A.
The following provisions shall be considered the overriding performance
standards against which all proposed stormwater control measures shall
be evaluated and shall apply throughout the Township of White.
B.
Any landowner and any person engaged in the alteration or development
of land which may affect stormwater runoff characteristics shall implement
such measures as are reasonably necessary to prevent injury to health,
safety, or other property. Such measures shall include such actions
as are required:
(1)
To assure that the maximum rate of stormwater runoff is no greater
after development than prior to development activities. Development
activities will be considered any activity that has occurred after
the effective date of the original White Township Stormwater Management
Ordinance;
(2)
To manage the quantity, velocity, and direction of resulting stormwater
runoff in a manner which otherwise adequately protects health and
property from possible injury;
(3)
To meet any and all requirements of the NPDES permit; and
(4)
To provide stormwater BMPs to control the volume of stormwater being
generated by the development. The stormwater BMPs are an integral
part of the stormwater management plan.
C.
For all regulated activities, unless preparation of an SWM site plan is specifically exempted in § 263-14.
D.
SWM site plans approved by the Township, in accordance with § 263-24, shall be on site throughout the duration of the regulated activity.
E.
The Township may, after consultation with DEP, 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.[1]
[1]
Editor's Note: See 35 P.S. § 691.1 et seq.
F.
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 and the Clean
Streams Law. Various BMPs and their design standards are listed in
the Erosion and Sediment Pollution Control Program Manual (E&S
Manual[2]), No. 363-2134-008, as amended and updated.
G.
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 chapter.
(3)
For projects that add impervious area to a parcel, the total impervious area on the parcel is subject to the requirements of this chapter; except that the volume controls in § 263-15 and the peak rate controls of § 263-16 do not need to be retrofitted to existing impervious areas that are not being altered by the proposed regulated activity.
H.
Stormwater flows onto adjacent property shall not be created, increased,
decreased, relocated, or otherwise altered without written notification
to the adjacent property owner(s). Such stormwater flows shall be
subject to the requirements of this chapter.
I.
All regulated activities shall include such measures as necessary
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, 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 this commonwealth.
(e)
Disconnect impervious surfaces by directing runoff to pervious
areas, wherever possible.
(3)
Incorporate methods described in the Pennsylvania Stormwater Best
Management Practices Manual (BMP Manual[3]). If methods other than green infrastructure and LID methods
are proposed to achieve the volume and rate controls required under
this chapter, the SWM site plan must include a detailed justification
demonstrating that the use of LID and green infrastructure is not
practicable.
J.
The design of all facilities over karst shall include an evaluation
of measures to minimize adverse effects.
K.
Infiltration BMPs should be spread out, 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.
L.
Normally dry, open top, storage facilities should completely drain
both the volume control and rate control capacities over a period
of time not less than 24 hours and not more than 72 hours from the
end of the design storm.
M.
The design storm volumes to be used in the analysis of peak rates
of discharge should be obtained from the latest version of the Precipitation-Frequency
Atlas of the United States, National Oceanic and Atmospheric Administration
(NOAA), National Weather Service, Hydrometeorological Design Studies
Center, Silver Spring, Maryland. NOAA's Atlas 145 can be accessed
at: http://hdsc.nws.noaa.gov/hdsc/pfds/.
N.
For all regulated activities, SWM BMPs shall be designed, 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, the Clean Streams Law, and the Storm Water Management Act.[4]
[4]
Editor's Note: See 32 P.S. § 680.1 et seq.
O.
Various BMPs and their design standards are listed in the BMP Manual.
B.
Agricultural activity is exempt from the SWM site plan preparation
requirements of this chapter 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 chapter provided the activities
are performed according to the requirements of 25 Pa. Code Chapter
102.
D.
Exemptions from any provisions of this chapter shall not relieve the applicant from the requirements in § 263-15D through N.
E.
The Township may deny or revoke any exemption pursuant to this section
at any time for any project that the Township believes may pose a
threat to public health and safety or the environment.
B.
Infiltration practices shall be used to the extent practicable to
reduce volume increases and promote groundwater recharge. A combination
of successive practices may be used to achieve the applicable minimum
control requirements. Design calculations must be provided for all
stormwater facilities, including detention ponds, BMPs, ditches, swales,
inlets, pipes, culverts, etc. All BMPs must be shown on the recorded
plan.
C.
Required BMPs (for all developments not qualifying for water quality
volume retention). A minimum of 80% of the ten-year, twenty-four-hour
storm runoff volume must be treated by stormwater BMPs. All stormwater
management plans must include a minimum of two of the following BMPs
with the plan:
D.
Other BMPs may be used as approved by the municipal engineer.
F.
Water quality volume retention.
(1)
Water quality volume retention will be the calculated volume of stormwater
runoff from impervious or semi-impervious areas which is required
to be captured and mitigated through various BMPs.
(2)
This may be achieved through the use of structural or nonstructural
BMPs.
(3)
The water quality volume is the difference in stormwater runoff volume
between the predevelopment conditions and the post-development conditions
as calculated for the two-year storm event.
(4)
All impervious areas must drain to a stormwater BMP.
G.
The green infrastructure and low-impact development practices provided in the BMP Manual shall be utilized for all regulated activities wherever possible. Water volume controls shall be implemented using the Design Storm Method in Subsection G(1) or the Simplified Method in Subsection G(2) below.
(1)
The Design Storm Method (CG-1 in the BMP Manual[1]) is applicable to any size of regulated activity. This
method requires detailed modeling based on site conditions.
(a)
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.
(b)
For modeling purposes:
[1]
Existing (predevelopment) nonforested pervious areas must be
considered meadow in good condition.
[2]
20% of existing impervious area, when present, shall be considered
meadow in good condition in the model for existing conditions. If
constructing facilities to accommodate the resulting volume requirement
is believed by the developer to be unfeasible on site, the developer
may submit a modification request along with technical support documentation
for review by the Township. The Township may grant a modification
to alternatively construct off-site volume controls providing that
the alternative site is located within the same subwatershed as the
project site and the peak discharge rates downstream of the project
site are not increased above predevelopment magnitudes. The developer
shall consider on-site facilities to the maximum extent practicable
before considering off-site alternatives.
[3]
Design and construction of the off-site controls shall be subject
to review and approval by the Township. Costs shall be the responsibility
of the developer. Design documentation shall demonstrate that the
proposed facilities are effective in removing an amount equal to the
project's increase in the two-year storm volume from the overall
runoff where the facility is to be located.
[4]
In lieu of construction of off-site controls, the developer
may request and the Township may accept payment into the Township
stormwater fund. The cost shall be based upon the Township's
current fee schedule (adjusted annually) based upon an established
cost per cubic foot of storage.
(2)
The Simplified Method (CG-2 in the BMP Manual[2]) provided below 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 or
for projects that require design of stormwater storage facilities.
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 the surface waters of this 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 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 predevelopment
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 met. 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.
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 contains a riparian buffer.
B.
Except as required by 25 PaChapter 102, the Riparian Buffer Easement
shall be measured to be the greater of the limit of the 100-year floodplain
or a minimum of 50 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 Township
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 the municipal Subdivision and Land Development
Ordinance.[1]
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.
G.
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.
A.
The purpose of these criteria is to provide post-construction requirements
for redevelopment projects. The intent of these criteria is to improve
stormwater runoff and drainage patterns on existing properties while
encouraging redevelopment and urban renewal. Since these properties
would have been developed under a previous version of this chapter,
and in some cases, even previous to any related ordinance, the predevelopment
condition to be used for the new stormwater management plan and related
calculations shall be the condition of the property previous to the
existing development occurring.
B.
When redevelopment occurs, an additional opportunity exists to receive
credit toward the existing White Township Municipal Authority stormwater
management system user fee, established under Resolution No. MA-2-15,
dated December 21, 2015. A developer shall work with the White Township
municipal engineer or other designated staff to determine the level
of credit, where applicable. Please refer to the White Township Appeal
and Credit Manual for Stormwater Fees for more details about this
policy.
C.
When a development qualifies as a redevelopment project, the existing
stormwater facilities (if any) may be used provided they meet the
requirements of this chapter.
D.
If the existing stormwater facilities are in place, a report detailing
the condition of the infrastructure to be used is required. This report
must be signed and sealed by a professional engineer licensed in Pennsylvania.
E.
The developer shall make all necessary repairs or modifications to
the existing facilities as detailed in the engineer's report.
F.
If no or insufficient stormwater facilities exist at the time of the proposed redevelopment, the developer shall submit a plan that meets the requirements of this chapter for the entirety of the development and that falls into accord with the criteria established in § 263-5 and the subsequent requirements of this chapter.
G.
Additionally, land development that qualifies as redevelopment shall
meet at least one of the following criteria:
(1)
Reduce impervious cover. Reduce existing site impervious cover by
at least 20%.
(2)
Provide treatment. Provide water quality treatment for at least 20%
of the site's predevelopment impervious cover and 100% of any
new impervious cover, not to exceed 150% of the total new impervious.
(3)
Apply innovative approaches. Utilize innovative approaches to reduce
stormwater impacts across the site. Examples include green roofs and
pervious parking materials.
(4)
Provide off-site treatment. Provide equivalent stormwater treatment
at an off-site facility within the same watershed and as immediately
downstream of the site as feasible.
(5)
Address downstream issues. Address downstream channel and flooding
issues through channel restoration, increase in existing system capacity
and/or other off-site remedies.
(6)
Combination of measures. Any combination of (1) through (5) above
that is acceptable to White Township.
