. Meckes said the chances of those pathogens reactivating or regrowing after digestion are “slim to none.”
He also noted that reactivation has not been found at every plant using anaerobic thermophilic digestion with centrifuge dewatering. “Don’t jump the gun and assume you have a problem because you have that digestion process,” Meckes added.
To provide a level basis for seeking answers, the Water Environment Federation (WEF; Alexandria, Va.) in September issued a technical practice update (TPU) on reactivation and regrowth issues. The TPU includes an overview of related regulatory issues for biosolids stabilization and testing protocols, recommendations for communication strategies, and a description of known methods to address reactivation and regrowth.
“There was a lot of concern that once [WERF’s] report was released there could be some backlash in the biosolids community from a lot of the opponents of biosolids,” said Rhonda Bowen, recycling manager at Hampton Roads Sanitation District (Virginia Beach, Va.) and a co-chair of the WEF subcommittee that compiled the TPU.
Even though it might open a big can of worms, asking these tough questions is the only way to ensure that land application remains a viable option, said Chris Hornback, senior director for regulatory affairs at the National Association of Clean Water Agencies (NACWA; Washington, D.C.).
“The court of public opinion rules the day, and that’s ultimately where we will be judged on our response to this situation,” Hornback said.
To that end, the speed and extent with which the initial data was shared with stakeholders and the ongoing commitment toward research and communication are almost as important as the research results itself, Hornback added.
Hornback applauded WEF, WERF, and NACWA for moving so quickly and disbursing the information so widely.
“In fact, this project and our industry’s response, I think, have highlighted what we can accomplish when we all work together,” he said.
There are steps that treatment facilities can take to either avoid the reactivation or mitigate it. John Willis, vice president of Brown and Caldwell (Walnut Creek, Calif.), suggested four options for Class B systems. The first is land application of liquid biosolids, as there has been no documented reactivation or regrowth without dewatering, he said. Second, he suggested switching to a different dewatering technology, such as belt filter presses. Third, some form of post-dewatering treatment, such as lime addition, can be used to keep coliform levels in the acceptable range. Last, he suggested simply storing the dewatered solids until the fecal coliform reactivate and regrow and then die off.
To prevent reactivation and regrowth for Class A systems, he suggested keeping the solids hot from digestion through land application, using liquid land application, switching dewatering technologies, dosing dewatered biosolids with lime, and exploring multistage Class A thermophilic digestion. To date, systems with multistage anaerobic thermophilic digestion and centrifuge dewatering have shown no reactivation and regrowth, he said.
At press time, the second phase of research was expected to be completed by the end of the year, with a report on the findings due in spring 2007.
The objectives of the second phase are to verify and to better understand reactivation and regrowth and to develop mitigation strategies by answering the following questions:
- What combinations of wastewater process technologies lead to this observed increase in fecal coliforms?
- What specific process designs and operating conditions contribute to this increase in fecal coliforms?
- What are the mechanisms for reactivation?
- What conditions contribute to regrowth?
The study report, Examination of Reactivation and Regrowth of Fecal Coliforms in Centrifuge Dewatered, Anaerobically Digested Sludges (03-CTS-13T), was published in June. It can be obtained by searching WERF’s publication database at www.werf.org. The WEF TPU can be obtained through the WEF online bookstore at www.wef.org/marketplace. The TPU, free to WEF members, costs $55 for nonmembers.
— Steve Spicer, WE&T
Melding Technologies Helps To Perfect Predictions
Flash floods, by definition, occur quickly. Within minutes conditions can change, roads can wash out, and people can be trapped in quickly flooding areas. But by linking radar, rain gauge data, and hydrological maps, one system is able to predict precisely where floods will reach before the waters start to rise.
At WEFTEC®.06, scientists and other water professionals gathered to hear about this system from its developer, Philip Bedient.
“No one has ever linked storm surge with flood plains to figure out what’s going to be inundated,” Bedient said. “For flood prediction and flood alert purposes this [system] was pretty much dead on,” he said.
Bedient, who gave the keynote address at the annual luncheon of the Association of Environmental Engineering and Science Professors (AEESP; Champaign, Ill.), is the Herman Brown Endowed Professor of Engineering in the Department of Civil and Environmental Engineering at Rice University (Houston).
The Second Generation Rice University–Texas Medical Center Flood Alert System (FAS2) incorporates several technologies, including information from the National Weather Service and a hydrological model from the U.S. Army Corps of Engineers, to create a new tool that can predict the flooding effects of approaching storms.
“The goal of any flood alert system is to increase lead time,” Bedient said.
The FAS2 has been in place since spring of 1998. It has been operational during the last 30 storm events and has provided precise and timely information to the Texas Medical Center during Tropical Storm Allison in June 2001.
To predict peak flows, FAS2 combines available next-generation radar data with a real-time lumped model and a distributed hydrologic model. Bedient’s goal was to create a real-time system to predict the effects of storms as they approach, and use that information to alter evacuation routes.
For example, as Hurricane Rita approached, Bedient fed the latest weather and surge data into the model to predict its effects. If the storm surge had been 22 ft, as was once predicted, FAS2 showed that all of the major interstate evacuation routes from the center of Houston would have been flooded and impassable.
Luckily, when the storm made landfall, the surge had dropped and the effects were less severe. But, the model’s predictions proved accurate for the actual surge as well, Bedient said.
This type of technology is important in Houston because of the intense nature of Gulf Coast rainfalls, rapid urban development and expanded channels — generally clay soils with low infiltration capacity, high runoff rates, and mild slopes. It has become vital to provide early warnings to public and private entities while more permanent solutions are being developed.
While this system can predict flood patterns, it cannot take into account all possible events. For example, it would not have predicted the levy failure in New Orleans, he said.
“We’re trying to save lives with this, but we need a paradigm shift in coastal development,” Bedient said. “Katrina will be back.”
For the future of FAS2, the Engineering Research Center of the National Science Foundation has funded new systems through the Collaborative Adaptive Sensing of the Atmosphere (CASA) program. This distributed, high-resolution, radar-sensing network will help Houston provide timely and accurate forecasts, improve warning times, and direct emergency response at many levels.
Bedient described FAS2 as an operational system with many research capabilities added on. He noted that private sector involvement, in this case Texas Medical Center, is essential to ensure an operational product from university sources.
Bedient has worked on surface water problems including major floodplain studies, water quality assessments, and hydrologic modeling for a number of watersheds in Texas, Florida, and Louisiana and has also has performed groundwater monitoring and modeling studies at more than 25 hazardous waste sites across the United States.
More information on the FAS2 system can be found online at www.floodalert.org.
— Steve Spicer, WE&T
Moving Toward a Sustainable Future
Municipalities share water reuse experiences at WEFTEC®.06
As developments continue to sprout and sprawl throughout the nation — including areas with limited water resources — municipalities and developers alike are trying to lessen the environmental impact of development while designing innovative treatment and reuse options for wastewater. At WEFTEC®.06 in October, representatives from government, the wastewater field, and academia shared their personal tales of water reuse challenges and plans. The experience of two localities — one an established metropolitan area, and the other a new cluster development still in the planning stages — illustrate the variety and scope of reuse issues encountered by utilities across the United States.
Opening Up Reuse Options
In San Diego, the city’s Water Department owns two reclamation facilities that provide recycled water for irrigation and industrial uses. Currently, the facilities are not operating at maximum capacity because connecting customers through a dual piping system is a time-consuming process, explained community outreach specialist Lesley Robin at the WEFTEC.06 workshop, “Out of the Office and Into the Field: Real-Time Operational Issues with Water Reuse.”
San Diego, which currently imports 80% to 90% of its water each year and could face a 25% increase in demand by the year 2030, would like to maximize its water reuse options. In her presentation, Robin explained the process the Water Department has undertaken to have its water reuse goals approved by the City Council and citizens alike.
In 2004, the City Council asked the Water Department to conduct a water reuse study. The goal was to identify six additional uses for the water recycled at the San Diego’s two reclamation facilities. But there were challenges from the beginning.
Complicating the water reuse study was a 5-year-old mandate from the San Diego City Council that recycled water could be used only for nonpotable reuse.
“That forced the Water Department to … come up with what was feasible and present that information back to the City Council, which would involve their having to possibly reconsider their mandate,” Robin told Water Environment & Technology (WE&T). “The water reuse study was really expanding the boundaries of research and seeing what was feasible in addition to the nonpotable uses for irrigation and industrial purposes.”
A 67-member group of community stakeholders, dubbed the City of San Diego Assembly on Water Reuse, reviewed the study and provided feedback on the Water Department’s work. The group also took stands on water reuse issues and shared their views with the public.
Nine months later, the assembly met again to review the latest research, which included the most and least feasible water reuse options, based on the Water Department’s criteria. Suggested strategies included those that emphasized nonpotable use; those that offered a combination of nonpotable and indirect potable reuse projects; and those that focused on only indirect potable reuse.
“With indirect potable reuse, what was most feasible for San Diego was a process called reservoir augmentation, [which] means adding the highly treated recycled water to a drinking water reservoir,” Robin explained.
Despite the likelihood of possible public opposition, assembly members supported the indirect potable reuse option. The stakeholder group then presented its decision to several committees authorized by the city — including one comprised of four City Council members — prior to going to the full council.
The City Council committee reviewed the study and approved it for review by the full council — with a catch. First, the committee decided, the Water Department needed to hold public workshops on indirect potable reuse. At the first workshop, members of the stakeholders group spoke “fairly passionately,” Robin said, about their support of this form of reuse for the city. The committee then decided that it would be useful to hold more public workshops before presenting the plan to the City Council. At press time, these workshops had yet to occur.
“During this time, elected officials began to take sides on the issue of indirect potable use,” Robin said, “and that’s where we had some people supporting the idea, and others not supporting it.”
The involvement of elected officials has brought growing media attention, but the fate of San Diego’s water reuse options remains undecided.
Waste Not, Want Not
Wastewater is not waste at all, according to David Venhuizen of Venhuizen Consulting, who spoke at the WEFTEC.06 workshop “Integrating Centralized and Decentralized Wastewater Management.”
Rather, Venhuizen said, wastewater is a resource that should be reused as close as possible to where it is generated. Whether it’s stormwater or wastewater, whether it’s used for potable use or nonpotable uses such as irrigation, industrial uses, and toilet flushing, “it’s all water and it’s all good,” he said.
Venhuizen discussed a 526-ha (1300-ac) site outside of Austin, Texas, known as Headwaters, which will feature 1000 homes, commercial development, and land set aside for conservation purposes. The preliminary plan for Headwaters included a conventional collection system leading to a large wastewater treatment plant at one end of the development. One problem with this plan, Venhuizen said, is that several areas of the land have been denoted for irrigation, yet “this irrigation would be practiced for the sole purpose of getting rid of what is perceived to be a nuisance.” In other words, the reused wastewater would be irrigating land that did not particularly need watering, whereas it could be irrigating park space and residents’ yards.
“I call this practice ‘land dumping’,” said Venhuizen. “It’s an outright waste. We’ll never respect the watershed agenda anywhere as long as we focus on disposing of a nuisance instead of utilizing a resource,” he said.
A treatment process that produces effluent suitable for reuse is a must-have for a successful decentralized system, Venhuizen said. For the Headwaters development, he said landscape irrigation would be the best reuse option. “The idea is to create a zero-sum game where the water produced by each neighborhood is used to irrigate in that neighborhood,” Venhuizen said.
Cost, he said, would be trivial. “The reclaimed water distribution system would just be another pipe in the same trench as the effluent sewer lines,” he said.
In his plan for Headwaters, pipes would route the recycled water to subsurface drip irrigation fields located in residents’ front yards and on parkways — areas where the landscaping does not undergo much change.
Venhuizen admits that onsite irrigation might be met with some resistance by those who flinch at using their own wastewater to water their lawns. In that case, the recycled water could be used to irrigate parkway medians instead. And if there is resistance even to that idea, “you can still enjoy all the other advantages of the decentralized concept and just drain the effluent down to those areas that would be irrigated under the conventional wastewater plan,” Venhuizen said.
— Meghan H. Oliver, WE&T