A.
For all regulated activities, unless specifically exempted in § 236-14.
(1)
Preparation and implementation of an approved SWM site plan is required.
(2)
No regulated activities shall commence until the municipality issues
written approval of a SWM site plan, which demonstrates compliance
with the requirements of this chapter.
(4)
The SWM site plan approved by the municipality shall be on site throughout
the duration of the regulated activities.
B.
For all regulated earth disturbance activities, erosion and sediment
control BMPs shall be designed, implemented, operated, and maintained
during the regulated earth disturbance activities (e.g., during construction)
to meet the purposes and requirements of this chapter and to meet
all requirements under Title 25 of the Pennsylvania Code (including,
but not limited to, Chapter 102 Erosion and Sediment Control) and
the Clean Streams Law.[1] Various BMPs and their design standards are listed in
the Erosion and Sediment Pollution Control Program Manual (E&S
Manual), No. 363-2134-008 (April 15, 2000), as amended and updated.
[1]
Editor's Note: See 35 P.S. § 691.1 et seq.
C.
For all regulated activities, stormwater BMPs shall be designed,
installed, implemented, operated, and maintained to meet the purposes
and requirements of this chapter and to meet all requirements under
Title 25 of the Pennsylvania Code and the Clean Streams Law,[2] conform to the state water quality requirements, meet
all requirements under the Storm Water Management Act[3] and any more stringent requirements as determined by the
municipality.
D.
The municipality may, after consultation with PADEP and/or DCCD,
approve measures for meeting the state water quality requirements
other than those in this chapter, provided that they meet the minimum
requirements of, and do not conflict with, state law including, but
not limited to, the Clean Streams Law.[4]
[4]
Editor's Note: See 35 P.S. § 691.1 et seq.
E.
All regulated activities shall include, to the maximum extent practicable,
measures to:
(1)
Protect health, safety, and property.
(2)
Meet the water quality goals of this chapter by implementing measures
to:
(a)
Minimize disturbance to floodplains, wetlands, natural slopes,
existing native vegetation, and woodlands.
(b)
Create, maintain, or extend riparian buffers and protect existing
forested buffers.
(c)
Provide trees and woodlands adjacent to impervious areas whenever
feasible.
(d)
Minimize the creation of impervious surfaces and the degradation
of waters of the commonwealth and promote groundwater recharge.
(e)
Protect natural systems and processes (drainageways, vegetation,
soils, and sensitive areas) and maintain, as much as possible, the
natural hydrologic regime.
(f)
Incorporate natural site elements (wetlands, stream corridors,
mature forests) as design elements.
(g)
Avoid erosive flow conditions in natural flow pathways.
(h)
Minimize soil disturbance and soil compaction.
(i)
Minimize thermal impacts to waters of the commonwealth.
(j)
Disconnect impervious surfaces by directing runoff to pervious
areas wherever possible and decentralize and manage stormwater at
its source.
(3)
Applicants are encouraged to incorporate the techniques for low-impact
development practices described in the "Pennsylvania Stormwater Best
Management Practices Manual (BMP Manual)" to reduce the costs of complying
with the requirements of this chapter and the state water quality
requirements.
F.
Impervious areas:
(1)
The measurement of impervious areas shall include all the impervious
areas in the total proposed development, even if development is to
take place in stages.
(2)
For development taking place in stages, the entire development plan
must be used in determining conformance with this chapter.
(3)
For projects that add impervious area to a developed parcel, the
new impervious area is subject to the requirements of this chapter;
and any existing impervious area that is within the new proposed limit
of disturbance is also subject to the requirements of this chapter.
G.
If diffused flow is proposed to be concentrated and discharged onto
adjacent property, the applicant must document that adequate downstream
conveyance facilities exist to safely transport the concentrated discharge,
or otherwise prove that no erosion, sedimentation, flooding, or other
harm will result from the concentrated discharge.
(1)
The applicant must demonstrate the post-development peak discharge
depth and velocity across the adjoining property is no greater than
the pre-development condition during a 100-year storm event; and that
it will not result in concentrated flow erosion during a ten-year,
twenty-four-hour storm event.
(2)
The applicant must provide an executed easement for newly concentrated flow across adjacent properties, if it cannot be demonstrated that the requirements in § 236-13G(1) above have been achieved.
H.
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.
I.
Where watercourses traverse a development site, drainage easements
projecting at least five feet from the extents of the watercourse
(with a minimum width of 20 feet) 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. Also, maintenance, including mowing of vegetation
within the easement, may be required except as approved by the appropriate
governing authority.
J.
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 drainage ways shall be subject to approval by PADEP under regulations at 25 Pa. Code Chapter 105.
K.
Any stormwater management facilities or any facilities that constitute water obstructions (e.g., culverts, bridges, outfalls, or stream enclosures, etc.) that are regulated by this chapter, that will be in or adjacent to waters of the commonwealth (including wetlands), shall be subject to approval by PADEP under regulations at 25 Pa. Code Chapter 105. When there is a question whether wetlands may be involved, it is the responsibility of the applicant 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 PADEP.
L.
Should any stormwater management facility require a dam safety permit under PADEP Chapter 105, the facility shall be designed in accordance with Chapter 105 and meet the regulations of Chapter 105 concerning dam safety which may be required to pass storms larger than a 100-year event. Any stormwater management facilities regulated by this chapter that will be located on or discharged onto State highway rights-of-way shall be subject to approval by the Pennsylvania Department of Transportation (PennDOT).
M.
When stormwater management facilities are proposed within 1,000 feet
of a downstream municipality, the stormwater analysis shall be submitted
to the downstream municipality's engineer for review and comment.
N.
Infiltration of runoff through seepage beds, infiltration trenches,
etc., and the minimization of impervious surfaces are encouraged,
where soil conditions and geology permit, to reduce the size or eliminate
the need for detention facilities.
O.
Infiltration BMPs should be dispersed throughout the site, made as
shallow as practicable, and located to maximize use of natural on-site
infiltration features while still meeting the other requirements of
this chapter.
P.
It shall be the applicant's responsibility to verify if the
project site is underlain by carbonate geology. Stormwater shall not
be discharged into sinkholes or other carbonate features (e.g., closed
depressions). Whenever a Stormwater management facility will be in
an area underlain by carbonate geology, a geological evaluation of
the proposed location shall be conducted to determine the design parameters
of proposed BMPs. The evaluation may include the use of impermeable
liners to reduce or eliminate the separation distances. The design
of facilities over karst shall include an evaluation and implementation
of measures to minimize adverse effects, shall be designed in accordance
with the PA BMP Manual, and must include a carbonate geology report
prepared by a registered Pennsylvania Geologist or Engineer, which
shall include the following:
(1)
The evaluation of soil permeability, depth to bedrock, seasonal high-water
table, susceptibility for sinkhole formation, suitability of stormwater
management facilities, subgrade stability, and maximum infiltration
capacity in depth of water per unit area.
(3)
The design of all stormwater management facilities over karst features
shall include an evaluation of measures to minimize adverse effects
and to prevent groundwater contamination, and where necessary, sinkhole
formation.
(4)
A plan for remediation of any identified karst features.
(5)
Impacts of stormwater management facilities on adjacent karst features
and impacts of karst features on adjacent stormwater management facilities.
Q.
Roof drains shall not be connected to streets, sanitary or storm
sewers, or roadside ditches in order to promote overland flow and
infiltration/percolation of stormwater where it is advantageous to
do so. When it is more advantageous to connect directly to streets
or storm sewers, then the municipality may at its discretion permit
it on a case-by-case basis.
B.
The applicant must demonstrate that the following BMPs are being
utilized to the maximum extent practicable to receive consideration
for the exemptions:
(1)
Design around and limit disturbance of floodplains, wetlands, natural
slopes over 15%, existing native vegetation, and other sensitive and
special value features.
(2)
Maintain riparian and forested buffers.
(3)
Limit grading and maintain non-erosive flow conditions in natural
flow paths.
(4)
Maintain existing tree canopies near impervious areas.
(5)
Minimize soil disturbance and reclaim disturbed areas with topsoil
and vegetation.
(6)
Direct runoff to pervious areas.
C.
Direct runoff to pervious areas. The applicant must demonstrate that
the proposed development/additional impervious area will not adversely
impact the following:
D.
An applicant proposing regulated activities, after demonstrating compliance with § 236-14A, B and C, may be exempted from various requirements of this chapter according to the following table:
|
New Impervious Area*
(square footage)
|
Applicant Must Submit to the Municipality
|
|---|---|
|
0 to 999
|
—
|
|
1,000 to 4,999
|
Volume controls, SWM site plan & report
|
|
Greater than 5,000
|
Rate controls, volume controls, SWM site plan and report
|
|
*Gravel in the existing condition shall be considered pervious
and proposed gravel shall be considered impervious.
|
(1)
Requirement for additional stormwater management controls.
(a)
The municipal governing body reserves the right to require additional
stormwater management controls if an exempted project is determined
to be causing adverse impacts of any kind (i.e., land cover changes).
(2)
Obligation to meet other requirements.
(a)
Nothing in this section shall relieve the applicant of any responsibility
under other regulations such as, but not limited to, municipal ordinances
or codes and state and federal regulations related to stormwater management,
NPDES permitting requirements for erosion and sediment pollution control
and post-construction stormwater management, stream and wetland encroachment
or floodplain management.
E.
The purpose of this section is to ensure consistency of stormwater
management planning between local ordinances and NPDES permitting
(when required) and to ensure that the applicant has a single and
clear set of stormwater management standards to which the applicant
is subject. The municipality may accept alternative stormwater management
controls provided that:
(1)
The applicant, in consultation with the municipality, PADEP and/or
DCCD, states that meeting the requirements of the volume controls
or rate controls of this chapter is not possible or creates an undue
hardship.
(2)
The alternative stormwater management controls, proposed by the applicant,
are documented to be acceptable to the municipality, PADEP and/or
DCCD for NPDES requirements pertaining to post construction stormwater
management requirements.
F.
Forest management and timber operations are exempt from rate and
volume control requirements and SWM site plan preparation requirement
of this chapter provided the activities are performed according to
the requirements of 25 Pa. Code Chapter 102. It should be noted that
temporary roadways are not exempt.
G.
Agricultural activities are exempt from the requirements of this
chapter provided the activities are performed according to the requirements
of 25 Pa. Code Chapter 102.
H.
Linear roadway improvement projects that create additional impervious
area are not exempt from the requirements of this chapter. However,
alternative stormwater management strategies may be applied at the
joint approval of the municipality and the Dauphin County Conservation
District (if an NPDES permit is required) when site limitations (such
as limited right-of-way) and constraints (as shown and provided by
the applicant) preclude the ability of the applicant to meet the enforcement
of the stormwater management standards in this chapter. All strategies
must be consistent with PADEP's regulations, including NPDES
requirements.
I.
The municipality may, after an applicant has demonstrated compliance with § 236-14A, B and C, grant a modification of the requirements of one or more provisions of this chapter if the literal enforcement will exact undue hardship because of peculiar conditions pertaining to the land in question, provided that such modification will not be contrary to the public interest and that the purpose and intent of the chapter is observed.
(1)
All requests for a modification shall be in writing and shall state
in full the grounds and facts of unreasonableness or hardship on which
the request is based, the provision or provisions of the chapter involved,
and the minimum modification necessary.
J.
All requests or exemptions or modifications shall be at the discretion
of the municipal governing body. Demonstration that a proposed project
meets exemption or modification requirements does not necessarily
obligate the municipal governing body to grant the request for exemption
or modification. The municipal governing body may consider any and
all relevant factors such as, but not limited to, runoff concentration,
slope, soil characteristics, existing problems, adjacent properties,
sensitive environmental features and recommendations from other municipal
entities such as planning commissions, municipal engineers and solicitors
in determining whether or not to grant any request for exemption or
modification.
A.
The green infrastructure and low-impact development practices provided
in the BMP Manual and in Appendix B[1] of this chapter shall be utilized for all regulated activities
to the maximum extent practicable.
[1]
Editor's Note: Said Appendix is included as an attachment to this chapter.
B.
Stormwater runoff volume controls shall be implemented using the
Design Storm Method or the Simplified Method. For regulated activities
equal to or less than one acre, this chapter establishes no preference
for either method; therefore, the applicant may select either method
on the basis of economic considerations, the intrinsic limitations
on applicability of the analytical procedures associated with each
methodology, and other factors.
(1)
The Design Storm Method (CG-1 in the BMP Manual) is applicable to
any sized regulated activity. This method requires detailed modeling
based on site conditions.
(a)
Do not increase the post-development total runoff volume when
compared to the pre-development total runoff volume for the two-year/twenty-four-hour
storm event.
(b)
For hydrologic modeling purposes:
[1]
Existing nonforested pervious areas must be considered meadow
(good condition) for pre-development hydrologic calculations.
[2]
Fifty percent of existing impervious area, when present on the
proposed project site, and within the new proposed limit of disturbance,
shall be considered meadow (good condition) for pre-development hydrologic
calculations for re-development.
(2)
The Simplified Method (CG-2 in the BMP Manual) is independent of
site conditions and should be used if the Design Storm Method is not
followed. This method is not applicable to regulated activities greater
than one acre. For new impervious surfaces:
(a)
Stormwater facilities shall capture at least the first two inches
of runoff from all new impervious surfaces.
(b)
At least the first one inch of runoff from new impervious surfaces
shall be permanently removed from the runoff flow, i.e., it shall
not be released into surface waters of the commonwealth. Removal options
include reuse, evaporation, transpiration, and infiltration.
(c)
Wherever possible, infiltration facilities should be designed
to accommodate infiltration of the entire permanently removed runoff;
however, in all cases at least the first 1/2 (0.5) inch of the permanently
removed runoff should be infiltrated.
C.
All applicable worksheets from Chapter 8 of the BMP Manual must be used when establishing volume controls.
D.
Actual field infiltration tests at the location of the proposed elevation
of the stormwater BMPs are required when 5,000 square feet or greater
of new impervious surface is added. Infiltration test shall be conducted
in accordance with BMP Manual. The municipality shall be notified
24 hours prior to infiltration tests being conducted as to provide
an opportunity for the municipality to witness the tests.
A.
Lands contained within Dauphin County that have not had release rates
established under an approved Act 167 stormwater management plan:
(1)
Post-development discharge rates shall not exceed the pre-development
discharge rates for the one-year, two-year, ten-year, twenty-five-year,
fifty-year, and 100-year, twenty-four-hour storm events.
B.
Lands contained within Dauphin County that have had release rates
established under an approved Act 167 stormwater management plan:
(1)
Post-development discharge rates shall not exceed the pre-development
discharge rates for the one-year, fifty-year, and 100-year storms.
(2)
For the two-year, ten-year, and twenty-five-year storms, the post-development
peak discharge rates shall be in accordance with the approved release
rate map for the individual watershed.
C.
Infiltration, exfiltration, evapotranspiration, and/or any other
environmentally-dependent discharge rates are prohibited in the modeling
of rate controls.
A.
In order to protect and improve water quality, a riparian buffer
easement shall be created and recorded as part of any subdivision
or land development that encompasses a riparian buffer.
B.
Except as required by Chapter 102, the riparian buffer easement shall
be measured to be the greater of the limit of the 100-year floodplain
or a minimum of 35 feet from the top of the streambank (on each side).
C.
Minimum management requirements for riparian buffers.
(1)
Existing native vegetation shall be protected and maintained within
the riparian buffer easement.
(2)
Whenever practicable, invasive vegetation shall be actively removed
and the riparian buffer easement shall be planted with native trees,
shrubs and other vegetation to create a diverse native plant community
appropriate to the intended ecological context of the site.
D.
The riparian buffer easement shall be enforceable by the municipality
and shall be recorded in the appropriate County Recorder of Deeds
Office, so that it shall run with the land and shall limit the use
of the property located therein. The easement shall allow for the
continued private ownership and shall count toward the minimum lot
area a required by Zoning, unless otherwise specified in the municipal
Zoning Ordinance. 3800-PM-BCW0100j Rev. 4/2018 Model Ordinance - 12.
E.
Any permitted use within the riparian buffer easement shall be conducted
in a manner that will maintain the extent of the existing 100-year
floodplain, improve or maintain the stream stability, and preserve
and protect the ecological function of the floodplain.
