Density as a Best Management Practice (BMP)

4 06 2010

High Point Neighborhood mentioned in Ped Shed Post
photo credit:

The Ped Shed, a blog focused on walkable urban design and sustainable placemaking by Laurence “L.J.” Aurbach, recently had a post about density as a best management practice (BMP). The post provides a good outline of the evolution of the stormwater regulatory environment. The main point of the post is that well intentioned stormwater regulations make it difficult to build dense walkable environments that ultimately exacerbate stormwater management issues.

The author states:

“But the universal and inflexible application of BMPs and LID can have significantly negative consequences on the quality of urban places and the health of watersheds. LID purports to encourage smart growth and urban redevelopment, but as a rule this support is nominal, little more than lip service. In general practice, LID puts urban density at a competitive disadvantage.”

He cites three studies, two by the EPA (Protecting Water Resources with Higher-Density Development, Using Smart Growth Techniques as Stormwater Best Management Practices) and one by Jacob and Lopez (Is Denser Greener? An evaluation of higher density development as an urban stormwater quality best management practice.) All of them provide compelling data as to the benefits of density with regard to stormwater run-off and pollutant loads, and are well worth reading.

I agree with him that when developing an urban vs suburban site, more expensive stormwater BMPs are typically utilized (i.e. underground detention, green roofs) to meet stormwater regulations.

However, site area, property costs, and market dynamics are a large factor in determining appropriate BMPs and cost effective solutions. If you can build significantly more square footage due to a better market environment and/or need to maximize your investment in land cost (which often reflects the market potential and property entitlements) then the cost of best management practices that maximize these potentials can be offset.

The examples of offsite mitigation are very intriguing. I wholeheartly agree that opportunities for this on properties in close proximity to the development is an effective way to mitigate stormwater impacts while spreading (and hopefuly lowering) the cost across multiple properties. In regard to infill developement, this can be very difficult in practices but not impossible. Public space can be designed to accommodate the needs of neighboring properties. Using green roofs, pervious pavements, and other BMPs on surrounding properties can greatly reduce the volume of runoff being diverted to these offsite areas and therefore their size  can be diminished to a point that can be integrated better into urban environments.

-Brian Phelps

Tennessee Ranks in the bottom ten…again

2 12 2009

In the list of healthiest and least healthiest states releases from Forbes this month the southern region of the country is once again lagging behind. All in all eight of the bottom 10 were states from the south, including Tennessee which ranked number 44 overall and number 49 in obesity.

Why does this relate to green infrastructure you might ask? There are in fact many ways to relate green infrastructure to our health. (Check out the numbers from the earlier post ‘Triple Bottom Line of Green Infrastructure) Some are the obvious reasons such as cleaner streams and rivers, cleaner air, etc, that often create a more desirable environment to become engaged in and interact both physically and socially. But take a step back and consider green infrastructure planning; in brief planning amongst, preserving and restoring our natural infrastructure systems, such as river corridors, woodland networks and open spaces. This type of planning allows us to integrate greenway trails, bikeways and neighborhood trails into our built environment in a responsible way. The more access communities have to resources such as these allows them more opportunities to get the recommended 30 minutes of physical activity per day, increasing the overall heath of the community. There is a strong link between lack of physical activity and chronic diseases such as heart disease and diabetes.

Other more indirect regional health benefits stem from increasing the amount of land for natural storm water retention which in turns allows communities to become more resistant to natural disasters. Green infrastructure also can reduce the erosion of precious top soil, which aids local farms. The entire region benefits when a collection of local farms can provide healthy food. Working farms—and forests—also have a significant impact on local economies by providing jobs, aiding tourism and supporting local manufacturing.

So in the end, green infrastructure benefits extend beyond immediate storm water benefits and reducing our carbon footprint. By integrating the green infrastructure planning principles we can also provide opportunities to make our communities healthier, reduce overall healthcare costs and hopefully move Tennessee up in the ranks of healthiest states.

-Sara Putney

Shelby Bottoms Greenway in the Cumberland River Corridor