A.
Removal of spring and surface water. All subdivisions shall be related
to the drainage pattern affecting the areas involved, with proper
provision to be made for adequate storm drainage facilities. The subdivider
may be required by the Planning Board to carry away by pipe or open
ditch any spring or surface water that may exist either previous to
or as a result of the subdivision; such drainage facilities shall
be located in the street right-of-way, where feasible, or in perpetual
unobstructed easements of appropriate width. A culvert or other drainage
facility shall, in each case, be of adequate size to accommodate the
potential runoff from the entire upstream drainage area, whether inside
or outside the subdivision area. The design and size of this facility
shall be subject to the approval of the Town Engineer.
B.
Drainage structure to accommodate potential development upstream. A culvert or other drainage facility shall, in each case, be large enough to accommodate potential runoff from its entire upstream drainage area, not only the anticipated discharge from the property being subdivided but also the anticipated runoff that occurs when property at a higher elevation in the drainage basin is developed. The Town Engineer shall approve the design and size of facility based on anticipated runoff from the following storm frequencies under conditions of total potential development permitted by Chapter 250, Zoning, in the watershed:
(1)
For watersheds with drainage areas of fewer than 320 acres, all structures
should be designed to carry the peak runoff for a twenty-five-year
storm.
(2)
For watersheds with drainage areas of between 320 acres and 640 acres,
the structures should be designed to carry peak runoff for a fifty-year
storm.
(3)
For watershed with drainage areas larger than one square mile, all
structures should be designed to carry peak runoff for a one-hundred-year
storm. The only acceptable method for calculating anticipated runoff
shall be computed by the soil cover complex method as utilized by
the Soil Conservation Service of the United States Department of Agriculture.
C.
Responsibility for drainage downstream. The subdivider's engineer
shall study and submit a written report of the effect of each subdivision
on the existing downstream drainage facilities outside the area of
the subdivision. This study shall be reviewed by the Town Engineer
and the Orange County Soil and Water Conservation District. Where
it is anticipated that the additional runoff incident to the development
of the subdivision will overload an existing downstream drainage facility
during a twenty-five-year storm, provision for the storage of the
increased runoff must be made by the developer.
D.
Land subject to flooding. Land subject to periodic or occasional
flooding or land deemed by the Planning Board to be uninhabitable
shall not be platted for residential occupancy nor for such other
uses as may increase danger to health, life or property or aggravate
the flood hazard, but such land within the plat shall be set aside
for such uses as shall not be endangered by periodic or occasional
flooding.
E.
Easements. 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 with the lines of such
watercourse and such further width or construction, or both, as the
Town Engineer may deem adequate to the purposes but in no case fewer
than 30 feet in width and of such width as to encompass the flood
of record, plus three feet in elevation. Drainage easements shall
be carried from the road to a natural watercourse or to other drainage
facilities. When a proposed drainage system will carry water across
private land outside the subdivision, appropriate rights must be secured
and indicated on the plat.
F.
House and lot drainage. Drainage of individual lots and dwellings,
including footing drains, to assure proper runoff from roofs, driveways
and paved surfaces shall be required for Planning Board approval.
The installation of such facilities shall be required prior to the
issuance of a certificate of occupancy.
