Community Preservation Initiative

• Secretary’s priorities for the Massachusetts Executive Office of Environmental Affairs
• “Encourage and empower local actions that preserve and enhance the quality of life - community by community, watershed by watershed”
• “Preserve open space” 
• “Invest in new technologies, products and practices that enhance environmental protection and economic growth”

• What is a buildout analysis?
• A GIS analysis to project all possible future growth in a town given present legal and environmental constraints
• parcel based v. photo based
• look at each parcel to determine if it can be subdivided or can support additional development under the current zoning
• look at the aggregate of developable land in each zoning category, based on photo-interpretation of land use & ignoring parcel boundaries 
• this statewide project is photo based

• the state is presenting these analyses to local decision makers to help them evaluate potential impacts of future development on their community and to create a receptive environment for the discussion of alternatives
• impact metrics
• number of housing units
• population/number of schoolchildren 
• sq. feet of comm./industrial space
• gallons of water demand 
• miles of roads 
• we avoid direct fiscal projections
• alternatives include zoning by-law changes, open space protection, regional cooperation

• Many contractors, consistent methodology
• Steps in the process
• collect maps and documentary information 
• state, regional and local sources
• compile and update information if necessary into GIS 
• analyze buildout potential using overlay and spreadsheet tools 
• present results in integrated map form
• Skills required - a team approach
• planner familiar with zoning & local issues & a GIS analyst
• Cost
• $8k per town

• Documents
• Current town zoning by-law - Cooperative data
• development effort by MassGIS and RPA’s. Zoning polygons have detailed attributes referencing town zoning by-law as well as generalized codes. Orthophoto is preferred base.
• Any additional land use controls relating to subdivisions, flood zones, parking etc.
• Current zoning map or maps including overlay districts
• Board of health regulations
• Conservation by-laws such as local wetlands or riverfront protection and any associated map
• Other GIS coverages
• land use
• protected open space
• recent subdivisions if filed with town

• black and white ortho to check detail of development
• Q3 floodplains data from FEMA 
• classified slopes (based on USGS 25k DEM)
• Areas of Critical Environmental Concern
• locations of public water supply wells and wellhead protection zones
• USGS/MassGIS hydro
• wetlands (1" = 400' if available)
• Interpreted from 1:12,000 scale CIRs
• Field checked, scanned, edited
• 26 classes of wetlands
• then Recompiled onto 5k scale Orthophoto base
• Rivers Protection Act buffers
• soils
• parcel maps if available

• collect zoning and other data from town
• compile all GIS info and get local review
• identify all undeveloped areas 
• subtract permanently protected open space 
• subtract other absolute constraints if any (eg slope > 25%)
• overlay zoning codes with developable areas
• overlay partial constraints (e.g. floodplains, wetlands, overlay districts)
• list area totals by zoning code with partial constraints
• compute “yield” of housing & industrial/commercial square footage

• Yield Calculations (residential)

For residential zones, several factors reduce the net yield of housing units. The area for roads can be figured from right of way and minimum lot width.  Other partial constraints reducing the total yield might include wetlands or floodplains (where allowable as part of gross lot minimum area), poorly drained soils and odd lot configurations.

Raw land * adjustment for roads and other constraints / minimum lot size in residential zone = yield of housing units

The adjustment for roads might be 10%; other factors might add 
as much as 15%.
 
• Yield Calculations (other)

For industrial/commercial areas, calculations are more complex. Typical limiting factors in the zoning include:
• floor area ratio
• percent lot coverage
• height limits
• parking requirements 
• open space requirements
It is critical to look at past patterns of development in estimating the most likely future scenarios.

The “aggregate” method - pros and cons

• compared to a more detailed parcel-based approach  - surprisingly accurate
• doesn’t provide infill analysis for urbanized areas
• ignores likelihood of development
• alternative scenarios - a more automated tool
• combining the buildout results with other kinds of GIS inventory such as habitat identification or water resources 

• State recognizes that long-term economic growth depends on quality of life 
• If the Community Preservation Act passes, cities and towns will have a local option to provide additional funding for open space, affordable housing and historic preservation
• State agencies are bound by Executive Order 385 to understand growth management implications of their actions

Last Updated 4/19/2000
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