Wednesday, May 18, 2011
Legacy Update: Environmental Quality and Sustainability
The long term viability of Forsyth County will likely depend upon our ability to balance future growth with the preservation and enhancement of our natural environment. With an increased demand for water and land resources, it is important that when we address future growth that we consider the environmental impacts of such growth. This chapter will discuss what steps have already taken place to address environmental quality within Forsyth County and what issues and strategies are appropriate over the next twenty years to ensure fiscally responsible, sustainable growth.
As has been discussed in previous chapters, the predominant land use pattern in Forsyth County has been low-density, suburban, single-family residential development. Nonresidential development has followed the residential development to create a sprawling development pattern. This type of development requires significant land resources while placing a considerable strain on the county’s water quality, air quality, energy resources and wildlife habitat.
The time has come for our community to assess the environmental impacts of sprawling development, both current and future. With the projected 120,000 new people and 66,000 jobs expected over the next twenty years, we must carefully plan our new growth in a way that minimizes the impact on our natural resources.
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Some general environmental planning considerations for development:
1. Stormwater management should be provided that mimics pre-development conditions of the existing forested site. Stormwater management should prevent exasperated stormwater surges as well as maintain current stream recharge regimes to the extent possible. Stormwater management should be accomplished off-line instead of on jurisdictional streams to maintain ecosystem functions and food sources. Low Impact Development (LID) techniques are encouraged for all new developments and redevelopment efforts. If impervious area exceeds ten (10) percent, stormwater management strategies that maintain or restore pre development hydrograph conditions are recommended. Information about LID practices and measures can be found at www.lowimpactdevelopment.org, http://www.epa.gov/owow/nps/lid/lidnatl.pdf and http://www.stormwatercenter.net/.
2. In watersheds supporting listed threatened or endangered species, these buffers should be 100’ for intermittent channels and 200’ for perennial channels. In watersheds without listed species, these buffers should be 50’ and 100’ respectively. Stream buffers provide shade and stream integrity. Buffers are essential ecosystem components that provide pollutant removal and biomass that sustains aquatic communities. Buffers should be permanently preserved as common conservation areas instead of subdivided. Where practicable, impacted streams should be relocated using state-of-the-art natural channel design and native vegetation instead of piping the streams. Local authorities should keep sewer lines, water lines, and other utilities out of riparian buffers by placement along floodplain edges.
3. Where aquatic life passage currently occurs or where aquatic passage can be restored, culverts 48” diameter or larger should be buried a foot into the streambed. Culverts less than 48” diameter should be buried to a depth equal to or greater than 20% their size to allow for aquatic life passage. Multiple barreled culverts should have a base flow barrel installed low enough to accommodate the active stream while flood stage barrels are placed higher for terrestrial life passage. These measurements should be based on natural thalweg depths. Aquatic life passage should be assured during low flow and drought conditions. Similarly, any riprap used should not interfere with aquatic life movement.
4. Sediment and erosion control measures should adhere to the design standards for sensitive watersheds (15A NCAC 4B .0124) where listed species are known downstream.
5. If any concrete will be used, work must be accomplished so that wet “green” concrete does not contact stream water.
6. Heavy equipment should be operated from the bank rather than in the stream channel in order to minimize sedimentation and reduce the likelihood of introducing other pollutants into the stream. Emergency spill containment equipment and materials should be available 24/7 while equipment and fuels are present on the worksite and in the vicinity of a stream or wetland.
7. Temporary or permanent herbaceous vegetation should be established on all bare soil within five (5) days of ground disturbing activities in the stream buffer to provide long-term erosion control. Natural fiber matting is recommended over plastic matting or matting containing plastic strands that can impinge and entrap small animals.
8. Project proponents, project developers, project investors and local government officials should visit http://www.ncwildlife.org/pg07_WildlifeSpeciesCon/pg7c3_impacts.pdf to learn more about historical or incremental diminishment of habitats associated with increases in imperviousness to aquatic and terrestrial wildlife habitats. Mitigative measures can significantly reduce these negative impacts and, in some instances, restore some of those lost or diminished environs.
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