Southeast Low-Impact Development
Low-impact development (LID) is a relatively new approach to land development that reduces and prevents stormwater pollution. The N.C. Coastal Federation promotes LID because it mimics nature's water cycle and is a key tool to protect and restore coastal waters.
LID Ordinances
The federation worked with New Hanover and Brunswick counties and Wilmington to develop local LID manuals and resolutions for voluntary use by developers. To begin the project, each county appointed a technical advisory committee made up of engineers, developers, county staff and planners. Larry Coffman, a nationally recognized leader in the development of LID, worked with the committees to prepare model resolutions and a draft LID manual.
Wilmington and the counties adopted their ordinances in 2008. See their Web sites for more information:
The manuals offer specific LID technologies as alternatives and voluntary options for developers to satisfy federal, state and local stormwater requirements. The manual describes several site-planning principles and practices and specific design standards for many typical LID techniques.
This project was funded by the NOAA and includes several public and private partners, including Brunswick and New Hanover counties, Wilmington, the N.C. Coastal Nonpoint Source Program of the state Division of Water Quality, the N.C. Division of Coastal Management and the federation.
Spreadsheet Could Spread Way for LID
They call it “LID EZ.” It’s just a spreadsheet, really, but it could end up changing the way we regulate and treat stormwater. It all sounds pretty arcane, but the spreadsheet will provide a standardized and easy way for state and local regulators to assess LID permit applications. Developers will have a time-saving tool to ensure that the LID techniques they’re using will meet state requirements. The state Division of Water Quality says the spreadsheet is an acceptable way to calculate LID’s effectiveness for permit applications. That kind of assurance should promote the use of LID
In designing their local LID ordinances, officials in New Hanover and Brunswick counties and Wilmington needed a standardized way to determine if certain LID techniques would meet state, federal or local regulatory requirements. Withers & Ravenel, an engineering firm, helped the counties develop the spreadsheet to accompany the LID design manual.
NCSU Economic Feasibility Study on LID
A team of researchers from N.C. State University compared the revenues and costs of a conventional development to those of LID for a small development in Brunswick County’s Lockwood Folly Watershed. The study developed an alternative LID plan for a 39-acre subdivision that was originally laid out with a conventional design. Overall the study found that there were cost savings with replacing conventional stormwater utilities such as curb and gutter, using narrower streets and eliminating stormwater ponds and that these cost savings were greater that the costs of implementing LID. It is interesting to note that an even larger financial margin came into play when considering that removal of the stormwater pond created an additional developable lot in the subdivision.
Brunswick County Government Center Retrofit Project
The federation is working with Brunswick County and Stantec to design several stormwater reduction measures at the Brunswick County Government Complex to enhance local water quality in the Lockwood Folly River. The measures will serve both to reduce actual polluted stormwater inputs into tributaries of the Lockwood Folly and to provide an example of innovative and effective techniques for small-site level stormwater control in a highly visible location. We hope this demonstration project will encourage others to implement LID measures elsewhere in the Lockwood Folly watershed.
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