Excavation. If during site plan review the Board finds any construction,
filling or excavation in excess of 300 square feet, or grading or
other alteration of more than 3,000 square feet, on a lot within the
proceeding three-year period, the Planning Board shall ensure that
such construction, filling, excavation, grading or alteration meets
the buffer requirements provided below and will not result in erosion
or in wetland, stream or lake pollution from surface or subsurface
runoff, before it shall grant approval.