1. For the purposes of this Chapter, 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. Any term defined within 25 PA Code (Chapter 102) shall be the default definition.
2. These definitions do not necessarily reflect the definitions contained in pertinent regulations or statutes and are intended for this Chapter only.
Agricultural activity–activities associated with agriculture such as agricultural cultivation, agricultural operation, and animal heavy use areas. This includes the work of producing crops, including tillage, land clearing, plowing, disking, harrowing, planting, harvesting crops, or pasturing and raising of livestock and installation of conservation measures. Construction of new buildings or impervious area is not considered an agricultural activity.
Applicant–a landowner, developer, or other person who has filed an application to the Township for approval to engage in any regulated activity at a project site in the Township.
As built plans–also referred to as record plans or as built drawings, are a set of plans, required to be submitted to the Township by the developer, at the completion of the project, showing the actual constructed size, location, elevation and detail of all SWM BMPs included in the approved SWM site plan. As built plans shall meet the requirements of Section 2.7- As Built Drawings of the Dover Township Construction Specifications and § 19-408.
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 Chapter. Stormwater BMPs are commonly grouped into one of two broad categories or measures: “structural” or “non-structural.” In this Chapter, 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.
CG-1–a standard method for design flood estimation in ungauged catchments that investigates set design storms characterized by a specific duration, temporal distribution, rainfall intensity, return frequency, and total depth of rainfall.
CG-2–a simplified method for design storm estimation that is focused on capturing and removing the first flush of stormwater runoff. This method is applicable to designing projects with a land disturbance of one-half acre or less.
Clean Water Act (CWA)–means the Federal Water Pollution Control Act, as amended, 33 U.S.C.A. §§ 1251-1387.
Cleaning agent–any product, substance, or chemical other than water that is used to clean.
Conservation district–a conservation district, as defined in Section 3(c) of the Conservation District Law (3 P. S. § 851(c)) that has the authority under a delegation agreement executed with DEP to administer and enforce all or a portion of the regulations promulgated under 25 Pa. Code 102.
Designated uses–uses specified in 25 Pa. Code §§93.4(a) and 93.9a - 93.9z for each water body or segment whether or not they are being attained. (25 Pa. Code § 93.1).
Design storm–the magnitude and temporal distribution of precipitation from a storm event measured in probability of occurrence (e.g., a five-year storm) and duration (e.g., 24 hours) used in the design and evaluation of stormwater management systems. Also, see Return period.
Detention volume–the volume of runoff that is captured and released into the waters of the Commonwealth at a controlled rate.
DEP–the Pennsylvania Department of Environmental Protection.
Development site (site)–see Project site.
Disturbed area–an unstabilized land area where an earth disturbance activity is occurring or has occurred.
Dry weather–condition in which there are no precipitation, snowmelt, drainage or other events producing a stormwater discharge for more than 48 consecutive hours.
Earth disturbance activity–a construction or other human activity which disturbs the surface of the land, including, but not limited to: clearing and grubbing; grading; excavations; embankments; road maintenance; building construction; and the moving, depositing, stockpiling, or storing of soil, rock, or earth materials.
Erosion–the natural process by which the surface of the land is worn away by water, wind, or chemical action.
Existing condition–the dominant land cover during the five-year period immediately preceding a proposed regulated activity.
FEMA–Federal Emergency Management Agency.
Floodplain–any land area susceptible to inundation by water from any natural source or delineated by applicable FEMA maps and studies as being a special flood hazard area. It also includes areas that comprise Group 13 Soils, as listed in Appendix A of the Pennsylvania DEP Technical Manual for Sewage Enforcement Officers (as amended or replaced from time to time by DEP).
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.
Green infrastructure–systems and practices that use or mimic natural processes to infiltrate, evapotranspire, or reuse stormwater on the site where it is generated.
HEC-RAS (Hydrological Engineering Centre - River Analysis System)–is a one-dimensional hydraulic modeling program based on four types of analysis in rivers: steady flow, unsteady flow, sediment transport, and water quality analysis. Models simulate the flow in natural riverbeds or artificial channels to determine water levels using various data inputs. HEC-RAS analyses are primarily developed for flood studies and determining potential drainage impacts to waterways.
Hydrologic soil group (HSG)–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 (NRCS1, 2).
Illicit connection–any physical connection to a municipal separate storm sewer system that can convey illicit discharges into the system.
Illicit discharge–any discharge to a municipal separate storm sewer that is not composed entirely of stormwater, except non-stormwater discharges as described in the “discharges authorized by this general permit” section of this general permit. Examples of illicit discharges include dumping of motor vehicle fluids, household hazardous wastes, grass clippings, leaf litter, animal wastes, or unauthorized discharges of sewage, industrial waste, restaurant wastes, or any other non-stormwater waste into a municipal separate storm sewer system. Illicit discharges can be accidental or intentional.
Impaired waters–surface waters that fail to attain one or more of its designated uses under 25 Pa. Code Chapter 93 and as listed in Categories 4 and 5 of Pennsylvania’s Integrated Water Quality Monitoring and Assessment Report.
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; additional indoor living spaces, patios, garages, tongue and groove trex deck, storage sheds, and similar structures; and any new streets, driveway, access drives, parking areas, and sidewalks. Any areas designed to be covered by loose surfacing materials such as gravel, stone, and/or crushed stone and intended for storage of and/or travel by motorized or non-motorized vehicles or travel by pedestrians shall be considered impervious. Surfaces or areas designed, constructed, and maintained to permit infiltration as specified herein may be considered pervious. For the purposes of this Chapter, a surface or area, such as a wooden deck with gaps between the boards, shall not be considered impervious if such surface or area does not diminish the capacity for infiltration of stormwater for storms up to, and including, a two-year, 24-hour storm event.
Infiltration testing–that testing performed with a double-ring infiltrometer in accordance with the current edition of the BMP Manual, at the location and elevation of the bottom of the proposed facility. Guidance for Infiltration Testing is found in Appendix 19-C of this Chapter.
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 or all of the following meanings: (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; or (b) the division or allocation of land or space 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 § 503(1.1) of the PA Municipalities Planning Code.
Low impact development (LID)–site design approaches and small-scale stormwater management practices that promote the use of natural systems for infiltration, evapotranspiration, and reuse of rainwater. LID can be applied to new development, urban retrofits, and revitalization projects. LID utilizes design techniques that infiltrate, filter, evaporate, and store runoff close to its source. Rather than rely on costly large-scale conveyance and treatment systems, LID addresses stormwater through a variety of small, cost-effective landscape features located on-site.
Modified rational method–the modified rational method provides a way to calculate the hydrograph from a catchment-based on rational method C values and the peak intensity. There is no “loss method” associated with the modified rational method. The underlying assumption is that the peak intensity is maintained for a long enough duration to reach peak flow at the outlet of the catchment. This results in a trapezoidal hydrograph, as shown below.
A. Qpeak is determined from the rational method (see definition for Rational method).
B. Q=CiA
C. When using English units, i is intensity in: in/hr, A = area, acres; Q = flow, cfs; and C is runoff coefficient, dimensionless. The time to reach the peak is based on the time of concentration in the catchment, which the user can manually enter or calculate using a variety of methods (Rational method). The length of the recession leg is based on the time of concentration times a recession multiplier which is set in the calculations options. The intensity and duration are taken from the IDF curves (tables) based on the duration and frequency (return period) of the storm.
Municipal separate storm sewer–a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains): (i) owned or operated by a state, city, town, borough, county, parish, district, association, or other public body (created by or pursuant to State law) having jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes, including special districts under State law such as a sewer district, flood control district or drainage district, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under § 208 of the CWA that discharges to surface waters; (ii) designed or used for collecting or conveying stormwater; (iii) which is not a combined sewer; and (iv) which is not part of a Publicly Owned Treatment Works (POTW) as defined at 40 CFR 122.2. (25 Pa. Code § 92a.32(a) and 40 CFR § 122.26(b)(8)).
Municipal separate storm sewer system (MS4)–all separate storm sewers that are defined as “large” or “medium” or “small” municipal separate storm sewer systems pursuant to 40 CFR §§ 122.26(b)(4), (b)(7), and (b)(16), respectively, or designated under 40 CFR § 122.26(a)(1)(v) (25 Pa. Code §92a.32(a) and 40 CFR § 122.26(b)(18)).
Municipality–a city, town, borough, county, township, school district, institution, authority, or other public body created by or pursuant to State law and having jurisdiction over disposal of sewage, industrial wastes, or other wastes (25 Pa. Code § 92a.2).
Non-structural BMPs–actions that involve management and source controls such as (1) policies and ordinances that provide requirements and standards to direct growth to identified areas, promote redevelopment, protect areas such as wetlands and riparian areas, maintain and/or increase open space, provide buffers along water bodies, minimize impervious surfaces, and minimize disturbance of soils and vegetation; (2) education programs for developers and the public about minimizing water quality impacts; (3) measures such as minimizing the percentage of impervious area after development, use of measures to minimize directly connected impervious areas, and source control measures such as good housekeeping, maintenance, and spill prevention; and other BMPs as referenced in the current version of the Pennsylvania Stormwater BMP Manual.
NRCS–Natural Resources Conservation Service, a subset of the United States Department of Agriculture.
Ordinance–a law enacted by the government of a municipality.
Outfall–a point source as defined by 40 CFR § 122.2 at the point where a municipal separate storm sewer discharges to surface waters and does not include open conveyances connecting two municipal separate storm sewers, or pipes, tunnels, or other conveyances which connect segments of the same stream or other surface waters and are used to convey surface waters. (25 Pa. Code § 92a.32(a) and 40 CFR § 122.26(b)(9)).
Owner or operator–the owner or operator of any “facility” or “activity” subject to regulation under the NPDES program. (25 Pa. Code §92a.3(b)(1) and 40 CFR §122.2).
Permittee–the owner or operator of a regulated small MS4 authorized to discharge under the terms of this general permit.
Point source–a discernible, confined, and discrete conveyance, including, but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, Concentrated Aquatic Animal Production Facility (CAAP), Concentrated Animal Feeding Operation (CAFO), landfill leachate collection system, or vessel or other floating craft from which pollutants are or may be discharged (25 Pa. Code § 92a.2).
Pollutant–any contaminant or other alteration of the physical, chemical, biological, or radiological integrity of surface water which causes or has the potential to cause pollution as defined in section 1 of the Pennsylvania Clean Streams Law, 35 P.S. § 691.1 (25 Pa. Code § 92a.2).
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 Township are planned, conducted, or maintained.
PSRM–the Penn State Runoff Model.
PULS method–the modified PULS routing method, also known as storage routing or level-pool routing, is based upon a finite difference approximation of the continuity equation, coupled with an empirical representation of the momentum equation (Chow, 1964; Henderson, 1966).
Qualified professional–any person licensed by the Pennsylvania Department of State or otherwise qualified by law to perform the work required by this Chapter.
Rational method–the rational method solves for peak discharge based on watershed area, rational coefficient, and rainfall intensity for the watershed. The following equation is used to compute flow using the rational method:
Q = CiA | ||
Q | 0 | Flow (cfs) for drainage area A |
C | Weighted runoff coefficient for drainage area A | |
i | Intensity (in/hr.) for the given design frequency and storm duration (this value is taken from the I-D-F curves for your design area) | |
A | Drainage area (acres) | |
C, the rational coefficient, is the parameter that is most open to engineering judgment. In many cases, an area-weighted average of C coefficients is used as the C for the entire drainage area.
Regulated activities–any earth disturbance activities or any activities that involve the alteration or development of land in a manner that may affect stormwater runoff.
Regulated earth disturbance activity–activity involving earth disturbance subject to regulation under 25 Pa. Code 92, 25 Pa. Code 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).
Riparian buffer–a permanent area of trees and shrubs located adjacent to streams, lakes, ponds and wetlands.
Runoff–any part of precipitation that flows over the land.
SCS curve number method–the SCS curve number method is simple, widely used, and an efficient method for determining the approximate amount of runoff from a rainfall event in a particular area. Although the method is designed for a single storm event, it can be scaled to find average annual runoff values. The curve number is based on the area’s hydrologic soil group, land use, treatment, and hydrologic condition.
Sediment–soils or other materials transported by surface water as a product of erosion.
Small projects guide–option of stormwater management guidance, found in Appendix 19-D of this Chapter, for regulated activities that propose 501 to 2,000 square feet of new impervious area.
State water quality requirements–the regulatory requirements to protect, maintain, reclaim, and restore water quality under Title 25 of the Pennsylvania Code and the Clean Streams Law.
Stormwater–
A. Runoff from precipitation, snow melt runoff, and surface runoff and drainage. “Stormwater” has the same meaning as “storm water” (25 Pa. Code § 92a.2).
B. 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 site plan–the plan prepared by the developer or his representative indicating how stormwater runoff will be managed at the development site in accordance with this Chapter. Stormwater management site plan will be designated as SWM site plan throughout this Chapter.
Structural BMPs–stormwater storage and management practices including, but not limited to, wet ponds and extended detention outlet structures; filtration practices such as grassed swales, sand filters, and filter strips; infiltration practices such as infiltration basins and infiltration trenches; and other BMPs as referenced in current version of the Pennsylvania Stormwater BMP Manual (363-0300-002).
Subdivision–as defined in The Pennsylvania Municipalities Planning Code, Act of July 31, 1968, P.L. 805, No. 247.
Surface waters–perennial and intermittent streams, rivers, lakes, reservoirs, ponds, wetlands, springs, natural seeps, and estuaries, excluding water at facilities approved for wastewater treatment such as wastewater treatment impoundments, cooling water ponds, and constructed wetlands used as part of a wastewater treatment process (25 Pa. Code § 92a.2).
Total maximum daily load (TMDL)–the sum of individual waste load allocations for point sources, load allocations for nonpoint sources and natural quality and a margin of safety expressed in terms of mass per time, toxicity, or other appropriate measures (25 Pa. Code § 96.1).
Urbanized area (UA)–land area comprising one or more places (central place(s)) and the adjacent densely settled surrounding area (urban fringe) that together have a residential population of at least 50,000 and an overall population density of at least 1,000 people per square mile, as defined by the United States Bureau of the Census and as determined by the latest available decennial census. The UA outlines the extent of automatically regulated areas.
Wasteload allocation (WLA)–the portion of a surface water’s loading capacity that is allocated to existing and future point source discharges (25 Pa. Code § 96.1).
Water quality criteria–numeric concentrations, levels or surface water conditions that need to be maintained or attained to protect existing and designated uses (25 Pa. Code § 93.1).
Water quality standards–the combination of water uses to be protected and the water quality criteria necessary to protect those uses (25 Pa. Code § 92a.2).
Waters of this Commonwealth–any and all rivers, streams, creeks, rivulets, impoundments, ditches, watercourses, storm sewers, lakes, dammed water, wetlands, ponds, springs, and all other bodies or channels of conveyance of surface 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 this Commonwealth.
Wetland–areas that are inundated or saturated by surface or groundwater 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, and similar areas.
USDA–United States Department of Agriculture.
(Ord. 2022-01, 7/25/2022)