Planning Commission approval of a site plan shall expire if any of the following circumstances occurs:
(a) The site plan is not submitted for stamping and signature by the Chairman within six calendar months of the Planning Commission’s resolution of site plan approval, with or without modifications.
(b) A complete application for either a building permit or certificate of occupancy is not submitted within one calendar year of the stamping and signing of the site plan by the Chairman.
(c) Work authorized under a building permit is not commenced and diligently pursued through the completion of substantial construction within thirty months of the stamping and signing of the site plan by the Chairman. Upon prior written request to the Planning Commission, including a statement of justification for the requested time extension, the time period for submission of the site plan or submission of the complete application for a building permit or certificate of occupancy may be individually extended for a maximum period of six calendar months and one calendar year, respectively, from their otherwise specified termination dates.