[Ord. 441, 7/2/2012]
1.
For all regulated activities, unless preparation of an SWM site plan is specifically exempted in § 23-302:
2.
All SWM site plans for regulated activities shall include such measures
as necessary to:
A.
Protect health, safety, and property.
B.
Meet the water quality goals of this chapter, as stated in § 23-103, by including measures that:
(1)
Minimize disturbance to floodplains, wetlands, wooded areas,
and existing vegetation.
(2)
Maintain or extend riparian buffers.
(3)
Avoid erosive flow conditions in natural flow pathways.
(4)
Minimize thermal impacts to waters of the commonwealth.
(5)
Disconnect impervious surfaces by directing runoff to pervious
areas.
(6)
Minimize soil disturbance and compaction.
C.
Incorporate the techniques for low-impact development practices described
in the Pennsylvania Stormwater Best Management Practices Manual (BMP
Manual).
3.
Stormwater flows onto adjacent property shall not be created, increased,
relocated, or otherwise altered without the written notification of
the adjacent property owner(s) by the developer. Copies of all such
notifications shall be included in the SWM site plan submission.
4.
For all regulated activities where erosion and sediment control is
required in accordance with Title 25 of the Pennsylvania Code and
the Clean Streams Law, the SWM site plan shall include the required
erosion and sedimentation control measures. Necessary E&S BMPs
shall be designed in accordance with the Erosion and Sediment Pollution
Control Program Manual (E&S Manual) 2, No. 363-2134-008 (April
15, 2000), as amended and updated. Approval of the SWM site plan by
the Borough shall be conditioned on the applicant obtaining erosion
and sedimentation control approval from the appropriate agency(ies),
when applicable.
5.
For all regulated activities where NPDES permitting is required in
accordance with the Clean Water Act (33 U.S.C. § 1251 et
seq. [1972], as amended), the SWM site plan shall include the information
required in the applicant's NPDES permit application. Approval
of the SWM site plan by the Borough shall be conditioned on the applicant
obtaining NPDES permit approval from the appropriate agency(ies),
when applicable.
7.
Special Management Areas. SWM site plans involving regulated activities within special management areas shall be prepared in a manner consistent with the guidance provided in Chapter 7 of the BMP Manual. The SWM site plan submission shall include design details for SWM BMPs within said special management area.
8.
A SWM site plan may propose that stormwater related to the proposed
regulated activities be accommodated by existing stormwater management
facilities on adjoining or nearby properties, provided that the SWM
site plan documents the following:
A.
The use of the stormwater management facilities located on said adjoining
or nearby property is approved in writing by the owner of the property.
B.
The stormwater management facilities located on said adjoining or
nearby property are designed in a manner that can accommodate the
stormwater management needs of the regulated activity in a manner
consistent with all requirements of this chapter. The SWM site plan
shall include all documentation necessary for the Borough to confirm
such compliance.
9.
The design storm volumes to be used in the analysis of peak rates
of discharge shall be obtained from the Precipitation-Frequency Atlas
of the United States, Atlas 14, Volume 2, Version 3.0, as amended
and updated, United States Department of Commerce, National Oceanic
and Atmospheric Administration (NOAA), National Weather Service, Hydrometeorological
Design Studies Center, Silver Spring, Maryland. NOAA's Atlas
14 can be accessed at http://hdsc.nws.noaa.gov/hdsc/pfds/.
10.
SWM site plans, once approved by the Borough, shall remain on site
throughout the duration of the regulated activity and be available
for review as may be necessary by representatives of the Borough.
11.
The design of all facilities over karst shall include an evaluation
of measures to minimize adverse effects.
12.
The Borough 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. The Borough shall maintain a record of consultations
with DEP pursuant to this subsection.
[Ord. 441, 7/2/2012]
1.
A property owner or developer of any regulated activity that meets
the following exemption criteria is, upon approval from the Borough,
exempt from the formal SWM plan submission requirements of this chapter
as specified herein. However, the property owner or developer shall
be subject to all other requirements of this chapter other than the
formal SWM plan submission requirements for which an exemption or
exemptions have been authorized. The criteria for exemption in this
section apply to the total development proposed, including instances
in which the development is proposed to take place in phases. The
date of enactment of this chapter shall be the starting point from
which future development and the respective exemption criteria shall
be cumulatively considered and regulated.
A.
Regulated activities that involve equal to or less than 1,000 square
feet of impervious surface shall be exempted from the peak rate control,
volume control and the SWM site plan preparation and submission requirements
of this chapter. The applicant shall complete page 1 of the Municipal
Stormwater Management Worksheet from the Stormwater Management Design
Assistance Manual (see Plan Appendix C) and file said worksheet with
the Borough.
B.
Regulated activities that involve greater than 1,000 square feet and equal to or less than 5,000 square feet of impervious area, and where all the proposed impervious area can be entirely disconnected, may be exempted from the peak rate control requirements of this chapter. A SWM site plan shall be submitted to the Borough in accordance with Part 4 of this chapter. In addition, the applicant shall complete the Stormwater Management Worksheets from the Stormwater Management Design Assistance Manual (see Plan Appendix C) and file said worksheets with the Borough.
C.
Agricultural activities shall be exempt from the rate control, volume control and SWM site plan preparation and submission requirements of this chapter, provided that the agricultural activities are performed in accordance with the requirements of 25 Pa. Code Chapter 102. Further, such activities shall not be subject to the exemption approval process of § 23-302, Subsection 2, of this chapter.
D.
Forest management and timber operations are exempted from the rate
control, volume control and SWM site plan preparation and submission
requirements of this chapter, provided that the forest management
and timber operations are performed in accordance with the requirements
of 25 Pa. Code Chapter 102.
E.
Regulated activities involving domestic gardening for single-family consumption shall be exempted from volume control, rate control, and SWM site plan preparation and submission requirements of this chapter, and shall not be subject to the exemption approval process of § 23-302, Subsection 2, of this chapter.
F.
In-kind repair. In-kind replacement, and maintenance of existing surfaces, and structures shall be exempted from volume control, rate control, and SWM site plan preparation and submission requirements of this chapter and shall not be subject to the exemption approval process of § 23-302, Subsection 2, of this chapter.
2.
Authorization of exemptions. The Borough shall determine, in accordance
with the following requirements and process, whether a proposed regulated
activity may be exempted from any of the requirements of this chapter:
A.
The property owner or developer proposing the regulated activity shall submit, in writing on a form supplied by the Borough, a request for said proposed regulated activity to be exempted from allowable requirements of this chapter pursuant to Subsection 1. The written request shall identify the project and shall indicate the specific exemption criteria, as listed in § 23-302, Subsection 1, that apply to the project.
B.
Upon receipt of the exemption request form, the Borough Council or
its designee shall either approve or deny the exemption request. If
the exemption request is denied, the Borough Council or its designee
shall direct the property owner or developer to submit the information
required to demonstrate that the proposed regulated activity complies
with the requirements of this chapter or meets the exemption criteria.
C.
Exemption request approval shall be at the discretion of the Borough
and shall be subject to the following:
(1)
The Borough may deny any exemption request or suspend or revoke
any approved exemption request at any time for any project where the
Borough believes that the proposed regulated activity poses a threat
to public health, safety, property, or the environment.
(2)
Approval of an exemption request does not relieve the property
owner or developer from other applicable requirements of this chapter
or of other Borough ordinances or regulations.
(3)
The Borough reserves the right to deny an exemption request
if a drainage problem is known or identified by the Borough to exist
or is expected to exist downstream from the proposed regulated activity.
4.
The applicant must demonstrate that the following BMPs are being
utilized to the maximum extent practicable to receive consideration
for the exemptions:
A.
Design around and limit disturbance of floodplains, wetlands, natural
slopes over 15%, existing native vegetation, and other sensitive and
special value features.
B.
Maintain riparian and forested buffers.
C.
Limit grading and maintain nonerosive flow conditions in natural
flow paths.
D.
Maintain existing tree canopies near impervious areas.
E.
Minimize soil disturbance and reclaim disturbed areas with topsoil
and vegetation.
F.
Direct runoff to pervious areas.
5.
The applicant must demonstrate that the proposed development/additional
impervious area will not adversely impact the following:
[Ord. 441, 7/2/2012]
1.
Impervious Area.
A.
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 phases.
B.
For development taking place in phases, the total proposed impervious
area within the SWM site plan must be used in determining conformance
with this chapter.
C.
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 § 23-304 and the peak rate controls of § 23-305 do not need to be retrofitted to existing impervious areas that are not being altered by the proposed regulated activity.
2.
Normally dry, open-top storage facilities, designed as such, shall
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. However, any designed infiltration
volume at such facilities is exempt from the minimum twenty-four-hour
standard, i.e., may infiltrate in a shorter period of time, so long
as none of the stormwater intended for infiltration is discharged
into the surface waters of the commonwealth.
3.
Infiltration BMPs shall 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.
4.
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. The applicant must
provide an executed easement for newly concentrated flow across adjacent
properties.
5.
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.
6.
Where watercourses traverse a development site, drainage easements
(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 the mowing of vegetation
within the easement, may be required, except as approved by the appropriate
governing authority.
7.
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 located 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 through the joint permit application process or, where deemed
appropriate by PADEP, the general permit process.
8.
Any stormwater management facilities regulated by this chapter that
will be located on or discharged onto state highway rights-of-ways
shall be subject to approval by the Pennsylvania Department of Transportation
(PennDOT).
9.
Stormwater shall not be transferred from one watershed to another,
unless:
10.
Consideration shall be given to the relationship of the subject property
to the drainage pattern of the watershed. A concentrated discharge
of stormwater to an adjacent property shall be within an existing
watercourse or confined in an easement or returned to a pre-development
flow type condition.
11.
No outlet structure from a stormwater management facility, or swale,
shall discharge directly onto a Borough or state roadway, unless otherwise
approved by the Borough.
12.
Minimization of impervious surfaces and infiltration of runoff through
seepage beds, infiltration trenches, etc., are encouraged, where soil
conditions and geology permit, to reduce the size or eliminate the
need for detention facilities.
13.
Easements shall be established for all on-site stormwater management
or drainage facilities, including but not limited to detention facilities
(above or below the ground), infiltration facilities, all stormwater
BMPs, drainage swales, and drainage facilities (inlets, manholes,
pipes, etc.).
14.
Design guidance from the most current version of the Pennsylvania
Stormwater Best Management Practices Manual, or equivalent resource
as precoordinated with the Borough, shall be consulted when choosing
design criteria for infiltration/water quality BMPs.
[Ord. 441, 7/2/2012]
1.
The low-impact development practices provided in the BMP Manual shall be utilized for all regulated activities. Water volume controls shall be implemented using the Design Storm Method in § 23-304, Subsection 1A, or the Simplified Method in § 23-304, Subsection 1B. For regulated activity involving less than one acre of impervious coverage that does not require hydrologic routing to design the stormwater facilities, 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/or other factors. The Design Storm Method in § 23-304, Subsection 1A, shall be used for all regulated activity involving greater than one acre of impervious coverage.
A.
The Design Storm Method (CG-1 in the BMP Manual) may be used for
any size of regulated activity. This method requires detailed modeling
to achieve the following standards:
(1)
The post-development total runoff volume shall not increase
for all storms equal to or less than the two-year, twenty-four-hour-duration
precipitation.
B.
The Simplified Method (CG-2 in the BMP Manual) is independent of
site conditions and may be used for projects involving regulated activities
proposing equal to or less than one acre of impervious coverage and
that do not require design of stormwater storage facilities. When
the Simplified Method is used to address stormwater management needs
of new impervious surfaces, the following design standards shall be
achieved:
(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 and shall not be
released into the surface waters of the commonwealth. Removal options
for the first one inch of runoff include, but are not necessarily
limited to, reuse and infiltration.
(3)
Infiltration facilities shall be designed to accommodate infiltration of as much of the permanently removed runoff as site conditions will allow. If the soils within the project area do not allow for infiltration of the entire first one inch of runoff from new impervious surfaces, other forms of runoff volume control shall be used to achieve the required removal volume. Such measures may include, but are not limited to, vegetated roofs, biorention, and capture-and-reuse systems. In addition, the Infiltration Alternative authorized in § 23-304, Subsection 1C, may be employed.
C.
Infiltration Alternative. Where infiltration is not possible due to soil characteristics or is not desirable given other characteristics, water quality control may be proposed as an alternative to strict adherence to the volume control standards of § 23-304 of this chapter. Where water quality control is proposed, the following standards shall be achieved:
(1)
At a minimum, the following documentation shall be provided
to justify the proposal to reduce the infiltration requirements:
(a)
Description of and justification for field infiltration/permeability
testing with respect to the type of test and test locations.
(b)
An interpretive narrative describing existing soils of the site
and their structure as these relate to the interaction between soils
and water characteristics of the site. In addition to providing soil
and soil profile descriptions, this narrative shall identify depth
to seasonal water tables and depth to bedrock and provide a description
of all subsurface elements (restrictive layers, geology, etc.) that
influence the direction and rate of subsurface water movement.
(c)
A qualitative assessment of the site's contribution to
annual aquifer recharge shall be made, along with the identification
of any restrictions or limitations associated with the use of designed
infiltration facilities.
(d)
The provided documentation must be signed and sealed by a professional
engineer or geologist.
(2)
Water quality BMPs shall be implemented on all permanent stormwater
discharges from the proposed project site to achieve pollutant removal
efficiencies in accordance with the Table 304.1.
|
Table 304.1 Required Pollutant Removal Efficiencies for
Infiltration Alternatives
| |||
|---|---|---|---|
|
Pollutant Load
|
Units
|
Required Removal Efficiency
(%)
| |
|
Total suspended solids (TSS)
|
Pounds
|
85%
| |
|
Total phosphorus (TP)
|
Pounds
|
85%
| |
|
Total nitrate (NO3)
|
Pounds
|
50%
| |
(3)
Design guidance from the most current version of the Pennsylvania
Stormwater Best Management Practices Manual, or equivalent resource
as pre-coordinated with the Borough, shall be consulted when choosing
design criteria for water quality BMPs.
[Ord. 441, 7/2/2012]
1.
Post-development discharge rates shall not exceed the pre-development
discharge rates for the one-, two-, five-, ten-, twenty-five-, fifty-,
and one-hundred-year, twenty-four-hour storms. 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 pre-development analysis for one-, two-, five-, ten-, twenty-five-,
fifty-, and one-hundred-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.
2.
For computation of pre-development peak discharge rates, 20% of existing
impervious areas, when present, shall be considered meadow.
[Ord. 441, 7/2/2012]
Where an applicant proposes to utilize riparian buffers as the
means to meet the requirements of this chapter, said riparian buffers
shall be established and/or maintained in accordance with the BMP
Manual or the publication Riparian Forest Buffer Guidance, published
November 2010, by the Pennsylvania Department of Environmental Protection,
and as may be amended or updated.
[Ord. 441, 7/2/2012]
1.
Any drain or conveyance, whether on the surface or subsurface, that
allows any nonstormwater discharge including sewage, process wastewater,
and wash water to enter the waters of the commonwealth is prohibited.
3.
The following discharges are authorized unless they are determined
to be significant contributors to pollution to the waters of the commonwealth:
A.
Discharges from firefighting activities.
B.
Potable water sources, including waterline flushing.
C.
Irrigation drainage.
D.
Air-conditioning condensate.
E.
Springs.
F.
Water from crawl space pumps.
G.
Pavement wash waters where spills or leaks of toxic or hazardous
materials have not occurred (unless all spill materials have been
removed) and where detergents are not used.
H.
Diverted stream flows.
I.
Flows from riparian habitats and wetlands.
J.
Uncontaminated water from foundations or from footing drains.
K.
Lawn watering.
L.
Dechlorinated swimming pool discharges.
M.
Uncontaminated groundwater.
N.
Water from individual residential car washing.
O.
Routine external building wash-down (which does not use detergents
or other compounds).
P.
Water discharged in well testing for potable water supplies.
[Ord. 441, 7/2/2012]
Roof drains, sump pumps, and footer drains should discharge
to infiltration or vegetative BMPs unless otherwise approved by the
Borough and, to the maximum extent practicable, satisfy the criteria
for DIAs. Discharges of each should be conveyed in such a manner as
to not cause water problems for adjoining property owners.
[Ord. 441, 7/2/2012]
No person shall modify, remove, fill, landscape, or alter any
SWM BMPs, facilities, areas, or structures in any manner, without
the written approval of the Borough, with the exception of necessary
maintenance activities such as mowing.
[Ord. 441, 7/2/2012]
1.
Stormwater runoff from all development sites shall be calculated
using either the Rational Method or a soil cover complex methodology.
Methods shall be selected by the qualified professional based on the
individual limitations and suitability of each method for a particular
site.
2.
Peak Flow Rates:
A.
Rational Method: May be used for drainage areas up to 20 acres. Extreme
caution should be used by the qualified professional if the watershed
has more than one main drainage channel, if the watershed is divided
so that hydrologic properties are significantly different in one versus
the other, if the time of concentration exceeds 60 minutes, or if
stormwater runoff volume is an important factor.
B.
Soil Cover Complex Method: May be used for drainage areas greater
than 20 acres. This method is recommended for design of stormwater
management facilities and where stormwater runoff volume must be taken
into consideration.
3.
Rainfall Values:
A.
Rational Method: The Pennsylvania Department of Transportation Drainage
Manual, Intensity-Duration-Frequency Curves, Publication 584, Chapter
7A, latest edition, shall be used in conjunction with the appropriate
time of concentration and return period.
B.
Soil Cover Complex Method: The Soil Conservation Service Type II,
twenty-four-hour rainfall distribution shall be used in conjunction
with rainfall depths from NOAA Atlas 14.
4.
Time of concentration shall be computed using the NRCS Segmental
Method as described in TR-55 (SCS 1986 or most current update). The
length of sheet flow shall be limited to 100 feet. The Manning's
"n" Roughness Coefficient from TR-55 shall be used for sheet flow.
Time of concentration for channel and pipe flow shall be computed
using Manning's Equation.
[Ord. 441, 7/2/2012]
1.
Any stormwater management facility designed to store runoff and requiring
a berm or earthen embankment shall be designed to provide an emergency
spillway to handle peak rate of stormwater runoff up to and including
the one-hundred-year post-development flow, with a blocked primary
outlet structure. The height of embankment must be set as to provide
a minimum one foot of freeboard through the spillway, above the maximum
water surface elevation, computed when the spillway functions for
the one-hundred-year post-development inflow, with a blocked outlet
structure. The primary outflow structure must be designed to pass
all design storms (up to and including the one-hundred-year event)
without discharging through the emergency spillway. The maximum water
depth within any stormwater management facility shall be no greater
than eight feet when functioning through the primary outlet structure.
2.
A stormwater management facility berm cross sections must be at least
five feet wide at the top and eight feet wide through the emergency
spillway. For fill embankments, the side slopes shall be no steeper
than 3:1.
3.
A cutoff and key trench of impervious material shall be provided
under all embankments four feet or greater in height.
4.
Trash racks must be provided to prevent clogging of primary outflow
structure stages for all orifices equivalent to 12 inches or smaller
in diameter.
5.
Any stormwater management facility may be required to be fenced with
a minimum four-foot-high fence of material acceptable to the Borough.
Gates with a minimum opening of 10 feet shall be provided for access.
6.
Exceptions to these requirements may be made at the discretion of
the Borough for BMPs that retain or detain water but are of a much
smaller scale than traditional stormwater management facilities.
[Ord. 441, 7/2/2012]
1.
Storm sewers must be able to convey post-development runoff from
a ten-year design storm without surcharging inlets where appropriate.
When connecting to an existing storm sewer system, the applicant must
demonstrate that the proposed system will not exacerbate any existing
stormwater problems and that adequate downstream capacity exists.
2.
A minimum pipe size of 15 inches in diameter shall be used in all
roadway systems (public or private) proposed for construction. Pipes
shall be designed to provide a minimum velocity of 2 1/2 feet
per second when flowing full, but in all cases, the slope shall be
no less than 1/2%. Arch pipe of equivalent cross-sectional area may
be substituted in lieu of circular pipe where cover or utility conflict
conditions exist.
3.
Inlets, manholes, pipes, and culverts shall be constructed in accordance
with the specifications set forth in PennDOT's Publication 408,
latest edition, and as detailed in the PennDOT Publication 72M, Standards
for Roadway Construction (RC), latest edition, or as approved by the
Borough Engineer. All material and construction details (inlets, manholes,
pipe trenches, etc.) must be shown on the SWM site plan, and a note
added that all construction must be in accordance with PennDOT's
Publication 408 and PennDOT's Publication 72M, latest editions.
4.
Accessible drainage structures shall be located on continuous storm
sewer system at all vertical dislocations, at all locations where
a transition in storm sewer pipe sizing is required, at all vertical
and horizontal angle points exceeding five degrees and at all points
of convergence of two or more storm sewer pipes.
5.
All storm drainage piping discharging to the ground surface shall
be provided with either reinforced concrete headwalls and end sections
or plastic and metal end sections compatible with the pipe size involved
in accordance with PennDOT Publication 408 and Publication 72M.
6.
Outlet protection shall be provided at all surface discharge points
with storm drainage piping.
7.
Swales must be able to convey post-development runoff from a ten-year
design storm with six inches of freeboard to top of the swale.
8.
Swales shall have side slopes no steeper than 3:1.
