Validity of Approved Plan. Once a stormwater management plan has
been approved, together with a subdivision or land development plan
approval, or together with the issuance of a zoning permit, said stormwater
management plan shall be valid only for the subdivision, land development,
or zoning permit approved. Any further development on the lot or lots
requiring a revision of the approved plan, or other construction or
activities, as defined by municipal zoning regulations, shall require
the submission of a new, amended, or revised stormwater management
plan, and other information specified herein.
A. Exemptions From Plan Preparation. The following activities are specifically exempt from the plan preparation and submission provisions of this chapter, but remain subject to the design standards and criteria specified in Part
3 of this chapter (and erosion and sediment pollution control requirements).
(1)
Noncommercial home gardening;
(2)
Agriculture, when operated in accordance with an approved conservation
plan, or erosion and sedimentation control plan;
(3)
Forest management operations, conducted in accordance with the
PA DEP's "Soil Erosion and Sedimentation Control Guidelines for
Forestry," and an approved erosion and sediment pollution control
plan;
(4)
Regulated activities may be exempt from the plan preparation
and submission provisions of this chapter if the total impervious
area associated with such activities will be less than 2,500 square
feet. The municipality and its Engineer shall review all regulated
activities to determine if the activity or activities may be exempt
from the plan preparation and submission provisions of this chapter.
In addition to the criteria in this chapter subsection, the municipality
and its Engineer may require that regulated activities maintain a
minimum distance between proposed impervious areas/stormwater management
facility outlets and downslope property line(s).
B. All regulated activities that do not fall under the exemption criteria
referenced herein shall submit a drainage plan to the municipality
for review. These criteria shall apply to the total proposed development,
even if development is to take place in stages. Impervious cover shall
include, but not be limited to, any roof, parking, or driveway areas;
and any new streets and sidewalks. Any areas designed to initially
be gravel or crushed stone shall be assumed to be impervious.
(1)
Stormwater drainage systems shall be provided in order to permit
unimpeded flow along natural watercourses, except as modified by stormwater
management facilities or open channels consistent with this chapter.
(2)
The existing points of concentrated drainage that discharge
onto adjacent property shall not be altered without permission of
the affected property owner(s), and shall be subject to any applicable
discharge criteria specified in this chapter.
(3)
Areas of existing diffused drainage discharge shall be subject
to any applicable discharge criteria in the general direction of the
existing discharge, whether proposed to be concentrated or maintained
as diffused drainage areas, except as otherwise provided by this chapter.
If diffused flow is proposed to be concentrated and discharged onto
adjacent property, the applicant/developer must document that adequate
downstream conveyance facilities exist to safely convey the concentrated
discharge, or otherwise prove that no erosion, sedimentation, flooding,
or other harm will result from the concentrated discharge.
(4)
Where a site is traversed by watercourses, drainage easements
shall be provided conforming to the line of such watercourses. The
terms of the easement shall prohibit excavation, the placing of fill
or structures, and any alterations that may adversely affect the flow
of stormwater within any portion of the easement. Maintenance, including
mowing of vegetation within the easement, shall be required, except
as approved by the appropriate governing authority.
(5)
When it can be shown that, due to topographic conditions, natural
drainageways on the site cannot adequately provide for drainage, open
channels may be constructed conforming substantially to the line and
grade of such natural drainageways. Work within natural drainageways
shall be subject to approval by PA DEP through the joint permit application
process, or, where deemed appropriate by PA DEP, through a general
permit or small projects permit.
(6)
Any stormwater management facilities regulated by this chapter
that would be located within or adjacent to wetlands or other waters
of the commonwealth shall be subject to approval by PA DEP through
the joint permit application process, or, where deemed appropriate
by PA DEP, the general permit process. When there is a question whether
wetlands may be involved, it is the responsibility of the applicant/developer,
or his agent, to show that the land in question cannot be classified
as wetlands, otherwise approval to work in the area must be obtained
from PA DEP.
(7)
Any stormwater management facilities regulated by this chapter
that would be located on state highway rights-of-way shall be subject
to approval by PA DOT.
(8)
Minimization of impervious surfaces, and infiltration of stormwater
runoff through stormwater infiltration facilities are encouraged where
soil conditions permit in order to reduce the size, or eliminate the
need for detention facilities.
(9)
In order to promote overland flow and infiltration, roof drains
should not discharge directly to streets or storm sewers. Roof drains
may discharge directly to streets or storm sewers when deemed necessary
by the municipality and its Engineer. Under no circumstances shall
roof drains discharge directly to sanitary sewer systems.