A. 
The following requirements shall apply to all regulated activities, unless preparation of an SWM site plan is specifically exempted in § 177-12:
(1) 
Preparation and implementation of an approved SWM site plan is required.
(2) 
No regulated activities shall commence until the Borough issues written approval of an SWM site plan, which demonstrates compliance with the requirements of this chapter.
(3) 
The Borough shall be notified of construction operations prior to commencement so that an inspection can be completed.
(4) 
After the installation of stormwater management facility, the overseeing professional engineer (design engineer) should submit a letter indicating that the facility was installed per the approved plan.
B. 
SWM site plans approved by the Borough, in accordance with § 177-22, shall be on site throughout the duration of the regulated activity.
C. 
These standards apply to the landowner and any person engaged in regulated activities.
D. 
Stormwater drainage systems shall be provided in order to permit unimpeded flow along natural watercourses, except as modified by SWM BMPs or open channels consistent with this chapter.
E. 
If diffused flow is proposed to be concentrated and discharged onto adjacent property with permission from the receiving property owner, the developer 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 and downstream easements shall be established to provide drainage paths for concentrated discharge. Maximum use shall be made of the existing on-site natural and man-made stormwater management facilities.
F. 
A concentrated discharge of stormwater to an adjacent property shall be within an existing watercourse or otherwise an easement shall be required. Pipe outlets shall also be provided with erosion-resistant material or energy dissipaters to calm the anticipated velocity and discharge of stormwater.
G. 
Discharge points from any facility must be 15 feet from any property line with adequate BMPs to ensure no channelizing of flows onto neighboring property.
H. 
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.[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, as amended and updated.
[1]
Editor's Note: See 35 P.S. § 691.1 et seq.
I. 
Impervious areas shall be subject to the following standards:
(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 § 177-14 and the peak rate controls of § 177-15 do not need to be retrofitted to existing impervious areas that are not being altered by the proposed regulated activity.
(4) 
Stormwater flows onto adjacent or downstream property shall not be created, increased, decreased, relocated, impeded, or otherwise altered without written notification of the affected property owner(s). Notification shall include a description of the proposed development and the stormwater flows that are being created, increased, decreased, relocated, impeded, or otherwise altered. Adjacent property shall, at a minimum, include any property having a shared boundary with the subject property of the SWM site plan; however, if in the judgement of the designated plan reviewer additional properties are being affected, additional notifications may be required. Proof of notification shall be included as part of the SWM plan submission to the Borough. Such stormwater flows shall be subject to the requirements of this chapter.
J. 
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). 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, acceptable to the designated plan reviewer, demonstrating that the use of LID and green infrastructure is not practicable.
K. 
Infiltration BMPs should be dispersed throughout the project site at strategic locations, 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 and not more than 72 hours from the end of the design storm.
M. 
The design storm precipitation depths to be used in the analysis of peak rates of discharge shall be as obtained in PennDOT's Drainage Manual, Publication 584, Appendix 7A; or 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.
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[2] and the Storm Water Management Act.
[2]
Editor's Note: See 35 P.S. § 691.1 et seq.
O. 
Various BMPs and their design standards are listed in the BMP Manual.
P. 
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.
Q. 
Stormwater management facilities which involve a state highway shall be subject to the approval of PennDOT.
R. 
Stormwater management facilities which involve a county highway or a county facility shall be subject to the approval of Allegheny County.
S. 
Minimization of impervious surfaces and maximization of infiltration of runoff through seepage beds, infiltration trenches, etc., are encouraged, where soil conditions permit, to reduce the size or eliminate the need for detention facilities.
T. 
Where a development site is traversed by watercourses other than permanent streams, 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. Also, maintenance, including mowing of vegetation within the easement, shall be required, except as approved by the appropriate governing authority.
U. 
The Pa. Code, Title 25, Chapter 105, Rules and Regulations, apply to the construction, modification, operation or maintenance of both existing and proposed water obstructions and encroachments throughout the watershed, including work in wetlands. Inquiries on permit requirements or other concerns shall be addressed to the DEP, Bureau of Waterways Engineering and Wetlands, in Harrisburg.
V. 
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 DEP through the joint permit application process or, where deemed appropriate by DEP, through the general permit process.
W. 
Stormwater resulting from regulated activities shall not be discharged into sinkholes.
X. 
To the maximum extent practicable, incorporate the techniques for low-impact development practices described in the BMP Manual.
A. 
Regulated activities that result in cumulative earth disturbances less than one acre, as well as proposed impervious area less than 4,000 square feet, are exempt from the requirements in § 177-17, except as provided below.
B. 
Earth disturbances between 0.25 acre (10,890 square feet) and one acre of earth disturbance, as well as proposed impervious area between 750 square feet and 4,000 square feet, must submit a SWM site plan to the Borough which shall consist of the items and related supportive material needed to determine compliance with § 177-13.
C. 
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.
D. 
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.
E. 
Roadway resurfacing and maintenance projects which do not increase impervious area and underground infrastructure projects are exempt from the provisions of this chapter, provided the activities meet the requirements of all other municipal, state and federal requirements. Exemptions from any provisions of this chapter shall not relieve the applicant from the requirements in § 177-11C through § 177-13N.
F. 
The Borough may deny or revoke any exemption pursuant to this section at any time for any project that the Borough believes may pose a threat to public health and safety or the environment.
G. 
Voluntary green stormwater infrastructure (GSI) retrofit projects that are solely intended to better manage runoff from existing development and are not part of new development or redevelopment are exempt from the stormwater management provisions of this chapter. This does not exempt such projects from any other municipal, state, or federal regulation.
A. 
Projects proposing less than 750 square feet of additional impervious area are exempt from any stormwater management plan.
B. 
Projects proposing greater than 750 square feet but less than 4,000 square feet of additional impervious area must submit the following stormwater management information to the Borough:
(1) 
Brief description of the proposed project, including proposed stormwater management facilities, including types of materials to be used, and an approximation of the square footage of additional impervious areas.
(2) 
Sketch plan showing location of proposed improvements and stormwater management facilities in relation to the property lines and existing structures, septic systems and/or water wells, and roadways.
(3) 
Supporting runoff volume calculations and stormwater BMP sizing calculations, as requested.
C. 
Capture and detention can be accomplished by a variety of methods, including, but not limited to:
(1) 
Rain barrels.
(2) 
Rain gardens.
(3) 
Stone sumps or infiltration trenches filled with clean AASHTO No. 3 stone and 40% void space.
(4) 
A combination of the above methods.
(5) 
Other methods as approved by Borough staff.
D. 
In all cases, the detention method shall be designed to drain all accumulated runoff not less than 24 hours and not more than 72 hours after the end of the storm event. Appropriate soil percolation conditions must be available for stone sumps and rain gardens and must be demonstrated by percolation tests.
E. 
A maintenance agreement must be signed by the property owner to ensure the proper continual inspection and maintenance of the capture and detention method.
F. 
The property owner shall submit the following stormwater management information for review by the Borough staff:
(1) 
A written description of the proposed project, including the dimensions of all proposed impervious surfaces.
(2) 
A scale drawing showing existing and proposed features of the property.
(3) 
A written description of the proposed stormwater management methods.
(4) 
Dimensioned drawings of the proposed stormwater management methods and their locations.
(5) 
A list of proposed impervious surfaces and their square footage.
(6) 
Supporting documentation, such as assumptions, calculations, rain barrel size, stone size, percolation tests, etc.
(7) 
Draft operation and maintenance agreement.
(8) 
Construction of the proposed improvements shall not begin prior to receiving approval of the stormwater management plan from the Borough.
A. 
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 or the Simplified Method, or alternative design criteria as allowed by Pa. Code Title 25, Chapter 102.
B. 
The Design Storm Method (CG-1 in the BMP Manual) is applicable as a method to any size of regulated activity. This method requires detailed modeling based on site conditions. The following shall be incorporated into the CG-1 method:
(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) 
At least the first one inch of runoff from the net increase in 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. If the developer provides justification that the listed removal options are not feasible, and the designated plan reviewer agrees, runoff shall be detained in a facility designed for a twenty-four- to seventy-two-hour dewatering time in an area with a dedicated stormwater system and shall be detained in a facility designed for a seventy-two-hour dewatering time in an area contributory to a combined sewer system before discharge to local stormwater systems or the environment.
(3) 
For modeling purposes:
(a) 
Existing predevelopment nonforested pervious areas must be considered meadow in good condition.
(b) 
20% of existing impervious area, when present, shall be considered meadow in good condition in the model for existing conditions.
C. 
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 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:
(1) 
Stormwater facilities shall capture at least the first two inches of runoff from the net increase in impervious surfaces.
(2) 
At least the first one inch of runoff from the net increase in 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. If the developer provides justification that the listed removal options are not feasible, and the designated plan reviewer agrees, runoff shall be detained in a facility designed for a twenty-four-hour dewatering time in an area with a dedicated stormwater system and shall be detained in a facility designed for a seventy-two-hour dewatering time in an area contributory to a combined sewer system before discharge to local stormwater systems or the environment.
(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.
(4) 
This method is exempt from the requirements of § 177-15.
A. 
For areas not covered by a release rate map from an approved Act 167 Stormwater Management Plan, 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. This is the equivalent to a 100% release rate area when compared to those rates shown in the maps contained in Appendix A. This predevelopment to post-development control is not to be misconstrued as the same as the "conditional direct discharge" areas on the release rate maps. 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. Peak flows should be computed using the methods included in the chapter titled "Stormwater Calculations and Methodology" of the PADEP Stormwater Management BMP Manual.
B. 
For areas covered by a release rate map from an approved Act 167 Stormwater Management Plan, 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. These maps are contained in Appendix A of this chapter.[1] For any areas not shown on the release rate maps, the post-development discharge rates shall not exceed the predevelopment discharge rates for the specified design events. Peak flows should be computed using the methods included in Chapter 8 of the PADEP Stormwater Management BMP Manual.
[1]
Editor's Note: Said maps are on file in the Borough offices.
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. The intent of this chapter in establishing a riparian buffer is to protect and improve stream water quality. The riparian buffer is intended to slow overland flow to the stream through the presence of native grasses, trees and shrubs, allowing infiltration/groundwater recharge; causing deposition of sediment, nutrients, pesticides, and other pollutants in the buffer rather than in the stream; and reducing erosion by providing stream bank stabilization. The trees provide shade for streams, which keeps waters cooler and reduces evaporation.
B. 
Except as required by Pa. Code Title 25, Chapter 102, the riparian buffer easement shall be required for all streams with a contributing watershed area of greater than 10 acres. The riparian buffer easement shall be measured to be a minimum of 35 feet from the top of the streambank on each side.
C. 
Riparian buffers shall be subject to the following minimum management requirements.
(1) 
No use or construction within the riparian buffer shall be permitted that is inconsistent with the intent of the riparian buffer as described in § 177-16A.
(2) 
Existing native vegetation shall be protected and maintained within the riparian buffer easement.
(3) 
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 Borough and shall be recorded with the County of Allegheny 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 required by Zoning, unless otherwise specified in the municipal Zoning Ordinance.
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.
F. 
Stormwater drainage pipes shall be permitted within the riparian buffer easement, but they shall cross the easement in the shortest practical distance. Other structural stormwater management facilities are not permitted within the riparian buffer easement.
G. 
The following conditions shall apply when public and/or private recreation trails are permitted by the Borough within riparian buffers:
(1) 
It is preferred that trails be designed to be permeable and for nonmotorized use only; however, impermeable trails are permitted provided they have adequate drainage.
(2) 
Trails shall be designed to have the least impact on native plant species and other sensitive environmental features.
H. 
Septic drainfields 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.
I. 
Underground utilities shall be permitted within the riparian buffer easement; however, work shall be performed to minimize disturbance area and removal of trees. Restoration within the riparian buffer easement shall be with native species of trees, grasses, and other plantings. One tree shall be planted for each tree removed and the restoration shall be designed by a Registered Professional with the requisite experience. Aboveground utilities shall only be permitted to cross the easement perpendicular to the easement or in the shortest practical distance. Existing utilities may remain and be maintained as required.
J. 
Public streets and private streets shall be permitted within the riparian buffer easement; however, work shall be performed to minimize disturbance area and removal of trees. The disturbed area shall require an offset riparian buffer at a 1:1 ratio with native species of trees, grasses, and other plantings. One tree shall be planted for each tree removed, and the restoration shall be designed by a registered professional with the requisite experience. Public streets and private streets shall only be permitted to cross the easement perpendicular to the easement or in the shortest practical distance.