Subdivision Regulations – Norwich

Case Studies

Subdivision Regulations – Norwich

Community overview

Norwich is a fast growing community of more than 3,500 residents located in the upper Connecticut River Valley. With close ties to adjacent Hanover New Hampshire – the two communities share a school district – Norwich is heavily influenced by economic activity at Dartmouth College and the Dartmouth Medical Center. Consequently, the pressure for residential development throughout the Town’s still-rural countryside has grown steadily in recent years. Looking for creative approaches for managing both the pattern and density of rural residential development, the Town adopted innovative subdivision regulations.

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Norwich Subdivision Regulations (2006)

In the late 1990s, the Norwich Planning Commission began to consider alternatives to the standard subdivision regulations and two-acre minimum lot size that had guided rural residential development for the previous decade.  They were concerned with the growing trend of the subdivision and subsequent development of forest land located on substandard class 4 roads.  They feared that subdividers would try to maximize the development capacity of large, isolated tracts of land at the allowed density of one unit for every two acres.  They formed a rural lands committee to research regulatory concepts to better manage rural development patterns and densities.

The committee identified several concepts used to guide development in the rural district.  First among these is that regulations should control density, but not necessarily require large lots. Rather, the committee felt that requiring large lots could actually exacerbate the fragmentation of resource lands. Instead they felt that by allowing small lots ­– but not in conjunction with high development densities – that large tracts of resource lands would remain intact.

The second identified concept was that development density should be based upon site conditions and proximity to Norwich Village, rather than a uniform, district-wide zoning density. Thus, density is based on the development capacity of individual parcels, and addressed the goals of the Town Plan of concentrating development near the Village and along major road corridors, rather than in locations far from the Village and along narrow, gravel roads. Finally, the committee felt that all residential subdivisions should be held to high resource protection standards. In particular, design standards related to farmland, wildlife habitat, productive forest land and identified scenic resources, should be developed.

In response to the committee’s report, the Planning Commission prepared an innovative set of subdivision regulations that are used to determine the maximum residential density of a parcel. Density is based on the “developable” portion of the lot, which excludes wetlands, floodplains and very steep (gradient in excess of 25%) slopes, and only gives partial credit for marginally suitable lands (e.g., slopes with gradient between 15% and 25%, land  within riparian or wetland buffers). Once the developable portion of the lot is determined, the number of housing units is determined utilizing a scoring system based upon location from the village, road characteristics, and proximity to key open space (e.g., Appalachain Trail corridor).  Regardless of the number of houses that are allowed – which ranges between one housing unit for every two acres to one unit for every 20 acres – the minimum lot size is ½ acre. Finally, subdivisions must meet detailed resource protection standards.

Lessons Learned

  • Separating the concept of lot size from development density requires a certain amount of citizen education, but is ultimately a useful tool for discouraging resource fragmentation.
  • To maintain the rural character of the Town, it is important that regulations address both the density of development and the potential impacts on a variety of natural and cultural resources.
  • Requiring a moderately complicated site analysis could place a financial burden on landowners. To avoid that, municipal planning staff provides the analysis needed to determine development density using standard GIS software. Because that is not as accurate as actual site assessment, applicants have the option of providing their own survey data.

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