Urban Agriculture 2: Agri-Sewage

I've written before about the importance of urban agriculture, particularly during the current food-price crisis. That we are also going through serious water shortages in many parts of the globe begs a question that I had wondered about while I was in South Africa: where are urban farmers getting their water? The answer, according to a report by the International Water Management Institute (IWMI), is Sewage. The World Health Organization tells us that 10% of the world's population relies of food grown in fields watered and fertilized with untreated human waste. The IWMI report argues that not only will that be an inevitable reality for the conceivable future, but that it might not be all bad -- if we deal with it constructively.

The Guardian excerpts a section from the report that lays out the situation:
"As long as developing countries lack suitable transport to deliver large quantities of perishable produce to urban areas, urban agriculture will remain important. In the face of water scarcity generally and a lack of access to clean water, urban farmers will have no alternative except to use … polluted water." That polluted water can produce significant yields. In Ghana's capital Accra (pop. close to 2 mil.) 200,000 residents purchase vegetables produced on just 100 hectares of urban agricultural land that is irrigated with sewage. That is a lot of food, but it is also a direct vector for dihoreal diseases and cholera. The pratice, they go on to say, is not limited to Africa but is also found in China, India, Vietnam and Latin America.

So what to do? The IWMI makes clear that outlawing the agricultural use of nutrient rich waste water is simply not an option. Shortages of both clean potable water and affordable food make it a necessary reality. They are happy that cities are finally willing to discuss what had been a tacitly accepted practice. Instead of introducing strict standards or restrictions that will be impossible to enforce, the report recommends promoting practices like drip-irrigation (which keeps bacteria off the edible parts of the crops), creating infrastructure in markets to carefully wash produce before sale, and the use of settling pools and other low-tech forms of water filtration. (Some of these same simple biofiltration technologies are used in Canada and elsewhere to provide low-cost sewage treatment and storm water remediation services from smaller centres like St. Stephen (NB) to larger cities like Edmonton (AB). As search for "wetlands" on The Federation of Canadian Municipalities Green Municipal Fund database turns up a number of examples.)

Distasteful as it may seem, there are multiple advantages to using waste water for irrigation; it relieves stress on fresh water supplies (agriculture currently consumes close to 70% of global fresh water supplies), it is rich in nitrogen, phosphorous, and potassium and provides an alternative to costly chemical fertilizers, and it supports both a needed source of food and the livelihoods of urban (largely female) farmers. It also serves an important ecological function; in the same way that settling pools and wetlands can clean waste water before agricultural use, the fields themselves serve to further filter the water reducing its impact on surrounding rivers and streams.

To rethink cities as productive parts of our ecosystem, not just monstrous consumers of resources, is the challenge that we currently face. We also have to address the pressures placed on our cities by rapid population growth, urban poverty, and deficits in needed or aging infrastructure. Looking for linked solutions to these problems guided by principles like "Zero Waste" is something that we are comfortable with, up to a point. Waste water agriculture might be a bit beyond that point for some of us. (But so might other aspects of "accepted" agri-business practices if we knew about them - case in point, the regular scandals that plague industrial meat manufacture, this time in Canada.) But from the IWMI report it is clear that "sustainable" practices can be born of necessity and test some of our preconceptions about what is possible, practical and safe. It also shows that while necessity may push innovation, careful guidance and support is necessary to minimize risks and maximize returns.

The best summary of the report that I have found is here (although not as easy on the eyes as the National Geo. piece linked above).

UPDATE: Sustainablog has just put up an interesting post, excerpted from Lester Brown's Plan B 3.0: Mobilizing to Save Civilization, on the need to raise the productivity of water used for agriculture. They don't touch on the waste water issue though. Read more...

ReCoding our Cities

Building codes and zoning bylaws can often be a major barrier to sustainable building and planning. If they don't block a project completely, added costs and red-tape can deter all but the largest or most determined developments. While I was in Portland last week, I discovered an interesting group called ReCode Portland. Their aim is to review the city's zoning and building code and to identify and remove barriers to sustainability. But surprisingly, perhaps, they are not based out of a municipal office...

Nestled in the buffer zone that runs around Tryon State Park there is a small farm. The people of Tryon Life Community Farm grow some of their own food, raise goats and chickens, run a kindergarten and an ecological education centre, and live communally in a variety of quirky artistically designed structures. Like many alternative communities it is equal parts hard work, idyllic dream, and zoning nightmare. Simply trying to combine so many different land-uses (residential, agricultural, educational, commercial...) on one small plot put them at odds with state and municipal regulations.

Thanks to support from the community and the city, the farm got a variety of site specific permits to allow them to do what they do. But that didn't satisfy them. Other attempts at creating alternative communities are often based on a certain amount of escapism and a desire to start from scratch (Paolo Soleri's beautiful project is back in the news, for example). Often they get marginalized as a result. Tryon Life went in another direction. Aware of that existing codes and regulations blocked new forms of sustainable urbanism, instead of trying to escape the code, they decided to help change it.

Since being set up a little over a year ago, the ReCode Portland project has attracted a broad base of support beyond the farm, including the local green builders guild, consultants, planners and community members. With a core membership of 14 council members and various other partners, they have successfully applied pressure and worked with the State to begin legalizing greywater use (already permitted in other States like Washington and Arizona). Their sights are now set on State and local codes that block homeowners from adding secondary dwellings, or using sustainable design principles or new materials like passive ventilation or AirKrete walls.

More fundamentally, they are looking for ways to shift codes to support innovation and experimentation. This includes putting in place experimental and owner-builder class permits that would allows greater freedom to chose and test new materials and designs. All of this is geared towards making increased density and efficiency accessible to individual homeowners, so that we can begin to transform the housing stock we already have without depending entirely on major new redevelopments.

The city has recently given ReCode a grant worth close to $10,000 to support their work. While I was there, some joked that it might seem a bit odd for the city to be funding people to be their critics. From what I saw, it was money well spent.

More here.

Get Ready 2 : More on "Building Resilient Cities"

Unsurprisingly, most of the media seems to have stopped reading about two paragraphs into the executive summary of the new UN-World Bank publication ""Building Resilient Cities." As a result coverage is based on the dramatic statistics about the size of Asia's cities and their vulnerability to extreme weather. On that front it doesn't offer up much news (although it does fit nicely with other similar coverage closer to home, this time from New York City). But "Building Resilient Cities" is a beast of a very different sort.

While it does provide a useful synthesis of sectoral risks and case studies of responses, the real meat here is in the sections dealing not with what to do, but how to get it done. Unlike your usual report, the primer is designed as a tool to help cities start doing. The materials are laid out to guide a city through the processing of forming a Climate Change Team and bringing together silo-ized departments, evaluating the level of risk faced by the city, and then identifying ways to address those risks. The crucial step here is the first one.

The primer returns in various ways to the fact that climate change is a challenge, not just to our infrastructure, or our buildings, but to the structure of our municipal institutions and how we have organized ourselves up until now. Responding to climate change -- whether by reducing our emissions, or reducing the risks we face, or both -- is a crosscutting project that fits badly into the traditional divisions that structure a municipality. Creating a strong institutional home for climate change, one that helps coordinate action across multiple departments, is the number one priority for action cited by the report.

While Canadian cities face different natural risks than cities in Asia, we will face risks all the same. Here as well we need to worry about silos as much as sewers. Given that, the resources compiled in "Building Resilient Cities" should be of interest here as much as anywhere else. Even if the dramatic stats and case studies may be familiar to some, the excercise in institution building that the primer lays out charts a well designed path for cities trying to plan their approach to climate change. Read more...

Get Ready: Building Climate Resilient Cities

In the same vein as the Federal Engineers report discussed earlier, a new UN-World Bank report released last week aims to point the way to climate proofing our cities. "Building Resilient Cities" is focused on the large cities in the Asia-Pacific region. Up until recently the majority of our attention here in the North has been focused on reducing emissions. The publicity value of committing to GHG reductions has attracted many municipal politicians and media outlets. But results have been slow in coming - see the US Mayor Climate Protection Agreement for example.

Increasingly though adaptation is starting to get the attention it needs. Initially the key guidelines seem familiar: Don't build on floodplains or unstable slopes, protect coastal defenses, build more resilient infrastructure... I'll be giving a closer look to the report later in the week and am curious to see whether the report tangles with why such seemingly common-sense ideas are often so hard to put into practice.


Eco-Density / Condo-Destiny

I was a guest of Radio-Canada's national afternoon show "Ailleurs c'est ici" on Wednesday. They had me in to discuss Eco-Density, Vancouver's trade-marked take on denser mixed-use developments. You can listen (in French) here. It was a basic introduction to the plan and the environmental advantages of livable dense communities. A trickier issue that we didn't get a chance to cover though -- and an important one -- is the way these environmental and social benefits are being undercut by Vancouver's poor track record when it comes to protecting both office space and lower income housing downtown.
Cities are dynamic places. When you throw a new gear into the works, the behaviour of the whole system can change. In this case, the opening of progressively more zoning to residential development and the resort economics of Vancouver's real estate market has meant that high end condominiums have rapidly choked out all other forms development in the downtown area, often displacing existing offices. 5 to 1 returns on condos compared to office space has meant a 10 to 1 imbalance in new developments. While city officials are supportive of office space, the actual square footage being built hasn't changed in the past three years.

Non-market rate housing is in the same boat. By definition it is not meant to turn a profit, and the city government has been either unwilling or unable to competently defend either against the tide of condos. See for example the Mayor's 2006 reduction of -- already agreed upon -- affordable housing in the Olympic village, and the CCPA's excellent report on the links between affordability and sustainability.

This started years before the recently released Eco-Density Charter came into effect, and some say there's no need to worry. Matthew Kahn, an economist at UCLA, argues that cities win when they attract high-payed (and high-property-tax-paying) professionals to their downtowns. And if they buy property but don't live there (as is the case for many vacation-home condos in Vancouver) "It's a free lunch, with these people moving in, paying taxes, and demanding no services at all."

Common wisdom about free lunches aside, his argument stands up in a very limited way. But as soon as you look beyond the tax base you realize that this type of development undermines the key principles now used to justify it: Eco-Density's commitment to build more sustainable and livable cities. What you end up with instead is a dormitory resort downtown whose residents reverse commute to suburban office parks, crossing paths in the sky train with the suburbanites who are commuting into the core to work low-paid jobs as coffee clerks in so-called mixed-use towers. I simplify for effect, but you see my point.

The balance is a tricky one, and the (real estate) market is certainly not going to sort it out for us. This seems like a clear case where the question is not whether the government should intervene in the market, but how. It is also makes a good example of the need to combine social and environmental sustainability. Often, as here, you can't have one without the other. You can't have the truly mixed-use localized communities that Eco-Density stands for unless you protect the ability of a variety of income groups to live, work and play there.

UPDATE 08.19.2008: WorldChanging has recently put what is happening in Vancouver in a broader context of a shift that is taking place in cities throughout. The discussion was sparked by this interesting article by Alan Ehrenhalt in The New Republic the "demographic inversion" that is once again turning cities centers across North America into homes for the wealthy rather than the poor. Read more...


This is a blog for news and views on the future of sustainable cites. A major revamp is in the works. Until then I am keeping this version up as an archive of my past writing.

You can expect occasional updates, but not with the same frequency as in the past.

You can also find my writing on urban redesign and sustainability in ReNew Canada, The Mark, Sustainable Cities Canada, WorldChanging, and other more specialized academic publications.

Info on my consulting work, c.v. and current research focus is all here.