Environmental engineer proposes an updated approach to drinking water quality management

For the last 20 years the California-based National Water Research Institute has awarded the Clarke Prize, a medallion and $50,000, to an individual in the U.S. who has implemented better water science research and/or policy development to solve real-world water challenges. This year’s winner is Rhodes Trussell, Chairman and CEO of Trussell Technologies, Inc., an environmental engineering consulting firm based in Pasadena, California.

NWRI considers Dr. Trussell to be an authority on a vast number of treatment technologies, ranging from conventional treatments such as filtration, disinfection, and biological processes, to advanced treatment such as membranes and advanced oxidation. He is the author of peer-reviewed articles and technical reports on all of these topics, including the textbooks MWH’s Water Treatment: Principles and Design and Principles of Water Treatment. He has also worked on hundreds of water and wastewater engineering projects across the globe, and has developed the process design for treatment plants ranging in size from 1 to 900 million gallons per day in capacity. Because his focus is on implementing practical solutions to improve water quality and meet regulatory and public health needs, his efforts have resulted in better water policy and the widespread adoption and acceptance of many new treatment technologies.

Recipients give a lecture on a topic of their choice to the award ceremony. Dr. Trussell chose the topic How Safe Is Safe in the Treatment of Drinking Water for the Public? He provided an overview of the topic relative to both the growth of human commerce and the development of our scientific understanding. He said that the new era calls for a hybrid of the precautionary approach because, if implemented in a simple way, the Precautionary Principle could quickly deplete resources to solve problems that may not ultimately prove important. He suggested that there are four principles that environmental engineers might adopt as guidelines:

  1. We should generally agree that we prefer not to have these man made chemicals in our environment or drinking water.
  2. We should recognize that this first principle is not universally achievable; therefore, we need a screen to help make intelligent investments and decisions before settled science is available.
  3. In the treatment of both drinking water and wastewater, we should seek continuous improvement, implementing affordable broad spectrum treatment technologies as they become available.
  4. We should find substitutes for man made compounds that persist through our treatment processes and in the water environment, giving priority to those with adverse effects.

He went on to say that of the four guidelines, the second – developing a screening process for toxics – is arguably the most important and most difficult to achieve. The need for a screen that can be used before settled science is available, however, leads to an essential question: Does the dialogue in the drinking water community need a new, more robust discussion on the questions of risk and when water is safe? As a society, when we gather scientific data about what our collective risks are, we reach agreement easily.

For example, data from the Centers for Disease Control and Prevention (CDC) (CDC, 2012) show a U.S. citizen’s risk of dying from heart disease is about 24 percent, and the risk of dying from cancer is about the same (23 percent). But when we have a community or national discussion about the appropriate level of risk to which each citizen should be exposed as a result of a public service, such as the provision of drinking water, consensus is much harder to find. So far, where both environmental risk and risks associated with drinking water are concerned, our industry generally tries to engage the public in a discussion about the risk on the outcome side of a proposed project, attempting to find what risk is acceptable. The problem is one of communication.
When an engineer or scientist seeks to understand the safety of alternative outcomes, he or she normally begins by estimating the level of risk. For the layman, however, seeking safety is about avoiding risk altogether. Better bridges must be built between the scientist’s understanding of risk and the layman’s understanding of safety. That bridge might be the concept of de minimis risk. The term comes from the Latin “de minimis non curat lax,” or “the law does not concern itself with trifles.” A de minimis risk, then, is a risk that is too small to be concerned with. Someone exposed to that risk is considered “virtually safe.”
While most agree on the de minimis principle, there are often strong disagreements in specific circumstances as to what level of risk is, in fact, de minimis. For the public to accept the decision, the specifics cannot be resolved by science alone and are usually decided by an accepted authority, a regulator, court of law, or organizations like the National Academies.

Dr. Trussell’s lecture also includes discussion of considering both pathogens and anthropogenic chemicals in a similar framework as “Chemicals of Concern”.

He concluded his lecture by saying:

“Conquering waterborne disease was one of the greatest accomplishments of the Twentieth Century. Beyond treatment, our Twentieth Century paradigm was to seek natural water sources that had not been contaminated. The trace organic compounds we now see in drinking water are harbingers of a new era where the growth of population and commerce make the natural water paradigm increasingly unworkable.
Where trace organic chemicals are concerned, a new paradigm is needed for safe water. Ultimately, conventional regulations must be expanded to more effectively address impaired sources, but our traditional approach of risk assessment and regulation is too cumbersome to deal effectively with this new age. We should examine the Precautionary Principle to see if we can implement a more proactive approach.”

The entire Clarke 2013 lecture is available at http://www.clarkeprize.com/resources/2013_Clarke_Prize_Lecture2.pdf

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