Township of Lower Gwynedd, PA
Montgomery County
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Table of Contents
Table of Contents
 
GENERAL REFERENCES
Sewers generally — See Ch. 1060.
Water generally — See Ch. 1066.
Subdivision and land development — See Ch. 1230.
Building Code — See Ch. 1440.
Plumbing and Drainage Code — See Ch. 1444.
Topsoil removal — See Ch. 1474.
Exhibits A and B Appendix 1241A Appendix 1241B

§ 1241.01 General provisions.

[Ord. 434. Passed 6-21-2005]
(a) 
Short Title. This chapter shall be known and may be cited as the "Lower Gwynedd Township Stormwater Management Chapter."
(b) 
Statement of Findings. The Board of Supervisors of the Township finds that:
(1) 
Stormwater runoff from lands modified by human activities threatens public health and safety by causing decreased infiltration of rainwater and increased runoff flows and velocities, which overtax the carrying capacity of existing streams and storm sewers and greatly increases the cost to the public to manage stormwater.
(2) 
Inadequate planning and management of stormwater runoff resulting from land development and redevelopment throughout a watershed can also harm surface water resources by changing the natural hydrologic patterns, accelerating stream flows (which increase scour and erosion of streambeds and streambanks, thereby elevating sedimentation, destroying aquatic habitat and elevating aquatic pollutant concentrations and loadings such as sediments, nutrients, heavy metals and pathogens). Groundwater resources are also impacted through loss of recharge.
(3) 
A program of stormwater management, including reasonable regulation of land development and redevelopment causing loss of natural infiltration, is fundamental to the public health, safety, welfare and the protection of the people of the Township and all the people of the commonwealth, their resources and the environment.
(4) 
Stormwater can be an important water resource by providing groundwater recharge for water supplies and base flow of streams, which also protects and maintains surface water quality.
(5) 
Public education on the control of pollution from stormwater is an essential component in successfully addressing stormwater.
(6) 
Federal and state regulations require certain municipalities to implement a program of stormwater controls. These municipalities are required to obtain a permit for stormwater discharges from their separate storm sewer systems under the National Pollutant Discharge Elimination System (NPDES).
(7) 
Nonstormwater discharges to municipal separate storm sewer systems can contribute to pollution of waters of the commonwealth by the Township.
(c) 
Purpose. The purpose of this chapter is to promote health, safety and welfare within Lower Gwynedd Township and its watershed by minimizing the harms and maximizing the benefits described in Section 1241.01(b) of this chapter through provisions designed to:
(1) 
Manage stormwater runoff impacts at their source by regulating activities that cause the problems.
(2) 
Provide review procedures and performance standards for stormwater planning and management.
(3) 
Utilize and preserve the existing natural drainage systems as much as possible.
(4) 
Manage stormwater impacts close to the runoff source, which requires a minimum of structures and relies on natural processes.
(5) 
Focus on infiltration of stormwater, to maintain groundwater recharge, to prevent degradation of surface and groundwater quality and to otherwise protect water resources.
(6) 
Maintain existing flows and quality of streams and watercourses.
(7) 
Meet legal water quality requirements under state law, including regulations at 25 Pa. Code Chapter 93.4a to protect and maintain existing uses and maintain the level of water quality to support those uses in all streams, and to protect and maintain water quality in special protection streams.
(8) 
Prevent streambank and streambed scour and erosion.
(9) 
Provide for proper operations and maintenance of all permanent stormwater management best management practices (BMPs) that are implemented in the Township.
(10) 
Provide a mechanism to identify controls necessary to meet the NPDES permit requirements.
(11) 
Implement an illegal discharge detection and elimination program to address nonstormwater discharges into the municipal separate storm sewer system.
(d) 
Statutory Authority. The Township is empowered to regulate land use activities that affect stormwater runoff by the authority of the Act of July 31, 1968, P.L. 805, No. 247, the Municipalities Planning Code, as amended, and the Second Class Township Code.
(e) 
Applicability.
(1) 
This chapter applies to any regulated earth disturbance activities within the Township and all stormwater runoff entering into the municipal separate storm sewer system from lands within the boundaries of the Township.
(2) 
Earth disturbance activities and associated stormwater management controls are also regulated under existing state law and implementing regulations. This chapter shall operate in coordination with those parallel requirements; the requirements of this chapter shall be no less restrictive in meeting the purposes of this chapter than state law.
(f) 
Exemptions. Any regulated earth disturbance activity that meets the following exemption criteria is exempt from the requirements of Sections 1241.03(c)(1), 1241.03(d)(1) and 1241.04(a)(1) of this chapter. This exemption shall not relieve the applicant from implementing such measures such as erosion and sedimentation controls as are necessary to protect health, safety and property.
(1) 
Use of land for gardening for home consumption.
(2) 
Forest management operations that are following the Department of Environmental Protections' management practices contained in its publication "Soil Erosion and Sedimentation Control Guidelines for Forestry" and are operating under an erosion and sedimentation control plan.
(g) 
Compatibility with Other Requirements.
(1) 
Approvals issued and actions taken under this chapter do not relieve the applicant of the responsibility to secure required permits or approvals for activities regulated by any other code, law, regulations or chapter. To the extent that this chapter imposes more rigorous or stringent requirements for stormwater management, the specific requirements contained in this chapter shall be followed.
(2) 
Nothing in this chapter shall be construed to affect any of the Township's requirements regarding stormwater matters which do not conflict with the provisions of this chapter. Conflicting provisions in other Township Chapter or regulations shall be construed to retain the requirements of this chapter addressing state water quality requirements.

§ 1241.02 Definitions.

[Ord. 434. Passed 6-21-2005]
(a) 
Word Usage. For the purposes of this chapter, certain terms and words used herein shall be interpreted as follows:
(1) 
Words used in the present tense include the future tense; the singular number includes the plural, and the plural number includes the singular; words of masculine gender include feminine gender; and words of feminine gender include masculine gender.
(2) 
The word "includes" or "including" shall not limit the term to the specific example but is intended to extend its meaning to all other instances of like kind and character.
(3) 
The words "shall" and "must" are mandatory; the words "may" and "should" are permissive.
(b) 
Terms Defined. As used in this chapter, the following terms shall have the meaning indicated:
(1) 
Accelerated Erosion — The removal of the surface of the land through the combined action of human activities and the natural processes, at a rate greater than would occur because of the natural process alone.
(2) 
Alteration — As applied to land a change in topography as a result of the moving of soil and rock from one location or position to another; the changing of surface conditions by causing the surface to be more or less impervious; or, earth disturbance.
(3) 
Applicant — A landowner, developer or other person who has filed an application for approval to engage in any regulated earth disturbance at a project site in the Township.
(4) 
BMP (Best Management Practice) — Activities, facilities, designs, measures or procedures used to manage stormwater impacts from regulated earth disturbance activities, to meet state water quality requirements, to promote groundwater recharge and to otherwise meet the purposes of this chapter. BMPs include, but not limited to, infiltration, filter strips, low-impact design, bioretention, wet ponds, permeable paving, grassed swales, forested buffers, vegetative controls, sand filters and detention basins.
(5) 
BMP Operations and Maintenance Plan — The plan, prepared at the direction of the applicant, indicating how stormwater runoff will be managed at the particular site of interest according to this chapter.
(6) 
Conservation District — The Montgomery County Conservation District.
(7) 
Conveyance — A stormwater management facility designed to transmit stormwater runoff which shall include streams, channels, swales, pipes, conduits, culverts, storm sewers, etc.
(8) 
Cut — An excavation; the difference in vertical elevation between a point on the surface of original ground and a point on the final grade; or the material removed in excavation.
(9) 
Dam — An artificial barrier, together with its appurtenant works, constructed for the purpose of impounding or storing water or another fluid or semifluid, or a refuse bank, fill or structure for highway, railroad or other purpose which does or may impound water or another fluid or semifluid.
(10) 
DEP — The Pennsylvania Department of Environmental Protection.
(11) 
Design Storm — The magnitude and temporal distribution of precipitation from a storm event measured in probability of occurrence (e.g., a five-year storm) and duration (e.g., 24 hours), used in the design and evaluation of stormwater management systems.
(12) 
Designee — The agent of Lower Gwynedd Township involved with the administration, review or enforcement of any provisions of this chapter by contract or memorandum of understanding.
(13) 
Detention Basin — An impoundment structure designed to manage stormwater runoff by temporarily storing the runoff and releasing it at a predetermined rate.
(14) 
Developer — A person that seeks to undertake any regulated earth disturbance activities at a project site in the Township.
(15) 
Development — See "earth disturbance activity." The term includes redevelopment.
(16) 
Development Site — The specific tract of land where any regulated earth disturbance activities in the Township are planned, conducted or maintained.
(17) 
Drainage Easement — A right granted by a landowner to a grantee, allowing the use of private land for stormwater management purposes.
(18) 
Earth Disturbance Activity — A construction or other human activity which disturbs the surface of the land, including, but not limited to, clearing and grubbing, grading, excavations, embankments, road maintenance, building construction and the moving, depositing, stockpiling or storing of soil, rock or earth materials.
(19) 
Erosion — The process by which the surface of the land, including channels, is worn away by water, wind or chemical action.
(20) 
Erosion and Sediment Control Plan — A plan for a project site which identifies BMPs to minimize accelerated erosion and sedimentation.
(21) 
Existing Conditions — The initial condition of a project site prior to the proposed construction.
(22) 
Fill — Any act by which earth, sand, gravel, rock or any other material is placed, pushed, dumped, pulled, transported or moved to a new location above the natural surface of the ground or on top of the stripped surface, including the conditions resulting therefrom; the difference in elevation between a point on the original ground and a designated point of higher elevation on the final grade; or the material used to make a fill.
(23) 
Freeboard — A vertical distance between the elevation of the design high water and the top of a dam, levee, tank, basin or diversion swale. The space is required as a safety margin in a pond or basin.
(24) 
Grade — A slope, usually of a road, channel or natural ground, specified in percent and shown on plans as specified herein.
A. 
(To) Grade — To finish the surface of a roadbed, top of embankment or bottom of excavation.
(25) 
Groundwater Recharge — Replenishment of existing natural underground water supplies.
(26) 
Impervious Surface — A surface that prevents the infiltration of water into the ground. Impervious surface includes, but is not limited to, any roof, bituminous or concrete parking or driveway areas and any new streets and sidewalks. Any surface areas designed to initially be gravel or crushed stone shall be assumed to be impervious surface. Previous paving materials shall always be considered an impervious surface for the purpose of calculating impervious surfaces/coverage limits under this chapter, Chapter 1230 (Subdivision and Land Development), and Title Six (Zoning), and such previous paving materials shall not be permitted to be installed for groundwater recharge purposes unless a maintenance agreement is entered into by and between the developer and the Township for the perpetual maintenance and repair of the previous paving materials, and provided further that a cash escrow is deposited with the Township, in an amount satisfactory to the Township Engineer, to ensure the perpetual maintenance and repair the same.
[Amended 8-25-2015 by Ord. No. 500]
(27) 
Impoundment — A retention or detention basin designed to retain stormwater runoff and release it at a controlled rate.
(28) 
Infiltration Structures — A structure designed to direct runoff into the ground (e.g., seepage pits, seepage trench)
(29) 
Inlet — A surface connection to a closed drain; a structure at the diversion end of a conduit; the upstream end of any structure through which water may flow.
(30) 
NPDES — National Pollutant Discharge Elimination System, the federal government's system for issuance of permits under the Clean Water Act, which is delegated to DEP in Pennsylvania.
(31) 
NRCS — Natural Resource Conservation Service (previously SCS).
(32) 
Open Channel — A drainage element in which stormwater flows with an open surface. Open channels include, but shall not be limited to, natural and man-made drainageways, swales, streams, ditches, canals and pipes flowing partly full.
(33) 
Outfall — A point source as described in 40 CFR § 122.2 at the point where the Township's storm sewer system discharges to surface waters of the commonwealth.
(34) 
Outlet — Points of water disposal from a stream, river, lake, tidewater or artificial drain.
(35) 
Peak Discharge — The maximum rate of stormwater runoff from a specific storm event.
(36) 
Person — An individual, partnership, public or private association or corporation or a governmental unit, public utility or any other legal entity whatsoever which is recognized by law as the subject of rights and duties.
(37) 
Pipe — A culvert, closed conduit or similar structure (including appurtenances) that conveys stormwater.
(38) 
Point Source — Any discernable, confined and discrete conveyance, including, but not limited to, any pipe, ditch, channel, tunnel or conduit from which stormwater is or may be discharged, as defined in State Regulation at 25 Pa. Code § 92.1.
(39) 
Project Site — The specific area of land where any regulated earth disturbance activities in the Township are planned, conducted or maintained.
(40) 
Recharge Volume — The calculated volume of stormwater runoff from impervious areas which is required to be infiltrated at a site and may be achieved through use of structural or nonstructural BMPs.
(41) 
Redevelopment — Earth disturbance activities on land which has previously been disturbed or developed.
(42) 
Regulated Earth Disturbance Activity — Earth disturbance activity of one acre or more, or any disturbance requiring submission of a land development plan. This includes an earth disturbance activity on any portion of, part or during any state of a larger common plan of development. This only includes road maintenance activities involving 25 acres or more of earth disturbance.
(43) 
Return Period — The average interval, in years, within which a storm event of a given magnitude can be expected to occur. For example, the twenty-five-year return period rainfall would be expected to occur on the average once every 25 years or have a four percent chance of occurring every year.
(44) 
Riser — A vertical pipe extending from the bottom of a pond that is used to control the discharge rate from the pond for a specified design storm.
(45) 
Road Maintenance — Earth disturbance activities within the existing road cross-section, such as grading and repairing existing unpaved road surfaces, cutting road banks, cleaning or clearing drainage ditches and other similar activities.
(46) 
Runoff — Any part of precipitation that flows over the land surface.
(47) 
Sediment Basin — A barrier, dam, retention or detention basin located and designed to retain rock, sand, gravel, silt or other material transported by water.
(48) 
Sediment Pollution — The placement, discharge or any other introduction of sediment into the waters of the commonwealth occurring from the failure to design, construct, implement or maintain control measures and control facilities in accordance with the requirement of this chapter.
(49) 
Sedimentation — The process by which mineral or organic matter is accumulated or deposited by the movement of water.
(50) 
Separate Storm Sewer System — A conveyance or system of conveyances (including roads with drainage systems, Township streets, catch basins, curbs, gutters, ditches, man-made channels or storm drains) primarily used for collecting and conveying stormwater runoff.
(51) 
Sheet Flow — Runoff that flows over the ground surface as a thin, even layer, not concentrated in a channel.
(52) 
Soil-Cover Complex Method — A method of runoff computation developed by the NRCS that is based on relating soil type and land use/cover to a runoff parameter called "curve number" (CN).
(53) 
Soil Group, Hydrologic — A classification of soils by the NRCS into four runoff potential groups. The groups range from A soils, which are very permeable and produce little runoff, to D soils, which are not very permeable and produce much more runoff.
(54) 
Spillway — A depression in the embankment of a pond or basin which is used to pass peak discharge greater than the maximum design storm controlled by the pond.
(55) 
State Water Quality Requirements — As defined under state regulations, protection of designated and existing uses (see 25 Pa. Code Chapters 93 and 96), including:
A. 
Each stream segment in Pennsylvania has a designated use, such as cold water fishery or potable water supply which is listed in Chapter 93. These uses must be protected and maintained under state regulations.
B. 
"Existing uses" are those attained as of November, 1975, regardless of whether they have been designated in Chapter 93. Regulated earth disturbance activities must be designed to protect and maintain existing uses and maintain the level of water quality necessary to protect those uses in all streams and to protect and maintain water quality in special protection streams.
C. 
Water quality involves the chemical, biological and physical characteristics of surface water bodies. After regulated earth disturbance activities are complete, these characteristics can be impacted by addition of pollutants such as sediment, and changes in habitat through increased flow volumes and/or rates, as a result of changes in land surface area from those activities. Therefore, permanent discharges to surface waters must be managed to protect the stream bank, streambed and structural integrity of the waterway to prevent these impacts.
(56) 
Storm Frequency — See "return period."
(57) 
Storm Sewer — A system of pipes and/or open channels that convey intercepted runoff and stormwater from other sources, but excludes domestic sewage and industrial wastes.
(58) 
Stormwater — The surface runoff generated by precipitation reaching the ground surface.
(59) 
Stormwater Management Facility — Any structure, natural or man-made, that, due to its condition, design or construction, conveys, stores or otherwise affects stormwater runoff. Typical stormwater management facilities include, but are not limited to, detention and retention basins, open channels, storm sewers, pipes and infiltration structures.
(60) 
Subarea — The smallest drainage unit of a watershed for which stormwater management criteria have been established in the stormwater management plan.
(61) 
Surface Waters of the Commonwealth — Any and all rivers, streams, creeks, rivulets, impoundments, ditches, watercourses, storm sewers, lakes, dammed water, wetlands, ponds, springs and all other bodies or channels of conveyance of surface water, or parts thereof, whether natural or artificial, within or on the boundaries of this commonwealth.
(62) 
Swale — A low-lying stretch of land which gathers or carries surface water runoff.
(63) 
Time of Concentration (Tc) — The time for surface runoff to travel from the hydraulically most distant point of the watershed to a point of interest within the watershed. This time is the combined total of overland flow time, concentrated flow time and flow time in pipes or channels, if any.
(64) 
Township — Lower Gwynedd Township, Montgomery County, Pennsylvania.
(65) 
Tree Dripline — A boundary line marking the outer edges of the branches of a tree.
(66) 
Tree Protection Zone — An area 15 feet radially from the trunk of the tree to be retained or the distance from the trunk to the tree dripline, whichever is greater, in which no construction activity shall occur. Where there is a group of trees or woodlands, the tree protection zone shall be the aggregate of the protection zones for the individual trees.
(67) 
Watercourse — A channel or conveyance of surface water, such as a stream or creek, having defined bed and banks, whether natural or artificial, with perennial or intermittent flow.
(68) 
Watershed — Region or area drained by a river, watercourse or other body of water, whether natural or artificial.

§ 1241.03 Stormwater management for water quality.

[Ord. 434. Passed 6-21-2005]
(a) 
General Requirements for Stormwater Management.
(1) 
All regulated earth disturbance activities and land developments within the Township shall be designed, implemented, operated and maintained to meet the purposes of this chapter through these three elements:
A. 
Erosion and sediment control prevention during the earth disturbance activities;
B. 
Water quality protection measures after completion of earth disturbance activities, including operations and maintenance; and
C. 
Stormwater runoff rate and volume control.
(2) 
No regulated earth disturbance activities within the Township shall commence until the requirements of this chapter are met.
(3) 
Erosion and sediment control during regulated earth disturbance activities shall be addressed as required by Section 1241.03(c).
(4) 
Postconstruction water quality protection shall be addressed as required by Section 1241.03(d). Operations and maintenance of permanent stormwater BMPs shall be addressed as required by Section 1241.04.
(5) 
All best management practices (BMPs) used to meet the requirements of this chapter shall conform to the state water quality requirements and any more stringent requirements as determined by the Township.
(6) 
For regulated earth disturbance activities within the Neshaminy Creek Watershed, the additional stormwater management provisions identified in Appendix 1241A of this chapter shall also be applicable.[1]
[Added 2-24-2015 by Ord. No. 497]
[1]
Editor's Note: Appendix 1241A is included as an attachment to this chapter.
(b) 
Permit Requirements by Other Government Entities. The following permit requirements apply to certain regulated earth disturbance activities and must be met prior to commencement of regulated earth disturbance activities, as applicable.
(1) 
All regulated earth disturbance activities subject to permit requirements by DEP under regulations at 25 Pa. Code Chapter 102.
(2) 
Work within natural drainageways subject to permit by DEP under 25 Pa. Code Chapter 105.
(3) 
Any stormwater management facility that would be located in or adjacent to surface waters of the commonwealth, including wetlands, subject to permit by DEP under 25 Pa. Code Chapter 105.
(4) 
Any stormwater management facility that would be located on a state highway right-of-way or require access from a state highway shall be subject to approval by the Pennsylvania Department of Transportation (PENNDOT).
(5) 
Culverts, bridges, storm sewers or any other facilities which must pass or convey flows from the tributary area and any facility which may constitute a dam subject to permit by DEP under 25 Pa. Code Chapter 105.
(c) 
Erosion and Sediment Control During Regulated Earth Disturbance Activities.
(1) 
No regulated earth disturbance activity or land development within the Township shall commence until approval by the Township Engineer and the Montgomery County Conservation District of an erosion and sediment control plan for construction activities.
(2) 
In addition, under 25 Pa. Code Chapter 92, a DEP NPDES Permit for Stormwater Discharges Associated with Construction Activities is required for any earth disturbance greater than one acre.
(3) 
Evidence of any necessary permit(s) for regulated earth disturbance activities from the appropriate DEP regional office or County Conservation District must be provided to the Township.
(4) 
A copy of the erosion and sediment control plan and any required permit, as required by DEP regulations, shall be available at the project site at all times.
(d) 
Water Quality Requirements After Regulated Earth Disturbance Activities Are Complete.
(1) 
No regulated earth disturbance activities within the Township, unless exempt under criteria listed in Section 1241.01(f), shall commence until approval by the Township Engineer of a plan which demonstrates compliance with water quality requirements listed in this chapter, after construction is complete.
(2) 
The BMPs must be designed, implemented and maintained to meet state water quality requirements and any other more stringent requirements as determined by the Township.
(3) 
Preconstruction stormwater infiltration and runoff conditions must be replicated so that postconstruction stormwater discharges do not degrade the physical, chemical or biological characteristics of any receiving waters.
(4) 
Water quality treatment BMPs must be used to ensure filtering out of the chemical and physical pollutants from stormwater runoff.
(5) 
The volume and rate of postconstruction stormwater discharges must be managed to prevent the physical degradation of receiving waters.
(6) 
Postconstruction stormwater BMPs in accordance with state and Township standards must be implemented with required operation and maintenance measures listed on the plan and in agreements signed by the landowner.
(7) 
Evidence of any necessary permit(s) for regulated earth disturbance activities from the appropriate DEP regional office must be provided to the Township.
(8) 
For regulated earth disturbance activities within the Neshaminy Creek Watershed, the additional stormwater management provisions identified in Appendix 1241A of this chapter shall also be applicable.[2]
[Added 2-24-2015 by Ord. No. 497]
[2]
Editor's Note: Appendix 1241A is included as an attachment to this chapter.

§ 1241.04 Stormwater BMP operations and maintenance plan requirements.

[Ord. 434. Passed 6-21-2005]
(a) 
General Requirements.
(1) 
No regulated earth disturbance activity or land development within the Township, unless exempt under criteria listed in Section 1241.01(f), shall proceed until approval by the Township Engineer of a BMP operations and maintenance plan, which describes how the permanent stormwater BMPs will be properly operated and maintained and contains all stormwater management facilities and erosion and sedimentation controls and their design computations.
(2) 
The following items shall be included with the BMP operations and maintenance plan:
A. 
Map(s) of the project area shall be submitted on twenty-four-inch by thirty-six-inch or thirty-inch by forty-two-inch sheet in a form that meets the requirements for recording at the offices of the Recorder of Deeds of Montgomery County. The contents of the map(s) shall include, but not be limited to:
1. 
Clear identification of the location and nature of permanent stormwater facilities and BMPs.
2. 
A location map showing the relation of the project site relative to adjoining highways, Township boundaries or other identifiable landmarks.
3. 
Existing and proposed contours at intervals of 2 feet, or others as appropriate, on the site and within 100 feet of the property lines.
4. 
A North arrow.
5. 
Written and graphic scales.
6. 
The property boundaries showing all courses, distances, area and Tax Map parcel numbers of adjoining properties.
7. 
Areas having slopes 15% and greater shall be shown on the map. The total steep slope area (less than 15%), and the amount disturbed.
8. 
Existing streams, lakes, ponds, wetlands or other bodies of water within the project site area and within 100 feet of the property lines.
9. 
Other physical features, including flood hazard boundaries, sinkholes, streams, existing drainage courses, underdrains, nonnatural water sources, recharge pits, wetlands, waters of the commonwealth, forested areas, prominent land forms and areas of natural vegetation to be preserved.
10. 
The locations of all existing and proposed utilities, on-site septic systems, wells, sanitary sewers and waterlines within 100 feet of property lines of the project site.
11. 
The soils on the site shall be delineated. Soils information, including the soil limitation classification and the hydrologic soil group.
12. 
Proposed final changes to the land surface and vegetative cover. The amount of impervious coverage and total land disturbance.
13. 
Proposed final structures, roads, paved areas and buildings.
14. 
A plan of the grading of the subject regulated earth disturbance.
15. 
A plan of the erosion and sedimentation control procedures to be utilized along with all design computations.
16. 
Landscape plan. A complete plan which identifies all landscape/vegetative BMP measures. The species, size, spacing and specific maintenance requirements for plantings and seeding shall be listed, including the mowing rates, if applicable, and the seeding mixes and rates.
17. 
Stormwater management plan. A complete plan of the stormwater drainage system showing all pipes, swales, channels, structures and detention basins and/or other existing and proposed stormwater management facilities shall be submitted as part of the stormwater management plan. The drainage areas into each inlet or structure must be delineated on the plan of the stormwater drainage system.
18. 
A suitable map of the total watershed with predevelopment and postdevelopment areas outlined.
19. 
Suitable maps and drawings showing all existing and proposed drainage facilities affecting the subject property.
20. 
The following information shall be included in the stormwater report and calculations.
(A) 
A general description of the proposed development.
(B) 
A general description of temporary and permanent accelerated erosion control.
(C) 
A general description of temporary and permanent sedimentation control.
(D) 
A general description of stormwater management both during and after development.
(E) 
A study of the watershed in which the site is located to assess the impact the proposal will have on downstream conditions.
(F) 
Computations of the stormwater runoff for all points of runoff concentration before and after development, including:
[1] 
The design computations for the stormwater drainage systems, including storm drain pipes and inlets, runoff control measures and culverts and drainage channels.
[2] 
Computations of the stormwater runoff before, during and after construction, including all supporting material.
[3] 
The flood routing and/or storage requirement calculations.
(G) 
The estimated development schedule for the site, including:
[1] 
Stripping and/or clearing.
[2] 
Rough grading and installation of erosion and sediment control facilities and practices.
[3] 
Installation of improvements, including streets, underground utilities, buildings, driveways, parking areas and other structures and facilities.
[4] 
Final grading and vegetative establishment, including program of operations for conversion of erosion and sediment controls to permanent stormwater management facilities.
(H) 
A map and statement describing temporary control measures and facilities for use during earthmoving.
[1] 
Types, locations and dimensional details of erosion and sedimentation control.
[2] 
Protection of existing trees and shrubs.
[3] 
Facilities to prevent tracking of mud by construction vehicles off the site.
(I) 
A permanent stormwater management program.
[1] 
A statement regarding conformance with requirements of this chapter, including BMPs.
[2] 
Types, locations, dimensioned details and specifications of stormwater management facilities and BMPs, including:
[a] 
Detailed plans of the trash rack and antivortex device, if required.
[b] 
Detailed plans of all required off-site improvements.
[3] 
Design considerations and calculations supporting the stormwater management program, including:
[a] 
A stage storage curve for all detention/retention basins.
[b] 
Computations for the sizing of the pipe barrel and perforated riser.
[4] 
Establishment of permanent vegetation or other soil stabilization measures, including:
[a] 
All landscape and vegetative BMP measures.
[b] 
Seeding mixes and rates.
[c] 
Mowing rates, if applicable.
[5] 
The location of wells and septic tank leach fields.
[6] 
The location and legal descriptions of rights-of-way, easements or lands offered for dedication related to the management of stormwater.
(J) 
Maintenance procedures and ownership arrangements for temporary and permanent stormwater management facilities, including BMPs.
[1] 
Methods and frequency of removing and disposing of sediment and other materials from stormwater management facilities both during and upon completion of the project.
[2] 
Proposed ownership and financial responsibility for permanent stormwater management facilities, including BMPs.
[3] 
Operating and maintenance arrangements for permanent stormwater management facilities and BMPs, including the identity of the person(s) responsible for such operations and maintenance.
21. 
For detention basins, the following information shall be submitted.
(A) 
General description of proposed facilities and the operation of the runoff control measures.
(B) 
A sketch of the berm embankment and outlet structure, indicating the embankment top elevation, embankment side slopes, top width of embankment, slope of basin floor, emergency spillway elevation, outlet structure dimensions, outlet pipe size and length, cut-off trench location and dimensions, dimensions and spacing of anti-seep collars, and if required, temporary riser location and dimensions.
(C) 
Design computations of the outlet pipe and outlet structure.
(D) 
A plot of the stage/storage (acre/feet versus elevation) and all supporting computations.
(E) 
Flood routing computations and hydrographs for all required storms.
(F) 
Time of concentration and curve number computations.
(G) 
A detailed plan of the trash rack and anti-vortex device, if required.
(H) 
A plan showing the grading and landscaping around the detention basin.
B. 
A description of how each permanent stormwater BMP will be operated and maintained, the frequency of the required maintenance and the identity of the person(s) responsible for operations and maintenance.
C. 
The lot, tax parcel number and street address of the project site, the name and address of the owner of the property, the name and address of the developer or equitable owner of property and the name, address and seal of the registered professional engineer responsible for the preparation of the plan.
D. 
A statement, signed by the landowner, acknowledging that the stormwater BMPs are fixtures that can be altered or removed only after approval by the Township.
E. 
Certification of ownership and desire to record the plan.
(b) 
Responsible for Operation and Maintenance of BMPs.
(1) 
The BMP operations and maintenance plan for the project site shall establish responsibilities for the continuing operation and maintenance of all permanent stormwater BMPs, as follows:
A. 
Maintenance by Township after dedication. If the Township accepts dedication of lands on which stormwater management facilities are located, appropriate long-term financial security shall be provided by the developer in an amount to be established from time to time by the Board of Supervisors by resolution.
B. 
Maintenance by private entity/individual lot owner. When a private entity or individual lot owner retains ownership of a stormwater management facility, such entity shall be responsible for the maintenance of the facility, and approval of the plans shall be conditioned upon the private entity or individual lot owner agreeing to be responsible for all maintenance of the facility. Such agreement shall be in writing, be in recordable form and shall, in addition to any other terms deemed necessary by the Township, contain a provision permitting inspection by Lower Gwynedd Township or its designee of all such facilities. A description of the facility or systems and the terms of the required maintenance shall be incorporated on the recorded subdivision, land development or regulated earth disturbance activity plan of the property. In addition, the Township may require as a condition of plan approval that any deed conveying any interest in such lot contain language indicating that the conveyance is subject to an express covenant by the grantee that the grantee will maintain the stormwater management facility.
C. 
Maintenance programs for stormwater and sedimentation control facilities. As part of the requirement for plan approval, specific maintenance programs for all stormwater management facilities shall be included on the final record plans. In addition, maintenance programs for both the temporary and permanent erosion and sedimentation control facilities, including disposal of materials removed from the control facilities or project area, must be included on the plans. The maintenance programs must include a schedule for inspection of the various control measures and facilities. At a minimum, the sediment control facilities should be inspected after each storm event, as well as on a weekly basis. The BMP facilities maintenance schedule should follow the recommendations in the Pennsylvania Handbook of BMP Practices for Developing Areas or the Pennsylvania Stormwater BMP Manual. The type of maintenance, such as clean-out, repair, replacement, regrading and reseeding for each of the control measures and facilities, is also to be included in the plan.
D. 
Unauthorized alteration or failure to maintain. Any unauthorized alteration of a stormwater or sedimentation control swale, basin, structure or facility, or the failure of any person, individual lot owner or private entity to properly maintain any stormwater management facility shall be construed to be a violation of this chapter and is declared to be a public nuisance, subjecting the violator to any and all penalties, or as otherwise provided by law.
(2) 
The Township shall make the final determination on the continuing operations and maintenance responsibilities. The Township reserves the right to accept or reject the operations and maintenance responsibility for any or all of the stormwater BMPs.
(c) 
Township Review of BMP Operations and Maintenance Plan.
(1) 
The Township shall review the BMP Operations and Maintenance Plan for consistency with the purposes and requirements of this chapter and any permits issued by DEP.
(2) 
The Township shall notify the applicant, in writing, whether the BMP operations and maintenance plan is approved.
(3) 
An as-built survey of all stormwater BMPs and an explanation of any discrepancies with the BMP operations and maintenance plan must be submitted to the Township in paper and digital (.dwg) formats.
(d) 
Adherence to Approved Plan. It shall be unlawful to alter or remove any permanent stormwater BMP required by an approved BMP operations and maintenance plan or to allow the property to remain in a condition which does not conform to an approved BMP operations and maintenance plan unless an exception is granted in writing by the Township. A note shall be placed on the plan stating this requirement.
(e) 
Operations and Maintenance Agreement for Privately Owned Stormwater BMPs.
(1) 
The property owner shall sign an operations and maintenance agreement with the Township covering all stormwater facilities and BMPs that are to be privately owned. The agreement shall be in a form approved by the Board of Supervisors.
(2) 
Other items may be included in the agreement where determined necessary to guarantee the satisfactory operation and maintenance of all permanent stormwater facilities and BMPs. The agreement shall be subject to the review and approval of the Township.
(f) 
Stormwater Management Easements.
(1) 
Where stormwater or surface water will be gathered, discharged or drained over lands within or beyond the boundaries of the subdivision, land development or regulated earth disturbance activity site, the applicant or owner shall reserve or obtain easements over all lands affected thereby, provided that no easement or right-of-way for drainage purposes exists on such affected land. Such easements shall be adequate for such discharge of drainage and for the carrying off of such water and for the maintenance, repair and reconstruction of the same, including the right of passage over and upon the same by vehicles, machinery and other equipment for such purposes, and which shall be of sufficient width for such passage and work and that would provide ingress to and egress from a public right-of-way. The width of the easement shall be determined by the Township Engineer, but in no case be less than 20 feet in width. The owner shall convey, free of charge or cost, such easements to the Township upon demand.
(2) 
Stormwater management easements shall be provided by the property owner if necessary for access for inspections and maintenance or preservation of stormwater runoff conveyance, infiltration and detention areas and other BMPs, by persons other than the property owner. The purpose of the easement shall be specified in the operations and maintenance agreement.
(3) 
All easements shall be fully described with metes and bounds on the BMP operations and maintenance plan.
(4) 
The following note shall be placed on all plans which propose permanent BMPs: "The BMP facilities shown on these plans are a basic and perpetual part of the stormwater management system for the proposed site located in Lower Gwynedd Township, Montgomery County, and as such are to be protected and preserved in accordance with the approved plans by the owners, their successors and assigns of these lands. Lower Gwynedd Township and/or its agents reserve the right and privilege to enter upon these lands from time to time for the inspection of said facilities in order to determine that the structural and design integrity is being maintained and the proper operation and maintenance of the facility is being conducted."
(g) 
Recording of Approved BMP Operations and Maintenance Plan and Related Agreements.
(1) 
The owner of any land upon which permanent BMPs will be placed, constructed or implemented, as described in the BMP operations and maintenance plan, shall record the following documents in the Office of the Recorder of Deeds for Montgomery County within 15 days of approval of the Stormwater BMP operations and maintenance plan by the Township:
A. 
The operations and maintenance plan, or a summary thereof;
B. 
Operations and maintenance agreements under Section 1241.04(e), and
C. 
Easements under Section 1241.04(f).
(2) 
The Township may suspend or revoke any approvals granted for the project site upon discovery of the failure of the owner to comply with this subsection.
(h) 
Plan Submission. For the purpose of complying with this chapter, the below steps shall be followed for a BMP operations and maintenance plan submission. For any activities that require a DEP joint permit application and regulated under Chapter 105 (Dam Safety and Waterway Management) or Chapter 106 (Floodplain Management) of DEP's Rules and Regulations, require a PENNDOT highway occupancy permit or require any other permit under applicable state or federal regulations, the permit(s) shall be part of the plan.
(1) 
Three copies of the BMP operations and maintenance plan accompanied by the requisite Township review fee shall be submitted, except as required in the Subdivision and Land Development Regulations for preliminary plan submission.

§ 1241.05 Design criteria and requirements.

[Ord. 434. Passed 6-21-2005]
(a) 
Design Criteria.
(1) 
General.
A. 
All land areas shall be graded to secure proper drainage away from buildings and to prevent the collection of stormwater pools. Drainage provisions shall be of such design as to carry surface waters to the nearest practical adequate street, storm drain, or natural watercourse. The developer shall construct and/or install such drainage structures and/or pipes as are determined by the Township Engineer to prevent erosion, damage and siltation, and to satisfactorily carry off surface waters. The rate of stormwater runoff from any proposed subdivision, land development, or regulated earth disturbance activity within the Wissahickon Watershed after full development shall not exceed the peak rate of discharge prior to development. For any proposed subdivision, land development, or regulated earth disturbance activity within the Neshaminy Creek Watershed, post development rates of runoff shall not exceed the peak rates of runoff identified in Appendix 1241A of this chapter.[1]
[Amended 2-24-2015 by Ord. No. 497]
[1]
Editor's Note: Appendix 1241A is included as an attachment to this chapter.
B. 
Stormwater discharge shall be carried by conduit to prevent excessive surface flow on or across streets, sidewalks, drives, parking areas and any other paved surface or traveled way where infiltration practices such as previous paving would not be feasible. Culverts or bridges shall be required at all stream crossings of any street or roadway, using design criteria for a one-hundred-year peak flow rate. Natural swales or open drains of any type may be used only where there is no danger to structures or abutting property.
C. 
Identified natural watercourses (streams or creeks) which have continuous flow shall remain open and shall not be piped or covered unless required by the Board of Township Supervisors as approved by the Township Engineer and DEP.
D. 
The stormwater management plan for each regulated earth disturbance activity or land development shall take into account and provide for upstream areas within the entire watershed in computing discharge quantities, sizing of pipes, inlets and other structures. The runoff from any proposed development shall be subject to evaluation which includes the anticipated runoff from other existing or proposed developments within the same watershed. Stormwater management facilities designed to serve more than one property or development in the same watershed are encouraged, in which case consultation with the Township is required prior to design.
E. 
The Board of Supervisors may require, based upon the advice of the Township Engineer, stormwater retention or detention devices, basins, subsurface recharge facilities or other delayed-release devices or designs to contain the excess storm discharge and prevent downstream flow increases an/or encourage groundwater recharge.
(2) 
Storm Sewer.
A. 
Storm sewers (pipes or other structures) shall be reinforced concrete pipe, have a minimum grade of 1/2% and a minimum inside diameter of 18 inches or a cross-sectional area of 254 square inches. Roof drains or yard drains shall not connect to any sanitary sewer and shall not discharge water directly over any sidewalk. Storm drainage facilities should be located within the paved areas of roadways. Where storm sewers discharge into existing drainage channels at an angle greater than 30° with the downstream channel flow, the far side bank shall be stabilized by the use of riprap or masonry and/or concrete walls. The stabilization shall be designed to prevent erosion and frost heave under and behind the stabilizing media.
B. 
Storm sewer systems shall be constructed in accordance with Township specifications, which are approved by resolution of the Board of Supervisors. If a particular design or device is not specifically approved within the Township specifications, the Township Engineer must review and approve the same.
(3) 
Erosion and Sedimentation Control. Prior to the commencement of any regulated earth disturbance activity or land development, the following criteria shall be met:
A. 
No changes shall be made in the contour of the land and no grading, excavating, removal or destruction of the topsoil, trees or other vegetative cover of the land shall be commenced until such time as a plan for minimizing soil erosion and sedimentation has been submitted and approved.
B. 
Measures used to control erosion and reduce sedimentation shall, as a minimum, meet the standards and specifications of the Pennsylvania Department of Environmental Protection. The Township Engineer shall ensure compliance with the appropriate specifications, copies of which are available from the district.
C. 
Plans shall preserve salient natural features, keep cut/fill operations to a minimum and ensure conformity with natural topography so as to create the least erosion potential and adequately handle the volume and velocity of surface water runoff. Whenever feasible, natural vegetation shall be retained, protected and supplemented. The disturbed area and the duration of exposure shall be kept to a practical minimum. Disturbed soils shall be stabilized as quickly as practicable. Temporary vegetation and/or mulching shall be used to protect critical areas during development.
D. 
The permanent (final) vegetation, erosion control and drainage shall be installed as soon as practical in the development. Provisions shall be made to effectively accommodate the increased runoff caused by changed soil and surface conditions during and after development. Sediment in all runoff water shall be trapped by the use of filters, sediment basins, silt traps or similar measures until the disturbed area is fully stabilized. Such devices shall be periodically cleaned of all silt and debris to ensure proper operation.
E. 
During grading operations, necessary measures for dust control must be exercised.
F. 
Grading equipment will not be allowed to cross-flowing streams. Provision shall be made for the installation of temporary culverts or bridges which are subject to DEP approval.
G. 
Permanent retention or detention basins shall be provided when required by the Board. The location of such basins shall be approved by the Board upon advice from the Township Engineer.
H. 
No person, corporation or other entity shall block, impede the flow of, alter, construct any structure or deposit any material or thing or commit any act which will affect normal or flood flow in any swale, stream or watercourse without having obtained prior approval from the Township and/or the Pennsylvania Department of Environmental Protection, whichever is applicable. It is the responsibility of any person, corporation or other entity doing any act on or across a communal stream, watercourse or swale or upon the floodplain or right-of-way during the period of the activity to return it to its original or equal condition after such activity is completed.
I. 
Whenever sedimentation is caused by stripping vegetation, regrading or other development, it shall be the responsibility of the person, corporation or other entity causing such sedimentation to remove it from all adjoining surfaces, drainage systems and watercourses and to repair any damage at his expense as quickly as possible.
J. 
Maintenance of all drainage facilities and watercourses, both existing and proposed, within the proposed site shall be the responsibility of the developer until such time as one of the following is accomplished:
1. 
A right-of-way for these facilities is offered for dedication by the developer and is accepted by the Township, at which time it shall then be the responsibility of the Township.
2. 
An easement acceptable to the Township is established. In the case of a subdivision, the maintenance shall then be the responsibility of the individual lot owners over whose property the easement passes. For land developments or regulated earth disturbance activities, the maintenance shall thereafter be the responsibility of the owner.
3. 
A homeowners' association, approved by the Township, assumes responsibility for the maintenance of the development, including the maintenance of the watercourses and/or drainage facilities, provided that the Township Engineer approves the assumption of maintenance of such facilities.
K. 
The installation and design of the required BMPs shall be in accordance with standards and specification found in DEP's Erosion and Sediment Pollution Control Program Manual dated April 15, 2000, or latest edition, the Pennsylvania Handbook of Best Management Practices for Developing Areas or the Pennsylvania Stormwater BMP Manual.
L. 
Criteria contained in this chapter shall not remove or alter the requirement for the developer to submit plans and specifications to the Pennsylvania Department of Environmental Protection under the Clean Streams Act of 1972 where Department of Environmental Protection's permits are required.
M. 
Three days prior to the commencement of any operation in the construction or installation of any drainage facility or erosion and sedimentation control facility, the owner shall notify the County Conservation District and the Township Engineer, who shall inspect the work, materials, construction and installation for compliance with Township requirements. The applicant shall be required to test materials as required by the Township Engineer.
N. 
Sediment basins, retention basins and detention basins shall neither be located within nor discharge into a tree protection zone where no established watercourse exists.
(b) 
Engineering Design Standards.
(1) 
General.
A. 
Storm drainage required. Overland or sheet flow is encouraged over concentrated flow. A storm sewer system and all appurtenances shall be required to be constructed by the developer or subdivider in any area from which the surface or subsurface drainage could impair public safety or cause physical damage to adjacent lands or public property. The system shall be designed to collect water at any point where three to five cubic feet per second is accumulated, at the bottom of all vertical grades and immediately upgrade from all street intersections. The system shall discharge to the nearest practical natural drainage channel or storm system.
B. 
Storm sewer and drainage facilities, such as gutters, catch basins, bridges and culverts, shall be installed; and, the land shall be graded for adequate drainage and in such a manner as to permit unimpeded flow of natural watercourses as shown on the grading plan submitted and approved with the land development or BMP operation and maintenance plan. Storm sewers shall be constructed so as to minimize erosion and maintenance costs.
C. 
Storm drainage facilities shall be designed to convey the flow of surface water without damage to persons or property. The system shall ensure drainage at all points along streets and shall provide positive drainage away from buildings and on-site wastewater disposal sites.
D. 
The Township may require a primarily underground system to accommodate frequent floods and a secondary surface system to accommodate larger, less frequent floods. Drainage plans shall be consistent with local and regional drainage plans. The facilities shall be designed to prevent the discharge of excess runoff onto adjacent properties.
E. 
Off-site improvements. Any increase in runoff may require necessary corrective measures, including deeds of easement, deemed appropriate by the Board of Supervisors to alleviate any off-site drainage problem affected by the earth disturbance activity. The costs for such measures will be borne entirely by the developer or subdivider.
F. 
Total watershed evaluation. The future use of undeveloped areas upstream shall be taken into account in the design of all storm sewer systems. The capacity and maximum anticipated present flow of the body or system receiving the proposed system(s) discharge shall be calculated to verify its capability of receiving any additional flow caused by the development or subdivision. The runoff from any proposed development shall be subject to an evaluation which includes the anticipated runoff from other existing or proposed developments within the same watershed. Stormwater management facilities designed to serve more than one property or development in the same watershed are encouraged. Consultation with the Township is required prior to the design of such facilities.
G. 
In addition to any other requirement of this chapter, the developer may be required to participate in off-site storm drainage improvements in the drainage basin within which the proposed development is located.
(2) 
Underdrains.
A. 
All building foundations, grade slabs and basement floors located in soils that have a limitation degree of moderate to severe seasonal high water table, as defined by the Montgomery County Soil Survey, shall be provided with an underdrain system. This system shall provide for drainage of the enclosed volume above the slab and relief of subsurface water to a depth of not less than six inches below the slab or foundation bottom. The system shall consist of a perforated pipe field in coarse, gravel-filled trenches that are in direct contact with the slab or foundation subbase. The excavation shall provide a minimum of 0.05-foot/foot slope to the gravel-filled trenches.
B. 
All proposed roadways shall be constructed with an underdrain system consisting of six-inch perforated pipe wrapped in a Class 1 geotextile material. The underdrain shall be bedded with a minimum of 6 inches of 2B stone. The bedding material shall extend to the bottom of the base course. The underdrain shall discharge to an inlet.
(3) 
Storm Drain Pipes and Inlets.
A. 
All pipe and inlets shall meet material capacity and construction specifications as outlined in the latest revisions of the PENNDOT Form 408 and the PENNDOT Design Manual or as outlined in the Township specification as approved by resolution of the Board of Supervisors. Inlets at street intersections shall be placed on the tangent and not on the curved portion.
B. 
Design flow rate. The storm drain system shall be designed to carry a one-hundred-year peak flow rate. The design one-hundred-year peak flow rate into each inlet shall be indicated on the stormwater drainage plan. The one-hundred-year flow rate shall be determined by the rational formula as follows:
Q
=
CiA
Where:
Q
=
Peak runoff rate in cubic feet per second (cfs)
C
=
Runoff coefficient equal to the ratio of the peak runoff rate to the average rate of rainfall over a time period equal to the time of concentration.
i
=
Average rainfall intensity in inches per hour for a time equal to the time of concentration.
A
=
Drainage area in acres.
NOTE: Appropriate values for the runoff coefficient and rainfall intensity can be found in the commonwealth of Pennsylvania Department of Transportation Design Manual, Part 2, Highway Design, Chapter 10.
C. 
Overflow system. An overflow system shall be provided to carry flow to the detention basin when the capacity of the storm drain pipe system is exceeded.
D. 
Inlet capacity. All inlets must be designed to accommodate the one hundred-year peak flow rate. The capacity of all C-type, M-type or S-type inlets shall be determined from the commonwealth of Pennsylvania Department of Transportation Design Manual, Part 2, Highway Design.
E. 
Straight pipe sections. Wherever possible, all storm drain pipes shall be designed to follow straight courses. No angular deflections of storm sewer pipe sections in excess of 5° shall be permitted. No vertical curves shall be permitted in the storm drain pipe system.
F. 
Minimum grade and size. All storm drain pipes shall be reinforced concrete pipe designed to maintain a minimum grade of 1/2%. All storm pipes shall have a minimum inside diameter of 18 inches or a cross-sectional area of 254 square inches, except that pipes under a fill of 25 feet or greater shall not be less than 24 inches or have a cross-sectional area of less than 453 square inches.
G. 
Pipe capacity. The capacity of all pipe culverts shall, as a minimum, provide the required carrying capacity as determined by the following sources:
1. 
United States Department of Transportation.
2. 
Federal Highway Administration.
3. 
Hydraulic Design Series Number 5.
4. 
Hydraulic Design of Highway Culverts, Second Edition.
H. 
Pipe arches. Where headroom is restricted, equivalent pipe arches may be used in lieu of circular pipe.
I. 
Allowable headwater depth. At all inlets or manholes, the maximum allowable headwater depth shall be one foot below the top of the inlet grate or the manhole cover.
J. 
Horizontal pipe deflections. A manhole or inlet shall be provided at all horizontal deflections in the storm pipe system exceeding 5°.
K. 
Minimum and maximum cover. A minimum of three feet of cover shall be maintained over all storm drain pipes in yard areas. The top of storm drain pipes shall be at least 1/2 foot below subgrade elevation. The maximum cover over storm drain pipes shall be 10 feet unless special structural design calculations are submitted or approved.
L. 
Match crowns. The crowns of all pipes tying into an inlet or manhole shall be set at equal elevations.
M. 
Diversions of runoff. All storm drain pipes shall be designed to carry the runoff into a detention basin or similar facility utilized to protect water quality or to control the rate of runoff.
N. 
Manholes. Manholes shall not be more than 400 feet apart where pipe sizes of 24 inches or less are used, and not more than 450 feet apart where larger sizes are installed. Manholes shall be installed at all points of abrupt change in alignment.
O. 
Structural backfill. All storm drainage structures shall be backfilled in twelve-inch layers with 2A material to a dimension at the base of the structure 12 inches outside all faces of the structure tapering to a width of 24 inches outside all faces of the structure at the top of the structure in accordance with the drawing titled, "Lower Gwynedd Township Storm Drainage Structural Backfill," prepared by CKS Engineers, Inc., dated September 2004 (as may be amended from time to time by a resolution of The Board of Supervisors), which is included at the end of this chapter as Exhibit B and is expressly deemed a part hereof.
(4) 
Runoff Control.
A. 
The rate of stormwater runoff from any proposed subdivision or land development or regulated earth disturbance activity after full development shall not exceed the peak discharge prior to development. The two-year, five-year, ten-year, twenty-five year, fifty-year and one-hundred-year storms shall be fully analyzed. Where, in the judgment of the Township Engineer, the quantity of stormwater runoff will cause detrimental impact, quantity will be a consideration in the method of stormwater regulations. This standard shall be maintained for all storms, that is, both high-frequency and low-frequency.
B. 
Runoff control devices. The increased runoff which may result from any earth disturbance activity shall be controlled by permanent runoff control measures that will provide the required runoff control specified above. All runoff control devices will be evaluated for the effectiveness to maintain the above-mentioned standard for all storms with a return period of up to 100 years.
C. 
For all regulated earth disturbance activities within the Neshaminy Creek Watershed, post development rates of runoff shall not exceed those peak rates identified in Appendix 1241A of this chapter.[2]
[Added 2-24-2015 by Ord. No. 497]
[2]
Editor's Note: Appendix 1241A is included as an attachment to this chapter.
(5) 
Detention Basins/Stormwater Rate Management Facilities.
A. 
The use of regional detention basins to combine and eliminate numerous smaller basins is encouraged. Consultation with the Township is required prior to design of a regional detention basin.
B. 
Design of detention basins. All detention basins shall be designed as per the procedures developed by the United States Department of Agriculture, NRCS, as outlined in its Technical Release No. 55, Urban Hydrology for Small Watersheds, Soil Cover Complex Method. All other stormwater management facilities shall be designed in accordance with these specifications, the Pennsylvania Handbook of Best Management Practices for Developing Areas or the Pennsylvania Stormwater BMP Manual.
C. 
Basin design criteria. The following design criteria shall be used in the design of all detention basins and/or other stormwater management facilities in the Township. The basins shall be designed to detain the quantity of water resulting from a one-hundred-year, twenty-four-hour storm (see Soil Cover Complex Method, TR-55, by the NRCS) under full development conditions released at a maximum outflow rate equal to the peak discharge of the one-hundred-year storm prior to development. This criteria shall be met for all frequency storms and must be analyzed of the two-, five-, ten-, twenty-five-, fifty- and one-hundred-year storms. For all regulated earth disturbance activities within the Neshaminy Creek Watershed, post development rates of runoff shall not exceed those peak rates identified in Appendix 1241A of this chapter.[3] All flows in excess of the above-mentioned standard shall flow over an emergency spillway.
[Amended 2-24-2015 by Ord. No. 497]
[3]
Editor's Note: Appendix 1241A is included as an attachment to this chapter.
D. 
Maximum depth of detention basins. The maximum depth of water in a detention basin shall not exceed four feet.
E. 
Emergency spillway. Whenever possible, the emergency spillway for detention basins shall be constructed on undisturbed ground. Emergency spillways shall be constructed of reinforced concrete, vegetated earth or other approved material. All emergency spillways shall be constructed so that the detention basin berm is protected against erosion. The minimum capacity of all emergency spillways shall be equal to the peak flow rate from the postdevelopment one-hundred-year design storm. Emergency spillways shall extend along the upstream and downstream berm embankment slopes. The upstream edge of the emergency spillway shall be a minimum of three feet below the spillway crest elevation. The downstream slope of the spillway shall, as a minimum, extend to the top of the berm embankment. The emergency spillway shall not discharge over earthen fill and/or easily erodible material. The discharge path of the emergency spillway shall be evaluated to ensure that downstream properties or structures are not impacted.
F. 
Anti-seep collars. Anti-seep collars shall be poured-in-place concrete and installed around the principal pipe barrel within the normal saturation zone of the detention basin berms. The collar shall be poured against the pipe bell. The anti-seep collars and their connections to the pipe barrel shall be watertight. The anti-seep collars shall extend a minimum of two feet beyond the outside of the principal pipe barrel. The spacing between collars shall be 16 feet. The use of an O-ring pipe shall be required for all basin discharge pipes.
G. 
Freeboard. "Freeboard" is the difference between the design flow elevation in the emergency spillway and the top of the settled detention basin embankment. The minimum freeboard shall be one foot and the maximum freeboard shall be two feet.
H. 
Slope of detention basin embankment. The maximum slope of earthen detention basin embankments shall be 4 to 1. The top or toe of any slope shall be located a minimum of 10 feet from any property line. Whenever possible, the side slopes and basin shape shall be amenable to the natural topography. Straight side slopes and rectangular basins shall be avoided whenever possible.
I. 
Width of berm. The minimum top width of detention basin berms shall be 10 feet.
J. 
Slope of basin bottom. In order to ensure proper drainage of the detention basin, a minimum grade of 2% shall be maintained for all sheet flow. A minimum grade of 1% shall be maintained for all channel flow.
K. 
Energy dissipaters. Energy dissipating devices (riprap, level spreaders, end sills, etc.) shall be placed at all basin outlets. Forebays or split flow controls are encouraged at the inlet to all basins. When a forebay or split flow control is not used, an energy dissipating device shall be used. Riprap at the inlet to a basin shall extend to the bottom of the basin.
L. 
Key trench. All basin berms in fill areas are to have a key trench. The minimum depth shall be one foot and increased to a depth of three feet at the maximum point of fill. The minimum width of the key trench shall be 8 feet.
M. 
Landscaping and grading of detention basins. All landscaping and grading standards particularly applicable to detention basins as required by these specifications shall be met.
N. 
Detention basins in yard areas. Detention basins shall be allowed in the required yard areas only in accordance with the following regulations:
1. 
Single-family residential districts. In all single-family residential districts, where the lot is used for single-family residential purposes, no part of any detention basin shall occupy more than twenty-five percent of the required yard area, measured as to linear dimension or surface area. The detention basins shall be located on the perimeter of the lot, shall be entirely within the lot lines and shall be located as far from the dwelling as possible. If a property in a single-family residential district is used for other than a single-family dwelling, detention basins shall be located in accordance with Paragraph (b)(5)C hereof. No detention basin shall be located within 100 feet of any building, whether such building is on the same lot or any adjacent lot.
2. 
Multifamily residential districts. In all multifamily residential districts, where the lot is used for residential purposes, no part of any detention basin shall be located in the required yard area of any individual dwelling unit. No part of any detention basin shall occupy more than 35% of the required yard area, measured as to linear dimension or surface area, of any district yard. No detention basin shall be located within 100 feet of any building, whether such building is on the same lot or on any adjacent lot.
3. 
Nonresidential districts. In all nonresidential districts, no part of any detention basin shall occupy more than 15% of the required yard area, measured as to linear dimension or surface area. No detention basin shall be located within 200 feet of any building, whether such building is on the same lot or on any adjacent lot.
4. 
General regulations in all districts. In all districts, no part of any detention basin shall occupy any area or portion of the pedestrian or vehicular circulation system on the lot. No part of any detention basin shall be located within 25 feet of any property line. All manufactured parts of any detention basin shall be screened by evergreen plantings so as to be invisible from off of the property.
O. 
Underground detention basin. Underground stormwater detention may be accomplished by means of pipe storage or other acceptable methods. Construction materials, specifications and construction techniques for underground stormwater detention basins shall be in accordance with the drawing entitled "Lower Gwynedd Township Storage Basin," prepared by CKS Engineers, Inc., dated September 2004 (as may be amended by the resolution of the Board of Supervisors), which is included at the end of this chapter as Exhibit A and is expressly deemed a part thereof.
(6) 
Culverts and Drainage Channels.
A. 
Design flow standard. All culverts and drainage channels shall be designed to carry a flow rate equal to a one-hundred-year, twenty-four-hour storm (Soil Cover Complex Method by the NRCS, Technical Release No. 55).
B. 
Erosion prevention. All drainage channels shall be designed to prevent the erosion of the bed and bank areas. The flow velocity in all vegetated drainage channels shall not exceed the maximum permissible velocity to prevent erosion. Suitable bank stabilization shall be provided where required to prevent erosion of the drainage channels. Where storm sewers discharge into existing drainage channels at an angle greater than 30° from parallel to the downstream channel flow, the far-side bank shall be stabilized by the use of riprap or masonry and/or concrete walls. The stabilization shall be designed to prevent erosion and frost heave under and behind the stabilizing media.
C. 
Maximum side slope. Any vegetated drainage channel requiring mowing of the vegetation shall have a maximum grade of four horizontal to one vertical.
D. 
Design standard. Because of the critical nature of vegetated drainage channels, the design of all vegetated channels shall, as a minimum, conform to the design procedures outlined in the Erosion and Sediment Pollution Control Program Manual. Several acceptable sources outline procedures for nonvegetated drainage channels, including the following:
1. 
United States Department of Transportation.
2. 
Federal Highway Administration.
3. 
Hydraulic Design Series No. 5.
4. 
Hydraulic Design of Highway Culverts, Second Edition.
E. 
Bridges and culverts shall be designed to support expected loads and to carry expected flows and shall be constructed at least to the width of the cartway and to the full width of the right-of-way where appropriate. The design of culverts and bridges, through which streams drain over an area of one-half square mile, shall be approved by the Pennsylvania Department of Environmental Protection or its successor.
(7) 
Water Quality.
A. 
Any regulated earth disturbance shall specify permanent stormwater BMPs to be implemented, operated and maintained to meet legal water quality requirements.
B. 
In order to protect and maintain water quality, additional stormwater runoff created by the development project must be captured, stored and treated. The volume of additional stormwater runoff to be captured, stored and treated is called the "water quality volume" (WQv). The water quality volume is the storage capacity needed to treat 90 percent of the average annual stormwater rainfall from the developed areas of the site.
1. 
The following formula is used for determining WQv in acre-feet of storage:
WQv=[(.17)(Rv)(A)], where
A
=
Area in acres.
Rv
=
Volumetric Runoff Coefficient [0.05 + 0.009(I)], where I is the impervious surface ratio (example: I = 50 for 50 percent impervious cover)
2. 
Runoff treatment BMPs must be employed where necessary to ensure the water quality requirements are met.
C. 
The volume and rate of any stormwater discharge permitted under this chapter must be managed to prevent the physical degradation of receiving waters, such as by streambank scour and erosion. If a detention facility is proposed which is part of the BMPs approved for the project, the facility(ies) must be designed to provide for a twenty-four-hour extended detention of the one-year, twenty-four-hour storm event (i.e., the stormwater runoff will be released over a minimum 24 hours for the one-year, twenty-four-hour storm event).
D. 
For all regulated earth disturbance activities within the Neshaminy Creek Watershed, the volume control criteria identified in Appendix 1241A of this chapter shall be applicable.[4]
[Added 2-24-2015 by Ord. No. 497]
[4]
Editor's Note: Appendix 1241A is included as an attachment to this chapter.
(8) 
Groundwater Recharge/Infiltration.
A. 
Postconstruction stormwater infiltration of runoff shall replicate preconstruction infiltration of runoff to the maximum extent possible.
B. 
In calculating the volume of runoff that can be infiltrated at a site, the following methodology shall be used:
1. 
Rev = [(S)(Rv)(A)]/12, where:
Rev
=
Recharge Volume (acre-feet)
S
=
Soil specific recharge factor (inches)
A
=
Site area contributing to the recharge facility (acres)
Rv
=
Volumetric runoff coefficient, Rv = 0.05 + 0.009(I), where:
I
=
Percent impervious area, and
S shall be obtained based upon hydrologic soil group based upon the table below:
Hydrologic Soil Group
Soil Specific Recharge Factor
(S)
A
0.38
B
0.25
C
0.13
D
0.06
2. 
If more than one hydrologic soil group (HSG) is present at a site, a composite recharge volume shall be computed based upon the proportion of total site area within each HSG.
C. 
In selecting the appropriate infiltration BMPs, the applicant shall consider the following:
1. 
Permeability and infiltration rate of the site soils.
2. 
Slope and depth to bedrock.
3. 
Seasonal highwater table.
4. 
Proximity to building foundations and wellheads.
5. 
Erodibility of soils.
6. 
Land availability and topography.
D. 
Soil investigation. In designing an infiltration BMP, a key element is an analysis of the soil. The Township Engineer shall require, witness and receive a certification from an experienced soils scientist in accordance with commonly accepted professional standards. Said certification shall include:
1. 
The locations and results of all test borings, test pits or auger holes in order to determine the type of soil;
2. 
The seasonal high-water level; and
3. 
The slope and depth to bedrock.
E. 
Infiltration capacity. Infiltration rates may be determined from permeability testing, percolation testing or hydraulic conductivity testing:
F. 
Infiltration rate. Percolation tests shall be accepted as a means of determining the infiltration rate of a soil. The tests must be completed at the location and depth of the proposed infiltration area. The percolation rate may be converted to infiltration rate in inches per hour as follows:
Infiltration rate (inches per hour) = 60/ (percolation rate, minutes per inch)
G. 
Soil characteristics.
1. 
There must be a minimum depth of 24 inches between the bottom of any infiltration BMP and the seasonal high-water table and/or bedrock (limiting zones).
2. 
There must be an infiltration and/or percolation rate sufficient to accept the additional stormwater load and to drain completely as determined by field tests.
3. 
Infiltration BMPs shall be located a minimum of 15 feet away from the foundation wall of any building.
H. 
Any infiltration BMP shall be capable of completely infiltrating the impounded water within 96 hours.
I. 
During the period of land disturbance, runoff shall be controlled prior to entering any proposed infiltration area. Areas proposed for infiltration BMPs shall be protected from sedimentation and compaction during the construction phase, so as to maintain their maximum infiltration capacity.
J. 
Infiltration BMPs shall not be constructed nor receive runoff until the entire contributory drainage area to the infiltration BMP has received final stabilization.
K. 
Subsurface recharge system. Aggregate fill shall be clean stone between two inches and four inches in diameter. Larger stone shall be placed near the bottom of the system and smaller stone near the top. An appropriate geotextile fabric shall line the bottom and sides, with sufficient excess material left at the top to fold over the aggregate fill when placed, prior to the placement of the topsoil layer.
L. 
Prefabricated systems. When prefabricated systems are proposed, the applicant shall adhere to all recommended manufacturer's specifications in addition to the requirements of this section.
M. 
Emergency overflow. Each subsurface recharge system shall be designed with an emergency overflow/surcharge system to protect the system in the event of a storm of higher intensity.
(c) 
Grading and Landscaping.
(1) 
Drainage Channels, Detention and Retention Areas. All storm drainage channels, detention and retention areas, whether existing or proposed, shall be graded and planted to effectively naturalize areas so as to become an integral and harmonious part of the landscape by contour and type of plant materials used.
(2) 
All detention basins, side slopes and bottoms shall be seeded with an appropriate seed mixture specifically suited to the levels of periodic inundation for which the system is designed. No-mow basins shall only be allowed as approved by the Township.
(3) 
When a detention or retention basin is proposed in any district, the basin(s) should conform to the requirements of the Lower Gwynedd Township Subdivision and Land Development Chapter and the following landscape requirements:
A. 
All stormwater management facilities shall complement the adjacent land use. Creative, natural, nonsymmetrical appearance and design shall be utilized whenever deemed feasible by the Township Engineer and may include:
1. 
The use of free flowing shapes such as peninsulas and islands. Gradation of side slopes shall be no steeper than 4 to 1 maximum. Other design approaches may be approved by the Township Engineer and the Lower Gwynedd Township Planning Commission.
(A) 
Basins designed as geometric shapes, especially rectangles, are discouraged, unless, in the opinion of the Township Engineer or the Lower Gwynedd Township Planning Commission, no other approach is feasible.
B. 
Basin shall be landscaped to diminish negative visual aspects and to promote and encourage native wildlife to complement surrounding land use and existing plant material.
1. 
The portion of the basin which is dry most of the time shall be landscaped in a combination of the following (none constituting more than 50% of the area), as listed in the Army Corps of Engineers Wetlands Manual as FACW or FAC Plants appropriate for periodic wet habitat:
(A) 
Sod forming naturalized grasses, Redtop or approved equal.
(B) 
Dense ground covers, birdsfoot trefoil or approved equal.
(C) 
Innovative methods as approved by the Township Engineer.
(D) 
Additionally, woody shrubs shall be located along the edge of the basin floor in minimum groups of five.
C. 
The portion of the basin which is wet most of the time shall be landscaped in a combination of the following, none constituting more than 50% of the area as listed in the Army Corps of Engineers Wetlands Manual listed in Paragraph (c)(3)B above:
1. 
Naturalized grasses, Switchgrass or approved equal.
2. 
Wildflowers mixture.
3. 
Herbaceous native clump-forming vegetation or ground cover.
4. 
Innovative methods as approved by the Township Engineer.
D. 
Basin perimeter landscaping shall consist of approved plant materials which provide wildlife habitat, shelter and/or food sources, and which are seasonally wet tolerant as classified in the Wetlands Manual listed in Paragraph (c)(3)B above.
1. 
There shall be a minimum of one approved tree and five approved shrubs per 2,500 cubic feet of basin storage at the one-hundred-year storm design elevation.
2. 
The trees shall be a combination of shade, flowering and evergreen trees types, and shrubs shall be a combination of deciduous, needled and broadleaf evergreen types.
3. 
A wildflower mixture with meadow grasses shall be utilized for ground cover for a minimum of 20% of the basin perimeter where the probability of erosion is minimal. Wildflower sod, if used, shall follow the same criteria as set forth below:
(A) 
An approved Northeastern mix of a minimum of 12 varieties of wildflowers with a blend of native clump meadow grasses that will attract butterflies and hummingbirds, flowering from late spring through the fall season.
(B) 
Minimum germination rate: 60%
(C) 
Seeding rate: 4 pounds per acre or as approved.
(D) 
The remaining basin perimeter shall be seeded or sodded with permanent low-maintenance fine grasses.
E. 
The landscape architect or other authorized design professional shall submit, for the Township Engineer's approval, a chart indicating the wildlife food value of each plant material proposed for the basin and the basin perimeter.
American Wildlife and Plants - A Guide to Wildlife Food Habits, by Martin, Zim and Nelson, Dover Books, shall be used as a reference in developing the chart. Other sources can be used if approved in advance by the Township Engineer.
1. 
The plant material list shall comprise sufficient wildlife values, aesthetic values and compatibility with surrounding landscape.
2. 
The basin floor shall be constructed with a minimum of a twelve-inch depth of well-drained soil. This can be accomplished by tilling into the existing soil coarse sand and other material to create a well drained situation or by the addition of new soil.
(A) 
Soil tests shall be submitted for approval.
(B) 
Alternatives such as liners shall be used where limestone soils are anticipated.
3. 
The following shall be strictly enforced:
(A) 
No fertilizer, lime, herbicide or pesticide shall be applied to the basin or surrounding area except as necessary to establish vegetation.
(B) 
No Phragmites australis or other invasive plants shall be allowed in any basin or surrounding area.
(C) 
Only fine-rooted shrubs, herbaceous plants and ground cover are allowed to be planted on the damming berm of any basin.
F. 
Continuously flowing natural watercourses shall be maintained, except that removal of debris and correction of severe erosion shall be required. The use of bioengineering techniques shall be encouraged to correct and stabilize erosion along natural or man-made watercourses.
G. 
Intermittent streams shall be maintained essentially at their existing alignments and gradients. They may be improved by minor regrading, subject to the approval of the Township Engineer and other regulatory agencies. They shall be planted and stabilized in vegetative cover with erosion preventive improvements such as coconut fiber blankets, straw blankets or synthetic fiber blankets.
H. 
Drainageways and basins should be compatible with the adjacent land uses. Innovative basin forms and grading must be utilized wherever physically possible and as determined by the Lower Gwynedd Township Planning Commission. Plantings shall be selected to blend with the natural surroundings using rock outcroppings, boulders, natural structures and bioengineering methods.
I. 
Stormwater structures shall not include exposed concrete unless completely and visually screened from all paths, streets or dwelling units. All exposed concrete stormwater facilities shall be designed using stone facing or approved alternatives.
J. 
Fences may be required at the discretion of the Board of Supervisors.
(4) 
Trees and shrubs shall be placed so as to provide a suitable visual barrier at the time of planting. If evergreen trees are used, they shall be of six feet to eight feet in height, placed in a double, staggered row, 10 feet on center. Trees shall not be placed on the top of the detention basin.
(5) 
Native deciduous trees shall be a minimum of 3 - 3-1/2 inches in caliper, native shrubs shall be a minimum of 24 inches to 36 inches in height, and native evergreen trees shall be a minimum of 6 feet to 8 feet in height at the time of installation. Trees and shrubs shall be spaced in accordance with the characteristic spread of each specific species at maturity.
(6) 
The screening requirement shall be waived only with the expressed consent of the Board of Supervisors.
(7) 
Topsoil. A minimum of twelve inches of topsoil material shall be placed on all areas affected by the basin construction (bottom of basin, side slopes, top of berm, etc.). The material must meet the requirements of the Pennsylvania Department of Transportation Form 408 specifications, as amended.
(8) 
Subsurface Recharge System. In order to preserve the integrity of the system, at no time shall any trees be planted in or around a subsurface recharge system. As a general rule, the dripline of a mature tree should not be located within five feet of a subsurface recharge system.
(9) 
Grading Design Criteria.
A. 
Cuts. No excavation shall be made with a cut face steeper than 3 to 1, horizontal to vertical, except under the condition in which the material in which the excavation is made is sufficiently stable to sustain a slope of steeper than three horizontal to one vertical. A written statement to that effect is required from a licensed civil engineer having experience in soils engineering and shall be submitted to the Township Engineer and approved by him. The statement shall affirm that the site has been inspected and that the deviation from the slope will not result in injury to persons or damage to property. Retaining walls will be required if a stable slope cannot be maintained. Any retaining wall design must be approved by the Township Engineer. The toe of the slope or headwall of any cut must be located a minimum of five feet from property lines. No excavation shall endanger adjoining properties.
B. 
Fills. No fill shall be made which creates any exposed surface steeper in slope than three horizontal to one vertical, except where the fill is located so that settlement, sliding or erosion will not result in property damage or be a hazard to adjoining property, streets or buildings. A written statement from a licensed civil engineer licensed by the commonwealth of Pennsylvania and having experience in soils engineering, certifying that he has inspected the site and that any proposed deviation from the slope specified above will not endanger any property or result in property damage, must be submitted to and approved by the Township Engineer.
1. 
A concrete or stone masonry wall constructed in accordance with Township specifications may be required to support the face of the fill where above slopes are exceeded.
2. 
The top of any fill or toe of the slope of any fill shall be located five feet from any property line.
3. 
Fill placement and compaction. All fill shall be placed mechanically and shall be free of any debris or organic material, roots and stumps. Fill shall be placed in consecutive, maximum eight-inch layers and compressed or compacted mechanically with equipment weighing not less than 10 tons or with similar sheepsfoot roller or compactors having equivalent compression capability. The Township shall require, at the owner's expense, a test certifying the adequate compaction of fill materials as required above or in accordance with the requirements of the Township Engineer. All detention basin fill shall be compacted to 95% modified proctor density (ASTM 1557).
(10) 
Permanent removal of topsoil shall be prohibited in all developments.
(11) 
All existing trees on a site shall be protected. A four-foot-high wooden snow fence mounted on steel posts located eight feet on center shall be placed at the dripline, along the boundary of all trees to remain.

§ 1241.06 Inspections and right of entry.

[Ord. 434. Passed 6-21-2005]
(a) 
Inspections.
(1) 
The Township or its designee shall inspect all phases of the construction, operations, maintenance and any other implementation of stormwater facilities and BMPs.
(2) 
During any stage of the regulated earth disturbance activities, if the Township or its designee determines that any stormwater facilities or BMPs are not being implemented in accordance with this chapter, the Township may suspend or revoke any existing permits and other approvals until the deficiencies are corrected.
(b) 
Right of Entry.
(1) 
Upon presentation of proper credentials, duly authorized representatives of the Township may enter at reasonable times upon any property within the Township to inspect the implementation, condition or operation and maintenance of the stormwater facilities and BMPs in regard to any aspect governed by this chapter.
(2) 
BMP owners and operators shall allow persons working on behalf of the Township ready access to all parts of the premises for the purposes of determining compliance with this chapter.
(3) 
Persons working on behalf of the Township shall have the right to temporarily locate, on any stormwater facility or BMP in the Township, such devices as are necessary to conduct monitoring and/or sampling of the discharges from such BMPs.
(4) 
Unreasonable delays in allowing the Township access to a stormwater facility or BMP is a violation of this Article.

§ 1241.07 Fees and expenses.

[Ord. 434. Passed 6-21-2005]
(a) 
General. The Township may charge a reasonable fee for review of the BMP operations and maintenance plans and for implementation of the Phase II NPDES stormwater program to defray review costs incurred by the Township. The applicant shall pay all such fees.
(b) 
Township Stormwater Management Plan Review Fee. Lower Gwynedd Township shall establish a review fee schedule by resolution of the Township Supervisors based on Lower Gwynedd Township's costs for reviewing the BMP operations and maintenance plans. The Township shall periodically update the review fee schedule to ensure that review costs are adequately reimbursed.
(c) 
Expenses Covered by Fees. Appropriate long-term financial security shall be paid to the Township in an amount established from time to time by resolution of the Board of Supervisors to cover the items listed below. The fee shall be in addition to the amount paid by the applicant/developer under Section 1241.04(b)A.
(1) 
Administrative/clerical costs.
(2) 
The review of all stormwater management plans, including an as-built plan and the BMP operations and maintenance plan by the Township and the Township Engineer.
(3) 
The site inspections, including, but not limited to, preconstruction meetings, inspections during construction of stormwater facilities and BMPs and final inspection upon completion of the stormwater facilities and BMPs.
(4) 
Any additional work required to monitor and enforce any provisions of this chapter, correct violations and assure proper completion of stipulated remedial actions.
(5) 
The implementation of Phase II of the National Pollutant Discharge Elimination System (NPDES) established by the Pennsylvania Department of Environmental Protection in order to defray the costs to the Township in administering the NPDES Phase II requirements.

§ 1241.08 Prohibitions.

[Ord. 434. Passed 6-21-2005]
(a) 
Prohibited Discharges.
(1) 
No person in the Township shall allow, or cause to allow, stormwater discharges into the municipal separate storm sewer system which are not composed entirely of stormwater, except as provided in Paragraph (a)(2) below and discharges allowed under a state or federal permit.
(2) 
Discharges which may be allowed based on a finding by the Township that the discharge(s) do not significantly contribute to pollution to surface waters of the commonwealth, are:
A. 
Discharges from fire-fighting activities.
B. 
Potable water sources, including dechlorinated waterline and fire hydrant flushings.
C. 
Irrigation drainage.
D. 
Routine external building washdown (which does not use detergents or other compounds).
E. 
Air-conditioning condensate.
F. 
Water from individual residential car washing.
G. 
Springs.
H. 
Water from crawl space pumps.
I. 
Uncontaminated water from foundation or from footing drains.
J. 
Flows from riparian habitats and wetlands.
K. 
Lawn watering.
L. 
Pavement wash waters where spills or leaks of toxic or hazardous materials have not occurred (unless all spill material has been removed) and where detergents are not used.
M. 
Dechlorinated swimming pool discharges.
N. 
Uncontaminated groundwater.
(3) 
In the event that the Township determines that any of the discharges identified in Paragraph (a)(2) significantly contribute to pollution of waters of the commonwealth, or if so notified by DEP, the Township will notify the responsible person to cease the discharge.
(4) 
Upon notice provided by the Township under Paragraph (a)(3), the discharger will have a reasonable time, as determined by the Township, to cease the discharge consistent with the degree of pollution caused by the discharge.
(5) 
Nothing in this subsection shall affect a discharger's responsibilities under state law.
(b) 
Prohibited Connections. The following connections are prohibited, except as provided in Section 1241.08(a)(2) above:
(1) 
Any drain or conveyance, whether on the surface or subsurface, which allows any nonstormwater discharge, including sewage, process wastewater and wash water, to enter the separate storm sewer system, and any connections to the storm drain system from indoor drains and sinks.
(2) 
Any drain or conveyance connected from a commercial or industrial land use to the separate storm sewer system which has not been documented in plans, maps or equivalent records and approved by the Township.
(c) 
Roof Drains.
(1) 
Roof drains shall not be connected to streets, sanitary or storm sewers or roadside ditches except as provided in Section 1241.08(c)(2).
(2) 
When it is more advantageous to connect directly to streets or storm sewers, connections of roof drains to streets or roadside ditches may be permitted by the Township.
(3) 
Roof drains shall discharge to infiltration areas or vegetative BMPs to the maximum extent practicable.
(d) 
Alteration of BMPs.
(1) 
No person shall modify, remove, fill, landscape or alter any existing stormwater BMP, unless it is part of an approved maintenance program, without the written approval of the Township.
(2) 
No person shall place any structure, fill, landscaping or vegetation into a stormwater BMP or within a drainage easement, which would limit or alter the functioning of the BMP, without the written approval of the Township.

§ 1241.09 Enforcement and penalties.

[Ord. 434. Passed 6-21-2005]
(a) 
Public Nuisance.
(1) 
The violation of any provision of this chapter is hereby deemed a public nuisance.
(2) 
Each day that a violation continues shall constitute a separate violation.
(b) 
Enforcement Generally.
(1) 
Whenever the Township finds that a person has violated a prohibition or failed to meet a requirement of this chapter, the Township may order compliance by written notice to the responsible person. Such notice may require without limitation:
A. 
The performance of monitoring, analyses and reporting.
B. 
The elimination of prohibited connections or discharges.
C. 
Cessation of any violating discharges, practices or operations.
D. 
The abatement or remediation of stormwater pollution or contamination hazards and the restoration of any affected property.
E. 
Payment of a fine to cover administrative and remediation costs.
F. 
The implementation of stormwater BMPs.
G. 
Operation and maintenance of stormwater BMPs.
(2) 
Such notification shall set forth the nature of the violation(s) and establish a time limit for correction of these violations(s). Said notice may further advise that, if applicable, should the violator fail to take the required action within the established deadline, the work will be done by the Township or designee and the expense thereof shall be charged to the violator.
(3) 
Failure to comply within the time specified shall also subject such person to the penalty provisions of this chapter. All such penalties shall be deemed cumulative and shall not prevent the Township from pursuing any and all other remedies available in law or equity.
(c) 
Suspension and Revocation of Permits and Approvals.
(1) 
Any building, land development or other permit or approval issued by the Township may be suspended or revoked by the Township for:
A. 
Noncompliance with or failure to implement any provision of the permit.
B. 
A violation of any provision of this chapter.
C. 
The creation of any condition or the commission of any act during construction or development which constitutes or creates a hazard or nuisance, pollution or which endangers the life or property of others.
(2) 
A suspended permit shall be reinstated by the Township when:
A. 
The Township Engineer or designee has inspected and approved the corrections to the stormwater management and erosion and sedimentation control facilities or the BMPs or the elimination of the hazard or nuisance, and/or;
B. 
The Township is satisfied that the violation of the ordinance, law or rule and regulation has been corrected.
(3) 
A permit which has been revoked by the Township cannot be reinstated. The applicant may apply for a new permit under the procedures outlined in this chapter.
(d) 
Penalties.
(1) 
Any person, partnership or corporation violating the provisions of this chapter shall be guilty of a misdemeanor and, upon conviction, shall be subject to a fine of not more than $1,000 for each violation, recoverable with costs, or imprisonment of not more than 30 days, or both. Each day that the violation continues shall be a separate offense.
(2) 
In addition, the Township, through its Solicitor, may institute injunctive, mandamus or any other appropriate action or proceeding at law or in equity for the enforcement of this chapter. Any court of competent jurisdiction shall have the right to issue restraining orders, temporary or permanent injunctions, mandamus or other appropriate forms of remedy or relief.