Low Impact Development: Quick Facts and Information for Builders, Developers and Municipalities

What is LID?

Low Impact Development is an innovative approach to site development and stormwater management. It combines cost effective practices, ecologically-friendly techniques and design enhancements for better land, water and air quality.

The LID Approach

Low Impact Development is a balanced approach, focusing on integrated site design and preservation of existing natural systems. It works well for many stakeholders: developers, municipalities and consumers.

Goals of LID

Better stormwater management at the source. Lessening runoff, providing natural areas of absorption and reducing impermeable surfaces.
More pleasing neighborhood designs. Preserving open space, native plants and undisturbed land.
Using innovative techniques for infrastructure (streets, curbs, lots, gutters, sidewalks, landscaping).
Lower development costs and manage sites better by protecting and using natural systems and processes.
More buildable land. Reducing pond and stormwater treatment areas.
Reduces flooding, stream damage, water quality issues and erosion

Municipal Benefits--LID for Cities and Counties

Low Impact Development holds great promise for municipalities who want to preserve their natural resources and manage stormwater with the latest techniques. Cities and counties with LID codes already in place are pleased with the results. Less stormwater being diverted into drains and ponds mean fewer overflows, less standing water and a reduction in flooding. Water quality is improved.

In addition, pilot programs in Seattle and Tacoma have shown that LID practices actually can increase home values and the aesthetic appearances of neighborhoods. Rain gardens, natural vegetation, bioretention swales and other LID techniques fit in with landscaping and create more green neighborhoods.

Non-profit agencies like the Puget Sound Partnership have a wealth of information and resources available to municipal staff who are interested in adopting LID codes and implementing LID. Pierce County also sponsors workshops throughout the year to give elected officials and local government staff members training and information on LID.

We encourage cities and counties who are interested in the substantial benefits of LID in their communities to contact the Puget Sound Partnership (program manager for Stormwater and Combined Sewer Overflows, 360-725-5455), the WSU Puyallup extension (253-798-3257) or the Pierce County Water Division (CIP Manager at 253- 798-6162) for assistance in making the transition.

LID Myths

Low Impact Development is not a growth management program. It's not only for green builders or environmentalists. It's usually not more expensive--it often saves money versus traditional development. It's not a specialized technique working on only a few sites. It's not a "new" technology--it's been practiced on the East Coast with verified results for almost 20 years.

What About Costs?

LSE Inc. and many developers/builders who work with our firm are excited about LID in part because of cost-savings potential. Most sites can incorporate some, if not all, LID practices. When feasible, Low Impact Development can save anywhere from 15%-25% of the cost of development compared to a traditional site.

LID can save you money over traditional vault/pond stormwater systems for many sites. How much?

The Seattle Natural Drainage System project found that they were able to lower development costs around 34%-45% over traditional stormwater techniques.

In Bellingham, developers found that LID bioretention systems were 70%-80% cheaper than site infrastructure requiring vaults, ponds and traditional stormwater management.

LSE Inc. has also helped developers and builders to add lots to sites. Smaller retention ponds, fewer impermeable surfaces and using wetlands/marginal land for bioretention means your site can have more land to develop. Less work, less infrastructure can equal a greater profit margin.

Does It Work For Every Site?

LID techniques such as limiting soil compaction and retaining native vegetation can usually be done on most sites. Stormwater management using bioretention and permeable asphalt/concrete work in a wide variety of conditions. However, soil quality, slope, and drainage are three factors that limit LID. Additional factors that come into play include water table level and nearness to watersheds and rivers.

History of LID

Before 1990, most communities were relying on traditional stormwater management technologies developed around or before the 1970's--retention ponds, underground vaults, ditches, drains and detention basins. The philosophy was based on slowing down runoff and capturing the stormwater in holding areas or conveying it to treatment plants or other off-site locations.

Phase One of the National Pollutant Discharge Elimination System (NPDES) program began in 1990, which forced many communities to rethink their stormwater programs. Municipalities, civil engineers and developers were also seeing that traditional site infrastructure had some weaknesses that could cause flooding, pollution and other scenarios in adverse conditions.

In the mid-1990's, Prince George County in Maryland began developing a comprehensive approach to a new way of managing building sites and stormwater: Low Impact Development. As guidelines, BMP's (Best Management Practices), pilot studies and research models began gathering evidence and sharing insight, the practices of LID spread to states on the East Coast and mid-West.

Here in the Northwest, innovative site design and water management became issues in the 1980's. Porous pavement and green roofs were beginning to be used in building projects in the mid-80's. Various housing developments (such as Klahanee and Northwest Landing) began to preserve open space and wetlands, retain natural vegetation, and use site design to promote better water and resource management.

In 1990, King County's surface water and stormwater manual already mentioned bioswales and ponds. Several conferences and publications in the next few decades helped to alert the Northwest to new principals of water and site management. In 2001, the first Northwest LID conference identified obstacles and created goals for implementation. Starting in 2002, case studies and code changes began appearing. Pilot projects in Seattle and other communities provided research data to support the case for LID in the Northwest. In 2005, the Puget Sound Action Team assisted 5 cities and 11 counties with imlementing LID codes.

In recent years, more research projects have collected data that confirmed the ability of LID practices to process stormwater, filter out pollutants, maintain performance and save money (see our Research section of our Resource sidebar for links to studies).Examples include Pierce County's 2002 pilot project at Kensington Estates, and a 2003 project at the Meadow on the Hylebos.

2007 saw the release of more research data. Pierce County sponsored two major conferences on LID, one for the general public and one for builders and developers. We expect to see more counties and cities adopt LID codes and processes in the coming years. The movement to manage sites and stormwater more effectively by modeling natural processes now has several decades of research as a foundation, and will only continue to gain momentum as builders, developers and consumers learn more about the cost-savings and resource-conserving features of LID.

(Timeline based on presentations given by Lorin Reinelt and Bruce Wulkan at the October 12, 2007 LID Conference)

The Next Step

LSE Inc. is one of the first firms in Pierce County to design and implement LID managed sites. We can provide you with photos and other resources that show LID in public areas, cities and residential neighborhoods.

Our expertise includes permeable concrete and asphalt, innovative stormwater systems (bioretention areas, rain gardens, swales), pervious pavers, preservation of natural habitat, maximization of site value, and more. We've worked on projects in both the public and private sector, and have an extensive understanding of both LID techniques and codes.

Call or email us today to set up an appointment. We will happily discuss your future projects and plans for development, and work with you to discover if Low Impact Development is a good fit for your sites.