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Appendix - Arden Hills Water Quality Task Force - June 2000 Endnotes e 8.) Best Management Practices Descriptions (excetpted from the National Resources Defense Council) -entire report is at www.NRDC.ore( BMP's- A set of defmed procedures that offer solutions using the appropriate scale technology and the best cost to benefit advantages for solving site specific problems. Non-Structnral BMP's- Best management practices for water quality measures that rely on programs or policies as opposed to Structural methods which rely on constructed components. Ideally implemented before growth or development occurs as part of a comprehensive pliiriiling process for water quality controls. Examples - Non-structural BMP's Buffers and Open Space Preservation As Table 5-1 and the case studies show, many municipalities employ stream and wetland buffer requirements, open space preservation, and other laws or programs as cost-effective means for reducing stormwater runoff and achieving other public goals. These programs are often the specific means of implementing larger growth management goals and are often linked with incentives to aid development in other areas. In addition to zoning-type ordinances, municipalities can also use economic incentives to reduce impervious cover or implement stormwater control through stormwater utilities where the fee is based on amount of impervious cover, inspection and permit fees linked to compliance, or dedicated contributions from land developers. Many local govemments have had great snccess, apparently often more than they expected, with a buffer system of protected natural areas around waterbodies, sensitive areas, or steep slopes. Forested buffers are an essential part of natural stream, lake, and wetland protection.25 They often provide highly desired community amenities as well. Not only do buffers allow the water resource to fimction more naturally, they also help reduce a site's overall imperviousness. An average buffer width of 100 feet can reduce imperviousness by up to 5 percent of a watershed. e SITE DESIGN MEASURES The case studies in this report highlight several communities and developers that have taken approaches that minimize overall imperviousness on a particular site. In many cases the developer initiated their approach independent of government requirements. Minimizing imperviousness, which is prevention focused, is more cost-effective than treating stormwater runoff and much more cost-effective than restoring waterbodies after they have been polluted or damaged. The case studies also offer insight into a particular difficult aspect of this approach to stormwater pollution prevention. Often existing local or state regulators make stormwater-conscious site design more difficult due to street, set-back, density, or other site development requirements. While generally the case studies show that it is important that local governments enforce their regulations, in these circumstances it is important for local governments to allow flexibility. Conservation Design Conservation-design development concentrates homes on a limited percentage of the land comprising a residential subdivision, while leaving the rest of the land as open space.31 As several of the case studies show, conservation design also reduces the amount of impervious road surface created, since the homes are not spread as far apart, and preserves a much greater percentage of undeveloped land. Narrower roads, shorter setbacks from residential streets that allow shorter driveways, or shared driveways also reduce impervious cover when designing residential developments.32 Traditional Neighborhood Design A more comprehensive approach to site-specific planning is the traditional neighborhood developments (INDs).37 Although aesthetic or cultural concerns motivate many proponents ofINDs, environmental concerns are also advanced with INDs. Like conservation-design developments, INDs have sought to minimize the impervious lIfootprint" of the built environment and preserve open space through compact development patterns that feature narrower roads, shared alleyways, smaller lots, and smaller front setbacks from the street. However, INDs in the case studies go a step further by adding the principle of mixed-use development. At their best, TNDs provide stores, offices, schools, day-care centers, recreational opportunities, and mass-transit facilities all within a short walk of residents' .