Robbinsville Township, Mercer County, New Jersey, population 14,543 (2019), is located 60 miles southwest of New York City. It uses a non-contiguous planned unit residential development (PURD) process to preserve open space and transfer density credits from its Rural Residential District to its Town Center (TC) zone. 

In addition to being zoned Rural Residential and identified as a priority for open space preservation, sending sites must be at least six acres and have frontage on an existing street. According to Code Section 142-13, sending site development credits are calculated by multiplying the acreage of the Rural Residential sending site by the site’s factor of soil suitability for septic: 0.5 credit X acreage with slight soil limitations. 0.3 credit X acreage with moderate limitations, and 0.05 credits X acreage with severe limitations. A bonus factor can then be applied depending on whether the site has a preservation priority ranking of 1 (20 percent) or a priority ranking of 2 (10 percent) based on the Priority Open Space Preservation Plan. Regardless of the above calculations, each eligible tract is entitled to at least one credit.

Section 142-82, Planned unit residential development, specifies that the sending site and noncontiguous receiving site are part of a single PURD application.  Potential receiving sites include parcels zoned Town Center 1, 2, and 3. To approve a transfer, six findings are required including that provisions are adequate to maintain the open space on the sending site. An easement must be recorded limiting sending site development. Town Center Zoning and Design Regulations have different base and enhanced densities depending on the zoning of the receiving site. In the TC1, base is 1.5 units per acre and enhanced density is an additional 1.2 units per acre. In the TC2, base is 4.2 units per acre and enhanced density is an additional 0.37 units per acre. In the TC3, base is 1.5 units per acre and enhanced density is an additional 1.0 units per acre.    

Per Section 142-83, Robbinsville can sell credits from land in the Rural Residential district that the township acquired prior to the effective date of the program. The township sells these credits at public auction and uses proceeds from those sales for open space preservation and the funding of a municipal transfer bank.