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Winter Issue of The Bridge on Sustainable Water Resources


Critical Issues and Sustainability Challenges for a Large Metropolitan Water-Wastewater Facility

Water-wastewater utilities face critical issues in every aspect of their operation.

Water and wastewater (W-WW) utilities and the people who operate them are public servants dedicated to protecting public health and the environment by providing safe drinking water and managing wastewater in an environmentally sound way at reasonable cost and with limited resources and authority. W-WW utilities, in keeping with the goals put forth by the United Nations in 1987, strive to “meet present needs without compromising the ability of future generations to meet their needs” (UN, 1987). This article provides an overview of the challenges W-WW utilities face based on the experiences of the author and his colleagues during 29 years of service at the Washington Suburban Sanitary Commission (WSSC).1

Washington Suburban Sanitary Commission: Historical Performance

WSSC is a progressive, not-for-profit W-WW utility that has been in business for 93 years. It serves about 1.8 million people in two suburban communities, Montgomery County and Prince George’s County, Maryland, adjacent to Washington, D.C.

To protect public health as well as the ecosystem, WSSC conducts about 500,000 laboratory analyses per year related to water quality and cleaned wastewater. Throughout its history, WSSC has met all water-quality standards for potable water, including the latest requirements of the Safe Drinking Water Act (SDWA) for turbidity, lead, and disinfection by-products (Figure 1a). In addition, treated waste-water has almost always been below the levels allowed by the Clean Water Act (CWA) for biological oxygen demand, suspended solids, phosphorus, nitrogen, and other regulated parameters (Figure 1b).

Figure 1a & 1b

Despite its good record, WSSC, like many other large W-WW utilities, faces major challenges related to infrastructure, emerging contaminants, and other critical issues. Providing safe drinking water and disposing of wastewater in a sustainable way is a complex undertaking that requires a multi-step cycle that faces major challenges at every step: ensuring the availability and quality of source water; properly treating water and wastewater; maintaining infrastructure; and returning clean water to the environment. Examples of these challenges are described below.

The Availability of Source Water

WSSC has been fortunate to have enough source water to provide safe drinking water to its customers. However, water utilities in other parts of the country (e.g., California, Georgia, and Texas) have experienced source water shortages. It is believed that by 2050 water shortages will become more widespread in the United States as a result of significant increases in population, water demand, and food production (IWMI, 2006) (Figure 2). In all likelihood, this will signal the end of the era of free source water and exacerbate funding and other challenges for W-WW utilities.

Figure 2

The Quality of Source Water

Historical Perspective

Today’s safe drinking water practices for ensuring high-quality water are the result of thousands of years of experience. About 3,000 years ago, driven by the limited availability of surface water, groundwater was discovered in the Middle East as a source of clean water (Issar, 2008). One thousand years later, the Romans developed aqueducts to convey surface water to large cities, supply potable water, and maintain sanitary conditions.

More recently, significant improvements in water quality were achieved by introducing filtration and disinfection in treatment systems. Filtration, which was first implemented in this country in 1906, improved the physical removal of contaminants and, at the time, reduced the incidence of typhoid by as much as 86 percent to fewer than 100 cases per 100,000 people. Further treatment with chlorine disinfectant to inactivate microorganisms practically eradicated the disease by the 1930s.

Unfortunately, this achievement created a false sense of security on the part of water practitioners and the public that all contaminants in water could be eliminated by available treatment practices. This resulted in less focus on source water quality.

Concerns about the quality of source water on a national scale reappeared in the mid/late decades of the 20th century with the development of new technologies for detecting contaminants at trace levels and advances in health sciences that provided a better understanding of the health implications of such contaminants. As a result, the treatment-based framework for providing safe water was gradually replaced by a multi-barrier approach that requires protective action at every point in the water cycle, beginning with the protection of source water.

Limitations of the Clean Water Act

Significant improvements in water quality were achieved in many U.S. rivers following the implementation of the Clean Water Act (CWA), which was enacted in 1971 to ensure that U.S. waters were swimmable and fishable. As an example, no more fires occurred on the Cuyahoga River, which had at least 13 fires due to oil pollution prior to 1971. Unfortunately, these improvements were not adequate for protecting source water, largely because the CWA does not include regulatory control over nonpoint sources of pollution.

Chromium Pollution

Chromium contamination is another, probably less noted, example of a CWA shortcoming in terms of protecting drinking water sources. A carcinogen in the hexavalent form (Cr6+ or Cr–6) (Kimbrough et al., 1999), chromium occurs naturally in the environment but is also released into the environment by a number of industries. About 44.3 million pounds of chromium were disposed of by U.S. industries in 2009, including 10.6 million pounds from electric utilities (Evans et al., 2011).

Assuming a U.S. population of 300 million, the chromium from electric utilities alone is equivalent to 44 milligrams (mg) per person per day. By comparison, the amount of chromium currently allowable in drinking water is 0.1 mg/liter. Assuming that 2 liters of water are consumed per person per day, exposure to chromium via drinking water is 220 times lower than the chromium released by just this one industry. If ongoing discussions of regulation of Cr–6 result in even lower allowable levels of chromium in drinking water, the ratio will be even larger.

Upgrading water treatment plants to achieve these extremely low levels of Cr–6 in drinking water would be very expensive and would substantially increase energy use and greenhouse gas emissions. Therefore, we believe it would be more economical and prudent to control chromium disposal and its release to the environment at the source by tightening controls in the CWA or Resource Conservation and Recovery Act, rather than controlling it “downstream” at water treatment plants by very stringent regulations that would require very costly plant upgrades.

The Safe Drinking Water Act

Like the CWA, SDWA provisions are not adequate for protecting source water. SDWA requires that states conduct a source water assessment (SWA) for each water intake to determine its susceptibility to pollution. However, the SDWA lacks any provision for controlling sources of pollution identified by SWAs. Control is left to voluntary partnerships at the local level, which rarely work unless utilities pay for controlling pollution by upstream dischargers.

Controlling Potential Oil Pollution

Another challenge to protecting source water is oil pollution caused by failures of oil pipelines that cross watersheds. These pipelines are loosely regulated by the federal government, but state and local agencies have no control over them.

In 1993, for example, about 477,000 gallons of petroleum products, which can contain harmful chemicals such as benzene and toluene, spilled into a tributary of the Potomac River upstream of the Fairfax County Water Authority Corbalis Water Treatment Plant. The plant, which provides potable water to about 1.5 million people close to the nation’s capital, was forced to shut down completely for 13 days (EPA, 1999).

Fortunately, a combination of water-conservation efforts by the community and the availability of alternative sources of drinking water enabled Fairfax Water to offset the loss of water production at Corbalis. If those water sources had not been available, however, the community would have been without a safe supply of potable water for two weeks.

Pollution from Natural Events

Natural hydrological events also affect source waters. In 1938, a catastrophic hurricane hit the Quabbin Reservoir, Boston’s primary water supply. Heavy rain and winds caused severe uprooting and stem breaks of approximately 75 percent of the trees in the Quabbin watershed (Ottenheimer, 1992). As a result, tree roots could no longer hold sediment and nutrients in place, and significant amounts of both washed into the reservoir, promoting the growth of algae (and the potential formation of algal toxins dangerous to humans), depleting oxygen from the water, and suffocating fish and other aquatic wildlife.

Treatment plants are also impacted by severe hydro-biological events, such as intense rain and major algal blooms.   Treatment plants are designed to operate optimally in terms of performance and costs within a certain range of conditions, and large, rapid variations can negatively impact their operation. During one such event, WSSC Potomac WFP faced a 40-fold increase in raw water turbidity (an increase of 21 nephelometric turbidity units [NTU] to 900 NTU in just 2 hours).

In the future, extreme hydrological events and rapid variations in source water quality are expected to become more frequent and more intense as a result of climate change. These events could greatly increase strains on drinking water treatment facilities.

Emerging Contaminants: A Major Challenge for Water Treatment Facilities

Emerging contaminants present serious challenges for water utilities. The European Union estimates that approximately 140,000 products, including pharmaceuticals and personal care products (PPCP), on the market contain compounds considered emerging contaminants (ChemSec, 2011). Our understanding of potential human health impacts and persistence in the environment of these compounds, as well as our capability of detecting them, are still limited. Moreover, no regulations or guidelines have been put in place for managing the vast majority of these compounds.

Potential impacts on aquatic organisms, as demonstrated by intersex fish (female characteristics observed in males or vice versa) have been widely reported. The media and the public consider the occurrence of intersex fish “the canary in the coal mine” of potential effects of emerging contaminants in drinking water on human health. Concerns include mixture effects (from the presence of multiple compounds), effects on vulnerable individuals (e.g., infants and very young children), and intergenerational effects.

However, because of significant differences between fish and human exposure, using intersex fish as the canary in the coal mine may not be appropriate. Fish are exposed to water that may contain low levels of contaminants continuously—24 hours a day, 7 days a week—whereas human exposure to water is dramatically lower. Each person drinks only about 2 liters of water a day and has limited dermal exposure.

More important, fish are exposed to much higher levels of contaminants in water as a result of bioaccumulation-biomagnification of contaminants via the aquatic food chain. Studies have shown that biomagnification can amplify very low aqueous concentrations in a river to high concentrations in aquatic organisms much higher on the food chain (Kelly et al., 2007). For example, DDT has been increased by 7 orders of magnitude, from 0.000003 parts per million (ppm) in a river to 20.00 ppm in birds that ingest fish exposed to contaminated water.

Although the canary in the coal mine image may be questionable for assessing human health implications from drinking water exposures, it may be appropriate for total exposure to contaminants. Based on the limited data currently available, we do not have reliable knowledge about the level of human exposure to these chemicals, but it is likely to be many times higher via food and chemicals than via drinking water.

What we do know is that removing trace levels of contaminants during the water treatment process would be extremely expensive and energy intensive. In addition, sometimes changes can have unintended consequences. For example, switching from chlorine to chloramine disinfection to reduce the formation of disinfection by-products (DBP) in tap water increased lead in water due to corrosion in lead pipes (e.g., Giammar, 2009). In other instances, the removal of organic matter in drinking water to reduce DBPs is believed to have caused pinhole leaks in copper pipes, requiring homeowners to spend millions of dollars collectively for repairs (Edwards and Sprague, 2001; Edwards et al., 2003).

Overall, using intersex fish as the canary in the coal mine not only seems unwarranted for water supply, at least for now, but it also diverts attention from a holistic approach to protecting public health, the ecosystem, and source waters. In addition, it puts the financial burden on water utilities and leaves the producers of emergent contaminants and upstream dischargers with no incentives to reduce pollution (e.g., by green chemistry or control at the source).

We believe that requiring water utilities to treat water to very low contaminant detection limits without considering pollution reduction/elimination at the source or from other exposure pathways would not only be a huge financial challenge to water utilities (as well as a moral dilemma about redirecting limited financial resources), but also might not achieve meaningful reductions in total exposures. Nevertheless, we recognize that water utilities must continue to monitor research; advocate/participate in relevant investigations; educate customers, the media, and others; and advocate a holistic approach in lieu of an inefficient, “silo-based” strategy.

Infrastructure Challenges

A major problem plaguing many W-WW utilities is pipe breaks and service interruptions caused by aging infrastructure. The American Society of Civil Engineers (ASCE) assigned water and wastewater infrastructure in the United States a grade of D– and cited a five-year funding shortfall of about $109 billion for the nation, above and beyond the $146 billion that will be spent by W-WW utilities (i.e., $255 billion total is required) (ASCE, 2010). Disruptions caused by pipe breaks can interfere with the distribution of potable water, adversely impact firefighters, damage roadways and other infrastructure, and potentially expose water to external contaminants.

Water Distribution Systems

In the late 1960s and early 1970s, WSSC installed approximately 350 miles of pre-stressed concrete cylinder pipe (PCCP), ranging from 18 to 96 inches in diameter. PCCP is a composite of concrete and pre-stressed steel cylinders. However, from 1975 on, numerous catastrophic PCCP failures occurred in the WSSC district (see example in Figure 3) arousing public outrage and causing tremendous damage to roads and adjacent infrastructure. The price tag for replacing all of the PCCP as a preventive measure, as the public desired, would have been about $2.9 billion. WSSC adopted a more economical approach of using nondestructive testing, monitoring, and inspection and replacing the segments at high risk of failure.

Figure 3

Wastewater Collection Systems

Similarly, W-WW utilities face major challenges related to sanitary sewer overflows (SSO). Houston, for example, conducted a study to monitor and model occurrences of fecal coliform upstream and downstream of SSO discharge points. The study revealed that because of highly polluted runoff from nonpoint sources, fecal coliform levels above and below the SSO discharge point differed by only about 1 percent. Thus, the benefit of SSO control was almost nil.

Nevertheless, the utility was required to allocate $1.2 billion for SSO control, funds that could have been used for extensive holistic actions in the watershed to achieve a much bigger improvement in water quality. Many other utilities face similar challenges.

Funding Issues

W-WW utility service is a capital-intensive undertaking, and many W-WW utilities face funding issues. Their asset/revenue ratio (11) is far higher than for other types of utility services, such as electric utilities (3.5) (Figure 4). In addition, some components of water and wastewater infrastructure (e.g., pipelines, tank structures) have 50 to 100 years of service life but generally must be paid for with 20- to 25-year loans. We urgently need to address this issue in particular to ensure the sustainability of water and wastewater services.

Figure 4

Communication Challenges

Until a few decades ago, W-WW utilities worked primarily with federal and state agencies and did not have much interaction with customers. This resulted in significant misunderstandings between utilities and their customers (Figure 5).

Figure 5

Times have changed, however. Today W-WW utilities are confronted not only by more stringent, sometimes conflicting, regulatory requirements, but they also receive inputs/questions on a daily basis from a growing number of other stakeholders. Computer-savvy groups and individuals often use social networking tools to pursue their objectives and ideas, which may or may not be based on sound science and may or may not lead to holistic solutions. In these situations, W-WW utilities may be pressured to make short-sighted decisions that do not take into account the larger context of sustainability.

Unfortunately, sensational reporting during crises makes communication particularly difficult, and fear mongering by advocacy groups addressing the contaminant du jour is often spread by the media. Educating customers and stakeholders on actual risks and persuading them to take a holistic, rational approach may be the most difficult challenge of all, especially during a crisis.

To address the communication challenge, W-WW utilities must establish a proactive relationship with stakeholders based on credibility and trust. Although it might take years to establish such a relationship, especially if public perceptions have been negative, only when utilities are considered credible and trustworthy will their arguments for addressing issues in a holistic sustainable way be heard above the noise.

Conclusions

W-WW utilities face critical issues in every aspect of their operation, including source water availability and quality, treatment for controlling emerging contaminants at trace levels, major rehabilitation and replacement of aging water distribution and waste-water collection infrastructure, serious funding issues, and communication challenges. To address these issues, we must educate our customers and the media and work collectively with legislative and regulatory agencies to expedite the transition from the current silo-based approach to addressing problems to a more efficient and long-term holistic approach.

Acknowledgment

The author greatly appreciates major contributions to this article by WSSC scientists, including Bob Buglass, Plato Chen, Dr. Martin Chandler, and Dr. Caroline Nguyen. The author is also grateful to WSSC management and the director of the National Research Council Water Science and Technology Board for their support.

References

ASCE (American Society of Civil Engineers). 2010. Report Card for America’s Drinking Water Infrastructure for 2009. Available online at http://www.infrastructurereportcard.org/fact-sheet/drinking-water. (Accessed September 16, 2011).

ChemSec (International Chemical Secretariat). 2011. “The EU regulation on chemicals.” Available online at http://www.chemsec.org/get-informed/eu-chemicals/reach.

Edwards, M., and N. Sprague. 2001. Organic matter and copper corrosion by-product release: a mechanistic study. Corrosion Science 43(1): 1–18.

Edwards, M., D. Bosch, G.V. Loganathan, and A.M. Dietrich. 2003. The Future Challenge of Controlling Distribution System Water Quality and Protecting Plumbing Infrastructure: Focusing on Consumers. In Proceedings of the IWA Leading Edge Conference. Noordwijk; Netherlands.

EPA (Environmental Protection Agency). 1999. Response to Oil Spills. Chapter 8. EPA: Washington, D.C.

EPRI (Electric Power Research Institute). 1998. Competition in the Water and Wastewater Industries. Industrial and Agricultural Technologies and Services, Report CR-110244.

Evans, L., B. Gottlieb, L. Widawsky, J. Stant, A. Russ, and J. Dawes. 2011. EPA’ s Blind Spot: Hexavalent Chromium in Coal Ash. Available online at http://www.psr.org/assets/pdfs/epas-blind-spot.pdf.

Giammar, D. 2009. Influence of Water Chemistry on the Dissolution Rates of Lead Corrosion Products. In Proceedings of the American Water Works Association Water Quality and Technology Conference. Seattle, Wash.: American Water Works Association.

Issar, A.S. 2008. The impact of global warming on the water resources of the Middle East: past, present, and future. 
Pp. 145–164 in Climatic Changes and Water Resources in the Middle East and North Africa. New York: Springer.

IWMI (International Water Management Institute). 2006. Water for Food, Water for Life: Insights from the Comprehensive Assessment of Water Management in Agriculture. Battaramulla, Sri Lanka: IWMI.

Kelly, B.C., M.G. Ikonomou, J.D. Blair, A.E. Morin, and F.A.P.C. Gobas. 2007. Food web-specific biomagnification of persistent organic pollutants. Science 317(5835): 236–239.

Kimbrough, D.E., Y. Cohen, A. Winer, L. Creelman, and C. Mabuni. 1999. A critical assessment of chromium in the environment. Critical Reviews in Environmental Science and Technology 29(1): 1–46.

Knight, Z., and R. Miller-Bakewell. 2007. Water Scarcity: A Bigger Problem than Assumed. New York: Merrill Lynch Equity Strategy. Available online at http://www.ml.com/media/86941.pdf.

Ottenheimer, D.G. 1992. Hurricane susceptibility and water quality at Quabbin Forest, Massachusetts. Master’s Thesis. SUNY College of Environmental Science and Forestry.

Tatham, C., R. Cicerone, and E. Tatham. 2006. Stakeholder Perceptions of Utility Role in Environmental Leadership. Denver, Colo.: Water Research Foundation, American Water Works Association, IWA Publishing.

UN (United Nations). 1987. Report of the World Commission on Environment and Development. A/RES/42/187, 96th Plenary Meeting, December 11, 1987.

  

FOOTNOTES

1 The views expressed in this article are those of the author and his colleagues. They are not intended to represent the official views of the Washington Suburban Sanitary Commission.

 

 

 

About the Author: Mohammad Habibian is environmental group leader, Washington Suburban Sanitary Commission, Laurel, Maryland.