|| Low Impact Development Pays
Communities, Land Use, Water
||low-impact, LID, water, watershed, conservation development
|| Low-impact development can result in advantages, such as lower development costs, less maintenance costs, more usable natural areas, thermal pollution reduction, and more phosphorus removal when compared to the traditional model of development.
A 217-acre mixed use development in Lakeville, MN was built to handle stormwater with ponding and a regional infiltration basin. The Vermillion River Watershed Joint Powers Organization in Dakota County, Friends of the Mississippi River, Emmons and Oliver Resources and others asked the question: what would be the:
* construction costs
* 30-year maintenance costs
* water quality impacts, and
* economic yield and quality of life issues
for a development with higher impacts on the land, and for a development with lower impacts? Computer models of a higher ("traditional") and lower (LID: "low impact development") build-out were created and found to perform better on all evaluated parameters.
The LID model incorporates on-lot best management practices (BMPs) for stormwater management: integrated, landscape-based designs including vegetated buffers, infiltration basins and grassy swales, but not including BMPs which some city officials, builders and home buyers find more challenging: narrower streets, smaller lot sizes, porous or pervious pavement, and green roofs.
Among the findings, the LID model has:
* Cheaper development costs per unit: $20,000 vs. $24,500 for the built development and $25,000 for the traditional model
* 40% lower 30-year maintenance costs compared to the traditional model
* More residential units than the traditional model (497 vs. 447) and twice the senior housing units
* More commercial square footage than the traditional model (220,000 vs. 183,000)
* More usable natural areas and lawns than either the built development or the traditional model
* Less than half the stormwater runoff volume of the built model, and two-thirds less runoff volume than the traditional model
* 50% more annual phosphorus removal from water bodies than in the traditional model
* Thermal pollution reduction (up to 12 degrees C.), essential to protecting trout habitat
See a 32-slide PowerPoint presentation at http://www.minnehahacreek.org/documents/lakeville_lid.pdf to learn more, or visit the web site below. For more information contact the Dakota County Water Resources Office at 952/891-7000 or Kevin Biehn at Emmons and Olivier Resources at 651/770-8448.
See also Forging the Link: Linking the Economic Benefits of Low Impact Development and Community Decisions (University of New Hampshire Stormwater Center: 2011 ), which documents, through a series of case studies and fact sheets, the advantages of LID in the economic terms of how municipal land use decisions are commonly made: http://www.unh.edu/unhsc/forgingthelink