What is a precise development (PD) plan?

If your property is zoned with the PD combing district with your base zoning, such as C-2, M-1 or R-2, you are required to sumbit a precise development plan of your proposed development to the Planning and Natural Resources Department to be reviewed and approved by either the department Director or, if appealed, the Board of Supervisors.  No use can be established, changed, or altered, no development can occur and no building or grading permit shall be issued for any use or development in the PD Combining District, except for one (1) single-family residence on a single lot, until an application for the site development plan review has been submitted and approved.