A.
For all regulated activities, unless preparation of an SWM site plan is specifically exempted in § 343-28:
B.
SWM site plans approved by the municipality, in accordance with § 343-38, shall be available onsite throughout the duration of the regulated activity.
C.
The municipality may, after consultation with DEP, approve measures
for meeting the state water quality requirements other than those
in this article, provided that they meet the minimum requirements
of, and do not conflict with, state law including, but not limited
to, the Clean Streams Law.[1]
[1]
Editor's Note: See 35 P.S. § 691.1 et seq.
D.
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 article and to meet
all requirements under Title 25 of the Pennsylvania Code and the Clean
Streams Law.
E.
Impervious areas.
(1)
The measurement of impervious areas shall include all of 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 article.
(3)
For projects that add impervious area to a parcel, the total impervious area on the parcel is subject to the requirements of this article; except that the volume controls in § 343-29 and the peak rate controls of § 343-30 do not need to be retrofitted to existing impervious areas that are not being altered by the proposed regulated activity.
F.
Stormwater discharges onto adjacent property shall not be created,
increased, decreased, relocated or otherwise altered without written
notification to the adjacent property owner(s) and approval of the
altered discharge by said owner(s). Such stormwater flows shall be
subject to the requirements of this subarticle.
G.
All regulated activities shall include such measures as necessary
to:
(1)
Protect health, safety, and property.
(2)
Meet the water quality goals of this article by implementing measures
to:
(a)
Minimize disturbance to floodplains, wetlands, and wooded areas.
(b)
Maintain or extend riparian buffers.
(c)
Avoid erosive flow conditions in natural flow pathways.
(d)
Minimize thermal impacts to waters of the commonwealth.
(e)
Disconnect impervious surfaces by directing runoff to pervious
areas, wherever possible.
(3)
Incorporate the stormwater management (SWM) best management practices
(BMPs), including the design standards and inspection and maintenance
requirements of such BMPs, described in the Pennsylvania Stormwater
Best Management Practices Manual (BMP Manual), and any subsequent
addenda or revisions thereto. Green infrastructure and LID methods
that satisfy the volume and rate controls required under this subarticle
shall be used to the maximum extent that is practicable. The SWM site
plan must include a detailed narrative that includes justification
demonstrating that the use of LID and green infrastructure for the
volume and rate control is not practicable.
H.
The design of all facilities over karst shall include an evaluation
of measures to minimize adverse effects.
I.
Infiltration BMPs should be spread out, made as shallow as possible,
and located to maximize use of natural on-site infiltration features
while still meeting the other requirements of this article.
J.
Normally dry, open stormwater management facilities should completely
drain both the volume control and rate control capacities over a period
of time not less than 24 and not more than 72 hours from the end of
the design storm.
K.
The design storm precipitation to be used in the analysis of runoff
volume and peak rates of discharge shall be obtained from the latest
version of the Precipitation Frequency Estimates (NOAA Atlas 14),
National Oceanic and Atmospheric Administration (NOAA), National Weather
Service, Hydrometeorological Design Studies Center, Silver Spring,
Maryland.
L.
Rainfall precipitation data shall be used with a NOAA Type B rainfall
distribution for all stormwater management analyses.
A.
Regulated activities that result in cumulative earth disturbances less than 5,000 square feet and 500 square feet of impervious area are exempt from the requirements in §§ 343-29, 343-30 and subarticle IV of this article. This exemption shall not relieve the applicant from meeting the water quality requirements of 25 Pa. Code, Chapter 93, and antidegradation requirements of 25 Pa. Code, Chapter 102.
B.
Agricultural activities are exempt from the SWM site plan preparation
requirements of this article provided the activities are performed
according to the requirements of 25 Pa. Code, Chapter 102.
C.
Forest management and timber operations are exempt from the SWM site
plan preparation requirements of this article provided the activities
are performed according to the requirements of 25 Pa. Code, Chapter
102.
D.
Exemptions from any provisions of this article shall not relieve the applicant from the requirements in § 343-27D. through L.
E.
The municipality may deny or revoke any exemption pursuant to this
section at any time for any project that the municipality believes
may pose a threat to public health and safety or the environment.
The green infrastructure and low-impact development practices
provided in the Pennsylvania Stormwater Best Management Practices
Manual (BMP Manual) shall be utilized for all regulated activities
wherever feasible. Runoff volume control shall be implemented using
the Design Storm Method (CG-1) in Subsection A or the Simplified Method
(CG-2) in Subsection B below. For regulated activity areas less than
or equal to one acre that do not require hydrologic routing to design
the stormwater facilities, this article establishes no preference
for either methodology; therefore, the applicant may select either
methodology on the basis of economic considerations, the intrinsic
limitations on applicability of the analytical procedures associated
with each methodology and other factors.
A.
The Design Storm Method (CG-1) is applicable to any size of regulated
activity. This method requires detailed modeling based on site conditions.
(1)
Do not increase the post-development total runoff volume for all
storms equal to or less than the two-year, twenty-four-hour duration
precipitation.
(2)
For modeling purposes:
(a)
Existing (predevelopment) nonforested pervious areas must be
considered meadow in good condition or its equivalent except for repair,
reconstruction or restoration of roadways or rail lines, or construction,
repair, reconstruction or restoration of utility infrastructure when
the site will be returned to existing conditions.
(b)
When the existing project site contains impervious area, 20%
of the existing impervious area to be disturbed must be considered
meadow in good condition or better, except for repair, reconstruction
or restoration of roadways or rail lines, or construction, repair,
reconstruction, or restoration of utility infrastructure when the
site will be returned to existing condition.
B.
The Simplified Method (CG-2 in the BMP Manual) provided below is
independent of site conditions and should be used if the Design Storm
Method (CG-1) is not followed. This method is not applicable to regulated
activities greater than one acre in area or for projects that require
design of stormwater storage facilities. For new impervious surfaces:
(1)
Stormwater facilities shall capture at least the first two inches
of runoff from all new impervious surfaces.
(2)
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 the surface waters of this commonwealth. Removal
options include reuse, evaporation, transpiration, and infiltration.
(3)
Wherever possible, infiltration facilities should be designed to
accommodate infiltration of the entire permanently removed runoff;
however, in all cases, at least the first 0.5 inch of the permanently
removed runoff should be infiltrated.
A.
For areas not covered by a release rate map from an approved Act
167 Stormwater Management Plan:
(1)
Post-development discharge rates shall not exceed the pre-development
discharge rates for the one-, two-, five-, ten-, twenty-five-, fifty-,
and 100-year, twenty-four-hour storm events. If it is shown that the
peak rates of discharge indicated by the post-development analysis
are less than or equal to the peak rates of discharge indicated by
the predevelopment analysis for one-, two-, five-, ten-, twenty-five-,
fifty-, and 100-year, twenty-four-hour storms, then the requirements
of this section have been satisfied. Otherwise, the applicant shall
provide additional controls as necessary to satisfy the peak rate
of discharge requirement.
B.
For areas covered by a release rate map from an approved Act 167
Stormwater Management Plan:
(1)
For the one-, two-, five-, ten-, twenty-five-, fifty-, and 100-year,
twenty-four-hour storm events, the post-development peak discharge
rates will follow the applicable approved release rate maps. For any
areas not shown on the release rate maps, the post-development discharge
rates shall not exceed the predevelopment discharge rates.
A.
Storm drains shall be designed, at a minimum, using the ten-year
runoff event without surcharging inlets. Storm drains tributary to
a multiple site SWM facility or crossing other properties must convey,
at a minimum, the following runoff events based upon the classification
of municipal street:
B.
Any storm drain system within state or federal rights-of-way or that
falls under the design criteria of any higher authority must meet
the requirements of that agency in addition to the minimum requirements
of this article.
C.
The use of properly designed, graded and stabilized drainage channels
is encouraged in lieu of storm drains in commercial and industrial
areas and, where approved by the City of Lock Haven, in residential
areas. Such channels shall be designed not only to carry the required
discharge without excessive erosion, but also to increase the time
of concentration, reduce the peak discharge and velocity, and permit
the water to percolate into the soil, where possible.
D.
Storm drain conveyance system stability (swales, open channels, and
pipe discharge aprons) shall be computed using a ten-year return period
peak runoff rate.
E.
When evidence is available or an analysis indicates that the existing
municipal storm drain systems have sufficient capacity as determined
by hydrograph summation and are accessible, the applicant may connect
stormwater facilities to the existing municipal storm drain system
so long as the peak rate of discharge does not exceed the amount permitted
by this article and the connection is approved by the municipality.
F.
The maximum encroachment of runoff conveyed in a curbed section on
the roadway pavement shall not exceed half of a through traffic lane
or one inch less than the depth of curb during the ten-year design
storm of five-minute duration. Inlets shall be spaced and provided
to control the encroachment of water on the pavement to these limits.
G.
Runoff events in excess of the indicated design event must be conveyed
safely downstream. In cases where the project site does not have direct
access to surface waters to discharge stormwater runoff, the applicant
must have the legal authority to discharge stormwater onto off-site
areas and include an off-site discharge analysis. The applicant must
provide documentation that the discharge from the project site will
not cause accelerated erosion or increased flooding on the properties
along the flow path of the runoff to a surface water. Where deemed
necessary by the municipality, the applicant shall submit an analysis
of the impacts of detained stormwater flows on downstream areas within
the watershed. These impacts shall be identified with concurrence
from the engineer of the municipality. The analysis shall include
hydrologic and hydraulic calculations necessary to determine the impact
peak discharge modifications from the proposed development have on
critical locations such as dams, tributaries, existing developments,
undersized culverts, flood-prone areas, etc. The analysis shall include
the impact of the modified quantity of discharged water to developed
downstream areas that experience flooding. The applicant must demonstrate
that the additional flow does not adversely impact downstream properties
or structures and the limits of said flooded area are not increased
by the proposed activity. Any regulated activity that adversely impacts
downstream properties, structures, public facilities, threatens the
public health or safety shall be prohibited by the municipality.
A.
In order to protect and improve water quality, any applicant may
not conduct earth disturbance activities within 150 feet of a perennial
or intermittent river, stream, or creek, or lake, pond or reservoir
when the project site is located in an exceptional value (EV) or high
quality (HQ) watershed attaining its designated use as listed by DEP
at the time of application and shall protect or enhance any existing
riparian buffer in accordance with the requirements of 25 Pa. Code,
Chapter 102. No earth disturbance activities will be permitted in
the riparian buffer area, with the exception of the activities stated
in 25 Pa. Code, § 102.14.(d).
B.
Applicants proposing or conducting earth disturbance activities when
the activity requires a permit under 25 Pa. Code, Chapter 102, where
the project site is located in an exceptional value (EV) or high quality
(HQ) watershed where there are waters failing to attain one or more
designated uses as listed in Category 4 or 5 on Pennsylvania's
Integrated Water Quality Monitoring and Assessment report, as amended
and updated, at the time of the application, and the project site
contains, is along or within 150 feet of a perennial or intermittent
river, stream, or creek, lake, pond or reservoir shall do one of the
following in accordance with the requirements of 25 Pa. Code, Chapter
102:
C.
A riparian buffer easement shall be created and recorded as part
of any subdivision or land development that encompasses a riparian
buffer.
D.
Except as required by 25 Pa. Code, Chapter 102, the riparian buffer
easement shall be measured to be the greater of the limit of the 100-year
floodplain or 35 feet from the top of the stream bank on each side.
E.
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.
F.
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 as required by Zoning, unless otherwise specified in Chapter 410, Zoning.
G.
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.
I.
Septic drain fields and sewage disposal systems shall not be permitted
within the riparian buffer easement and shall comply with setback
requirements established under 25 Pa. Code, Chapter 73.
