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Case Studies - Open Space Design (OSD)/Natural Resource Protection Zoning (NRPZ)

View case studies conducted on the Open Space Design (OSD)/Natural Resource Protection Zoning (NRPZ) module.

Newbury, Massachusetts: Rural Case Study

Caldwell Farm, Newbury, MA

Caldwell Farm is a 66-unit housing project built on an 125-acre site. The project developers, C.P. Berry Construction Company, chose to develop the property under Newbury's OSRD bylaw, resulting in 100 of the 125 acres being maintained as open space including fields, forest, freshwater, and saltwater wetlands adjacent to the Parker River National Wildlife Refuge and an Area of Critical Environmental Concern (ACEC).

The Bylaw

The Town worked with the Green Neighborhoods Alliance to adopt an OSRD bylaw (the first in the Commonwealth) that clusters development on a parcel in a way that conserves 50% or more of the land as open space. Under the Newbury bylaw, OSRD can be approved through a Special Permit process that is complementary to the standard requirements of the local Subdivision Rules and Regulations.

As an incentive to developers, the bylaw provides for density bonuses for historic preservation, creation of affordable housing, or protection of additional open space. The density bonus for the OSRD development cannot exceed 50% of the basic maximum number, which is determined by the basic 'by right" zoning regulations of the underlying district. Density bonuses can be awarded in the following circumstances:

  1. For each 10% of the site (over and above the required 50%) set aside as open space, a bonus of 5% of the basic maximum number may be awarded.
  2. For every dwelling unit set aside as affordable in perpetuity, one dwelling unit may be added as a density bonus.
  3. For every historic structure preserved and subject to a historic preservation restriction, one dwelling unit may be added as a density bonus.
Caldwell Farm, sited on beautiful rolling land bordering the Parker River and the Great Salt Marsh, received a "Best Overall Community" award from the National Association of Home Builders in 2007.
Caldwell Farm, sited on beautiful rolling land bordering the Parker River and the Great Salt Marsh, received a "Best Overall Com

Site Design Process:

Newbury strongly encourages those applicants proposing to develop under the OSRD bylaw to schedule a pre-application review with the Planning Department. The Planning Department invites the Conservation Commission, the Board of Health and the Historical Commission to attend this review. The purpose of the review is to minimize the applicant's cost of engineering and other technical experts and to commence negotiations with the Planning Board at the earliest possible stage in the development process. Applicants are encouraged to submit both a site context map and an existing conditions/site analysis map prior to the review, and to schedule a site visit.

Newbury's OSRD bylaw clearly outlines the design process in four steps:

  1. Identify all conservation areas to determine the potentially developable area.
  2. Locate housing sites.
  3. Align streets and trails.
  4. Draw in the lot lines, if the OSRD is not a condominium development.

Benefits:

At Caldwell Farm:

  • 80% of the parcel remains as open space
  • A circa 1800 farmhouse on the property has been preserved.
  • Walking trails cross the open space and provide pedestrian access to the saltwater wetlands
  • Because of the large percentage of open space preservation and the preservation of the historic farmhouse, the unit bonus provision of Newbury's OSRD bylaw allowed the developer to build 66 units versus the 62 units provided via by-right zoning.
  • The developer agreed to put in a shared wastewater treatment system that will be more protective of the environment than the minimum standards require and will take up less space.
  • The open space amenities bolstered the market prices in the development, including a clubhouse, swimming pool, gatehouse, walking paths and trails throughout the property and adjoining conservation lands, where a 2-bedroom home starts at $635,000.

Hopkinton, Massachusetts: Suburban 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.

Bylaw Discussion:

Hopkinton's OSLPD bylaw is designed to encourage the preservation of important site features on sites of 10 acres or more and to be growth neutral. 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.

Site Design Process:

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
  • 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.

Benefits:

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.

Rowley, Massachusetts: Rural Case Study

Wild Pasture Estates, Rowley, MA

Wild Pasture Estates is a 30-unit housing project that was recently permitted under the OSRD provisions of Rowley's Zoning Bylaw. Construction of the project began in the spring of 2005 on a 63-acre parcel of undeveloped open space. Of the 63 total acres, 37 acres were maintained as open space. The general design of the development used three clusters of homes to concentrate the development envelope between two large tracts of conservation area.

The Bylaw

The Town of Rowley has been committed to addressing the issue of open space development in their Zoning Bylaw. These efforts began with a standard cluster zoning bylaw that provided guidelines and incentives for concentrating residential development through the subdivision process. The Planning Board and other local agencies identified the need for a more flexible resource-oriented approach. As a result, the cluster bylaw has gradually evolved into the existing OSRD bylaw after several revisions adopted through Town Meeting.

In its current form, the Rowley OSRD Bylaw uses the fundamental tenets of OSRD with the four step site planning process:

  1. Identify all conservation areas to determine the potentially developable area.
  2. Locate housing sites.
  3. Align streets and trails.
  4. Draw in the lot lines, if the OSRD is not a condominium development.

Discussions with Rowley's citizenry revealed that many people were concerned that a more flexible approach to development would allow for a higher volume of residential units than what is allowed through conventional zoning bylaw provisions. To help address these concerns, the Rowley Bylaw requires a Yield Plan to determine how many units of housing could be developed under conventional zoning provisions. This plan is similar in form and content to a preliminary subdivision plan and shows the basic lotting that could occur with a conventional approach. However, in addition to a physical site plan, the yield analysis in the Rowley OSRD Bylaw requires a basic mathematical calculation to substantiate the number of units illustrated in the conventional lotting layout. The formula for potential site yield is as follows:

An applicant is required to both develop a Yield Plan and perform the computations above as part of the site yield analysis. The method that produces the lower number is the one chosen for the final yield.

As an incentive to developers, the bylaw provides for density bonuses for historic preservation, creation of affordable housing, or protection of additional open space. The density bonus for the OSRD development cannot exceed 50% of the basic maximum number, which is determined by the basic "by right" zoning regulations of the underlying district. Density bonuses can be awarded in the following circumstances:

  1. For each 10% of the site (over and above the required 50%) set aside as open space, a bonus of 5% of the Basic Maximum Number may be awarded.
  2. For every dwelling unit set aside as affordable in perpetuity, one dwelling unit may be added as a density bonus.
  3. For every historic structure preserved and subject to a historic preservation restriction, one dwelling unit may be added as a density bonus.

Bellingham, Massachusetts: Suburban Case Study

Woodbury Ridge, Bellingham, MA

Woodbury Ridge is an excellent example of an Open Space Residential Design (OSRD) development that incorporates Low Impact Development (LID) practices. Homes are clustered, linear feet of roadway is reduced, drainage goes into slightly pitched open drainage swales, and rooftop drainage also goes into swales thus eliminating stormwater drainage infrastructure.

OSRD Site Design with LID Techniques:

Instead of a conventional residential development, the Town of Bellingham, developer David Lachance, and site designers/engineers at Weston & Samson, Inc. designed an OSRD residential development. Their plan clustered the homes on 6 acres and preserved aesthetic natural landscape as permanent conservation land on 10.4 acres. They further reduced negative environmental impacts in the built land areas by incorporating LID practices into the subdivision. Instead of twelve one-acre lots allowed by right under Bellingham's zoning, the OSRD development created six smaller duplex lots ranging in area from .49 to .60 acres.

To help reduce the ecological impact of the project, the impervious roadway surface area was reduced by 50 percent and infiltration of rainfall was greatly increased. Two catch basins were installed but virtually all piped street drainage was eliminated instead using open drainage at 2% pitch with no crown to handle roadway drainage and allow runoff to slowly infiltrate into the soil. Impervious pavement was reduced to 45,400 square feet with 1,700 linear feet of 22 foot wide roadway and 500 linear feet of 16 foot wide one way loop roads. Pervious pavement (Grasspave2) was installed in twelve overflow parking spaces instead of 2,200 square feet of impervious pavement.

In addition to concentrating most of the construction in previously disturbed areas of the site, the six-acre OSRD development reduced the subdivision area by 100 percent. The Town and its residents gained 10.4 acres of protected natural land. Wetlands on site were protected by 50 to 100 foot natural vegetated buffers.

Benefits for the Town of Bellingham:

The natural hydrologic cycle and the base flows of local streams and wetlands will be maintained. Most of the stormwater will run into swales that will reduce the amount of runoff and sediment that would otherwise enter the public drainage system thereby lowering the municipality's cost for maintenance and replacement of aging or damaged infrastructure.

By concentrating the homes on part of the site and creating natural vegetative buffers, abutter privacy will be enhanced. On-site natural areas with unique or fragile habitats will be preserved and protected. Residents will be able to easily access both neighbors and wildlife habitats through an interconnected network of trails and open space.

Benefits for the Developer and Realtor:

The OSRD development plan for Woodbury Ridge gives benefits to the developer and realtor too. Valuable amenities such as access to trails, views to open space, and privacy from abutting properties can enhance marketing of homes and their selling prices. Developments designed with nature can enhance aesthetics and home values.

The developer benefits when the plan review process is streamlined which reduces time and costs. Designing with existing features of the terrain further decreases site development costs. Low impact development practices cost less than conventional drainage techniques to build and maintain due to a reduction in the size and number of detention facilities and the size and cost of pipes and drainage infrastructure.

Ipswich, Massachusetts

Partridgeberry Place, Ipswich, MA

Partridgeberry Place is a new 20-lot subdivision of single-family homes on 40 acres in the Ipswich River watershed. The Ipswich is well documented as an endangered river with severe and chronic reductions in base flow and continuing pressure from new residential and commercial development.

Partridgeberry Place is one of the first Open Space Residential Design projects to be built in Ipswich. The project preserves 74% (28 acres) as open space and uses LID to demonstrate an innovative approach to stormwater management.

OSRD Site Design Process:

Partridgeberry Place features a wide range of OSRD principles and techniques incorporated into a compact OSRD site design with single-family homes clustered on .2-acres lots with small yards. Land disturbance was minimized to maintain valuable natural features, hydrology, and mature trees. Together the main subdivision roadway at 18 feet wide and shorter driveways reduce impervious roadway surfaces, which are associated with polluted stormwater runoff.

This environmentally sensitive design preserves the rural character of the surrounding area and incorporates the patterns and beauty of the existing woodlands and landscape, to recreate the feeling of an old fashioned New England neighborhood.

 

LID Principles and Techniques:

Partridgeberry Place incorporates LID best management practices, including:

  • grass pavers for overflow parking areas
  • an open grass swale that drains to a central bioretention area
  • rain gardens on individual house lots
  • reduced lawn areas and use of native, drought-resistant vegetation for landscaping
  • infiltration of roof runoff through drywells

A shared septic system facilitates smaller lot sizes while still allowing on-site recharge of groundwater.

Collectively, these LID techniques will store, allow evaporation, naturally filter, and detain runoff so rainfall can infiltrate on site, lessen heat island effects, and reduce energy use and drainage infrastructure costs and maintenance.

Rain Gardens are Natural Filters:

Each home in Partridgeberry Place has a rain garden as part of its landscaping. They are planted with flood and drought resistant species, often ones native to New England, and soil is mixed with lots of sand so that water drains through it quickly. These rain gardens demonstrate that a garden can be a sophisticated pollution-prevention device, aesthetically pleasing, and a means of replenishing local groundwater resources.

A large scale half-moon shaped rain garden adjacent to a detention pond on the site was designed by engineers to hold a specific amount of stormwater and allow on-site recharge of groundwater and reduce runoff pollution.

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