Low-Impact Development: Do Opportunities Trump Challenges?

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EPA has a series of Barrier Buster fact sheets to explain the benefits of LID to home builders.

To reduce stormwater runoff on construction sites, the Environmental Protection Agency (EPA) is encouraging home builders to try low-impact development: practices that preserve or rebuild natural landscape features and minimize impervious surfaces to create functional, appealing on-site drainage that treats stormwater as a resource rather than a waste product.

It’s a followup to EPA’s earlier plan to mandate, rather than encourage, more effective post-construction stormwater controls — a regulatory proposal that NAHB helped nip in the bud in favor of helping its members understand these green practices.

Builders are experimenting with rain gardens, vegetated rooftops and permeable pavements – but several challenges remain.

Now, EPA has made improvements to a tool that can assist the industry: The National Stormwater Calculator, which helps builders estimate the annual amount of rainwater and frequency of runoff from construction sites, can now help you figure out how different green infrastructure technologies manage or prevent such runoff. The tool is supposed to make it easier for builders to meet local, state and upcoming national stormwater retention-based performance requirements.

Old Rules No Longer Apply

Traditional stormwater control has focused on moving water away from structures and cities as quickly as possible to avoid possible flooding. This means great amounts of stormwater are conveyed away from sites and into nearby bodies of water.

Coupled with agricultural and industrial runoff, it causes these lakes, rivers and bays to become even more impaired. Meanwhile, there is more attention being paid to climate change impacts, and that means regulators are focusing more on improving their programs and policies.

In other words, the current rules aren’t cutting it because of the sheer volume and episodic nature of stormwater discharge.

Confronting Several Challenges

But LID is not an easy answer.

These systems can be more complicated to install, requiring builders and developers to heavily rely on their team of engineers and architects and count on support from local regulators.

And they can’t be installed everywhere. Sometimes, there are site-specific physical limitations, and often higher costs associated with review, design, construction and operation. Concerns about the home owner’s perception of such devices — think “rain garden = mosquito condos” — and long-term maintenance are also barriers.

Local officials, especially in flood-prone areas, are concerned about the long-term performance of green infrastructure and potential liability. And if an LID device cannot manage peak flow rates, builders may have to construct retention ponds in addition to dispersed systems, using up more land.

Then there are requirements at odds with LID: Wider streets make room for fire trucks, but give a development even more impervious surfaces. That means builders must apply for variances or exemptions from city and county codes, slowing the plan-approval process.

The EPA Smart Growth Office Water Quality Scorecard helps municipalities remove barriers to green infrastructure. Local officials will need to substantially change the existing codes and ordinances to encourage better stormwater control.

Green Building Trends

Successful implementation of LID requires builders and developers to incorporate LID at the early stages of the project and collaboration among all parties including engineers, landscape architects, the public and government. Indeed, green building is all about collaboration.

Early practitioners have adopted LID methods into their projects for many years, but increasingly more builders are electing to use green practices, and their numbers grew even during the economic downturn.

The ICC 700 National Green Building Standard and other green building programs provide credit using LID principles.

However, LID will require continuing education for consumers, policy makers, builders and contractors to be most effective.

Like any stormwater management approach, LID requires routine inspections, maintenance, repair or replacement to ensure the devices are functioning properly. Public support will be necessary to secure a dedicated source of funding to ensure local governments have the resources to efficiently manage stormwater programs.

To learn more about low-impact development and other stormwater management techniques, contact Ty Asfaw. She’s also put together a resource page that offers lots of links to agencies and organizations that know about LID techniques.

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