A. 
See the provisions of Part 3 of this chapter for those portions of the Township that are within an Act 167 Stormwater Management Area. Stormwater management plans within an Act 167 Area must be consistent with the said Act 167. Areas not within an Act 167 Stormwater Management Area shall be subject to the same design requirements, except release rates, as listed in Part 3.
B. 
Velocity control measures. The Board of Supervisors, based upon the recommendations of the Township Engineer, may require specific sizes or types of stormwater velocity control measures based upon both the need to control the velocity and upon long-term maintenance concerns.
C. 
Stormwater runoff from any subdivision or land development (including during construction and earthmoving) shall not occur at a peak rate (measured in cubic feet per second) that is greater after development than occurred prior to development.
D. 
Runoff shall be controlled from a site using appropriate means of detention of water on the site and/or other approved types of stormwater management within the requirements of this Part 2.
E. 
Runoff that is detained shall be held and released at a predetermined controlled rate by appropriately installed devices. The release shall be in the same manner as the natural or predevelopment means of discharge from a site (such as point discharge or sheet flow.)
F. 
Stormwater runoff shall not be increased or redirected in such a way that it results in hazards to persons or property or interferes with the normal movement of vehicles.
G. 
All stormwater management methods are subject to approval by the Township Engineer, including all outlet locations.
H. 
All lots shall be laid out and graded to prevent cross lot drainage and to provide positive drainage away from proposed building locations and any primary or alternate septic system locations. Stormwater shall also not be redirected towards buildings or on-lot septic systems off of the site.
I. 
All stormwater management plans shall take into account and provide for existing flow from upstream areas within the entire watershed.
J. 
The existing points of natural drainage discharge onto adjacent property shall not be altered to increase flows nor shall the concentration of water runoff be increased because of development without the written approval of all affected landowners.
K. 
No stormwater runoff or watercourse shall be diverted in a way that overloads existing drainage systems or creates flooding or the need for additional drainage structures on other private properties or public lands without Township approval of provisions to be made by the developer for properly handling such conditions, including water runoff impoundments, if necessary.
L. 
An adequate storm sewer system consisting of inlets and underground drainage pipes with approved outlets shall be constructed where the runoff of stormwater and the prevention of erosion cannot be accomplished satisfactorily by surface drainage facilities, as determined by the Board of Supervisors, based upon recommendation of the Township Engineer. Such determination shall be based upon the expected velocity and depth of the stormwater flows (including depths in the street) and the proximity of dwellings.
(1) 
Underground flows. Any diverted or affected underground water flows shall be properly dissipated or controlled to prevent velocities or concentrations that could harm a street or cause erosion within the right-of-way. Appropriate methods of control may include, but are not limited to: perforated pipe or other methods to slow the discharge of the water.
M. 
Sequence of construction. No substantial grading shall occur and no building permits shall be issued for any building unless any detention basin, siltation basin or improved major swale approved to handle the resulting runoff is in place. Any detention basin shall be seeded and stabilized and have an installed outlet structure prior to the construction of any streets or buildings within that drainage basin.
N. 
Phasing. The phasing of a development shall ensure that all stormwater facilities needed to manage runoff from a phase are in place and functioning adequately prior to and after the construction of buildings in that phase. This shall, for example, include the extension of the main outfall line, this may require the use of temporary structures, which shall be shown on submitted plans. If the development occurs in phases, the entire system shall be shown as part of the preliminary plan submission.
A. 
The methods and design storms shall be consistent with Part 3 of this chapter and as indicated in Appendix C.[1]
[1]
Editor's Note: Said appendix is included as an attachment to this chapter.
B. 
The stormwater calculations shall include the following:
(1) 
Predevelopment and post-development drainage maps showing existing and proposed grades and including any off-site tributary area;
(2) 
Predevelopment and post-development runoff calculations;
(3) 
Detention basin design calculations (as applicable);
(4) 
Pipe and swale sizing calculations;
(5) 
Such information as the Township Engineer determines is needed to determine compliance with this Part 2, including, but not limited to, slopes, proposed elevations, typical cross sections and details.
C. 
Where crop farming or disturbed earth exists on the site prior to development, meadow in good condition shall be used as the starting base for the predevelopment calculation.
A. 
Within the 100-year floodplain, any stormwater management structures and systems shall be designed to handle a 100-year storm.
B. 
The stormwater management plan shall show that a 100-year storm can be safely conveyed without jeopardizing any principle building on or adjacent to the site.
C. 
All plans showing the proposed storm drainage construction must be accompanied by a complete design stamped and signed by a PA-registered engineer or surveyor.
A. 
Perforated risers, staggered orifices, V-notch wires, or other outlet structures as approved by the Township Engineer, may be required for outlet control.
B. 
All detention basins shall be designed with an emergency spillway.
(1) 
All stormwater detention facilities shall provide a minimum 1.0-foot freeboard above the maximum pool elevation association with the two-year through twenty-five-year runoff events. An emergency spillway shall be designed to pass the 100-year runoff event with a minimum 0.5-foot freeboard.
(2) 
The downstream slope of the spillway shall as a minimum extend to the toe of the berm embankment. The edge of the basin grading shall be within the subject property.
(3) 
All detention basin outflow structures shall be designed with trash racks over the outflows.
C. 
The minimum top width of a detention basin berm shall be 10 feet, unless the Township Engineer determines that a differing width is needed for maintenance and structural purposes.
D. 
In order to provide proper drainage, a minimum grade of 1.5%, directed toward the outlet structure, shall be maintained across the basin floor.
E. 
Slopes of basin. The maximum inside slope of earth detention basin embankments shall be five horizontal to one vertical. The maximum outside slope shall be five to one. The Board of Supervisors may permit a reduction of inside and outside slopes to a three to one maximum where the applicant proves that such slopes will be able to be properly and attractively maintained. The top or toe of any slope shall be located at a minimum of five feet from any property line. Whenever possible the side slopes and basin shape shall be amenable to the natural topography. Straight side slopes are prohibited. The maximum slope of an accessway for maintenance shall be eight horizontal to one vertical where such accessway is required by the Board of Supervisors, based upon the recommendations of the Township Engineer.
F. 
Where no existing point of concentration exists, the outfall from a detention basin shall not discharge closer than 30 feet from the adjoining property line, unless permission is given, in writing, by said adjacent property owner.
G. 
Where discharge from the detention basin is to be spread into sheet flow, the allowable flow shall be determined by the predevelopment flow rate for a two-year storm, across the length of the spreader.
H. 
Antiseep collars and a cutoff trench shall be required on basins having a berm height exceeding five feet. Watertight antiseep collars shall be installed around the discharge pipe at intervals not to exceed 24 feet or as approved by the Township Engineer. Such collars shall extend a minimum of two feet beyond the outside of the pipe.
I. 
Basins not having direct access to a public street shall have a twenty-five-foot wide, usable access easement to a public street for the purpose of maintenance.
J. 
The design engineer shall verify that the operation of the detention facility will not significantly increase downstream peaking conditions.
K. 
For the purpose of this section, a retention basin shall be required to meet the same standards as a detention basin.
L. 
Landscaped screening of detention basins.
(1) 
A detention basin with a basin depth of greater than 20 inches shall be screened from view of existing dwellings, a residential zoning district, or public streets, unless the basin would meet all of the following conditions:
(a) 
It would have an average slope of less than five to one on the inside of the berm of the basin;
(b) 
Either a) both the inside and outside of the basin would be planted in grass and intended to be mowed or planted in other attractive vegetative ground cover or b) would be designed to closely resemble a natural pond; and
(c) 
The basin would not be surrounded by a primarily metal fence.
(2) 
Any required screening shall meet the buffer yard standards of § 500-68C of Chapter 500, Zoning, unless the Board of Supervisors approve an alternate landscaping arrangement that serves the same purposes. This landscaping shall not be required along an area where natural vegetation will be maintained that will completely fulfill this purpose.
(3) 
Thorny and prickly shrubs (that are also attractive) are encouraged to be used around detention basins to discourage entry by children.
M. 
Areas of stormwater basins that are visible from streets and dwellings shall be attractively maintained.
N. 
All outflow structures from storage facilities shall be equipped with a regulatory device that will permit modification to regulate the amount of outflow; suitable anticortex and/or velocity retarders shall be used.
(1) 
Entrances to stormwater popes, including outflow popes in detention basins, shall have childproof gates or similar devices.
O. 
Retention basins. Aeration devices may be required, dependent upon the quality of the influent and detention time.
A. 
Standards. Construction and materials of storm drainage and control facilities (including pipes) and erosion control facilities shall be in accordance with the approved plans and any accompanying specifications. The construction details and standards of the following publications, or their successor publications, in their most recent revision, shall be used:
(1) 
"County Erosion and Sedimentation Control Handbook."
(2) 
PennDOT, Form 408, Specifications.
(3) 
PennDOT, RC Series, Roadway Construction Standards.
B. 
Pipe materials. All pipe materials shall meet PennDOT standards. Drainage pipes may be constructed out of corrugated metal, aluminized corrugated metal, corrugated polyethylene plastic, bituminous coated corrugated metal or reinforced concrete, or closely similar materials preapproved by the Township Engineer. However, only reinforced concrete shall be used for drainage pipes under the structure of streets, unless a material with similar characteristics is determined to be acceptable by the Township Engineer.
A. 
Open pipe ends must be fitted with concrete end walls, prefabricated end sections, riprap and/or energy dissipaters, as deemed appropriate by the Township Engineer.
B. 
Drainage pipes shall have a minimum slope of 0.5%, and drainage swales not designed for stormwater detention shall have a minimum slope of 2%. As a minimum, the tops of all pipes should be at the same elevation when changing pipe sizes.
C. 
Manholes or inlets be used at all changes in horizontal alignment, at changes of vertical grade and at all pipe intersections. No run of pipe shall exceed 400 feet in length without appropriate measures to allow cleanout.
D. 
Bridges and culverts shall meet PennDOT Construction Standards. PADEP shall be contacted to determine if a dams and waterways permit is required.
E. 
Appropriate safety grates shall be attached to all catch basins, stormwater inlets, pipe openings and other stormwater receiving structures, as needed. Along streets and pedestrian areas, bicycle-safe grates shall be used as needed.
F. 
Storm sewer outfall. Storm sewer outfall shall be designed, with respect to the elevation of the invert or other features, that when the receiving watercourse is within a twenty-five-year storm, the storm sewer will continue to drain the area it is designed to serve.
G. 
V-shaped swales shall not be permitted.
A. 
Where a subdivision or development is traversed by a watercourse, drainageway, channel or stream that the Township Engineer determines is subject to significant stormwater flows, there shall be provided a drainage easement established along the following:
(1) 
The 100-year floodway, where that is defined;
(2) 
Where a 100-year floodway is not defined, the 100-year floodplain;
(3) 
Where a 100-year floodplain is not defined, a width shall be used that includes a minimum of 25 feet on each side of the top of the primary bank of the waterway.
B. 
The drainage easements required by the above subsection are intended to preserve the unimpeded flow of natural drainage and to provide for future possible widening, deepening, relocating, improving or protecting of such drainage facilities. The Township Engineer may require up to a 0.5-foot freeboard and/or an additional ten-foot building setback if deemed necessary along newly constructed watercourses.
C. 
If a major man-made drainage channel would pass within close proximity to homes and possibly threaten the safety of persons, the Board of Supervisors, based upon the advice of the Township Engineer, may require such certain lengths of such channel to be placed within appropriate underground pipes.
D. 
It shall be the responsibility of the applicant to obtain all stormwater easements on, over or through other properties that are needed to carry out the proposed storm management plan.
A. 
All natural streams, channels, swales, drainage systems and/or areas of concentration of surface water shall be maintained in their existing condition unless alternation is approved by the Township Engineer. The applicant shall be responsible to obtain all necessary PADEP permits (see Chapter 105 of Title 25 of the Pennsylvania Code).
B. 
Creek alignments. Any change to the alignment of a watercourse or any blocking, impeding or redirecting of a watercourse shall only occur with written approval of PADEP and the Township Engineer.
A system for the ownership and maintenance responsibilities of all temporary and permanent stormwater facilities and erosion and sedimentation control facilities that is satisfactory to the Board of Supervisors shall be established prior to final plan approval, including:
A. 
Description of temporary and permanent maintenance requirements.
B. 
Identification of responsible individual, corporation, association or other entity for ownership and maintenance of both temporary and permanent stormwater management and erosion and sedimentation control facilities.
(1) 
Establishment of suitable easements for access to all facilities for maintenance.
(2) 
The Township may, at the complete discretion of the Board of Supervisors, decide not to accept an offer by the applicant for Township ownership of stormwater facilities.
(3) 
Stormwater facilities shall be designed to require minimal maintenance.
(4) 
All storm drainage facilities shall be properly maintained by the party designated as responsible on the final subdivision plan, unless the Board of Supervisors agree to accept a change in the party responsible of the party owning the facility.