Single Site Housing Limitations
It is impossible to build 95 two-bedrooms apartments/condos on a 6 acre parcel in Carlisle. This is because Carlisle lacks municipal piped water and a public sewer system.
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Read the full analysis here.
CAP continues to support the One-Site approach put forth in the Warrant Article for the Spring Town Meeting as the best way to
minimize the impact of the MBTA Zoning Act on Carlisle:
minimal rezoned acreage equals minimal development potential.
Water Supply Limitations
of 95 Unit One Site
Development
• Without piped water, a large well would be required for the development. Because this well would serve as the water supply for over 25 people, it would be regulated as a public water system under Massachusetts DEP’s drinking water regulations, which are contained at 310 CMR 22.00.
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• Public wells are required to have protective unbuilt areas around them, to prevent contamination and pollution, called Zone 1’s. The Massachusetts DEP rules specify how large the Zone 1 must be. The larger the development, the larger the Zone 1 must be.
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• A development of 95 two-bedroom apartments/condos would require a public well with a Zone 1 of over 7-1/2 acres. Nothing could be built in this area. Because this 7-1/2 acre unbuilt area is larger than the 6-acre parcel size we are analyzing, it would be impossible to build 95 units of housing on the 6-acre parcel.
Overall Limitations of a 45 Unit One Site Development
• It would also be impossible to build a development of half that size on a 6-acre parcel. For a development of 45 two-bedrooms housing units, the unbuilt Zone 1 would need to be approximately 5.5 acres. It would not be possible to fit the housing, driveway, parking, septic or wastewater treatment plant and leach field in the remaining half an acre.
• For projects with fewer than 45 units, a wastewater treatment plant would likely not be economically rational, as it would cost up to six times as much per unit as a conventional septic system. Therefore, the limiting factor on the site would be the number of bedrooms allowed under Title 5. The maximum number of bedrooms allowed under Title 5 on a 6-acre site would be 36.
What Might Be Possible on One Site
It might be possible to site 18 two-bedroom housing units (totaling 36 bedrooms) on a 6-acre site. It would be easier and more likely if a buildable but undeveloped 6 acre site is selected. If an already-developed site is selected, it might not be economically sensible to tear down the existing development, when all that can be gained is 18 housing units.
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These facts are consistent with Carlisle’s past experience with multi-family housing. The public wells at Benfield Farms and Woodward Village were possible because those were initially very large parcels, and the wells were located in portions that were broken off and placed under Conservation Restrictions. For Carlisle’s two most recent 40B proposals, Coventry Woods and Lifetime Green Homes, those applicants proposed a series of private wells that would have avoided the public water supply regulations.
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Planning Board Map of Potential Sites
Rezoning more acreage than the minimum allowed for a small adjacent town like Carlisle potentially compromises the Title V septic firewall, which would open the town up to 15 units per acre.
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Developing that kind of density on minimal acreage is virtually impossible without access to municipal utilities.