Easements across lots or along rear or side lot lines
shall be provided for utilities and shall be at least 20 feet wide.
Where a subdivision is traversed by a watercourse, drainageway, channel
or stream, there shall be provided a stormwater easement or drainage
right-of-way conforming substantially to the exterior lines of such
watercourse and such further width or construction, or both, as will
be required after a formal potential runoff analysis by a qualified
engineer has been submitted.