Nothing contained herein shall prohibit excavation incidental to construction of a driveway, private road, walk, wall or building or part thereto, or accessory thereto, for which any required building permits have been issued, where the excavation occurs on the same or contiguous parcel as the construction. In cases of real estate subdivision, the cut and fill of on-site soils are expected to be in balance and not hauled off the building site, except as provided below. Provision shall be made to restore an effective cover crop to any area of land from which topsoil has been removed or covered with fill within the first growing season following the start of such operation.