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.
A.
These definitions do not necessarily reflect the definitions contained
in pertinent regulations or statutes and are intended for this chapter
only.
B.
AGRICULTURAL ACTIVITY
APPLICANT
BEST MANAGEMENT PRACTICE (BMP)
CARBONATE GEOLOGY
CG-1
CG-2
CLEAN WATER ACT (CWA)
CLEANING AGENT
CONSERVATION DISTRICT
DEP
DESIGN STORM
DESIGNATED USES
DETENTION VOLUME
DEVELOPMENT SITE (SITE)
DISTURBED AREA
DRY WEATHER
EARTH-DISTURBANCE ACTIVITY
EROSION
EXISTING CONDITION
EXISTING PERMITTEE
EXISTING USES
FEMA
FLOODPLAIN
FLOODWAY
FOREST MANAGEMENT/TIMBER OPERATIONS
GREEN INFRASTRUCTURE
HEC-RAS (HYDROLOGICAL ENGINEERING CENTRE — RIVER ANALYSIS
SYSTEM)
HIGH-QUALITY OR EXCEPTIONAL VALUE WATERS
(1)
HYDROLOGIC SOIL GROUP (HSG)
ILLICIT CONNECTION
ILLICIT DISCHARGE
IMPAIRED WATERS
IMPERVIOUS SURFACE (IMPERVIOUS AREA)
INTEGRATED WATER QUALITY MONITORING AND ASSESSMENT REPORT
INTERMITTENT STREAM
KARST
LAND DEVELOPMENT (DEVELOPMENT)
LOAD ALLOCATION
LOW-IMPACT DEVELOPMENT (LID)
MODIFIED RATIONAL METHOD
MS4 REQUIREMENTS TABLE
MUNICIPAL SEPARATE STORM SEWER
(1)
(2)
(3)
(4)
MUNICIPAL SEPARATE STORM SEWER SYSTEM (MS4)
MUNICIPALITY
NONSTRUCTURAL BMPs
(1)
(2)
(3)
NRCS
ORDINANCE
OUTFALL
OWNER OR OPERATOR
PEAK DISCHARGE
PERMITTEE
PERVIOUS AREA
POINT SOURCE
POLLUTANT
PROJECT SITE
PSRM
PULS METHOD
QUALIFIED PROFESSIONAL
RATIONAL METHOD
REGULATED ACTIVITIES
REGULATED EARTH-DISTURBANCE ACTIVITY
RETENTION VOLUME/REMOVED RUNOFF
RETURN PERIOD
RIPARIAN BUFFER
RUNOFF
SCS CURVE NUMBER METHOD
SEDIMENT
STATE WATER QUALITY REQUIREMENTS
STORMWATER
STORMWATER MANAGEMENT FACILITY
STORMWATER MANAGEMENT SITE PLAN
STRUCTURAL BMPs
SUBDIVISION
SURFACE WATERS
TOTAL MAXIMUM DAILY LOAD (TMDL)
URBANIZED AREA (UA)
USDA
WASTELOAD ALLOCATION (WLA)
WATER QUALITY CRITERIA
WATER QUALITY STANDARDS
WATERS OF THIS COMMONWEALTH
WATERSHED
WETLAND
As used in this chapter, the following terms shall have the meanings
indicated:
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.
A landowner, developer, or another person who has filed an
application with the municipality for approval to engage in any regulated
activity at a project site in the municipality.
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 "nonstructural." In this chapter, nonstructural 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.
A sedimentary rock made mainly of calcium carbonate (CaCO3),
limestone, and dolomite.
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.
A simplified method for design storm estimation that does
not take into account site conditions and is focused on capturing
and removing the first flush of stormwater runoff. This method is
applicable to designing projects with a land disturbance of 0.5 acre
or less.
The Federal Water Pollution Control Act, as amended, 33 U.S.C.A.
§§ 1251 through 1387.
Any product, substance, or chemical other than water that
is used to clean the exterior surface of vehicles.
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 Chapter 102.
The Pennsylvania Department of Environmental Protection.
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."
Uses specified in 25 Pa. Code §§ 93.4(a) and
93.9a through 93.9z for each water body or segment whether or not
they are being attained. (25 Pa. Code § 93.1)
The volume of runoff that is captured and released into the
waters of the commonwealth at a controlled rate.
See "project site."
An unstabilized land area where an earth-disturbance activity
is occurring or has occurred.
Condition in which there are no precipitation, snowmelt,
drainage or other events producing a stormwater discharge for more
than 48 consecutive hours.
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.
The natural process by which the surface of the land is worn
away by water, wind, or chemical action.
The dominant land cover during the five-year period immediately
preceding a proposed regulated activity.
Any entity that has been designated as a regulated small
MS4 and has previously obtained permit coverage under the PAG-13 general
permit or obtained an individual NPDES MS4 permit.
Those uses actually attained in the water body on or after
November 28, 1975, whether or not they are included in the water quality
standards. (25 Pa. Code § 93.1)
Federal Emergency Management Agency.
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).
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.
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.
Systems and practices that use or mimic natural processes
to infiltrate, evapotranspire, or reuse stormwater on the site where
it is generated.
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.
A Pennsylvania surface water that meets one or more of the
following conditions with regards to chemistry (supports propagation
of aquatic life) and biology (supports a diverse community of aquatic
life).
EXCEPTIONAL VALUE WATERA surface water that meets one or more of the following conditions is an exceptional value water: located in a national or state wildlife refuge, game, or protection area; the water is considered an outstanding national, state, or local resource water; surface water is of exceptional recreation significance, the waterway is designated as a "wilderness trout stream" by the Fish and Boat Commission; and/or, the water is a surface water of exceptional ecological significance.
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. Note: See § 265-1001A and B.)
Any physical connection to a municipal separate storm sewer
system that can convey illicit discharges into the system and/or is
not authorized or permitted by the permittee.
Any discharge to a municipal separate storm sewer that is
not composed entirely of stormwater, except nonstormwater 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 nonstormwater
waste into a municipal separate storm sewer system. Illicit discharges
can be accidental or intentional.
Surface waters that fail to attain one or more of their 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.
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, storage
sheds, and similar structures; and any new streets, driveways, 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 nonmotorized
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 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, twenty-four-hour storm event.
The report published every other year by DEP to report on
the conditions of Pennsylvania's surface waters to satisfy Sections
305(b) and 303(d) of the CWA.
A body of water flowing in a channel or bed composed primarily
of substrates associated with flowing water, which, during periods
of the year, is below the local water table and obtains its flow from
both surface runoff and groundwater discharges. (25 Pa. Code § 92a.2)
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.
Inclusive of any or all of the following meanings:
The portion of a surface water's loading capacity that
is assigned or allocated to existing and future nonpoint sources and
natural quality. (25 Pa. Code § 96.1)
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.
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.
 |
|
Q peak is determined from the rational method. (See definition
for "Rational Method.").
|
|
Q = C i A
|
|
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.
|
A compilation of information regarding Pennsylvania MS4s,
surface waters that receive stormwater discharges from MS4s, surface
water impairments, and TMDLs that is posted to DEP's website
www.dep.pa.gov/MS4. The MS4 Requirements Table has been assembled
by DEP to assist MS4 permittees in determining applicable requirements
for the development of plans and implementation of BMPs, as well as
eligibility for the PAG-13 general permit. In general, the MS4 Requirements
Table will be updated prior to each renewal of this general permit
based on DEP's latest published Integrated Water Quality Monitoring
and Assessment Report.
A conveyance or system of conveyances (including roads with
drainage systems, municipal streets, catch basins, curbs, gutters,
ditches, man-made channels, or storm drains):
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 Section 208 of the CWA that discharges to surface waters;
Designed or used for collecting or conveying stormwater;
Which is not a combined sewer; and
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)].
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)].
Spring Garden Township, York County, Pennsylvania, a township
of the second class created by or pursuant to state law and having
jurisdiction over disposal of sewage, industrial wastes, or other
wastes (25 Pa. Code § 92a.2).
Actions that involve management and source controls, such
as:
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;
Education programs for developers and the public about minimizing
water quality impacts;
Measures such as minimizing the percentage of impervious area after development, use of measures to minimize directly connected impervious areas, street sweeping, and source control measures, such as good housekeeping, maintenance, and spill prevention; and other BMPs as referenced in Chapter 5 of the Pennsylvania Stormwater BMP Manual (363-0300-002).
Natural Resources Conservation Service, a subset of the United
States Department of Agriculture.
A law enacted by the government of the municipality.
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)].
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].
The maximum rate of stormwater runoff from a specific storm
event.
The owner or operator of a regulated small MS4 authorized
to discharge under the terms of this general permit.
Any area not defined as "impervious."
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).
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).
The specific area of land where any regulated activities
in the municipality are planned, conducted, or maintained.
The Penn State Runoff Model.
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).
Any person licensed by the Pennsylvania Department of State
or otherwise qualified by law to perform the work required by this
chapter.
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
|
=
|
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.
|
Any earth-disturbance activities or any activities that involve
the alteration or development of land in a manner that may affect
stormwater runoff.
Activity involving earth disturbance subject to regulation
under 25 Pa. Code Chapter 92, 25 Pa. Code Chapter 102, or the Clean
Streams Law.[2]
The volume of runoff that is captured and not released directly
into the surface waters of this commonwealth during or after a storm
event.
The average interval, in years, within which a storm event
of a given magnitude can be expected to occur one time. For example,
the twenty-five-year return period rainfall would be expected to occur
on average once every 25 years; or stated in another way, the probability
of a twenty-five-year storm occurring in any one year is 0.04 (i.e.,
a 4% chance).
A permanent area of trees and shrubs located adjacent to
streams, lakes, ponds and wetlands.
Any part of precipitation that flows over the land.
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.
Soils or other materials transported by surface water as
a product of erosion.
The regulatory requirements to protect, maintain, reclaim,
and restore water quality under Title 25 of the Pennsylvania Code
and the Clean Streams Law.
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 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 Chapter 6 of the Pennsylvania
Stormwater BMP Manual (363-0300-002).
As defined in the Pennsylvania Municipalities Planning Code,
Act of July 31, 1968, P.L. 805, No. 247.[3]
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)
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).
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.
United States Department of Agriculture.
The portion of a surface water's loading capacity that
is allocated to existing and future point source discharges (25 Pa.
Code § 96.1).
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).
The combination of water uses to be protected and the water
quality criteria necessary to protect those uses (25 Pa. Code § 92a.2).
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.
Region or area drained by a river, watercourse, or other
surface water of this commonwealth.
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.
