Low Impact Development (LID) Barriers for Community Sustainability
It’s interesting to me how misconceived green infrastructure and stormwater management are by both the general public and educated community planners. Implementation of Low Impact Development has lagged in communities because of a lack of understanding of what it actually is, how to accomplish the design, a lack of support and promotion by a number of authorities, and a lack of acceptance by the community.
Why do we care? In a world where only 1% of the planet’s freshwater is drinkable, we must change not just our behaviors but our policies and societal structure. Increased precipitation events can cause flooding and uncontrolled stormwater runoff that collects pollutants on surfaces and carries them into nearby water bodies, posing threats to coastal and limnological (inland aquatic) communities. According to the EPA, there’s a direct relationship between the amount of impervious built surfaces (conventional pavement, roofs, etc.) and the biological and physical conditions of downstream waters.
What is Low Impact Development?
Low Impact Development (LID) is “a land development approach that is intended to reduce development related impacts on water resources through the use of stormwater management practices that infiltrate, evapotranspirate, or harvest and use stormwater on the site where it falls” (EPA, 2013). LID uses natural systems instead of man-made, synthetic technologies to treat precipitation and runoff to improve water quality.
According to a report from the University of California Berkeley, ineffective stormwater management is a serious problem, yet we’re so apt to deny it during the planning process. It’s like a vicious cycle: uncertainty over the costs, benefits, and effectiveness of LID and other green infrastructural programs leads to hesitant planners and public voters. But how are we supposed to eliminate such uncertainty and mystery if we choose to use conventional models (that have track records of water pollution)?
Of course, the monitoring and sharing of green infrastructure data can greatly enhance the education level of environmental planning – however, many communities seem to still be stuck. State and federal regulators can accelerate local data collection and sharing to boost cost-effective green infrastructure deployment (which is being done, but only at a snail’s pace).
Sustainability and the Triple Bottom-Line
This new idea, called the “triple bottom-line” is a discovery that, within sustainable implementation in a community, the traditional bottom-line goal (increased economic development) can coexist with both enhanced social equity and environmental sustainability, thus creating a triple-win.
There’s a misunderstanding that LID increases costs and reduces profit margins, when in most studies and green infrastructure experiments, LID is cost-effective and does save money for communities, in addition to enhancing ecological services such as cleaning water and air, carbon sequestration from allowing more natural land, and providing local job opportunities in the green sector. LID also provides opportunities for community gardens, parks, and public appreciation for the planet. In many situations, LID reduces construction costs and provides a greater profit margin than conventional practices (Shaver, 2009).
Positive Benefits of Green Roofs
Green roofs have immediate and long-term benefits to the public. Positive net benefits accrue to building owners starting typically in year 20 for the assumed conditions. Moreover, green roofs mitigate current issues and provide relief from many infrastructure challenges.
- The peak flow rate and volume of stormwater runoff can be reduced by 22 to 93 percent, and by 30 to 86 percent, respectively (EPA, 2015).
- Green roofs sequester between 166 and 172 pounds of carbon per year.
- One hundred medium-sized trees planted in a public space can abate a net amount of 44,400 pounds of carbon dioxide per year. Those numbers can drastically change the environment and atmosphere in an urban area.
- The EPA suggests that by 2035 there will be 110 billion square feet of commercial real estate in the United States, which is an increase of 54% over 2003 figures.
- Modeling these new roofs using the National Oceanic and Atmospheric Administration’s (NOAA) heating and cooling data shows that, if green roofs had been built on all of these new structures since 2003, business and property owners could save a total of $95 billion dollars a year in avoided heating, cooling, and roof replacement costs.
- Rain barrels, rain gardens, porous pavement, tree box filters, vegetated buffers, swales, and bio-retention areas are also forms of LID.
A study by the Stormwater and Green Infrastructure Coalition and the EPA indicates that in Bristol Town Beach, Rhode Island, 125 trees were planted, creating environment and economic benefits, such as:
- 243,174 gallons of stormwater intercepted per year
- $2,123 in projected property value increases for the beach/park
- 9,540 kilowatts per hour of electricity conserved from the cooling effects of natural shade
- 2,932 therms of natural gas consumption reduced
- 58,772 pounds of atmospheric carbon reduced
Uptown Circle: A Low Impact Development Approach
In Normal, Illinois, a special LID approach was taken. The center of the traffic circle (above) provides stormwater management by using a flow system through a series of filters into two underground channels where the water is filtered by plants, and the speed at which the water travels is reduced (to create a path of least resistance, cleaning and filtering water better). The cistern beneath the structure holds as much as 75,000 gallons of stormwater collected from three acres of paved surfaces. The cost was upwards of $1.5 million, but the savings include:
- Capture and reuse of 1.4 million gallons reduction in annual potable water purchase ($7,600) and water saved for irrigation, on-site water features, ground water recharge, water uptake
- Improved site water quality (91% total suspended solids (TSS), 79% phosphorous, 64% nitrogen removal)
- Cost savings of $60,000 over a 50-year period
- Property values increased 9% ($1.5 million) from 2009-2010.
- Increased revenue of $680,000 through new conference events held in newly developed mixed-use development project
Conventional Development or Low Impact Development?
The misconception is that conventional development is less expensive up-front than green development. However, that’s rarely the case. The table above illustrates the cost differences in traditional (non-sustainable) development versus sustainable development. (Clicking the image will showcase detailed numbers and figures more effectively.)
In only one case, that of the Kensington Estates Project, did LID costs outweigh the environmental and financial savings. The majority of these cases show the refreshing and cost-effective benefits of LID.
LID is often more affordable up front during construction and has lower post-construction maintenance costs. Beyond the municipal savings, home values in sustainable communities are generally valued higher through the idea of modernization, cleaner water and air, green space, and appeal.Featured Image: Urban Planning Models from the Shanghai Expo, 2009. Image via IvanWalsh.com.