LID Histories and Cost-Benefit Analysis’ are Available
Residential communities that were developed using LID principals have actually been in place for up to 20 years, and new ones ranging from a few acres to thousands of acres in size are being started across the country. Data on the benefits of LID is available to evaluate the results. Municipalities and counties in states from Maryland and Virginia, to Massachusetts and Washington, and all across the country have adopted, or are in the process of adopting, guidelines and new ordinances to encourage Low Impact Development.
Reduced infrastructure costs.
Eliminating costs for detention ponds, curb and gutters, inlet and catch basins, and storm sewer pipe.
Increase in commercially viable land Land previously slated to hold large surface detention ponds is reclaimed for development.
Enhanced property values and redevelopment potential.
Land that has little or no vast underground infrastructure can be redeveloped more easily and cost-effectively.
Energy and potable water cost savings.
If rainwater is recycled for landscape irrigation, typically 50% of water usage, then water bills go down dramatically.
Enhanced ‘quality of life’ and aesthetics.
More vegetation, less concrete and an environmentally friendly design makes for a more livable development.
Greater marketability and valuable market positioning advantage for property owners/developers.
With growing demand for alternatively fueled vehicles, recycled products, natural foods and the like, being early to market with an environmentally sustainable development is a distinct advantage.
Reduced burden on local development support infrastructure.
If potable water supply requirement is reduced by half, then municipal potable water production requirements, and costs, drop dramatically
Today’s Methods Jeopardize the Sustainability of Our Water Supply
As impervious surfaces: concrete, asphalt and buildings, cover more and more of Houston’s surface area, rainwater which once was held in vegetation, evaporated into the atmosphere or soaked into soil and eventually percolated into underground water tables, now runs off quickly and in huge volumes. The result is a rapidly declining groundwater resource, increased subsidence and an urban flooding problem for which we’re simply running out of answers. In addition, these high volume flows devastate natural creeks, bayous and rivers by carrying away banks and the vegetation that once held them in place. As the severe erosion damage mounts, these natural waterways become even less efficient at carrying away the water – so we build bigger, man made channels, or widen and line the natural channel with concrete. These efforts are short-lived responses because they simply exacerbate the problem.
Equally negative, as the water is channelized and carried away, the pollutants such as the hydrocarbon-laden runoff from streets and parking lots are concentrated along the way. One pipe or channel full of concentrated pollutants feeds into another and another, and ultimately the load is discharged to the bays and estuaries on our shoreline. By the time it reaches the ‘end of the pipe,’ treating the pollution is just too big a job.
Regulatory Responses to the Problem Have Only Compounded The Problem
In an effort to make a dent in the runoff volume and pollution problem at one of the many sources, regulatory agencies now require Developers to implement Stormwater Quality Management Plans (SWQMP) for virtually every new commercial, multi-family or residential project. Unfortunately, the regulatory BMP responses are once again shortsighted, mostly ineffective and very costly.
Regulatory detention requirements mean that large surface stormwater detention ponds are now a common component of most commercial and residential developments. These ponds may do a reasonable job of detaining water briefly and helping alleviate the flooding problem, but they waste vast tracts of valuable real estate, breed mosquitoes, rodents and tort liability issues. And although they’re purported to have stormwater quality treatment attributes, those attributes are mostly myth.
Costly underground stormwater quality treatment systems are also now common components of these SWQMPs, but many treat only the first flush of stormwater, leaving the balance to flow through the system unimpeded and untreated. Even worse, many designs promote the development of immense colonies of anaerobic bacteria that grow rampantly in the large volume of nutrient rich static water that remains inside between rain events – flushing the polluted water into the watershed with the next rainfall, and trading one problem for another.
Developer Costs are Skyrocketing LID Can Be Cheaper
These problems are all interconnected, and LID holds the answer to many of them. The costs Developers must bear to meet the shortsighted regulatory responses to the stormwater problem are skyrocketing. The good news is that it seems we’ve reached “the tipping point”- the point at which it makes more economic sense to explore and implement alternatives rather than keep going down the same path.
Why Isn’t LID More Widespread Already?
If LID makes so much sense, why isn’t it more widespread already? There are many answers ranging from fear of the unknown, to ‘chicken or the egg’ concerns with regard to local regulatory acceptance and permitting issues.
Another key issue also stands out. LID, with it’s decentralized approach to stormwater retention, typically uses widely dispersed “rain gardens” and “bio-retention cells” rather than large surface detention ponds, street-side swales rather than curb and gutter. These features should greatly reduce, if not eliminate traditional storm sewer infrastructure resulting in lower development costs and an increase in marketable land. It’s one of the beauties of the concept, but the common methods used to achieve these goals are often seen as difficult to engineers and even more difficult to replicate. We believe it’s been an obstacle to the acceptance of LID.
LID Needs A System That Enables Systematic Design
Systematic, replicable implementation of LID principles can be more readily achieved using a “system” by which volumes, tolerances and safety factors are more easily engineered. Such a system would follow LID ideals and enable them. Finding the answer meant looking around the world and outside of the box.