Open Space Residential Design (OSRD)
Case Study

Olde North Mill, Hopkinton, MA

Olde North Mill is what is known, in the Town of Hopkinton, as an Open Space and Landscape Preservation Development (OSLPD). It consists of 34 buildable lots on a 100-acre parcel. Protected open space comprises 52% of the parcel area, and building lot prices were driven by their proximity to the open space, with the most expensive building lots abutting the open space. All wetlands on the property are also contained within the protected open space. This case study provides a good example of a developer and the Town doing the "right thing," even though a conventional subdivision was possible.

Single-family dwelling.Bylaw Discussion:

Designed to encourage the preservation of important site features on sites of 10 acres or more and to be growth neutral, Hopkinton's OSLPD bylaw was passed in 1988. OSLPD developments are allowed by special permit from the Planning Board. One provision of the OSLPD bylaw is that it allows the Planning Board to grant a reduction of all intensity regulations of the underlying zoning regulations for all portions of an OSLPD development if the Board finds that a reduction will result in better design and improved protection of natural and scenic resources. Dead-end streets and common driveways are also permitted under the OSLPD, and at least 50% of the land area of the development has to be set aside as common open space. Wetlands may comprise up to 50% of the open space. The common open space is conveyed either to the Town, a non-profit conservation corporation, or a corporation or trust owned by the OSLPD lot owners. If not conveyed to the Town, the open space must have a conservation restriction recorded.

Drawing of - 1. Yeild plan, 2. OSRD Concept Plan, 3. OSRD Modified Concept.

Site Design Process:

In 1988 a conventional subdivision plan (which is allowed by zoning) had been approved for this property that resulted in a court challenge, which was ultimately decided in favor of the developer. Fortunately, the subdivision was never built and a subsequent developer purchased the property. Although this developer could have built the previously approved conventional subdivision, he chose to re-design an open space development instead.

The original OSLPD concept plan for this development contained 43 buildable lots, and the Planning Board granted a maximum of 43 building lots. However, the developer chose to only build 34 lots. In this situation, maximizing profit did not mean building the number of maximum lots permitted. Factors that contributed to the developer's decision included proximity of the lots to wetlands, which would require time consuming and costly Conservation Commission filings; steering clear of the costs of building infrastructure for the nine additional lots; and avoiding carrying costs based on the time it would take to permit and complete building on the nine lots. Additionally, Olde North Mill was marketed and priced as an open space subdivision, and the value of three lots that abutted those additional nine lots rose significantly ($50,000 each), as they would now abut open space.

Added financial incentive for not building on the nine lots was provided to the developer in the form of a tax credit for donating the nine lots to the local land trust. The tax credit was determined by calculating the expected value of the nine lots after infrastructure construction. The developer was allowed, according to tax codes at that time, to spread the tax credit over five years and could amount to up to 30% of the developer's taxable income in any given year.

The Town and the developer worked in good faith to permit and develop this property. Since the developer could not claim his tax credit unless the Town approved all 43 lots as buildable, the Town went ahead and approved these lots with the understanding that the developer would not build upon them. Likewise, the developer was granted a reduction in the percentage of open space requirement- all with the understanding that nine lots were not to be built and that the actual open space upon completion of the project would be greater than required.


In the end, both the developer and the Town realized multiple benefits through good faith negotiations and the application of the Town's OSLPD bylaw. In addition to the tax credit, the developer received a reduction in the roadway right-of-way and pavement width and a waiver of the 100-foot perimeter buffer requirement. The Town also did not require drainage structures on all roads. Rather, the developer was allowed to design roads with shoulders that could absorb sheet flow.

The Town was able to prevent the construction of a conventional subdivison, which they did not want, and create a parcel of open space in a part of town where no such parcel existed before. The project was designed to minimize grading, cutting, and filling by having the developer adapt the location and placement of structures and ways to the existing landscape. A publicly accessible trail system is planned within the open space and a small parking area will be provided so that others may enjoy the space. This subdivision project also served as an example for other developers- if you are willing to work with the Town, the Town is willing to work with you.