Township of Whitehall, PA
Lehigh County
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A. 
General. Any landowner and any person engaged in the alteration or development of land which may affect stormwater runoff characteristics shall implement such measures consistent with the provisions of this chapter, Pennsylvania Act 167, Stormwater Management and any other applicable statutes and applicable watershed stormwater plan. In addition thereof, developers shall:
(1) 
Assure that the maximum rate of stormwater runoff is no greater after development than prior to development activities.
(2) 
Permit unimpeded flow of natural watercourses, except as may be modified by stormwater detention pond requirements in § 22-31.
(3) 
Ensure drainage of all points along streets.
(4) 
Intercept stormwater runoff along streets at intervals related to the extent and grade of the area drained.
(5) 
Provide positive drainage away from onsite sewage disposal systems.
(6) 
Take surface water from the bottom of vertical grades and lead water away from springs. Cross gutters at public street intersections and elsewhere shall not be permitted.
(7) 
In any instance where the Township is forced by the Pennsylvania Department of Transportation to be the permit applicant for a highway occupancy permit for drainage facilities to be constructed by a private developer on a state roadway, the developer shall be required to enter into an indemnification agreement with the Township, which shall identify maintenance responsibilities for the structures. This document shall be in a form acceptable to the Township Solicitor, and the Township will not agree to be a permit applicant to any such construction unless and until this agreement has been executed by both parties.
[Added 6-8-2009 by Ord. No. 2774]
Designs of storm drainage systems shall be prepared by a professional engineer, licensed to practice in Pennsylvania. Complete, detailed calculations shall be signed and sealed by the preparer and submitted with the preliminary plans.
A. 
Drainage plan. A site drainage plan for the proposed land development shall be prepared which illustrates the following information:
(1) 
Mapping of the watershed area or areas in which the proposed subdivision or land development is located including topography (at two foot intervals) of the proposed subdivision or land development and those areas within 400 feet of the proposed subdivision or land development.
(2) 
Calculations of runoff for all points of runoff concentration.
(3) 
Complete drainage systems for the land development. All existing drainage features which are to be incorporated in the design shall be identified. If the land development is to be developed in stages, a general drainage plan for the entire subdivision shall be presented with the first stage and appropriate development stages for the drainage system indicated.
(4) 
The existing points of natural drainage discharge and the mode of drainage onto adjacent property shall not be altered, unless the notarized, written consent of affected landowner(s) is obtained by the developer.
B. 
Diversion of runoff. No stormwater runoff or natural drainage shall be so diverted so as to overload existing drainage systems, create flooding or create the need for additional drainage structures on other private properties or public lands, without safe and adequate provisions being made by the developer for properly handling such conditions and the developer obtaining the written consent of downstream landowners.
C. 
Deed restrictions. Where a land development is traversed by watercourses other than permanent streams, there shall be provided a deed restriction conforming substantially with the line of such watercourse. The width of the restricted area shall be adequate to provide for unimpeded flow of storm runoff based on the 100-year storm and to provide a freeboard allowance as determined by using the calculations set forth in Appendix A.[1] The terms of restriction shall require periodic cutting and maintenance of the vegetation by the landowner and shall prohibit the alteration, obstruction or encroachment of any kind within the restricted area. The restriction shall further reserve a right-of-entry to the Township in the event of danger to public safety, exercisable only in the case of breach of responsibility by the landowner. These terms shall be secured through covenants included in the deeds of conveyance. If such area is determined by the Township Engineer to be integral to the stormwater system of the Township, a drainage easement must be provided.
(1) 
Drainage structures that are located in state highway rights-of-way shall be approved by the Pennsylvania Department of Transportation.
(2) 
All streets shall be so designed as to provide for the collection and conveyance of surface water from their rights-of-way.
[1]
Editor's Note: Appendix A is included at the end of this chapter.
D. 
Erosion of watercourse channels. Storm drainage facilities and appurtenances shall be so designed and provided so as to minimize erosion in watercourse channels and at all points of discharge.
E. 
Storm drainage easements. All storm drainage systems must be located within a public right-of-way or easement. The minimum easement width shall be 20 feet centered over the system.
F. 
Identification of storm drainage easements. All easements shall:
(1) 
Be shown on the record plan and utility plan.
(2) 
Be identified as to their purpose.
(3) 
Appear shaded or hatched on the record plan.
(4) 
Identify the easement holder.
G. 
DEP approval. Any proposal storm drainage plans which affect the drainage basin of any watercourse shall be approved by Pennsylvania Department of Environmental Protection, Division of Dam Safety and Waterway Management, if the drainage basin so affected has an area of 0.5 square miles or more.
A. 
Applicability of Act 167. If the land development is within a watershed with an approved Stormwater Management Plan enacted pursuant to Act 167, the criteria in the applicable plan shall be used.
(1) 
Any downstream analysis conducted to determine adequacy for accepting increased rates of runoff shall consider the 100-year storm event.
(2) 
The design or analysis of all natural or man-made overland drainage systems shall have adequate capacity for the 10- to 100-year return storm.
(3) 
For all development, the extent of the 100-year storm event shall be shown. Items such as overland flow (width and depth) and inlets which would backsurge shall be identified.
B. 
Design to protect from 100-year storm. In lieu of the requirements set forth in this § 22-30, storm drainage systems required by this chapter shall be designed to provide protection from a 10- to 100-year storm, unless a more conservative design is required by another regulation, or is required because of conditions particular to an individual development.
C. 
Design criteria standards. See Table 2.
Table 2
Area
Design Storm Return
(years)
Residential Areas:
Fixed Pipe
10
Total Conveyance
100
Nonresidential Area:
Fixed Pipe
25
Total Conveyance
100
D. 
Watersheds less than 200 acres. Stormwater runoff from watersheds of 200 acres or less shall be calculated by the rational method (See Appendix A[1]), except as the watershed size criteria may be modified by an approved Act 167 Stormwater Management Plan.
[1]
Editor's Note: Appendix A is included at the end of this chapter.
E. 
Watersheds greater than 200 acres. Stormwater runoff from watersheds of more than 200 acres shall be calculated using the soil cover complex method developed by the Soil Conservation Service or other appropriate method acceptable to the Township Engineer.
F. 
Verification. The design of any detention facility shall be verified by routing the proposed post-development hydrograph through the basin using storage indication techniques.
G. 
Submission of calculations. Complete detailed drainage calculations and applicable charts and hydrographs certified by the design engineer shall be submitted to the Township Engineer with the preliminary plan submission.
A. 
Compliance with Act 167. Whitehall Township has been designed in its entirety as a provisional no detention area pursuant to Act 167. As such all proposed developments must adhere to the regulations stated therein and in the attached watershed plans. (See Appendix C[1]).
[1]
Editor's Note: Appendix C is included at the end of this chapter.
B. 
When required. Stormwater detention facilities may be required for all land development proposals whenever the following two criteria have been met:
(1) 
The proposed rate and volume of runoff cannot be accommodated by all downstream fixed pipe or surface drainage system.
(2) 
Written permission has not been granted by the adjoining downstream owner(s) where runoff discharges onto the adjoiner, via a subsurface and/or surface drainage system to the main channel.
C. 
Maximum post peak rates. Whenever stormwater detention facilities are required, the maximum post-development peak rates of flow shall be governed by the following provisions:
(1) 
Post-development rates of runoff for the 2- , 5- , 10- , 25- , 50- and 100-year storm events shall not exceed predevelopment rates.
(2) 
Within watersheds for which there is an approved Act 167 Stormwater Management Plan, the detention facilities shall at minimum be designed to discharge post-development peak runoff rates consistent with the plan criteria except in the instance of off-site detention facilities implemented as per Subsection C(4).
(3) 
Within watersheds for which there is not an approved Act 167 Stormwater Management Plan, the detention facilities shall be designed to provide that the peak rate of runoff at all points of discharge from the site, when developed, will not exceed the peak rate of runoff at each of those points prior to development, except in the instance of off-site detention facilities implemented as per Subsection C(4).
(4) 
In certain instances, regional detention facilities and other off-site stormwater management facilities to provide runoff control for multiple development sites may be implemented in lieu of individual development site detention basins. Peak runoff rates of discharge from regional detention basins and other off-site stormwater management facilities shall be based upon maintaining existing peak runoff rates for the tributary area, except that other criteria for discharge may apply for regional detention facilities and other off-site stormwater management facilities located within a watershed with an approved Act 167 Stormwater Management Plan.
D. 
Design requirements. Where stormwater detention facilities are included as part of the storm drainage system, the following provisions will apply:
(1) 
Detention basins shall be designed so that they empty completely and no standing water remains.
(2) 
The developer shall demonstrate that such basins are designed, protected and located to assure that public safety is maximized and health problems are prevented. The following minimum criteria shall apply:
(a) 
Top berm width shall be minimum of 10 feet.
(b) 
Side slopes shall be three horizontal to one vertical or flatter.
(c) 
Any basin shall be enclosed with a four foot high durable chain link fence that includes a 10 foot wide gate with locking device and vehicle access to floor of the pond.
(d) 
All basins shall be screened from view with a dense, low maintenance, year round vegetative screen that will reach a height of four feet within two years.
(e) 
All basins shall incorporate a four inch impervious clay liner with a permeability coefficient of 1 x 10-7 cm/sec, verified by test results and a minimum of four inches of topsoil over the clay.
(f) 
All basins shall be seeded with PennDOT, formula B.
(3) 
The developer shall verify that the operation of the stormwater detention facility will not aggravate potential downstream peaking conditions.
(4) 
An emergency overflow spillway weir, constructed of concrete, six inches in thickness, shall be provided for stormwater detention facilities to handle runoff in excess of 100-year storm.
(5) 
If a portion of the land development will remain in common ownership, the developer shall provide an annotation on the record plan imposing a covenant running with the land requiring perpetual maintenance of the stormwater detention basin by either the owner of the development or lot owner.
(6) 
All detention basins in all areas must contain easements for Township emergency maintenance. Routine maintenance such as mowing of grass, etc., will be the responsibility of lot owner.
(7) 
All stormwater detention basin outlet structures shall be constructed of concrete.
(8) 
The bottom of the stormwater detention basin must slope to the outlet structure at a grade not less than 1%.
(9) 
Stormwater retention basins are not permitted.
(10) 
When the outflow of a stormwater detention basis flows downstream and into another detention basin the routed outflow hydrograph must be added to the existing inflow hydrograph and routed through the existing stormwater detention basin to determine the impact, if any. If there is a negative impact on the existing detention basin, the proposed stormwater detention basin must be altered to eliminate this impact.
(11) 
All stormwater detention basins must be provided with a minimum of one foot of freeboard above the maximum water elevation over the emergency spillway.
(12) 
All stormwater detention basin outlet structures smaller than four inches must be fitted with a debris deflector.
(13) 
Underground detention must be constructed with inspection ports (no less than 12 inches in diameter) and a clean out access hatch (no less than 36 inches in diameter).
(14) 
Regulations for the pumping of stormwater detention facilities.
(a) 
The stormwater detention facility shall provide sufficient capacity to hold runoff volume from the 100-year storm event plus an additional 40% thereof, without the pumps being in operation.
(b) 
All pumping systems shall be housed in a separate chamber.
(c) 
All pumping systems shall be a duplex model (two pumps).
(d) 
An emergency generator shall be part of the system, with automatic switchover feature.
(e) 
The pumping system shall, in the event of the failure of the pump or the generator, provide an alarm which shall send a signal to a monitoring service which shall immediately authorize and effect a service call. The name, address, telephone number and contact person of the then current monitoring service and the then current service company shall be provided to the Township.
(f) 
The pumping system shall be capable of completely dewatering the drainage facility within 48 hours after a storm event.
(g) 
A note shall be placed on the final plan stating that: the owner of this property shall, at the property owner's sole cost and expense, operate, maintain, repair and keep in proper working order, the stormwater drainage facility and the pumping system so as to properly accommodate and remove, in a timely and safe manner, the stormwater collected in the stormwater detention facility situate on this property. This obligation shall be a covenant running with the land and shall bind the owner and the owner's successors, heirs and assigns.
(h) 
In the event the property is abandoned, the pumping system shall remain functional. To that end, the electrical supply to the pump shall be designed to accept a separate and independently metered service without energizing any other equipment on the site.
(i) 
The developer shall execute an easement in favor of the Township, in form and content acceptable to the Township Solicitor, that permits the Township to have access to the property in order to facilitate the changes to said electrical service to the pump station.
A. 
Flanking inlets. When inlets are placed at a low point on a vertical curve, flanking inlets shall be provided two feet above the low point inlet or a maximum of 100 feet on either side of the low point inlet(s).
B. 
Design requirements. All storm sewer pipes must be reinforced cement concrete pipe and a minimum of 15 inches diameter. Pipes must be provided with a minimum of two feet of cover. When pipe sizes change in a junction, the crown of the pipes must match. If the pipe size does not change, developer shall provide a 0.10 foot minimum drop through the junction. If the Township Engineer deems it necessary, the energy grade shall control.
C. 
Safety grates. See Detail Plate WT-D-05.[1]
[1]
Editor's Note: The Detail Plates are included at the end of this chapter.
D. 
Inlet capacity. Inlet capacity calculations must be provided for all inlets involved in a stormwater drainage system.
E. 
Minimum velocity. All storm sewer pipes shall be designed so as to have a minimum velocity of 3.0 f.p.s.
F. 
Construction and materials.
(1) 
The following construction practices and materials shall be prohibited:
(a) 
Use of bubbler inlets.
(b) 
Use of flared end sections in sumps.
(c) 
Use of trench drains (and cross gutters) in Township streets or streets proposed to be dedicated to the Township.
(2) 
Unless otherwise permitted by the Township Engineer in writing, all pipe used in the construction of collection systems shall be RCP pipe.
G. 
Sumping of inlets. All inlets shall be sumped one inch below final road grade elevation. Initially, all inlets within the cartway shall be sumped one inch below the elevation of the base course. This practice will allow the inlets to effectively collect stormwater runoff prior to the placement of the wearing/surface course. Immediately prior to the placement of the wearing/surface course, the inlets tops shall be raised to achieve the one inch sump required herein. The developer shall ensure that sufficient clearance is provided in order to set the inlet top at the interim elevation required hereinabove. (See Detail Plate WT-D-02.[2])
[2]
Editor's Note: The Detail Plates are included at the end of this chapter.