All stormwater management system designs, plans and/or construction shall be subject to the following general requirements:
A. 
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.
B. 
The existing points of concentrated drainage that discharge onto adjacent property shall not be relocated and shall be subject to any applicable discharge criteria specified in this chapter.
C. 
Diffused drainage or flow.
(1) 
Areas of existing diffused drainage discharge shall be subject to any applicable discharge criteria in the general direction of existing discharge, whether proposed to be concentrated or maintained as diffused drainage areas.
(2) 
If diffused flow is proposed to be concentrated and discharged onto adjacent property, 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.
D. 
Where a development site is traversed by watercourses other than permanent streams, a drainage easement shall be provided conforming substantially 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 affect adversely the flow of stormwater within any portion of the easement. Also, maintenance and mowing of vegetation within the easement shall be required.
E. 
Any stormwater management facilities regulated by this chapter that would be located on state highway rights-of-way shall be subject to approval by the Pennsylvania Department of Transportation (PennDOT).
F. 
The Pennsylvania Department of Environmental Resources (DER), Chapter 105, Rules and Regulations, apply to the construction, modification, operation or maintenance of both existing and proposed dams, water obstructions and encroachments throughout the watershed, including work in wetlands. Inquiries on permit requirements or other concerns should be addressed to the Northcentral Regional Office, 200 Pine Street, Williamsport, Pennsylvania 17701.
A. 
General. The following general standards shall be applied to all development within Sayre Borough to promote flow attenuation, erosion and sediment control and flood control:
(1) 
All site development creating 10,000 square feet or more of impervious cover shall require submission of a drainage plan to Sayre Borough for review. This criteria shall apply to the total proposed development even if development is to take place in stages. Impervious cover shall include but not be limited to any roof, parking or driveway areas and any new streets and sidewalks. Any areas designed to initially be gravel or crushed stone shall be assumed to be impervious for the purposes of comparison to the waive criteria.
(2) 
Runoff from impervious areas must be drained to pervious areas of the property.
(3) 
Stormwater shall not be discharged into sanitary sewers. Stormwater from roof drains and from other impervious surfaces may be connected into storm sewers or drainage structures of the borough, provided that a drainage plan has been submitted and approved in accordance with this chapter and an appropriate permit has been issued by the borough.
[Amended 2-19-1996 by Ord. No. 746]
(4) 
Runoff from a site should not be concentrated or increased runoff discharged onto adjacent property without the written consent of the adjacent landowners.
B. 
Detention/infiltration standards.
(1) 
Postdevelopment rates of runoff from any regulated activity shall not exceed the peak rates of runoff prior to development for the one-, two-, five- and ten-year design storms.
(2) 
Minimization of impervious surfaces and 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.
A. 
Any stormwater facility located on state highway rights-of-way shall be subject to approval by the Pennsylvania Department of Transportation.
B. 
Any stormwater management facility required or regulated by this chapter shall be designed to provide an emergency spillway to handle flow up to the one-hundred-year postdevelopment conditions. The height of the embankment must be set as to provide a minimum 1.0 foot of freeboard above the maximum pool elevation computed when the facility functions for the one-hundred-year postdevelopment inflow. However, criteria for design and construction of stormwater management facilities are not the same criteria that are used in the permitting of dams under the DER Dam Safety Program. Depending upon the physical characteristics of a dam, a dam permit may be required and the design will have to meet the provisions of Chapter 105 of the Dam Safety and Encroachments Act.[1] Depending on the physical characteristics of a dam, the design could require that anywhere from a fifty-year to a PMF storm event be considered.
[1]
Editor's Note: See 32 P.S. § 693.1 et seq.
C. 
Any drainage conveyance facility that doesn't fall under Chapter 105 regulations must be able to convey, without damage to the drainage structure or roadway, runoff from the twenty-five-year design storm with a minimum 1.0 foot of freeboard measured below the lowest point along the top of the roadway. Roadway crossings located within designated floodplain areas must be able to convey runoff from a one-hundred-year design storm with a minimum 1.0 foot of freeboard measured below the lowest point along the top of the roadway. Any facility located within a PennDOT right-of-way must meet PennDOT minimum design standards and permit submission requirements.
D. 
Storm sewers must be able to convey postdevelopment runoff from a twenty-five-year design storm without surcharging inlets.
E. 
Capacity improvements. If the developer could prove that it would be feasible to provide capacity improvements to relieve the capacity deficiency in the existing drainage network, then adequate capacity improvements could be provided by the developer in lieu of stormwater management facilities on the development site. Any capacity improvements would be designed based on development of all areas tributary to the improvements and the capacity criteria specified in this chapter. The type and amount of development that the developer must consider shall be either based on current zoning or established by the municipality, whichever results in a greater amount of imperviousness. It shall be assumed that all new development upstream of a proposed capacity improvement would implement applicable stormwater management techniques, consistent with this chapter.
F. 
Adequate erosion protection shall be provided along all open channels and at all points of discharge.
A. 
Stormwater runoff from all development sites shall be calculated using either the rational method or a soil-cover-complex methodology.
B. 
The design of any stormwater detention facilities intended to meet the performance standards of this chapter shall be verified by routing the design storm hydograph through these facilities using the Storage-Indication Method. For drainage areas greater than 20 acres in size, the design storm hydograph shall be computed using a calculation method that produces a full hydrograph. The municipality may approve the use of any generally accepted full hydrograph approximation technique that shall use a total runoff volume that is consistent with the volume from a method that produces a full hydrograph.
C. 
All calculations consistent with this chapter using the soil cover complex method shall use the appropriate design rainfall depths for the various return period storms presented in PennDOT's Intensity-Duration Frequency Field Manual (May 1986). If a hydrologic computer model, such as PSRM or HEC-1, is used for stormwater runoff calculations, then the duration of rainfall shall be 24 hours.
D. 
All calculations using the Rational Method shall use rainfall intensities consistent with appropriate times of concentration for overland flow and return periods. Times of concentration for overland flow shall be calculated using the methodology presented in Chapter 3 of Urban Hydrology for Small Watersheds, SCS, TR-55 (as amended or replaced from time to time by SCS). Times of concentration for channel and pipe flow shall be computed using Manning's equation.
E. 
Where uniform flow is anticipated, the Manning equation shall be used for hydraulic computations and to determine the capacity of open channels, pipes and storm sewers.
F. 
Outlet structures for stormwater management facilities shall be designed to meet the performance standards of this chapter using any generally accepted hydraulic analysis technique or method.
The following items shall be included in the plan:
A. 
A narrative report describing the project and giving the purpose and engineering assumptions and calculations for control measures and facilities.
(1) 
General description of the project including statement of total earth disturbance.
(2) 
General description of stormwater management controls as outlined in Appendix B.[1]
[1]
Editor's Note: Appendix B is on file in the Borough Secretary's office.
(3) 
General description of erosion and sediment pollution controls as outlined in DER's Erosion and Sediment Pollution Control Program Manual and Chapter 102.
(4) 
General description of nonpoint source pollution controls.
(5) 
Expected project time schedule, including anticipated start and completion dates.
(6) 
A proposed schedule of inspections which will be performed by the applicant's engineer or designee and monitored by the Borough Engineer or the borough designee.
(7) 
A schedule for installation of the control measures and structures with tentative calendar dates.
(8) 
All calculations, assumptions and criteria used in the design of the control measures and structures as outlined in Appendix B.
(9) 
A maintenance program for all stormwater management, erosion and sediment controls for both the construction period and after construction is complete, including the responsible party. This program must include the proposed ownership of the permanent controls and details for financial responsibility for any required maintenance.
(10) 
A description of federal or state agency involvement with the project (i.e., United States Army Corps of Engineers, Department of Environmental Resources).
(11) 
Training and experience of person(s) preparing the plan.
B. 
Map(s) of the project area showing:
(1) 
The locations of the project relative to highways, municipalities or other identifiable landmarks (i.e., United States Geological Survey).
(2) 
North arrow and scale.
(3) 
Existing and proposed contours at intervals of two feet; in areas of steep slopes (greater than 15%), five-foot contour intervals may be used.
(4) 
Streams, lakes, ponds or other bodies of water within and in close proximity to the project area.
(5) 
The one-hundred-year floodplain and floodway.
(6) 
Easements and adjoining property owners.
(7) 
Existing structures, roads, paved areas, buildings and earth disturbances.
(8) 
Other physical features, including existing drainage swales and areas of natural vegetation to be preserved.
(9) 
Locations of existing and proposed underground utilities, sewers and waterlines.
(10) 
Soil types and boundaries.
(11) 
Proposed changes to land surfaces and vegetative cover.
(12) 
Areas to be cut and filled.
(13) 
Limits of disturbed areas.
(14) 
Proposed structures, including roads, paved areas and buildings.
(15) 
Wetlands as delineated according to the Federal Manual for the Identification and Delineation of Jurisdictional Wetlands.
(16) 
Existing and proposed stormwater management, erosion and sediment pollution control structures as discussed in the narrative, Appendix B and DER's Erosion and Sediment Pollution Control Program Manual.
(17) 
Road profiles for proposed rights-of-way.
(18) 
Details/profiles of all proposed stormwater management, erosion and sediment control structures as discussed in the narrative, Appendix B and DER's Erosion and Sediment Pollution Control Program Manual.
(19) 
Existing and proposed drainage areas and boundaries, including on-site and contributing off-site boundaries.
(20) 
When groundwater recharge methods such as seepage pits, beds or trenches are used, the locations of septic tank infiltration areas and wells must be shown.
(21) 
Areas subject to special deed restrictions affecting or affected by stormwater management.
(22) 
Easements and rights-of-way to proposed stormwater controls.
(23) 
A certificate, signed and sealed by an engineer registered in the Commonwealth of Pennsylvania and qualified under all applicable state and local laws to perform such duties indicating the compliance of the design of the stormwater management facilities and concepts with the provisions of this chapter.