Chapter 22 – Apendix A – Stormwater Management Ordinance

Download PDF

HAMPDEN TOWNSHIP

STORMWATER MANAGEMENT ORDINANCE

HAMPDEN TOWNSHIP

CUMBERLAND COUNTY, PENNSYLVANIA

EXHIBIT A

TABLE OF CONTENTS Page

Article I – General Provisions

Section 101 Short Title 1
Section 102 Statement of Findings 1
Section 103 Purpose 1
Section 104 Statutory Authority 2
Section 105 Applicability 3
Section 106 Repealer 3
Section 107 Severability 3
Section 108 Compatibility with Other Requirements 3
Section 109 Waiver Procedure 4
Section 110 Subsequent or Amended Publications, Standards, Laws, 4
Codes and Regulations

Article II – Definitions 4

Article III – Stormwater Management Standards

Section 301 General Requirements 9
Section 302 Exemptions 10
Section 303 Volume Controls 10
Section 304 Rate Controls 11
Section 305 Stormwater Management Districts 12
Section 306 Stormwater Management District Implementation Provisions 12
Section 307 Design Criteria for Stormwater Management Facilities 14
Section 308 Calculation Methodology 18
Section 309 Erosion and Sediment Control Requirements 19

Article IV – Stormwater Management Site Plan Requirements

Section 401 Plan Requirements 20
Section 402 Plan Submission 23
Section 403 Plan Review 23
Section 404 Modification of Plans 24
Section 405 Resubmission of Disapproved Stormwater Management Site Plans 24
Section 406 Recording of Documents 24
Section 407 Authorization to Construct and Term of Validity 25
Section 408 As-Built Plans 25

Article V – Operation and Maintenance

Section 501 Schedule of Inspections 25
Section 502 Right of Entry 25
Section 503 Responsibilities of Developers and Landowners 26
Section 504 Operation and Maintenance Agreement 27
Section 505 Municipal Stormwater Maintenance Fund 27
Section 506 Post-Construction Maintenance and Monitoring Inspection 27

Article VI – Fees and Expenses

Section 601 General 27
Section 602 Municipality SWM Site Plan Review Fee 28
Section 603 Expenses Covered by Fees 28
Section 604 Additional Costs 28

Article VII – Prohibitions

Section 701 Prohibited Discharges and Connections 28
Section 702 Roof Drains and Sump Pumps 29
Section 703 Alteration of SWM BMPs 29

Article VIII – Enforcement and Penalties

Section 801 Right-of-Entry 30
Section 802 Inspection 30
Section 803 Enforcement 30
Section 804 Suspension and Revocation 30
Section 805 Public Nuisances 31
Section 806 Enforcement Generally 31
Section 807 Enforcement Remedies 32
Section 808 Appeals 32

Article IX – References 32

Appendix A: Operation and Management Agreement Appendix B: Stormwater Management Design Criteria Appendix C: Cumberland County Release Rate Maps

ARTICLE I – GENERAL PROVISIONS

Section 101. Short Title

This Ordinance shall be known and may be cited as the “Hampden Township Stormwater Management Ordinance.”

Section 102. Statement of Findings

The Board of Commissioners of Hampden Township finds that:

A. Inadequate management of accelerated runoff of stormwater resulting from development throughout a watershed increases flows and velocities, contributes to erosion and sedimentation, overtaxes the carrying capacity of streams and storm sewers, greatly increases the cost of public facilities to carry and control stormwater, undermines flood plain management and flood control efforts in downstream communities, reduces groundwater recharge, threatens public health and safety, and increases non-point source pollution of water resources.

B. A comprehensive program of stormwater management, including reasonable regulation of development and activities causing accelerated runoff, is fundamental to the public health, safety and welfare and the protection of people of the Commonwealth, their resources and the environment.

C. Stormwater is an important water resource, which provides groundwater recharge for water supplies and base flow of streams, which also protects and maintains surface water quality.

D. 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).

E. Non-stormwater discharges to storm sewer systems can contribute to pollution of water of the Commonwealth.

Section 103. Purpose

The purpose of this Ordinance is to promote health, safety, and welfare within Hampden Township and its watershed by minimizing the harms and maximizing the benefits described in Section 102 of this Ordinance, through provisions designed to:

A. Meet legal water quality requirements under state law, including regulations at 25 Pa. Code Chapter 93 to protect, maintain, reclaim and restore the existing and designated uses of the waters of this Commonwealth.

B. Preserve the natural drainage systems as much as possible.

C. Manage stormwater runoff close to the source.

D. Provide procedures and performance standards for stormwater planning and management.

E. Maintain groundwater recharge, to prevent degradation of surface and groundwater quality and to otherwise protect water resources.

F. Prevent scour and erosion of stream banks and streambeds.

G. Provide proper operation and maintenance of all permanent Stormwater Management (SWM) Best Management Practices (BMPs) that are implemented within the Municipality.

H. Provide standards to meet NPDES permit requirements.

I. Meet general water quality and soil disturbance goals by implementing measures to:

1. Minimize disturbance to floodplains, wetlands, natural slopes over 15%, and existing native vegetation.

2. Preserve and maintain trees and woodlands by, for example, maintaining or extending riparian buffers, protecting existing forested buffers and by providing trees and woodlands adjacent to impervious areas whenever feasible.

3. Establish and maintain non-erosive flow conditions in natural flow pathways.

4. Minimize soil disturbance and soil compaction.

5. Direct runoff to pervious areas, wherever possible.

6. Incorporate the techniques for Low Impact Development Practices described in the most current version of “The Pennsylvania Stormwater Best Management Practices Manual” (SWM Manual)1.(Any footnote reference in this Ordinance is a reference to a corresponding number for a publication contained in Article IX – References.)

7. Minimize thermal impacts to waters of the Commonwealth.

Section 104. Statutory Authority

A. Primary Authority.

Hampden Township is empowered to regulate these activities by the authority of the Act of October 4, 1978, P.L. 864 (Act 167), 32 P.S. Section 680.1, et seq., as amended, the “Storm Water Management Act” and the First Class Township Code.

Hereafter, all earth disturbance activities and land development within Hampden Township, including without limitation, the location, design and construction within the watershed of storm water management systems, obstructions, flood control projects, subdivisions and land developments, highways and transportation facilities, facilities for the provision of public utility services and facilities owned or financed in whole or in part by funds from the Commonwealth, shall be in full compliance with the requirements of Cumberland County Storm Water

Management Plan and this Ordinance and shall be conducted in a manner consistent therewith. Any violation of the Cumberland County Storm Water Management Plan shall be considered a violation of this Ordinance.

B. Secondary Authority.

Hampden Township also is empowered to regulate land use activities that affect runoff by the authority of the Act of July 31, 1968, P.L. 805, No. 247, the Pennsylvania Municipalities Planning Code, as amended.

Section 105. Applicability

All regulated activities and all activities that may affect stormwater runoff, including land development and earth disturbance activity, are subject to regulation by this Ordinance as is reasonably necessary to prevent injury to health, safety or other property. The following activities are defined as “regulated activities” and shall be subject to the provisions of this Ordinance (unless otherwise exempted by Section 302):

A. Land development and/or redevelopment

B. Subdivision

C. Construction of new or additional impervious or semi-pervious surfaces (driveways, parking lots, etc.)

D. Construction of structures or additions to existing structures, as determined by the municipality

E. Diversion or piping of any natural or man-made stream channel

F. Installation of stormwater management facilities or appurtenances thereto

G. Forest management/timber operations that include logging road construction and timber harvesting

H. Earth disturbance activities

Section 106. Repealer

Any other ordinance provision(s) or regulation of Hampden Township inconsistent with any of the provisions of this Ordinance is hereby repealed to the extent of the inconsistency only.

Section 107. Severability

In the event that a court of competent jurisdiction declares any section or provision of this Ordinance invalid, such decision shall not affect the validity of any of the remaining provisions of this Ordinance.

Section 108. Compatibility with Other Requirements

Approvals issued and actions taken under this Ordinance do not relieve the Applicant of the responsibility to secure required permits or approvals for activities regulated by any other code, law, regulation or ordinance. To the extent that this Ordinance imposes more rigorous or stringent requirements for stormwater management, the specific requirements contained in this Ordinance shall prevail and be followed.

Section 109. Waiver Procedure

The provisions of this Ordinance are intended as minimum standards for the protection of the public health, safety and welfare. The Board of Commissioners may waive any mandatory provision of these regulations to the benefit of the applicant provided the waiver:

1. Is consistent with the purpose of this Ordinance as described in Section 103;

2. Will remove or reduce an unreasonable standard or undue hardship as it applies to the particular property, which is grossly disproportionate to any benefit derived from the standard, or when an alternative standard provides equal or better results.

3. Is consistent with Section 301 when involving water quality requirements.

It shall be the burden of the applicant to demonstrate compliance with the above conditions.

Section 110. Subsequent or Amended Publications, Standards, Laws, Codes and Regulations.

Any reference in this Ordinance to any publication, manual, standard, law, code or regulation shall include any and all subsequent amendments, supplements and successor publications, standards, laws, codes and regulations thereto without the need to amend this Ordinance to make specific reference thereto.

ARTICLE II – DEFINITIONS

For the purposes of this Ordinance, certain terms and words used herein shall be interpreted as follows:

A. 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.

B. 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.

C. The words “shall” and “must” are mandatory; the words “may” and “should” are permissive.

D. The word “person” includes an individual, firm, association, partnership, trust company, corporation, or any other entity.

E. The words “used or occupied” include the words “intended, designed, maintained, or arranged to be used, occupied or maintained”.

Accelerated Erosion – The removal of the surface of the land through the combined action of man’s activity and the natural processes of a rate greater than would occur because of the natural process alone.

Agricultural Activity – The work of producing crops, including tillage, land clearing, plowing, disking, harrowing, planting, harvesting crops, pasturing and raising of livestock, and installation of conservation measures. Construction of new buildings or impervious area is not considered an Agricultural Activity.

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; also the changing of surface conditions by causing the surface to be more or less impervious; land disturbance.

Applicant – A landowner, developer or other person who has filed an application to the Municipality for approval to engage in any Regulated Activity at a project site in the Municipality.

Best Management Practice (BMP) – Activities, facilities, designs, measures or procedures used to manage stormwater impacts from Regulated Activities, to meet State Water Quality Requirements, to promote groundwater recharge and to otherwise meet the purposes of this Ordinance. Stormwater BMPs are commonly grouped into one of two broad categories or measures: “structural” or “non- structural”. In this ordinance, non-structural BMPs or measures refer to operational and/or behavior- related practices that attempt to minimize the contact of pollutants with stormwater runoff whereas structural BMPs or measures are those that consist of a physical device or practice that is installed to capture and treat stormwater runoff. Structural BMPs include, but are not limited to, a wide variety of practices and devices, from large-scale retention ponds and constructed wetlands, to small-scale underground treatment systems, infiltration facilities, filter strips, low impact design, bioretention, wet ponds, permeable paving, grassed swales, riparian or forested buffers, sand filters, detention basins, and manufactured devices. Structural Stormwater BMPs are permanent appurtenances to the project site.

Board of Commissioners – The Board of Commissioner of Hampden Township

Channel Erosion – The widening, deepening, and headward cutting of small channels and waterways, due to erosion caused by moderate to large floods.

Conservation District – The Cumberland County Conservation District (CCCD).

Culvert – A structure with appurtenant works which carries a stream under or through an embankment or fill.

Design Storm – The magnitude and temporal distribution of precipitation from a storm event measured in probability of occurrence (e.g. a 5-year-storm) and duration (e.g. 24 hours), used in the design and evaluation of stormwater management systems. Also see Return Period.

Detention Volume – The volume of runoff that is captured and then infiltrated, evaporated, reused, or released into the waters of this Commonwealth at a controlled rate.

DEP – The Pennsylvania Department of Environmental Protection.

Development Site (also “Site”) – See Project Site.

Disconnected Impervious Area (DIA) – An impervious or impermeable surface which has its stormwater runoff disconnected from any stormwater drainage or conveyance system and is redirected or directed to a pervious area which allows for infiltration, filtration, and increased time of concentration.

Disturbed Area – An unstabilized land area where an Earth Disturbance Activity is occurring or has occurred.

Earth Disturbance Activity – Construction or other human activity which disturbs the surface of the land, including but not limited to, land clearing and grubbing, grading, excavations, embankments, land development, agricultural plowing or tilling, operation of animal heavy use areas, timber harvesting activities, road maintenance activities, oil and gas activities, well drilling, mineral extraction, and the moving, depositing, stockpiling, or storing of soil, rock or earth materials.

Erosion – The movement of soil particles by the action of water, wind, ice, chemical or other actions.

Existing Condition – The initial condition of a project site prior to the proposed construction.

FEMA – Federal Emergency Management Agency.

Floodplain – The lowland and relatively flat areas adjoining inland and coastal waters including, at a minimum, that area subject to a one percent or greater chance of flooding in any given year.

Floodway – The channel of the watercourse and those portions of the adjoining floodplains that are reasonably required to carry and discharge the 100-year flood. Unless otherwise specified, the boundary of the floodway is as indicated on maps and flood insurance studies provided by FEMA. In an area where no FEMA maps or studies have defined the boundary of the 100-year floodway, it is assumed — absent evidence to the contrary — that the floodway extends from the stream to 50 feet from the top of the bank of the stream.

Forest Management/Timber Operations – Planning and activities necessary for the management of forestland. These include conducting a timber inventory, preparation of forest management plans, silvicultural treatment, cutting budgets, logging road design and construction, timber harvesting, site preparation and reforestation.

Hydrologic Soil Group (HSG) – Refers to soils grouped according to their runoff-producing characteristics. The chief consideration is the inherent capacity of soil bare of vegetation to permit infiltration. Infiltration rates of soils vary widely and are affected by subsurface permeability as well as surface intake rates. Soils are classified into four HSGs (A, B, C, and D) according to their minimum infiltration rate, which is obtained for bare soil after prolonged wetting. The NRCS defines the four groups and provides a list of most of the soils in the United States and their group classification. The soils in the area of the development site may be identified from a soil survey report that can be obtained from local NRCS offices or conservation district offices. Soils become less pervious as the HSG varies from A to D (NRCS 3,4).

Impervious Surface (Impervious Area) – A surface that prevents the infiltration of water into the ground. Impervious surfaces (or areas) shall include, but not be limited to, roofs, patios, garages, storage sheds and similar structures, and streets, sidewalks, driveways, parking areas, and other paved surfaces.

Karst – A type of topography or landscape characterized by surface depressions, sinkholes, rock pinnacles/uneven bedrock surface, underground drainage and caves. Karst is formed on carbonate rocks, such as limestone or dolomite.

Land Development (Development) – Inclusive of any of the following activities: (i) the improvement of one lot or two or more contiguous lots, tracts, or parcels of land for any purpose involving (a) a group of two or more buildings, whether proposed initially or cumulatively, or a single nonresidential building on a lot or lots regardless of the number of occupants or tenure, or (b) the division or allocation of land or space, whether initially or cumulatively, between or among two or more existing or prospective occupants by means of, or for the purpose of streets, common areas, leaseholds, condominiums, building groups, or other features; (ii) any subdivision of land; (iii) development in accordance with Section 503(1.1) of the Pennsylvania Municipalities Planning Code.

Municipal Engineer – The Assistant Director of Public Works for Hampden Township

Municipality – Hampden Township, Cumberland County, Pennsylvania.

NRCS – USDA Natural Resources Conservation Service (previously SCS).

Peak Discharge – The maximum rate of stormwater runoff from a specific storm event.

Pervious Area – Any area not defined as impervious.

Project Site – The specific area of land where any Regulated Activities in the Municipality are planned, conducted or maintained.

Qualified Professional – Any person licensed by the Pennsylvania Department of State or otherwise qualified by law to perform the work required by the Ordinance.

Regulated Activities – Shall include, but not be limited to any Earth Disturbance Activities or any activities that involve the alteration or development of land in a manner that may affect stormwater runoff as specified in Section 105.

Regulated Earth Disturbance Activity – Activity involving Earth Disturbance subject to regulation under 25 Pa. Code Chapters 92, Chapter 102, or the Clean Streams Law.

Retention Volume/Removed Runoff – The volume of runoff that is captured and not released directly into the surface waters of this Commonwealth during or after a storm event.

Return Period – The average interval, in years, within which a storm event of a given magnitude can be expected to occur one time. For example, the 25-year return period rainfall would be expected to occur on average once every 25 years; or stated in another way, the probability of a 25-year storm occurring in any one year is 0.04 (i.e. a 4% chance).

Runoff – Any part of precipitation that flows over the land.

Sediment – Soils or other materials transported by surface water as a product of erosion.

State Water Quality Requirements – The regulatory requirements to protect, maintain, reclaim, and restore water quality under Pennsylvania Code Title 25 and the Clean Streams Law.

Stormwater – Drainage runoff from the surface of the land resulting from precipitation or snow or ice melt.

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 facilities.

Stormwater Management Plan – The Cumberland County Stormwater Management Plan for managing stormwater runoff adopted by the County of Cumberland as required by the Act of October 4, 1978, P.L. 864, (Act 167), as amended, and known as the “Storm Water Management Act”.

Stormwater Management Best Management Practices – See “Best Management Practice”. This term is the same as and also abbreviated as BMPs or SWM BMPs throughout this Ordinance.

Stormwater Management Site Plan (also “SWM Site Plan”) – The plan prepared by the developer, municipality, or other entity indicating how storm water runoff will be managed at the development site in accordance with this Ordinance.

Subdivision – As defined in the Pennsylvania Municipalities Planning Code, Act of July 31, 1968,

P.L. 805, No. 247 as reenacted and subsequently amended.

USDA – United States Department of Agriculture.

Waters of the Commonwealth – Rivers, streams, creeks, rivulets, impoundments, ditches, watercourses, storm sewers, lakes, dammed water, wetlands, ponds, springs and other bodies or channels of conveyance of surface and underground water, or parts thereof, whether natural or artificial, within or on the boundaries of this Commonwealth.

Watershed – Region or area drained by a river, watercourse or other surface water of the Commonwealth.

Wetland – Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions, including swamps, marshes, bogs, fens, and similar areas, and that has been identified and delineated as a wetland by a qualified design professional.

ARTICLE III – STORMWATER MANAGEMENT STANDARDS

Section 301. General Requirements

A. For all Regulated Activities, unless preparation of a SWM Site Plan is specifically exempted in Section 302:

1. Preparation and implementation of an approved SWM Site Plan is required.

2. No Regulated Activities shall commence until the Municipality issues written approval of a SWM Site Plan, which demonstrates compliance with the requirements of this Ordinance.

B. SWM Site Plans approved by the Municipality and as noted in Section 406, shall be on site throughout the duration of the Regulated Activity.

C. The Municipality, after consultation with DEP, may approve measures for meeting the State Water Quality Requirements other than those in this Ordinance, provided that they meet the minimum requirements of, and do not conflict with, State law including but not limited to the Clean Streams Law.

D. For all Regulated Earth Disturbance Activities, erosion and sediment control BMPs shall be designed, implemented, operated, and maintained during the Regulated Earth Disturbance Activities (e.g., during construction) to meet the purposes and requirements of this Ordinance and to meet all requirements under the Pennsylvania Code Title 25 and the Clean Streams Law. Various BMPs and their design standards are listed in the Erosion and Sediment Pollution Control Program Manual (E&S Manual)2, Commonwealth of Pennsylvania, Department of

Environmental Protection, No. 363-2134-008 (2000), as amended and updated.

E. For all Regulated Activities not exempted by Section 302, implementation of the Volume Controls in Section 303 is required.

F. For all new development projects, the measurement of impervious areas shall include all of the impervious areas in the total proposed development even if development is to take place in stages. Similarly, for new development projects taking place in stages, the entire proposed new development plan must be used in determining conformance with this Ordinance.

G. Stormwater flows/direct discharges onto adjacent property shall not be created, increased, decreased, relocated, or otherwise altered without written notification to approval of the adjacent downstream property owner(s). Such stormwater flows shall be subject to the requirements of this Ordinance.

H. The design of all facilities over Karst shall include an evaluation of measures to minimize adverse effects in accordance with the procedures outlined in Section 7.4 (Special Management Areas – Karst Areas) of the most current version of the SWM Manual1.

I. Storage facilities should completely drain both the volume control and rate control capacities within 72 hours from the end of the design storm subject to site conditions.

J. The design storm precipitation depth estimates to be used in the analysis of peak rates of discharge should be obtained from the Precipitation-Frequency Atlas of the United States, Atlas 14, Volume 2, U.S. Department of Commerce, National Oceanic and Atmospheric Administration (NOAA), National Weather Service, Hydrometeorological Design Studies Center, Silver Spring, Maryland, 20910. NOAA’s Atlas 145 can be accessed at Internet address:

http://hdsc.nws.noaa.gov/hdsc/pfds/.

K. For all Regulated Activities, SWM BMPs shall be designed, implemented, operated, and maintained to meet the purposes and requirements of this Ordinance and to meet all requirements under Title 25 of the Pennsylvania Code, the Clean Streams Law, and the Storm Water Management Act.

L. The Pennsylvania Department of Environmental Protection Pennsylvania Stormwater Best Management Practices Manual, December, 2006 (SWM Manual), is hereby referenced as guidance in meeting the requirements contained within this Ordinance.

Section 302. Exemptions

A. Regulated Activities resulting in less than or equal to 1,000 square feet of new impervious surface are exempt from Article IV SWM Site Plan preparation requirements including Sections 303 and 304 of this Ordinance. Regulated Activities greater than 1,000 square feet and less than or equal to 5,000 square feet of new impervious area may be exempt from the SWM Site Plan preparation requirements including Sections 303 and 304 of this Ordinance when justification is provided that stormwater impact is minimal.*

B. Regulated Activities meeting the following parcel size and square footage requirements are exempt from the peak rate control requirements, but not the volume control or SWM Site Plan preparation requirements of this Ordinance. These criteria shall apply to the total proposed development even if development is to take place in phases. November 12, 2002 shall be the starting point from which to consider tracts as “parent tracts” in which future subdivisions and respective impervious area computations shall be cumulatively considered.*

New Impervious Area Exemption Criteria for Peak Rate Control

Total Parcel Size (acres) Total Parcel Size (square feet) New Impervious Area Exemption (square feet)
<0.25 <10,890 1,000
.25 – 0.5 10,890 – 21,780 2,500
>0.5 >21,780 5,000

*Hampden Township has, at its discretion, the ability to deny exemption from any requirements of this Ordinance. Exemption from any requirements of this ordinance does not convey or grant exemption from any other requirements of this Ordinance or any other applicable local codes or ordinances (i.e., local building permit requirements).

Section 303. Volume Controls

Water volume controls shall be implemented using the Design Storm Method in Subsection 1 or the

Simplified Method in Subsection 2 below for all Regulated Activities not otherwise exempted by Section

302. For Regulated Activity areas equal to or less than one (1) acre that do not require hydrologic routing to design the stormwater facilities, this Ordinance establishes no preference for either

methodology; therefore, the applicant may select either methodology on the basis of economic considerations, the intrinsic limitations on applicability of the analytical procedures associated with each methodology, and other factors.

A. The Design Storm Method (see Section 8.7 of the most current version of the SWM Manual1) is applicable to any size of Regulated Activity. This method requires detailed modeling based on site conditions.

1. Do not increase the post-development total runoff volume for all storms equal to or less than the 2-year 24-hour duration precipitation.

2. For modeling purposes:

i. Existing (pre-development) non-forested pervious areas must be considered meadow or its equivalent.

ii. Twenty (20) percent of existing impervious area, when present, shall be considered meadow in the model for existing conditions.

B. The Simplified Method (see Section 8.7 of the most current version of the SWM Manual1) provided below is independent of site conditions and should be used if the Design Storm Method is not followed. This method is not applicable to Regulated Activities greater than one (1) acre or for projects that require design of stormwater detention or rate control facilities. For new impervious surfaces:

1. Stormwater facilities shall be sized to capture at least the first two inches (2”) of runoff from all new impervious surfaces.

2. At least the first one inch (1.0”) of runoff from new impervious surfaces shall be permanently removed from the runoff flow — i.e. it shall not be released into the surface waters of this Commonwealth. Removal options include reuse, evaporation, transpiration, and infiltration.

3. Infiltration facilities should be designed to accommodate infiltration of the entire permanently removed runoff; however, in all cases at least the first one-half inch (0.5”) of the permanently removed runoff shall be infiltrated.

4. The second one inch (1.0”) of runoff from new impervious surfaces shall be detained using structural and non-structural BMPs (as outlined in the most current version of the SWM Manual) and released at a controlled rate.

Section 304. Rate Controls (see Section 8.3 of the most current version of the SWM Manual1)

A. Areas not covered by a Release Rate Map from an approved Act 167 Stormwater Management Plan:

Post-development discharge rates shall not exceed the predevelopment discharge rates for the 1-, 2-, 10-, and 100-year storms. If it is shown that the peak rates of discharge indicated by the post- development analysis are less than or equal to the peak rates of discharge indicated by the pre- development analysis for 1-, 2-, 10-, and 100-year, 24-hour storms, then the requirements of this section have been met. Otherwise, the applicant shall provide additional controls as necessary to satisfy the peak rate of discharge requirement.

B. Areas covered by the Cedar Run Watershed Release Rate Map from an approved Act 167 Stormwater Management Plan (see Appendix C):

For the 1-, 2-, 10-, and 100-year storms, the post-development peak discharge rates will follow the applicable approved release rate maps (see Appendix C). For any areas not shown on the release rate maps, the post-development discharge rates shall not exceed the predevelopment discharge rates.

Section 305. Stormwater Management Districts

Hampden Township has been divided into two (2) stormwater management districts as shown on the Cedar Run Watershed Release Rate Map in Appendix C. All areas of the Municipality not specifically identified on the Watershed Release Rate Map are assumed to be in the 100% Release Rate District.

Standards for managing runoff from each subarea for the 1, 2, 10 and 100-year design storms are shown below. Development sites located in each of the districts must control post-development runoff rates to pre-development runoff rates for the design storms as follows:

DISTRICT CONTROL CRITERIA
100% Post-development peak discharge for all design storms must be no greater than pre- development peak discharges.
75% Post-development peak discharge for all design storms must be no greater than 75 percent of the pre-development peak discharges.

Section 306. Stormwater Management District Implementation Provisions (Performance Standards)

A. General – Post-development rates of runoff from any regulated activity shall not exceed the peak release rates of runoff prior to development for the design storms specified on the Stormwater Runoff Peak Rate Districts Map, Ordinance Appendix C and Section 304 of the Ordinance.

B. District Boundaries – The boundaries of the Stormwater Management Districts are shown on the Cedar Run Watershed Release Rate Map, which is available for inspection at the municipal office. A copy of the Map at a reduced scale in included in the Ordinance Appendix C.

C. Sites Located in More Than 1 District – For a proposed development site located within two or more release rate districts, the peak discharge rate from any subarea shall be the pre- development peak discharge for that subarea multiplied by the applicable release rate. The calculated peak discharges shall apply regardless of whether the grading plan changes the drainage area by subarea. An exception to the above may be granted if discharges from multiple subareas re-combine in proximity to the site. In this case, peak discharge in any direction may be a 100% release rate provided that the overall site discharge meets the weighted average release rate.

D. Off-Site Areas – Off-site Areas that drain through a proposed development site are not subject to release rate criteria when determining allowable peak runoff rates. However, on-site drainage facilities shall be designed to safely convey off-site flows through the development site.

E. Site Areas – Where the site area to be impacted by a proposed development activity differs significantly from the total site area, only the proposed impact area shall be subject to the release rate criteria.

F. “Downstream Hydraulic Capacity Analysis” – Any downstream capacity hydraulic analysis conducted in accordance with this Ordinance shall use the following criteria for determining adequacy for accepting increased peak flow rates:

1. Natural or man-made channels or swales must be able to convey the increased runoff associated with a 2-year return period event within their banks at velocities consistent with protection of the channels from erosion. Acceptable velocities shall be based upon criteria included in the DEP Erosion and Sediment Pollution Control Program Manual.

2. Natural or man-made channels or swales must be able to convey the increased 25-year return period runoff without creating any hazard to persons or property.

3. Culverts, bridges, storm sewers or any other facilities which must pass or convey flows from the tributary area must be designed in accordance with DEP, Chapter 105 regulations (if applicable) and, at a minimum, pass the increased 25-year return period runoff.

G. Regional Detention Alternatives – For certain areas, it may be more cost-effective to provide one control facility for more than one development site than to provide an individual control facility for each development site. The initiative and funding for any regional runoff control alternatives are the responsibility of prospective developers. The design of any regional control basins must incorporate reasonable development of the entire upstream watershed. The peak outflow of a regional basin would be determined on a case-by-case basis using the hydrologic model of the watershed consistent with protection of the downstream watershed areas. “Hydrologic model” refers to the calibrated model as developed for the Stormwater Management Plan.

H. Waiver of Peak Rate Control Requirement – For certain development sites in close proximity to stream channels, the Municipality may consider a waiver of the peak rate control requirement, upon recommendation of the Municipal Engineer. Developer is responsible to demonstrate “no harm” by providing engineering analysis, in accordance with the following:

1. Developer must demonstrate that discharge without peak rate control will improve drainage conditions by draining the development site prior to peak stream flows from the upstream drainage area.

2. Developer must demonstrate that all drainage facilities downstream from the site have adequate capacity to safely convey the undetained increased peak flows for the storm events listed in Section 304. This analysis may be required for any drainage facility between the development site and the discharge point of the nearest receiving stream.

Approval of a detention waiver shall not relieve the developer from meeting the Volume Control (Section 303) requirements.

Section 307. Design Criteria for Stormwater Management Facilities

A. Detention and Retention Facilities

1. Any stormwater management facility or BMP designed to store runoff and requiring a berm or earthen embankment required or regulated by this ordinance shall be designed to provide an emergency spillway to handle flow up to and including the 100-year post-development conditions.

2. The height of the embankment must be set as to provide a minimum 1.0 foot of freeboard above the maximum pool elevation computed when the facility functions for the 100-year post-development inflow.

3. Emergency spillways must be designed to pass the 100-year post-development flow assuming that all discharge orifices are completely clogged, and that any principal spillway grate is 50% clogged.

4. Should any stormwater management facility require a dam safety permit under DEP Chapter 105, the facility shall be designed in accordance with Chapter 105 and meet the regulations of Chapter 105 concerning dam safety which may be required to pass storms larger than 100-year event.

B. Any facilities that constitute water obstructions (e.g., culverts, bridges, outfalls, or stream enclosures), and any work involving wetlands as directed in PaDEP Chapter 105 regulations (as amended or replaced from time to time by PaDEP), shall be designed in accordance with Chapter 105 and will require a permit from PaDEP. Any other drainage conveyance facility that does not fall under Chapter 105 regulations must be able to convey, without damage to the drainage structure or roadway, runoff from the 25-year design storm with a minimum 1.0 foot of freeboard measured below the lowest point along the top of the embankment along the edge of the roadway. Any facility that constitutes a dam as defined in PaDEP Chapter 105 regulations may require a permit under dam safety regulations. Any facility located within a PennDOT right of way must meet PennDOT minimum design standards and permit submission requirements.

C. Storm sewers must be able to convey post-development runoff from a 25-year design storm without surcharging inlets.

D. Adequate erosion protection shall be provided along all open channels, and at all points of discharge.

E. The design of all stormwater management facilities shall incorporate sound engineering principles and practices. The Municipality shall reserve the right to disapprove any design that would result in the occupancy or continuation of an adverse hydrologic or hydraulic condition.

F. Storm drainage facilities shall be required as necessary to:

1. Permit the unimpeded flow of natural water courses;

2. Ensure the drainage of all low points along the line of streets and other applicable areas;

3. Intercept, retain or detain surface water runoff in a manner reasonably related to the extent and grade of the area drained;

4. Provide positive drainage away from on-site sewage disposal facilities and buildings.

G. General storm drainage facility design requirements:

1. Design of storm drainage facilities shall generally conform to Pennsylvania Department of Transportation Design Manual Part 2, Chapter 10.

2. The minimum design criteria shall be a 10-year storm with a five minute duration. Higher frequency conditions may be required by the Municipality where an overflow would endanger public or private properties.

3. The complete drainage system for the subdivision or land development shall be incorporated into the design. If the subdivision or land development is to be developed in phases, an overall stormwater facilities plan for the entire site shall be submitted with the Preliminary Plan.

4. Developer shall be responsible for obtaining any permits required by State or Federal agencies for construction of the facilities or points of discharge. Copies of hydrologic or other studies requested by other agencies shall be provided by the developer.

5. The existing points of drainage discharge, whether natural or constructed, shall not be altered without written approval from the affected property owner(s).

6. Stormwater runoff or natural drainage water shall not be diverted so as to overload existing drainage systems, or create flooding or the need for additional drainage structures on other private properties or public lands, without provisions being made by the developer for properly handling such conditions.

7. Facilities for storm drainage shall be designed to handle the anticipated peak discharge from the property being subdivided or developed as well to handle the anticipated increase in runoff that will occur when all upstream property is fully developed.

8. Where a watercourse runs across or through a subdivision or land development, a drainage easement, which conforms to the line of such watercourse, shall be provided at such a width as will be adequate to preserve the unimpeded flow of

natural drainage. Provisions for reasonable access for maintenance of these facilities shall be provided.

9. All drainage structures that are located within right-of-way of State highway agencies shall be approved by the applicable agency.

10. All streets shall be designed so that surface water is discharged from their rights- of-way. The minimum street cross-slope shall be two percent.

11. Storm drainage facilities, as required, shall be placed in front of the curb or curb line when located in a street right-of-way. When located in undedicated land, facilities shall be placed within an easement, as approved by the Municipal Engineer, who may require additional width of easement as circumstances warrant.

12. Street drainage shall not be permitted to cross intersections or the centerline of a road.

13. Storm water roof drains, sump pump discharge drains and other stormwater drainage facilities or groundwater discharges shall not:

a. Discharge directly over a sidewalk.

b. Discharge within five feet of any lot line.

c. Cross a lot line.

d. Be connected to streets, sanitary or storm sewers or roadside ditches, to promote overland flow and infiltration of stormwater where advantageous to do so. When it is more advantageous to connect directly to streets or storm sewers, then it shall be permitted on a case by case basis by the Municipality.

14. Stabilized outlets shall be provided for footer drains, floor drains, downspouts and other point discharges.

15. No person, corporation or other entity shall block, impede the flow of, or alter, construct any structure, or deposit any material or thing, or commit any act which will affect normal or flood flow in any stream or watercourse without having obtained prior approval from applicable Local, State and Federal agencies.

16. All street inlets shall be the combination inlet and hood type in compliance with PennDOT Standard Construction Drawings for Type C Special Inlet. The designation of Special means a 10-inch curb reveal which requires the road surface to be sloped into the inlet for additional effectiveness. Inlets shall be constructed of reinforced cast-in-place concrete or precast concrete with separate bottom and top units.

17. All storm drainage system manholes shall be reinforced cast-in-place concrete or precast concrete in compliance with PennDOT Standard Construction Drawings.

18. The minimum pipe size shall be 18-inch diameter for all storm drainage facilities. 12-inch diameter pipes shall be permitted in privately-owned systems on private property where no upstream drainage is contributed. All pipes shall meet

PennDOT Specifications. A headwall or end section shall be provided at the start and end of each pipe run.

19. All springs and sump pump discharges shall be collected by piping so as not to flow in the streets.

20. Underdrain shall be required at all low points on the street profile. The underdrain system shall be designed and installed in accordance with PennDOT Specifications. Combination Storm Sewer/Underdrain shall be permitted, where applicable.

21. Pavement Base Drain shall be provided along each side of each street, in accordance with PennDOT Standards. In locations where storm sewer is proposed, Combination Storm Sewer/Underdrain shall be permitted.

H. Storm drainage system design standards:

1 . Minimum slope of smooth-interior storm drainage pipes shall be 0.35 percent. Minimum slope for corrugated pipes shall be 0.50 percent.

2. Pipe runs between structures shall not exceed 400 feet.

3. Pipe runs shall be designed to align generally parallel to street centerlines, with perpendicular crossings as needed. Diagonal crossings should be avoided, to minimize conflicts with other underground facilities.

4. Pipes shall be designed with a minimum of 12 inches of cover between top of pipe and subgrade elevation for pipes within paved areas. Pipes outside paved areas shall have minimum of 12 inches of cover between top of pipe and finished ground elevation.

5. Inlet spacing shall be designed to limit spread of water on streets in accordance with PennDOT criteria.

6. Inlets, junction boxes or manholes shall be provided at all locations of pipe size change or direction change, whether horizontal or vertical.

7. Frames, covers and grates shall be provided in accordance with PennDOT standards. All inlets within paved areas shall have bicycle safe grates.

8. Pipe materials shall be one of the following:

a. High-density polyethylene.

b. Reinforced concrete.

c. Aluminized steel.

d. Galvanized steel.

9. Pipe trench excavation and backfill shall be in accordance with PennDOT Standards.

I. Storm drainage system design and construction shall be in conformance with standards and procedures that may be adopted by the Municipality from time to time. Where adopted, such standards shall take precedence over PennDOT standards that are referenced herein.

Section 308. Calculation Methodology

Stormwater runoff from all development sites shall be calculated using either the rational method or a soil-cover-complex methodology.

A. Any stormwater runoff calculations involving drainage areas greater than 200 acres, including on- and off-site areas, shall use generally accepted calculation technique that is based on the NRCS soil cover complex method. The table below summarizes acceptable computation methodologies for stormwater management plans. It is assumed that all methods will be selected by the design professional based on the individual limitations and suitability of each method for a particular site.

The Municipality may approve the use of the Rational Method to estimate peak discharges from drainage areas that contain less than 200 acres.

ACCEPTABLE COMPUTATION METHODOLOGIES FOR STORMWATER MANAGEMENT PLANS

METHOD METHOD DEVELOPED BY APPLICABILITY
TR-20 or commercial Package Based on TR-20 USDA – NRCS When use of full model is desirable or necessary
Tr-55 or Commercial Package Based on TR-55 USDA – NRCS Applicable for plans within the models limitations
HEC-HMS U.S. Army Corps of Eng. When use of full model is desirable or necessary
PSRM Penn State Univ. When use of full model is desirable or necessary
Rational Method or commercial package based on Rational Method Emil Kuiching (1889) For sites less than 200 acres
Other Methods Various As approved by the municipal engineer

B. All calculations consistent with this Ordinance using the soil cover complex method shall use the appropriate design rainfall depths for the various return period storms presented in Table A-1 in Appendix B of this Ordinance. If a hydrologic computer model such as PSRM or HEC-1 is used for stormwater runoff calculations, then the duration of rainfall shall be 24 hours. The NRCS ‘S’ curve shall be used for the rainfall distribution.

C. For the purposes of predevelopment flow rate determination, undeveloped land shall be considered as “meadow” good condition, unless the natural ground cover generates a lower curve number or Rational ‘C’ value (i.e. forest).

D. All calculations using the Rational Method shall use rainfall intensities consistent with appropriate times of concentration for overland flow and return periods from the Design Storm Curves from PA Department of Transportation Design Rainfall Curves (1986). Times of concentration for overland flow shall be calculated using the methodology presented in Chapter 3 of Urban Hydrology for Small Watersheds, NRCS, TR-55 (as amended or replaced from time to time by NRCS). Times of concentration for channel and pipe flow shall be computed using Manning’s equation.

E. Runoff Curve Numbers (CN) for both existing and proposed conditions to be used in the soil cover complex method shall be obtained from Table A-2 in Appendix B of this Ordinance.

F. Runoff coefficients (c) for both existing and proposed conditions for use in the Rational method shall be obtained from Table A-3 in Appendix B of this Ordinance.

G. Where uniform flow is anticipated, the Manning equation shall be used for hydraulic computations, and to determine the capacity of open channels, pipes, and storm sewers. Values for Manning’s roughness coefficient (n) shall be consistent with Table A-4 in Appendix B of this Ordinance.

H. Outlet structures for stormwater management facilities shall be designed to meet the performance standards of this Ordinance using any generally accepted hydraulic analysis technique or method.

I. The design of any stormwater detention facilities intended to meet the performance standards of this Ordinance shall be verified by routing the design storm hydrograph through these facilities using the Storage-Indication Method. For drainage areas greater than 20 acres in size, the design storm hydrograph shall be computed using a calculation method that produces a full hydrograph. The municipality may approve the use of any generally accepted full hydrograph approximation technique that shall use a total runoff volume that is consistent with the volume from a method that produces a full hydrograph.

J. The Municipality has the authority to require that computed existing runoff rates be reconciled with field observations and conditions. If the designer can substantiate through actual physical calibration that more appropriate runoff and time-of-concentration values should be utilized at a particular site, then appropriate variations may be made upon review and recommendations of the Municipal Engineer. Calibration shall require detailed gauge and rainfall data for the particular site in question.

K. An Impervious Area Flash (IAF) analysis shall be conducted for all sites. The analysis requires that the watershed impervious area be modeled without the pervious areas. The time of concentration should also be determined from the impervious areas only. If the IAF analysis results in a higher post-development peak runoff rate, this higher value must be used for the final design/comparison.

Section 309. Erosion and Sediment Control Requirements

A. Whenever the vegetation and topography are to be disturbed, such activity must be in conformance with Chapter 102, Title 25, Rules and Regulations, Part I, Commonwealth of Pennsylvania, Department of Environmental Protection, Subpart C, protection of Natural

Resources, Article II, Water Resources, Chapter 102, “Erosion Control,” and in accordance with the Cumberland County Conservation District (CCCD) and the standards and specifications of the Municipality.

B. No regulated activities shall commence until an Erosion and Sediment Control Plan consistent with this Ordinance is approved by the Municipality.

C. Evidence of any permits required by PaDEP or CCCD must be provided to the Municipality.

D. Plan review, approval and permitting functions under this Section may be delegated by the Municipality to another entity, if such agreement is entered into by the Municipality.

E. Additional erosion and sediment control design standards and criteria that must be applied where infiltration BMPs are proposed include the following:

1. Areas proposed for infiltration BMPs shall be protected from sedimentation and compaction during the construction phase, so as to maintain their maximum infiltration capacity.

F. A copy of the approved Erosion and Sediment Control Plan and any required permits shall be available at the project site at all times.

G. Any permanent stormwater detention or retention facility that also functions as a sediment control facility during construction must be designed to meet the permanent peak rate release design requirements for the 10-year storm event during the construction period. Documentation of this design shall be included with the Stormwater Management Site Plan. This requirement is in addition to design parameters that may be required by other agencies.

ARTICLE IV – STORMWATER MANAGEMENT (SWM) SITE PLAN REQUIREMENTS

Section 401 . Plan Requirements

The following items shall be included in the SWM Site Plan:

A. Appropriate sections from the Municipal Subdivision and Land Development Ordinance, and other applicable local ordinances, shall be followed in preparing the SWM Site Plans.

B. The Municipality shall not approve any SWM Site Plan that is deficient in meeting the requirements of this Ordinance. At its sole discretion and in accordance with this Article, when a SWM Site Plan is found to be deficient, the Municipality may either disapprove the submission and require a resubmission, or in the case of minor deficiencies the Municipality may accept submission of modifications.

C. Provisions for permanent access and maintenance easements as determined necessary by the Municipality for all physical SWM BMPs, such as ponds and infiltration structures, to implement the operation and maintenance plan discussed in Section 503 below.

D. The SWM Site Plan shall provide the following information:

1. The overall stormwater management concept for the project.

2. A determination of Site Conditions in accordance with the Site Assessment procedures outlined in Chapter 4 of the most current version of the SWM Manual1. A site assessment shall be completed for projects proposed in areas of carbonate geology or Karst topography.

3. Stormwater runoff design computations and documentation as specified in this Ordinance, or as otherwise necessary to demonstrate that measures have been taken to meet the requirements of this Ordinance, including the recommendations and general requirements in Section 301.

4. Expected project time schedule.

5. A soil erosion and sediment control plan, where applicable, as prepared for and submitted to the approval authority.

6. The effect of the project (in terms of runoff volumes, water quality, and peak flows) on surrounding properties and adjacent aquatic features and on any existing stormwater conveyance system that may be affected by the project.

7. Plan and profile drawings of all SWM BMPs including drainage structures, pipes, open channels, and swales.

8. The locations of existing and proposed on-lot wastewater facilities and water supply wells.

9. An operation and maintenance (O&M) plan for all proposed physical stormwater management facilities. This plan shall address long-term ownership and responsibilities for operation and maintenance as well as schedules for O&M activities.

10. Plans shall be no larger than 18-inch x 24-inch and shall be prepared in a form that meets the requirements for recording at the offices of the Recorder of Deeds of Cumberland County. The contents of the plan(s) shall include, but not be limited to:

a. The location of the project relative to highways, municipalities or other identifiable landmarks.

b. Existing contours at intervals of two (2) feet. In areas of steep slopes (greater than 15 percent), five-foot contour intervals may be used. Spot elevations at significant points are required.

c. Existing streams, lakes, ponds, or other bodies of water within the project area.

d. Other physical features including flood hazard boundaries, sinkholes, streams, existing drainage courses, areas of natural vegetation to be preserved, and the total extent of the upstream area draining through the site.

e. The locations of all existing and proposed utilities, sanitary sewers, and water lines.

f. An overlay showing soil names and boundaries.

g. Proposed changes to the land surface and vegetative cover, including the type and amount of impervious area that would be added.

h. Proposed structures, roads, paved areas, and buildings.

i. Final contours at intervals at two (2) feet. In areas of steep slopes (greater than 15 percent), five-foot contour intervals may be used. Spot elevations at significant points are required.

j. The name of the development, the name and address of the owner of the property, and the name of the individual or firm preparing the plan.

k. The date of submission, and any subsequent revision dates.

l. A graphic and written scale of one (1) inch equals no more than fifty (50) feet.

m. A North arrow.

n. The total tract boundary and size with distances marked to the nearest foot and bearings to the nearest degree.

o. Existing and proposed land use(s).

p. A key map showing all existing man-made features beyond the property boundary that would be affected by the project.

q. Plan and profile of all pipes, swales and open channels.

r. Overland drainage paths.

s. Stormwater management easements, a minimum of twenty feet in width, around all stormwater management facilities and permanent BMPs.

t. A twenty-foot wide access easement to provide access for inspection and maintenance of all stormwater management facilities and permanent BMPs.

u. A note on the plan indicating the location and responsibility for maintenance of stormwater management facilities that would be located off-site. All off-site facilities shall meet the performance standards and design criteria specified in this Ordinance.

v. A construction detail of any improvements to sinkholes.

w. A statement, signed by the landowner, acknowledging the stormwater management facilities and BMPs to be permanent fixtures that can be altered or removed only after approval of a revised plan by the municipality.

x. The following signature block for the Design Engineer:

“(Design Engineer), on this date (date of signature), have reviewed and hereby certify that the Drainage Plan meets all design standards and criteria of the Hampden Township Act 167 Stormwater Management Ordinance.”

y. An Erosion and Sediment Control Plan in accordance with Section 309.

z. A BMP Operations and Maintenance Plan in accordance with Section 503.

aa. All stormwater management facilities and permanent BMPs, including construction details.

bb. When infiltration methods are proposed, the locations of existing and proposed on-lot sewage disposal systems and infiltration areas and water supply wells.

E. Supplemental Information

1. A written description containing the following information shall be submitted:

a. The overall stormwater management concept for the project.

b. Stormwater runoff computations as specified in this Ordinance.

c. Stormwater management techniques to be applied both during and after development.

2. A geologic assessment of the effects of runoff on sinkholes as specified in this Ordinance.

3. A Declaration of Adequacy and Highway Occupancy Permit from the PennDOT when utilization of a PennDOT storm drainage system is proposed.

4. All calculations, assumptions, and criteria used in the design of the stormwater management facilities and BMPs.

Section 402. Plan Submission

A. For all activities regulated by this Ordinance, the steps below shall be followed for 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 PADOT Highway Occupancy Permit, or require any other permit under applicable state or federal regulations, the permit(s) shall be part of the plan.

B. The SWM Site Plan and application shall be submitted by the Developer as part of the submission for the Regulated Activity. .

C. Two (2) complete copies of the SWM Site Plan must be submitted to the Township.

D. All applicable fees shall be paid at the time of plan submission.

Section 403. Plan Review

.

A. The Municipal Engineer shall review the SWM Site Plan for consistency with the adopted Cumberland County Act 167 Stormwater Management Plan and this Ordinance. The Municipality shall require receipt of a complete plan, as specified in this Ordinance.

B. The Municipal Engineer shall review the SWM Site Plan for any submission or land development in accordance with the municipal subdivision and land development ordinance provisions not superseded by this Ordinance.

C. Should the SWM Site Plan be determined to be inconsistent with the Stormwater Management Ordinance, the Municipal Engineer will forward a disapproval letter to the Developer with a copy to the Township Manager citing the reason(s) for the disapproval. Any disapproved SWM Site Plans may be revised by the Developer and resubmitted consistent with this Ordinance.

D. In lieu of a disapproval letter, the Municipal Engineer may provide a list of comments that will bring the Plan into an approvable format, if adequately addressed.

E. For Regulated Activities requiring a PaDEP Joint Permit Application, the Municipal Engineer shall notify PaDEP whether the SWM Site Plan is consistent with the Stormwater Management Ordinance and forward a copy of the review letter to the Township Manager and the Developer. PaDEP may consider the Municipal Engineer’s review comments in determining whether to issue a permit.

F. The Municipality shall not approve any subdivision or land development for Regulated Activities if the SWM Site Plan has been found to be inconsistent with the Stormwater Management

23

Ordinance, as determined by the Municipal Engineer. All required permits from PaDEP must be obtained prior to approval or as a condition of approval.

G. The Director of Community Development and/or Assistant Director and/or Zoning Officer shall not issue a permit for any Regulated Activity until a SWM Site Plan has been approved by the Municipal Engineer. All required permits from PaDEP must be obtained prior to issuance of a permit.

H. The Developer shall be responsible for completing an “As-Built Survey” of all stormwater management facilities and BMPs included in the approved SWM Plan. The As-Built Survey and an explanation of any discrepancies with the design plans shall be submitted to the Municipal Engineer for final approval. In no case shall the Municipality approve the As-Built Survey until the Municipality receives a copy of an approved Declaration of Adequacy, Highway Occupancy Permit from the PennDOT District Office, and any applicable permits from PADEP.

I. The Municipality’s approval of a SWM Site Plan shall be valid for a period not to exceed one (1) year. This one-year time period shall commence on the date that the Municipality signs the approved SWM Plan. If stormwater management facilities included in the approved SWM Plan have not been constructed, or if an As-Built Survey of these facilities has not been approved within this one-year time period, then the Municipality may consider the SWM Site Plan disapproved and may revoke any and all permits. SWM Site Plans that are considered disapproved by the Municipality shall be resubmitted in accordance with Section 405 of this Ordinance. The Municipality may, at its discretion, grant time extensions for completion of work on approved SWM Plans. Nothing in this Section shall supersede a developer’s rights under the Pennsylvania Municipalities Planning Code to pursue approved plans.

Section 404. Modification of Plans

A. A modification to a submitted SWM Site Plan that involves a change in SWM BMPs or techniques, or that involves the relocation or redesign of SWM BMPs, or that is necessary because soil or other conditions are not as stated on the SWM Site Plan as determined by the Municipality, shall require a resubmission of the modified SWM Site Plan in accordance with this Article.

B. A modification to an already approved or disapproved SWM Site Plan shall be submitted to the Municipality, accompanied by the applicable review fee. A modification to a SWM Site Plan, for which a formal action has not been taken by the Municipality, shall be submitted to the Municipality, accompanied by the applicable review fee.

Section 405. Resubmission of Disapproved Storm Water Management Site Plans

A disapproved SWM Site Plan may be resubmitted, with the revisions addressing the Municipality’s concerns, to the Municipality in accordance with this Article. The applicable review fee must accompany a resubmission of a disapproved SWM Site Plan.

Section 406. Recording of Documents

A. The following documents shall be recorded in the Office of the Recorder of Deeds for Cumberland County prior to the start of any site construction:

1. The approved SWM Site Plan

2. The BMP Operations and Maintenance Plan, if such is not included in a recorded SWM Site Plan

3. Stormwater Facilities and BMP Maintenance and Monitoring Agreement

Section 407. Authorization to Construct and Term of Validity

The Municipality’s approval of a SWM Site Plan authorizes the Regulated Activities contained in the SWM Site Plan for a maximum term of validity of five years following the date of approval. Terms of validity shall commence on the date the Municipality signs the approval for an SWM Site Plan. If an approved SWM Site Plan is not completed according to this Section and Section 408 within the term of validity, then the Municipality may consider the SWM Site Plan disapproved and may revoke any and all permits issued by the Municipality. SWM Site Plans that are considered disapproved by the Municipality shall be resubmitted in accordance with Section 405 of this Ordinance.

Section 408. As-Built Plans

The Applicant shall be responsible for providing as-built plans of all SWM BMPs included in the approved SWM Site Plan. The as-built plans and an explanation of any discrepancies with the construction plans shall be submitted to the Municipality. As-Built plans shall be submitted to the Township in electronic files compatible with current Township software.

ARTICLE V – INSPECTIONS, OPERATION AND MAINTENANCE

Section 501. Schedule of Inspections

A. The Municipal Engineer or his/her designee shall be permitted to inspect all phases of the installation of the permanent stormwater management facilities and BMPs.

B. The Municipal Engineer or his/her designee shall be permitted inspect all phases of the site development work in progress, to insure compliance with Erosion and Sediment Control requirements. Inspection functions under this Section may be delegated by the Municipality to another entity, if such agreement is entered into by the Municipality.

C. During any stage of the work, if the Municipal Engineer determines that the permanent stormwater management facilities or BMPs are not being installed in accordance with the approved SWM Site Plan, the Municipality shall revoke any existing municipal permits and/or issue a stop work order until a revised SWM Site Plan is submitted and approved, as specified in this Ordinance.

Section 502. Right of Entry

A. Upon presentation of proper credentials, duly authorized representatives of the Municipality may enter at reasonable times upon any property within the Municipality to inspect the implementation, condition or operation of the stormwater BMPs in regard to any aspect governed by this Ordinance.

B. BMP owners and operators shall allow persons working on behalf of the Municipality ready access to all parts of the premises for the purposes of determining compliance with this Ordinance.

C. Persons working on behalf of the Municipality shall have the right to temporarily locate on any BMP in the Municipality such devices as are necessary to conduct monitoring and/or sampling of the discharges from such BMP.

D. Unreasonable delays in allowing the Municipality access to a BMP is a violation of this Ordinance.

Section 503. Responsibilities of Developers and Landowners

A. The Municipality shall make the final determination on the continuing maintenance and inspection responsibilities prior to final approval of the SWM Site Plan. The Municipality may require a dedication of such facilities as part of the requirements for approval of the SWM Site Plan. Such a requirement is not an indication that the Municipality will accept the facilities. The Municipality reserves the right to accept or reject the ownership and operating responsibility for any portion of the stormwater management controls.

B. Facilities, areas, or structures used as Stormwater Management BMPs shall be enumerated as permanent real estate appurtenances and recorded as deed restrictions or conservation easements that run with the land.

C. An Operation and Maintenance Plan shall be recorded as a restrictive deed covenant that runs with the land.

D. The Municipality may take enforcement actions against an owner for any failure to satisfy the provisions of this Article.

E. No regulated activities shall commence until a BMP Operations and Maintenance Plan (“O & M Plan”) consistent with this Ordinance is approved by the Municipality.

F. The SWM Site Plan Content requirements are applicable to the O & M Plan, and are incorporated herein by reference. O & M Plan requirements can be shown concurrently in the plan set with the SWM Site Plan requirements.

G. The O & M Plan shall establish responsibilities for the continuing operation and maintenance of all permanent stormwater facilities and BMPs, as follows:

1. If a Plan includes structures or lots which are to be separately owned and in which streets, sewers and other public improvements are to be dedicated to the Municipality, stormwater facilities and BMPs may also be dedicated to and maintained by the Municipality.

2. If a plan includes operations and maintenance by a single owner, or if sewers and other improvements are to be privately owned and maintained, then the operation and maintenance of stormwater facilities and BMPs shall be the responsibility of the owner.

H. The property owner shall enter into an Operations and Maintenance agreement with Hampden Township as noted in Section 504, below.

Section 504. Operation and Maintenance Agreements

The owner is responsible for operation and maintenance of the SWM BMPs. The owner shall enter into an Operations and Maintenance Agreement in the form included in Appendix A. If the owner fails to adhere to the Operation and Maintenance Agreement, Hampden Township may, but is not obligated to, perform the services required and charge the owner appropriate fees for services. Non-payment of fees may result in a lien against the property or other judicial action.

Section 505. Municipal Stormwater Maintenance Fund

If stormwater facilities are to be accepted by the Municipality for dedication, persons installing stormwater facilities or BMPs shall be required to pay as a condition of dedication funds to Hampden Township in order to defray the costs of operations and maintenance expenses associated with the dedicated facilities. The amount to be paid shall be the estimated costs for operations and maintenance of the facilities for ten (10) years, as determined by the Municipality.

Section 506. Post-Construction Maintenance and Monitoring Inspections

A. Stormwater facilities and permanent BMPs must be inspected in accordance with the O & M Plan. The property owner has two options to accomplish this:

1. Employing a qualified registered professional to conduct the inspections and prepare reports; or

2. Entering into an agreement with the Municipality for the Municipality to conduct the inspections and prepare reports. This can be included in the Operation and Maintenance Agreement.

B. If option A.1, above is chosen, the entity conducting the inspection shall be required to submit a report to the Municipality within one (1) month following completion of the inspection. The report will present documentation regarding the condition of the facility and recommendations for any necessary repairs. Any needed repairs shall be implemented by the Owner within one

(1) month of the report submission date.

C. If option A,2, above is chosen, the owner will be responsible for reimbursing the Municipality for the costs involved, such reimbursement to be specified in the Operation and Maintenance Agreement.

ARTICLE VI – FEES AND EXPENSES

Section 601. General

Applicant shall be responsible for the payment of all fees assessed by Hampden Township associated with the implementation and administration of this Ordinance..

Section 602. Municipality SWM Site Plan Review Fee

The Board of Commissioners shall establish a fee schedule by Resolution for all fees to be charged associated with this Ordinance. All fees may be amended by the Board by Resolution from time to time..

Section 603. Expenses Covered by Fees

The fees established and required by this Ordinance shall at a minimum cover:

A. Administrative Costs.

B. The review of the SWM Site Plan by the Municipality and the Municipal Engineer.

C. Fees and expenses to record plans and instruments at the County Recorder of Deeds Office.

D. Preconstruction meetings and site inspections.

E. The inspection of stormwater management facilities and BMPs during construction.

F. The final inspection upon completion of the stormwater management facilities and BMPs presented in the SWM Site Plan.

G. Work required to monitor and enforce provisions of this Ordinance, to correct violations, and to assure proper completion of remedial actions.

Section 604. Additional Costs

Developer will be invoiced for any additional costs incurred by the Hampden Township in the course of reviewing the SWM Site Plan. These costs may include, but are not limited to, special studies by qualified engineers or surveyors, field reconnaissance, and testing.

ARTICLE VII – PROHIBITIONS

Section 701. Prohibited Discharges and Connections

A. Any drain or conveyance, whether on the surface or subsurface, which allows any non- stormwater discharge including, but not limited to, sewage, process wastewater, wash water, ammonia, chlorine, petroleum products (gasoline, fuel oil, etc.) pesticides, pollutants and other hazardous materials to enter the Municipality’s separate storm sewer system or to enter the waters of the Commonwealth is prohibited.

Handling and disposal of all materials and wastes shall comply with all Federal and State requirements. Structural and non-structural BMPs, in accordance with Chapters 5 and 6 of the most current version of the SWM Manual, shall be implemented where necessary to preserve the quality of stormwater runoff.

B. Discharges to the Municipality’s separate storm sewer system or to waters of the Commonwealth which are not composed entirely of stormwater shall be prohibited, except (1) as provided in subsection C below, and (2) discharges allowed under a state or federal permit.

C. The following discharges are authorized unless they are determined to be significant contributors to pollution to the waters of this Commonwealth:

– Discharges from fire fighting activities, – Flows from riparian habitats and wetlands
– Potable water sources including dechlorinated water line and fire hydrant flushing – Uncontaminated water from foundations or from footing drains
– Irrigation drainage – Lawn watering
– Air conditioning condensate – Dechlorinated swimming pool discharges
– Springs – Uncontaminated groundwater
– Water from crawl space or basement sump pumps – Water from individual residential car washing
– 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 – Routine external building wash down (which does not use detergents or other compounds)

D. In the event that the Municipality or PaDEP determines that any of the discharges identified in Subsection C significantly contribute to pollution of the waters of this Commonwealth, the Municipality or PaDEP will notify the responsible person(s) to cease the discharge.

E. Nothing in this Section shall affect a discharger’s responsibilities under State or Federal law.

Section 702. Roof Drains and Sump Pumps

A. Roof drains and sump pumps shall not discharge to any impervious area, if site conditions permit.

B. Roof drains shall not be connected to streets, sanitary or storm sewers, or roadside swales, except as provided in Subsection C, below.

C. When it is more advantageous to connect roof drains directly to streets, storm sewers or roadside swales, such connections may be permitted by the Municipality on a case by case basis.

D. Roof drains shall discharge to infiltration areas or vegetative BMPs to the maximum extent practicable.

Section 703. Alteration of SWM BMPs

No person shall modify, remove, fill, landscape, or alter any SWM BMPs, facilities, areas, structures or easements without the written approval of the Municipality.

ARTICLE VIII – ENFORCEMENT AND PENALTIES

Section 801. Right of Entry

Upon presentation of proper credentials, the Municipality may enter at reasonable times upon any property within the Municipality to inspect the condition of the stormwater structures and facilities in regard to any aspect regulated by this Ordinance.

Section 802. Inspection

SWM BMPs must be inspected by the landowner, or the owner’s designee (including the Municipality for dedicated and owned facilities) according to the schedule in the O & M Plan. All inspection reports shall be submitted to the Municipality according to the schedule in the O & M Plan.

Section 803. Enforcement

The Director of Community Development or Assistant Director of Community Development is hereby authorized and directed to enforce all of the provisions of this Ordinance. All inspections regarding compliance with the SWM Site Plan shall be the responsibility of the Municipal Engineer or other qualified persons designated by the municipality.

A. A copy of the SWM Site Plan approved by the Municipality shall be on file at the site throughout the duration of the construction activity. Periodic inspections may be made by the Municipality or designee during construction.

B. It shall be unlawful for a person to undertake any Regulated Activity except as provided in an approved SWM Site Plan, unless specifically exempted in Section 302.

C. Inspections regarding compliance with the SWM Site Plan during project construction are a responsibility of the Municipality.

D. A Certificate of Occupancy and/or Zoning Permit shall not be issued unless all requirements of this Ordinance have been met.

Section 804. Suspension and Revocation

A. Any approval or permit issued by Hampden Township may be suspended or revoked for:

1. Non-compliance with or failure to implement any provision of the approved SWM Site Plan or Operation and Maintenance Agreement.

2. A violation of any provision of this Ordinance or any other applicable law, ordinance, rule or regulation relating to the Regulated Activity.

3. The creation of any condition or the commission of any act during the Regulated Activity which constitutes or creates a hazard or nuisance, pollution, or which endangers the life or property of others.

B. A suspended approval may be reinstated by Hampden Township when:

1. Hampden Township has inspected and approved the corrections to the violations that caused the suspension.

2. Hampden Township is satisfied that the violation has been corrected.

C. An approval that has been revoked by the Hampden Township cannot be reinstated. The applicant may apply for a new approval under the provisions of this Ordinance.

D. If a violation causes no immediate danger to life, public health, or property, at its sole discretion, the Municipality may provide a limited time period for the owner to correct the violation. In these cases, the Municipality will provide the owner, or the owner’s designee, with a written notice of the violation and the time period allowed for the owner to correct the violation. If the owner does not correct the violation within the allowed time period, the Municipality may revoke or suspend any, or all, applicable approvals and permits pertaining to any provision of this Ordinance.

Section 805. Public Nuisance

A. The violation of any provision of this ordinance is hereby deemed a public nuisance.

B. Each day that a violation continues shall constitute a separate violation

Section 806. Enforcement Generally

A. Whenever the Municipality finds that a person has violated a prohibition or failed to meet a requirement of this Ordinance, the Municipality may order compliance by written notice to the responsible person. Such notice may require without limitation:

1. The performance of monitoring, analyses and reporting;

2. The elimination of prohibited connections or discharges;

3. Cessation of any violating discharges, practices or operations;

4. The abatement or remediation of stormwater pollution or contamination hazards and the restoration of any affected property;

5. Payment of a fine to cover administrative and remediation costs;

6. The implementation of stormwater BMPs; and

7. Operation and Maintenance of stormwater BMPs.

B. Such notification shall set forth the nature of the violation(s) and establish a time limit for correction of these violation(s). Said notice may further advise that, if applicable, should violator fail to take the required action within the established deadline, the work will be done by the Municipality or designee and the expense thereof shall be charged to the violator.

C. Failure to comply within the time specified shall also subject such person to the penalty provisions of this Ordinance. All such penalties shall be deemed cumulative and shall not prevent the Municipality from pursuing any and all other remedies available in law or equity.

Section 807. Enforcement Remedies

A. Anyone violating the provisions of this Ordinance shall be guilty of a summary offense, and upon conviction shall be subject to a fine of not more than $1,000.00 for each violation plus court costs and attorney’s fees. Each day that the violation continues shall be a separate offense.

B. In addition, Hampden 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 Ordinance or to pursue any remedy available to Hampden Township. 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.

Section 809. Appeals

A. Any person aggrieved by any action of Hampden Township or its designee, relevant to the provisions of this Ordinance, may appeal to the Board of Commissioners within thirty (30) days of the action giving rise to the appeal.

B. Any person aggrieved by any decision of Board of Commissioners, as a result of a timely appeal made as provided in Section 809.A, above may appeal to the Cumberland County Court of Common Pleas within thirty (30) days of the decision by the Board.

ARTICLE IX – REFERENCES

1. Pennsylvania Department of Environmental Protection (DEP). No. 363-0300-002 (2006), as amended and updated. Pennsylvania Stormwater Best Management Practices Manual. Harrisburg, PA.

2. The Pennsylvania Department of Environmental Protection (DEP). 363-2134-008 (2000), as amended and updated. Erosion and Sediment Pollution Control Program Manual. Harrisburg, PA.

3. United States Department of Agriculture (USDA), National Resources Conservation Service (NRCS). National Engineering Handbook. Part 630: Hydrology, 1969-2001. Originally published as the National Engineering Handbook, Section 4: Hydrology. Available online at: http://www.wcc.nrcs.usda.gov/hydro/hydro-techref-neh-630.html.

4. United States Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS). 1986. Technical Release 55: Urban Hydrology for Small Watersheds, 2nd Edition. Washington, D.C.

5. US Department of Commerce (USDC), National Oceanic and Atmospheric Administration (NOAA), National Weather Service (NWS), Hydrometeorological Design Studies Center. 2004-2006. Precipitation-Frequency Atlas of the United States, Atlas 14, Volume 2, Silver Spring, Maryland, 20910. Internet address: http://hdsc.nws.noaa.gov/hdsc/pfds/.

APPENDIX A

OPERATION AND MAINTENANCE AGREEMENT STORMWATER MANAGEMENT BEST MANAGEMENT PRACTICES (SWM BMPs)

THIS AGREEMENT, made and entered into this day of , 20_ , by and between

, (hereinafter the “Landowner”), and the Township of Hampden, Cumberland County, Pennsylvania, (hereinafter “Hampden Township”);

WITNESSETH

WHEREAS, the Landowner is the owner of certain real property as recorded by deed in the land records of

Cumberland County, Pennsylvania, Deed Book at Page , or Instrument
No. (hereinafter “Property”).

WHEREAS, the Landowner is proceeding to build and develop the Property; and

WHEREAS, the SWM Site Plan (hereinafter referred to as the “Plan”) as approved by Hampden Township for the property identified herein, which is attached hereto as Appendix A and made part hereof, provides for management of stormwater within the confines of the Property through the use of BMPs; and

WHEREAS, Hampden Township, and the Landowner, his, her, its and/or their heirs, successors and assigns, agree that the health, safety, and welfare of the residents of Hampden Township and the protection and maintenance of water quality require that on-site SWM BMPs be constructed and maintained on the Property; and

WHEREAS, Hampden Township requires, through the implementation of the SWM Site Plan, that stormwater BMPs as required by said Plan and the Hampden Township Stormwater Management Ordinance be constructed and adequately operated and maintained by the Landowner, his, her, its, and/or their successors and assigns.

NOW, THEREFORE, in consideration of the foregoing promises, the mutual covenants contained herein, and the following terms and conditions, the parties hereto agree as follows:

1. The Landowner shall construct the BMPs in accordance with the plans and specifications identified in the SWM Site Plan.

2. The Landowner shall operate and maintain the BMPs as shown on the Plan in good working order in accordance with the specific maintenance requirements noted on the approved SWM Site Plan.

3. The Landowner hereby grants permission to Hampden Township, its authorized agents and employees, to enter upon the Property, at reasonable times and upon presentation of proper credentials, to inspect the BMPs whenever necessary. Whenever possible, Hampden Township shall notify the Landowner prior to entering the Property.

4. In the event the Landowner fails to operate and maintain the BMPs per paragraph 2, Hampden Township or its representatives may enter upon the Property and take whatever action is deemed necessary to maintain said BMPs. It is expressly understood and agreed that Hampden Township is under no obligation to maintain or repair said facilities, and in no event shall this Agreement be construed to impose any such obligation on Hampden Township.

5. In the event Hampden Township, pursuant to this Agreement, performs work of any nature, or expends any funds in performance of said work for labor, use of equipment, supplies, materials, and the like, or incurs any legal expenses in performing such work and/or enforcing the terms of this Agreement, the Landowner shall reimburse Hampden Township for all expenses (direct and indirect) incurred within ten (10) days of receipt of invoice from Hampden Township.

6. The intent and purpose of this Agreement is to ensure the proper maintenance of the onsite BMPs by the Landowner; provided, however, that this Agreement shall not be deemed to create or effect any additional liability of or on any party for damage alleged to result from or be caused by stormwater or stormwater runoff.

7. The Landowner, his, her, its and/or their heirs executors, administrators, assigns, and other successors in interests, shall and do hereby release and/or hold harmless Hampden Township of and from all damages, accidents, casualties, losses, occurrences and/or or claims which arise, might arise, are asserted or may be asserted against said the Hampden Township, its individual Commissioners, appointees, agents, subcontractors, appointees, employees and/or representatives from the construction, presence, existence, or maintenance of the BMP(s) by the Landowner or Hampden Township.

8. Hampden Township may inspect the BMPs whenever necessary to ensure their continued functioning.

This Agreement shall be recorded at the Office of the Recorder of Deeds of Cumberland County, Pennsylvania, and shall constitute a covenant running with the Property and/or equitable servitude thereon, and shall be binding on the Landowner, his, her, its and/or their administrators, executors, assigns, heirs and any other successors in interests, in perpetuity.

ATTEST:

WITNESS the following signatures and seals:

ATTEST: For Hampden Township:

Township Secretary (Township Seal)

Witness: For the Landowner:

(COMMONWEALTH OF PENNSYLVANIA)

: SS.

(COUNTY OF CUMBERLAND )

On this the day of , 20 before me, the undersigned officer, personally appeared , known to me (or satisfactorily proven) to be the person(s) whose name(s) is/are subscribed to the within instrument and acknowledged that he/she/they executed the same for the purposes therein contained.

IN WITNESS WHEREOF, I hereunto set my hand and official seal.

Notary Public

APPENDIX B TABLE A-1

DESIGN STORM RAINFALL AMOUNT (INCHES) FOR 24-HOUR STORM EVENT

RETURN FREQUENCY (YEARS) PRECIPITATION (INCHES)
1 2.40
2 2.90
5 3.55
10 4.45
25 5.40
50 6.60
100 7.60

Source: PennDOT “Storm Intensity-Duration-Frequency Charts”, May 1986.

TABLE A-2 RUNOFF CURVE NUMBERS (FROM NRCS (SCS) TR-55)

LAND USE HYDROLOGIC CONDITION RUNOFF CURVE NUMBER FOR

INDICATED

B C D
Open Space: 68 79 86 89
Poor Condition (grass cover < 50%)
Fair Condition (grass cover 50% to 75%) 49 69 79 84
Good Condition (grass cover > 75%) 39 61 74 80
Impervious Areas

Paved parking lots, roof, driveways Streets and roads:

Paved; w/ curbs and storm sewers Paved; w/ open ditches

Gravel Dirt

98

98

83

76

72

98

98

89

85

82

98

98

92

89

87

98

98

93

91

89

Urban Districts: 89 92 94 95
Commercial and Business
81 88 91 93
Residential Districts by average lot size: 77 85 90 92
1/8 acre or less (town houses)
¼ acre 61 75 83 87
1/3 acre 57 72 81 86
½ acre 54 70 80 85
1 acre 51 68 79 84
2 acres 47 66 77 82
Newly graded areas (pervious area, no vegetation) 81 89 93 95
Agricultural Lands:
LAND USE HYDROLOGIC CONDITION RUNOFF CURVE NUMBER FOR

INDICATED

B C D
Fallow: Poor 77 86 91 94
Bare soil
Crop residue cover 76 85 90 93
Crop residue cover Good 74 83 88 90
Pasture, grassland, or range Poor 68 79 86 89
Pasture, grassland, or range Fair 49 69 79 84
Pasture, grassland, or range Good 39 61 74 80
Agricultural Lands (continued): Row Crops:

Straight row Straight row

Straight row and crop residue cover Straight row and crop residue cover Contoured

Contoured

Contoured and crop residue cover Contoured and crop residue cover Contoured and terraced Contoured and terraced

Contoured, terraced & crop residue Contoured, terraced & crop residue

Poor Good Poor Good Poor Good Poor Good Poor Good Poor Good 72

67

71

64

70

65

69

64

66

62

65

61

81

78

80

75

79

75

78

74

74

71

73

70

88

85

87

82

84

82

83

81

80

78

79

77

91

89

90

85

88

86

87

85

82

81

81

80

Small Grain: Poor 65 76 84 88
Straight row
Straight row Good 63 75 83 87
Straight row and crop residue Poor 64 75 83 86
Straight row and crop residue Good 60 72 80 84
Contoured Poor 63 74 80 85
Contoured Good 61 73 81 84
Contoured and crop residue Poor 62 73 81 84
Contoured and crop residue Good 60 72 80 83
Contoured and terraced Poor 61 72 79 82
Contoured and terraced Good 59 70 78 81
Contoured, terraced & crop residue Poor 60 71 78 81
Contoured, terraced & crop residue Good 58 69 77 80
Meadow or Legumes: Poor 66 77 85 89
Straight row
Straight row Good 58 72 81 85
Contoured Poor 64 75 83 85
Contoured Good 55 69 78 83
Contoured and terraced Poor 63 73 80 83
Contoured and terraced Good 51 67 76 80
Meadow, continuous grass, protected from grazing and mowed for hay 30 58 71 78
Brush – brush/weed mixture Poor 48 67 77 83
LAND USE HYDROLOGIC CONDITION RUNOFF CURVE NUMBER FOR

INDICATED

B C D
Fair Good 35

30

56

48

70

65

77

73

Woods and grass combination (orchard) Poor Fair

ood

57

43

32

73

65

58

82

76

72

86

82

79

Woods oor Fair Good 45

36

30

66

60

55

77

73

70

83

79

77

Farmsteads – buildings, lanes, driveways, and surrounding lots 59 74 82 86

TABLE A-3

RATIONAL FORMULA RUNOFF COEFFICIENTS

TYPE OF DRAINAGE AREA RUNOFF COEFFICIENT
Lawns: 0.05-0.10
Sandy soil, flat, <2%
Sandy soil, average, 2-7% 0.10-0.15
Sandy soil, steep, >7% 0.15-0.20
Heavy soil, flat, <2% 0.13-0.17
Heavy soil, average, 2-7% 0.18-0.22
Heavy soil, steep, >7% 0.25-0.35
Business: 0.70-0.95
Downtown areas
Neighborhood areas 0.50-0.70
Residential: 0.30-0.50
Single-family areas
Multi units, detached 0.40-0.60
Multi units, attached 0.60-0.75
Suburban 0.25-0.40
Apartment dwelling areas 0.50-0.70
Industrial: 0.50-0.80
Light areas
Heavy areas 0.60-0.90
Parks, Cemeteries 0.10-0.25
Playgrounds 0.20-0.35
Railroad Yard Areas 0.20-0.40
Unimproved Areas 0.10-0.30
Streets: 0.70-0.95
Asphaltic
Concrete 0.80-0.95
Brick 0.70-0.85
Drives and Walks 0.75-0.85

Roofs 0.75-0.95

TABLE A-4

MANNING ROUGHNESS COEFFICIENTS

PIPE MATERIAL OR CHANNEL LINING ROUGHNESS COEFFICIENT
Cast Iron Pipe 0.013
Concrete Pipe 0.012
Corrugated Metal Pipe 0.024
Corrugated Metal Pipe – Paved Invert 0.019
High Density Polyethylene Pipe (HDPE) – Smooth Lined 0.012
High Density Polyethylene Pipe (HDPE) – Corrugated 0.018
Plastic Pipe (PVC, SDR, S&D) 0.011
Earth-lined Channel (few rocks) 0.020
Earth-bottomed Channel with Rock Sides 0.030
Grass-lined Channel 0.050

APPENDIX C
CUMBERLAND COUNTY RELEASE RATE MAP

 

Download PDF