Societal Value of Water Infrastructure Upgrade
Humor me this month. Last month you read about measles and, based on the requests for reprints and comments that I got, people saw the relevance to biosolids. Next month I promise I will get back on more conventional topics. I’ve already started collecting articles on micro plastics. For this month I am focusing on water infrastructure, a topic that I am really fascinated by. Everybody reading this blurb is a product of a particular mindset in how we get freshwater and how we deal with certain wastes and wastewater. We have come of age in the area of centralized treatment with water as the conveyance, and gravity flow as the primary means of transport. Like many of us, our pipes are also getting creaky and have sprung some leaks (See November 2010 library for example). In preparing this library I read that the American Society of Civil Engineers estimated in 2009 that the cost to modernize our water infrastructure was $2.2 trillion. That is a lot of money. So will we have the political will to spend it and if we do, what is the best system for that money?
Since we built our current infrastructure many things have changed. Now about 54% of our population lives near a coastline. And about that same percentage live in urban areas. At the same time, our precipitation patterns have changed. Water now behaves more like a manic depressive than an even keeled type (see figure below). We have many more high intensity events or their opposite- no events aka drought. See California and the Southwest if you want more proof of that one. And we have to consider a wider range of factors than we did when our existing infrastructure was constructed. Energy use and availability, climate change, ecosystem services- life has gotten a lot more complicated than it used to be when we worried about pathogens and NPDES permits.
This month’s library focuses on future options for water infrastructure in the US. Going through articles for the library, there were some hard choices to make. For example, I started by reading the text from the 2010 and 2014 Clarke Prize lectures (http://www.nwriusa.org/documents/2015ClarkePrizeNominationGuide_000.pdf). I found these on line and you can easily too. Both set the stage really well. The 2010 lecture by Jerry Schnoor had a more international focus and information on agriculture. The 2014 lecture by David Sedlak was much more the story of an engineer trying to look outside of the traditional box, while simultaneously promoting his new book. Still good information. I left both of those out because they are easy to find and not quite as rich in detail as the articles that made it in.
The first piece is actually co-authored by David Sedlak. It is a broad review of the modern context for urban water systems. The article starts by saying that what we got is broke and it is going to be tough to fix it. But there are new tools, both high tech tools and a better understanding of natural systems to help us. The new water framework- whatever that will look like has to embrace these 4 themes:
1. Increase water availability through greater efficiency, demand management, stormwater harvesting, desalinization and water reuse
2. Broaden treatment options though new technologies and natural processes, differentiating treatment levels to match intended use (read as doesn’t all have to meet potable standards) so that our systems are more resilient
3. Wastewater as a resource through energy and nutrient recovery (what will they think of next!)
4. Put all of this in the appropriate socio economic context- or as they phrase it ‘establishing an enabling environment by EXPLICITLY addressing institutional and management challenges, talking about costs and trade-offs and involving stakeholders
The rest of the paper details these four themes -- dense but good reading. From there we go to paper #2 which addresses above point #3. What is really interesting about paper #2 is that in Table 1 the authors put a price tag on the value of the constituents of wastewater. The price per cubic meter of water, nitrogen, methane, organic fertilizer and phosphorus are included. Water fetches the highest price because it is the most plentiful. But the VALUE per cubic meter of wastewater is about $0.35. The authors then go through a range of different options for capturing that value. These include many familiar things but there is also a big focus on decentralized treatment options and the relative costs for decentralized treatment in comparison to our standard centralized model. There is also a discussion of doing away with secondary aerated treatment and replacing this with anaerobic treatment -- why spend energy to recover energy. If you are at all interested in the treatment process -- this might be fascinating for you.
If you like a good story, you will likely enjoy paper #3. This is the tale of how Melbourne, Australia coped with the Millennium drought. Melbourne’s solution involved a lot of public outreach and low tech solutions, including capturing stormwater, conservation (reducing per capita consumption by 46% (and yes they still take showers there), price increases, and public outreach and education. Wastewater reuse has also been part of the solution. This has all been accomplished while taking into consideration and addressing environmental demands for water. The final section of the paper compares the situation in Melbourne to what is happening in the Southwest US.
Paper #4 was a tough choice- there was a really interesting one on that quantified the electricity use associated with water for the western U.S. I am happy to send that if you would like. But the winner was an article on centralized versus decentralized treatment systems. Centralized treatment is such a central part of our model (pun not even really intended) that it is very hard to think of accomplishing similar treatment on a localized level. I can get grey water diversion for toilets and irrigation- laundry to landscape is even a nice catchy phrase. Stormwater capture is easy to understand. But decentralized treatment is a hard one. Here different models and associated costs are presented. Pyrolysis, not one of my favorite things is discussed as a way to manage solids. It is also discussed that water can be treated and the solids that do move to a centralized facility would arrive in a more concentrated form.
Finally paper #5- co-authored by Megan Plumlee, a member of the Kennedy Jenks team, presents a really interesting accounting for the benefits of using reclaimed water for environmental enhancement. Instead of direct ocean discharge, a portion of the water from a plant in the Bay area in CA was used to augment stream flow. The authors do an inventory on stream health and see modest improvements in water quality and habitat including spotting a frog on the endangered species list. They also use previous work to put a dollar value on the recreational and aesthetic value for the improved stream. These are including in their accounting along with O&M cost of the conventional and environmental enhancement- no surprise here that environmental enhancement wins out.
In summary, we have very big challenges ahead, but also really big opportunities. Many of these opportunities can result in cities with stronger communities, more resilient water systems, and nicer streams. These are exciting times.
Sally Brown, University of Washington