Conservation Implementation

Marion County SWCD Asks:
What is a Low Impact Development & Why Should I Care?

What is a Low Impact Development (LID)?  A Low Impact Development is an innovative stormwater management land development approach with a basic principle that is modeled after nature. 

A LID manages rainfall at the source using uniformly distributed decentralized smaller than normal-scale control practices.  An LID's goal is to mimic a site's predevelopment storm water runoff or hydrology by using design techniques that infiltrate, filter, store, evaporate, and detain runoff close to its source.  

LID techniques are based on the premise that stormwater management should not be seen as stormwater disposal.  Instead of conveying and managing/treating stormwater in large, costly end-of-pipe facilities located at the bottom of drainage areas, LID’s address stormwater through small, cost-effective landscape features located at the lot level. These landscape features, known as Integrated Management Practices (IMPs), are the building blocks of LID. Almost all components of the urban environment have the potential to serve as an IMP. This includes not only open space, but also rooftops, street scapes, parking lots, sidewalks, and medians.  LIDs use a versatile approach that can be applied equally well to new development, urban retrofits, and redevelopment / revitalization projects.

Why should I care and why are more central
Indiana communities now considering using LID techniques?  
An LID has numerous benefits and advantages over conventional stormwater management approaches. In short, it is a more environmentally sound technology and a more economically sustainable approach to addressing the adverse impacts of urbanization. By managing runoff close to its source though intelligent site design, LID can enhance the local environment, protect public health, and improve community livability - all while saving developers and local governments money. The need for such an approach has never been greater. 

Current stormwater programs require that a wide array of complex and challenging ecosystem and human health protection goals be addressed. Many of these goals are not being met by conventional stormwater management technology, and communities are struggling with the economic reality of funding aging and ever-expanding stormwater infrastructure. The challenge of how to restore stream quality in watersheds that have already been densely developed is even more daunting. Simply relying on impervious reduction and/or conventional detention ponds to address these issues is not feasible, practical or sustainable. LID provides the key in its emphasis on controlling or at least minimizing the changes to the local hydrologic cycle or regime.

Communities can use LID to address a wide range of “Wet Weather” flow issues, including Combined Sewer Overflows (CSOs), National Pollutant Discharge Elimination System (NPDES) Stormwater Phase II permits, Total Maximum Daily Load (TMDL) permits, Nonpoint Source Program goals, and other Water Quality Standards.  Local permitting agencies can use LID as a model in revising local zoning and subdivision regulations in favor of more cost-effective, ecologically sound development practices. Developers can achieve greater project success and cost savings through the intelligent use of LID, and designers can apply these techniques for innovative, educational, and more aesthetically pleasing sites.

What are the costs associated with LID?  
Current experience has shown that LID often save money over conventional approaches through reduced infrastructure and site preparation work. LID case studies and pilot programs show at least a 25 to 30% reduction in costs associated with site development, stormwater fees, and maintenance for residential developments that use LID techniques.  These savings are achieved by reductions in clearing, grading, pipes, ponds, inlets, curbs and paving. Far outweighing any of the cost increases due to the use of LID, these infrastructure reduction savings enable builders to add value-enhancing features to the property, to be more flexible and competitive in pricing their products, or even to recover more developable space since there is no need to waste land for a stormwater pond.  Costs are very site specific. Each project will be unique based on the site's soil conditions, topography, existing vegetation, land availability etc.

More information about LID is available on the web at The Low Impact Development Center, a non-profit organization and the Environmental Protection Agency’s (EPA’s) web site. 

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