Low Impact Development

Eric Damian Kelly's picture

A grad student in our program at Ball State told me several months ago that he wanted to do his creative project (a thesis alternative) on "low impact development." His particular interest was in what we called "natural drainage systems" when I worked with the planners and landscape architects at Rahenkamp, Sachs Wells in Philadelphia 30 years ago.  I told him that it was a great topic and suggested some contemporary and older resources, including an excellent 1975 publication by the Urban Land Institute entitled Residential Storm Water Management. I also told the student that the big issue with such systems is maintenance.

The history is in itself interesting. The ULI was an early proponent of such systems because they saved costs at the development stage -- and seemed environmentally more responsible.  Today, as we seek more sustainable models for our communities and cope with the MS4 rules that now apply to all urbanized areas, local "green" groups and environmental control officers see such systems as a good alternative to the traditional systems of curbs, gutters and storm sewers.  

My comment did not dampen the student's enthusiasm and he has worked diligently on the project for many weeks.  We have talked about his research and findings. He missed a class last week to attend a full-day conference discussing this very subject.  We met today and I asked him how it was going. He said, "The big issue is maintenance, and nobody seems to have good answers to it."

I took no pleasure in being right about his major obstacle and about a probable major conclusion of his paper. He is the kind of student who, I hoped, might find that hidden success story somewhere that solved the problem.  But the issue is real.  The first time a city engineer or public works director told me that "maintenance is a problem" with such systems, I assumed that this was in the same league with "fire trucks need 100-foot radii on cul-de-sacs" and that there were a range of solutions.  As my colleagues and I at Duncan Associates have worked with local governments in writing development codes over the last 20 years, however, I have recognized the depth and complexity of the problem, particularly in residential areas.

Some developments use swales and ponds in easements that cross dozens or hundreds of individual lots. Even I recognized that immediately as a major problem waiting to happen.  All it takes is one homeowner to put a storage shed in the swale or to fence her or his entire yard, including the swale, to impede the flow of the swale and back water up onto "upswale" landowners. Even a chain link or mesh fence will, over time, gather debris and become a solid dam. Giving complete maintenance responsibility and management control to multiple individual homeowners is not a workable solution for an important public facility.

Some projects keep the swales in the ownership of an association. From a planning perspective, that is a better approach than "lotting out" the facilities. Homeowners' associations, however, have budget issues much like those of local governments – but few of them have staff engineers around to say "we must take care of this facility."  Thus, when the association budget is tight and it must choose among patching potholes, fixing the swimming pool and doing routine maintenance on the stormwater facilities, I would bet on the swales and ponds coming in last.

Local governments are typically not enthusiastic about accepting dedication of such facilities, in part because they are not staffed to maintain them.  Concrete, underground stormwater pipes need little routine maintenance. The streets and gutters used as the collection system primarily need sweeping, a job that most cities accomplish easily and regularly with big equipment.  Swales and ponds need occasional patrols to pick up trash and debris, periodic mowing (particularly in wet climates), and regular monitoring and occasional maintenance on filters, controlled outflow points and other critical elements.  None of it is high-tech and none of it is particularly expensive – and none of it fits the job description of anyone in the typical public works or streets department. Sure, parks departments mow lots of things – but they mostly do it with large tractors that mow six or eight feet at a swatch, equipment that is ill-suited to narrow, gradually sloped swales. 

Even if a particular local government is willing to undertake such maintenance tasks, I recall a conversation several years ago with a public works director who hated alleys.  I asked her why.  She said, "they are ideal for picking up trash and a good place for utilities."

"So, what is the problem?"

"Our trash trucks and utility maintenance equipment are large.  People plant trees in their backyards and the trees gradually grow large branches over the alley.  The only way to get our equipment through the alley is to through and trim the trees periodically. When we do that, I get hate mail and complaints for city council members. I hate alleys."

So what is my message today?  Well, one part of it is the hope that someone who reads this will blog or e-mail and say "We SOLVED that.  Here is the perfect solution."  Now I am always skeptical of professed easy solutions to complex problems (as I was when a colleague, in accurately, told me that his county had come up with a perfect TDR system), but I will certainly listen with interest.

My more important message, however, is that, as planners, we need to think through all of the implications of our proposals. I have colleagues suggesting local planning solutions to global warming.  Some of them are inherently practical, but some of them look good only on paper – because no one has thought about how to manage and maintain them over time. Most of us are not engineers and cannot fully design engineered solutions to complex infrastructure problems – but as we propose new planning concepts, we should at least be thinking about how they might work, or not, in a real community, over time, in good budget times and bad. 

Eric Damian Kelly is a professor of urban planning at Ball State University and a vice president of Duncan Associates.



Maintaining LID

Eric--thanks for this post. I work for a firm called SvR Design in Seattle that has been implementing LID for a number of years, perhaps most famously at the Hope VI High Point Redevelopment. You are right, maintenance is a big issue not only relating to natural drainage features, but also porous pavements, etc. I would encourage your student to review the maintenance guidelines for High Point as a good document for maintenance practices for LID. That document can be found at our website here http://www.svrdesign.com/resources.html under "Educational Resources."

I would also relate some recent work we did while writing an LID code for the City of Fife WA. There, the green infrastructure of LID in the right of way will be maintained by the municipality in the same way that the grey infrastructure of pipes, etc would be maintained. In short, the swales, raingardens, porous pavements are municipal infrastructure that better reflects the shared community values of the City and therefore the city will maintain that infrastructure. In their case, I believe that these costs will be borne by their utility fees. http://www.svrdesign.com/fife_lid.html

Eric Damian Kelly's picture

Thanks. Good information --

Thanks. Good information -- and I have shared it with my student.

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