Stormwater control measures shall be selected
by giving preference to the best management practices for pollutant
removal and flow attenuation as specified in the NYS Stormwater Management
Design Manual, the NYSDEC's Reducing the Impacts of Stormwater Runoff
from New Development, and the Westchester County Best Management Practices
Manual for Erosion and Sediment Control. The following minimum design
requirements shall apply to minor projects:
A. It is the responsibility of an applicant to include
sufficient information in the stormwater management and erosion control
and sediment plans so that the plans may be evaluated with respect
to the environmental characteristics of the affected areas, the potential
and predicted impacts of the proposed activity on community waters
and the effectiveness and acceptability of those measures proposed
for reducing or mitigating adverse impacts.
B. An application for stormwater management and erosion
and sediment control permits shall be made on forms provided by the
Town, and shall include the name(s) and address(es) of the owner,
contract vendee, or developer of the site, and of any consulting firm
retained by the applicant, together with the name and telephone number
of the applicant's principal contact at such firm. Each application
shall include a certification that any land clearing, construction,
or development involving the movement of earth shall be in accordance
with the plans approved and the permit issued. The permit will be
valid for the same period as the associated building or other municipal
permits. Where a building or other municipal permit is not issued,
the stormwater management and erosion and sediment control permits
shall expire within 180 days from the date of approval unless renewed
by the Town Engineer.
C. Required information.
(1) Each application shall be accompanied by the following,
unless specifically waived by the Town Engineer based on the scope
of the project:
(b)
A stormwater management and erosion and sediment
control plan for the site showing drainage patterns, on-site stormwater
appurtenances, wetlands, one-hundred-year floodplain, and proposed
use of the site, including areas of excavation, grading and filling.
(c)
Stormwater management improvements, including
calculations, designs and special measures regarding safety and maintenance
operations.
(d)
Stormwater conveyance system, including plans,
designs and materials to be used for improvements and erosion control
in channel sections of stormwater conveyance systems and erosion control
measures at culvert inlets and outfalls.
(2) Stormwater shall be managed on site using stormwater
control measures designed to afford optimum protection of ground-
and surface waters. Stormwater shall be calculated in accordance with
the methodology for determining stormwater volume and flow rates using
any one of the following methods:
(a)
For small watershed areas (up to 20 acres),
the Rational Method or TR-55.
(b)
For larger watersheds areas (up to 2,000 acres),
TR-55 or an equivalent widely accepted methodology.
(3) Stormwater control measures shall be designed based
upon the minimum twenty-five-year design storm for local conditions.
The design shall consider all existing and new impervious surfaces,
including but not limited to roof areas, driveways, patios, deck areas,
and walkways.
(4) Stormwater control measures may include, but shall
not be limited to, dry wells of precast concrete, recharge structures,
and infiltration trenches. Such measures may also include natural
and human-made landscape features such as depressions, blind ditches,
retention ponds, swales and other such measures. Inlets to infiltration
devices shall be protected from sediment at all times in order to
maintain their capacity.
(5) Infiltration devices shall not be installed upgradient
within 20 feet of the subsurface treatment system of a wastewater
treatment system. Infiltration devices for roadways, parking lots,
and other areas subject to vehicle traffic shall not be installed
within 100 feet of any water well, wetland or water body.
(6) Infiltration devices and buildings shall be designed
to maintain maximum attainable horizontal distance separation from
wells, water bodies and wetlands.
(7) The bottom of any infiltration device shall be a minimum
of two feet above seasonal high groundwater mark and two feet above
bedrock.
(8) Temporary erosion controls shall be required to prevent
siltation of water bodies during construction.
No application for approval of a major land
development activity as defined in this chapter shall be reviewed
until the approval authority has received a stormwater pollution prevention
plan (SWPPP) prepared in accordance with the specifications in this
chapter.
The SWPPP shall be prepared by a New York State
licensed professional engineer, architect, landscape architect or
soil scientist, and must be signed by the professional preparing the
plan who shall certify that the design of all stormwater management
practices meet the requirements in this chapter.
The applicant shall assure that all other applicable
environmental permits have been or will be acquired for the land development
activity prior to approval of the final stormwater design plan.
A copy of the approved SWPPP shall be retained
at the site of the land development activity during construction,
from the date of initiation of construction activities to the date
of final stabilization.