The words "shall" and "must" are mandatory; the words "may" and "should"
are permissive.
ACCELERATED EROSION
The removal of the surface of the land through the combined
action of human activities and natural processes, at a rate greater
than would occur because of the natural processes alone.
APPLICANT
A landowner, developer, or other person who has filed an
application with the Township for approval to engage in any earthmoving
or other regulated activity in the Township.
[Added by Ord. No. 2022-05, 10/6/2022]
BEST MANAGEMENT PRACTICE (BMP)
Activities, facilities, measures or procedures used to manage stormwater quantity and quality impacts from the regulated activities listed in §
23B-105, to meet state water quality requirements, to promote groundwater recharge and to otherwise meet the purposes of this Chapter
23B. Stormwater BMPs are commonly grouped into one of two broad categories or measures: structural and nonstructural. 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.
[Amended by Ord. No. 2022-05, 10/6/2022]
BIORETENTION
Densely vegetated, depressed features that store stormwater
and filter it through vegetation, mulch, planting soil, etc. Ultimately
stormwater is evapotranspirated, infiltrated, or discharged. Optimal
bioretention areas mimic natural forest ecosystems in terms of species
diversity, density, distribution, use of native plants, etc.
CAPTURE/REUSE
Stormwater management techniques such as cisterns and rain
barrels which direct runoff into storage devices, surface or subsurface,
for later reuse, such as for irrigation of gardens and other planted
areas.
CARBONATE BEDROCK
Rock consisting chiefly of carbonate minerals, such as limestone
and dolomite; specifically, a sedimentary rock composed of more than
50% by weight of carbonate minerals that underlies soil or other unconsolidated,
superficial material.
[Added by Ord. No. 2022-05, 10/6/2022]
CISTERN
An underground reservoir or tank for storing rainwater.
CLOSED DEPRESSION
A distinctive bowl-shaped depression in the land surface.
It is characterized by internal drainage, varying magnitude, and an
unbroken ground surface.
CONSERVATION DISTRICT
The agency with authority granted by a delegated agreement
executed by the DEP in order to administer and enforce all, or a portion
of, the regulations promulgated under 25 Pa. Code 102 - Lehigh County
Conservation District, its successors and assigns.
[Amended by Ord. No. 2022-05, 10/6/2022]
CONSTRUCTED WETLANDS
Constructed wetlands are similar to wet ponds (see below)
and consist of a basin which provides for necessary stormwater storage
as well as a permanent pool or water level, planted with wetland vegetation.
To be successful, constructed wetlands must have adequate natural
hydrology (both runoff inputs as well as soils and water table which
allow for maintenance of a permanent pool of water). In these cases,
the permanent pool must be designed carefully, usually with shallow
edge benches, so that water levels are appropriate to support carefully
selected wetland vegetation.
CULVERT
A pipe, conduit or similar structure including appurtenant
works which carries surface water.
DAM
An artificial barrier, together with its appurtenant works,
constructed for the purpose of impounding or storing water or another
fluid or semifluid or a refuse bank, fill or structure for highway,
railroad or other purposes which does or may impound water or another
fluid or semifluid.
DEP
The Pennsylvania Department of Environmental Protection.
DESIGN STORM
The depth and time distribution of precipitation from a storm
event measured in probability of occurrence (e.g., one-hundred-year
storm) and duration (e.g., twenty-four-hour) and used in computing
stormwater management control systems.
DETENTION BASIN
A basin designed to retard stormwater runoff by temporarily
storing the runoff and releasing it at a predetermined rate.
DEVELOPER
A person, partnership, association, corporation or other entity, or any responsible person therein or agent thereof, that undertakes any regulated activity of this Chapter
23B.
DEVELOPMENT SITE (SITE)
The specific tract of land for which a regulated activity
or earth disturbance is proposed, conducted, or maintained.
[Amended by Ord. No. 2022-05, 10/6/2022]
DIRECT RECHARGE (D-RE) BMP
A BMP which directs runoff to an underground infiltration
surface. Examples include infiltration trenches, seepage beds, and
drywells such that nearly all runoff becomes recharge to groundwater.
DRAINAGE EASEMENT
A right granted by a land owner to a grantee, allowing the
use of private land for stormwater management purposes.
DRAINAGE PLAN
The documentation of the proposed stormwater quantity and quality management controls to be used for a given development site, including a BMP operations and maintenance plan, the contents of which are established in §
23B-403.
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, land development, agricultural
plowing or tilling, timber harvesting activities, road maintenance
activities, mineral extraction, and the moving, depositing, stockpiling,
or storing of soil, rock or earth materials.
EROSION
The removal of soil particles by the action of water, wind,
ice, or other geological agents.
EROSION AND SEDIMENT CONTROL PLAN
A plan for a project site which identifies BMPs to minimize
accelerated erosion and sedimentation.
[Added by Ord. No. 2022-05, 10/6/2022]
EVAPOTRANSPIRATION (ET) BMP
A BMP which provides opportunity for runoff evaporation and
transpiration by vegetation. Examples include bioretention and surface
infiltration basins.
EXISTING USES
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, Chapter 93.1)
FEMA
Federal Emergency Management Agency.
[Added by Ord. No. 2022-05, 10/6/2022]
FILL
Man-made deposits of natural soils or rock products and waste
materials.
FREEBOARD
The incremental depth in a stormwater management structure,
provided as a safety factor of design, above that required to convey
the design runoff event.
HARDSHIP WAIVER REQUEST
A written request for a waiver alleging that the provisions of this Chapter
23B inflict unnecessary hardship upon the applicant. A hardship waiver does not apply to and is not available from the water quality provisions of this Chapter
23B and should not be granted.
HOT SPOT LAND USES
A land use or activity that generates higher concentrations
of hydrocarbons, trace metals or other toxic substances than typically
found in stormwater runoff. These land uses are listed in Appendix
23B-F.
HYDROLOGIC SOIL GROUP (HSG)
Soils are classified into four HSG's (A, B, C and D) to indicate
the minimum infiltration rates, which are obtained for bare soil after
prolonged wetting. The Natural Resources Conservation Service (NRCS)
of the U.S. Department of Agriculture 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 permeable as the HSG varies from A to D.
INFILTRATION PRACTICE
A practice designed to allow runoff an opportunity to infiltrate
into the ground, e.g. French drain, seepage pit, seepage trench, or
bioretention area.
LAND DEVELOPMENT
Any of the following activities:
(1)
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 residential or nonresidential buildings, whether proposed initially
or cumulatively, or a single nonresidential building on a lot or lots
regardless of the number of occupants of tenure; 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.
(3)
Development in accordance with § 503(1.1) of the Pennsylvania
Municipalities Planning Code, 53 P.S. § 10503(1.1).
LOW IMPACT DEVELOPMENT
A development approach that promotes practices that will
minimize post-development runoff rates and volumes thereby minimizing
needs for artificial conveyance and storage facilities. Site design
practices include preserving natural drainage features, minimizing
impervious surface area, reducing the hydraulic connectivity of impervious
surfaces and protecting natural depression storage.
LVPC
The Lehigh Valley Planning Commission.
MAINSTEM (MAIN CHANNEL)
Any stream segment or other conveyance used as a reach in
the Perkiomen Creek Headwaters Watershed hydrologic model.
MANNING EQUATION (MANNING FORMULA)
A method for calculation of velocity of flow (e.g., feet
per second) and flow rate (e.g., cubic feet per second) in open channels
based upon channel shape, roughness, depth of flow and slope. "Open
channels" may include closed conduits so long as the flow is not under
pressure.
MARYLAND STORMWATER DESIGN MANUAL
A stormwater design manual written by the Maryland Department
of the Environment and the Center for Watershed Protection. As of
January 2004, the Manual can be obtained through the following web
site: www.mde.state.md.us.
MINIMUM DISTURBANCE/MINIMUM MAINTENANCE PRACTICES (MD/MM)
Site design practices in which careful limits are placed
on site clearance prior to development allowing for maximum retention
of existing vegetation (woodlands and other), minimum disturbance
and compaction of existing soil mantle and minimum site application
of chemicals post-development. Typically, MD/MM includes disturbance
setback criteria from buildings as well as related site improvements
such as walkways, driveways, roadways, and any other improvements.
These criteria may vary by community context as well as by type of
development being proposed. Additionally, MD/MM shall include provisions
(e.g., deed restrictions, conservation easements) to protect these
areas from future disturbance and from application of fertilizers,
pesticides, and herbicides.
MPC
The Pennsylvania Municipalities Planning Code, Act 247 of
July 31, 1968, P.L. 805, 53 P.S. § 10101 et seq., as reenacted
and amended.
MUNICIPALITY (TOWNSHIP)
Lower Macungie Township, Lehigh County, Pennsylvania.
[Amended by Ord. No. 2022-05, 10/6/2022]
NPDES
National Pollutant Discharge Elimination System.
OIL/WATER SEPARATOR
A structural mechanism designed to remove free oil and grease
(and possibly solids) from stormwater runoff.
OUTFALL
"Point source" as described in 40 CFR 122.2 at the point
where the Township's storm sewer system discharges to surface waters
of the commonwealth.
OWNER
One with an interest in and often dominion over a property.
PEAK DISCHARGE
The maximum rate of flow of stormwater runoff at a given
location and time resulting from a specified storm event.
PERSON
An individual, partnership, public or private association
or corporation, firm, trust, estate, municipality, governmental unit,
public utility or any other legal entity whatsoever which is recognized
by law as the subject of rights and duties.
POINT SOURCE
Any discernible, confined and discrete conveyance, including,
but not limited to, any pipe, ditch, channel, tunnel or conduit from
which stormwater is or may be discharged, as defined in state regulations
at 25 Pa.Code § 92.1.
PUBLIC WATER SYSTEM
A system which provides water to the public for human consumption
which has at least 15 service connections or regularly serves an average
of at least 25 individuals daily at least 60 days out of the year.
(See 25 Pa.Code, Chapter 109.)
RATIONAL METHOD
A method of runoff calculation using a standardized runoff
coefficient (rational 'c'), acreage of tract, and rainfall intensity
determined by return period and by the time necessary for the entire
tract to contribute runoff. The Rational Method formula for peak rate
calculation is stated as follows: Q = ciA, where "Q" is the calculated
peak flow rate in cubic feet per second, "c" is the dimensionless
runoff coefficient (see Appendix 23B-C), "i" is the rainfall intensity
in inches per hour, and "A" is the area of the tract in acres. The
Rational Method formula for runoff volume calculation is as follows:
V = cPA/12 where "c" and "A" are as noted above, "P" is the total
depth of precipitation for the design event in inches, and "V" is
the total runoff volume in acre-feet.
REACH
Any of the natural or man-made runoff conveyance channels
used for watershed runoff modeling purposes to connect the subareas
and transport flows downstream.
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 and that are governed by this Chapter
23B as specified in §
23B-105.
REGULATED EARTH DISTURBANCE ACTIVITIES
Activity involving earth disturbance, other than agricultural
plowing or tilling, of 10,000 square feet or more subject to regulation
under 25 Pa. Code 92, 25 Pa. Code 102, or the Clean Streams Law, 35
P.S. § 693.1 et seq.
[Amended by Ord. No. 2022-05, 10/6/2022]
RELEASE RATE
The percentage of the pre-development peak rate of runoff
for a development site to which the post-development peak rate of
runoff must be controlled to avoid peak flow increases throughout
the watershed.
RETURN PERIOD
The average interval in years over which an event of a given
magnitude can be expected to recur. For example, the twenty-five-year
return period rainfall or runoff event would be expected to recur
on the average once every 25 years.
ROAD MAINTENANCE
Earth disturbance activities within the existing road cross-section
such as grading and repairing existing unpaved road surfaces, cutting
road banks, cleaning or clearing drainage ditches, and other similar
activities.
RUNOFF
Any part of precipitation which flows over the land.
[Amended by Ord. No. 2022-05, 10/6/2022]
SEDIMENT
Soils or other materials transported by surface water as
a product of erosion.
[Added by Ord. No. 2022-05, 10/6/2022]
SEDIMENT TRAPS/CATCH BASIN SUMPS
Chambers which provide storage below the outlet in a storm
inlet to collect sediment, debris, and associated pollutants, typically
requiring periodic clean out.
SEEPAGE PIT/SEEPAGE TRENCH
An area of excavated earth filled with loose stone or similar
material and into which surface water is directed for infiltration
into the ground.
SEPARATE STORM SEWER SYSTEM
A conveyance or system of conveyances (including roads with
drainage systems, municipal streets, catch basins, curbs, gutters,
ditches, man-made channels, or storm drains) primarily used for collecting
and conveying stormwater runoff.
SHEET FLOW
Stormwater runoff flowing in a thin layer over the ground
surface.
SOIL-COVER-COMPLEX METHOD
A method of runoff computation developed by NRCS which is
based upon relating soil type and land use/cover to a runoff parameter
called a curve number.
SPILL PREVENTION AND RESPONSE PROGRAM
A program that identifies procedures for preventing and,
as needed, cleaning up potential spills and makes such procedures
known and the necessary equipment available to appropriate personnel.
STATE WATER QUALITY REQUIREMENTS
As defined under state regulations; protection of designated
and existing uses (See 25 Pa.Code Chapters 93 and 96); including:
(1)
Each stream segment in Pennsylvania has a "designated use,"
such as "cold water fishes" or "potable water supply," which is listed
in Chapter 93. These uses must be protected and maintained, under
state regulations.
(2)
"Existing uses" are those attained as of November 1975, regardless
whether they have been designated in Chapter 93. Regulated earth disturbance
activities must be designed to protect and maintain existing uses
and maintain the level of water quality necessary to protect those
uses in all streams, and to protect and maintain water quality in
special protection streams.
(3)
Water quality involves the chemical, biological and physical
characteristics of surface water bodies. After regulated earth disturbance
activities are complete, these characteristics can be impacted by
addition of pollutants such as sediment, and changes in habitat through
increased flow volumes and/or rates as a result of changes in land
surface area from those activities. Therefore, permanent discharges
to surface waters must be managed to protect the stream bank, streambed,
and structural integrity of the waterway, to prevent these impacts.
STORAGE INDICATION METHOD
A method of routing or moving an inflow hydrograph through
a reservoir or detention structure. The method solves the mass conservation
equation to determine an outflow hydrograph as it leaves the storage
facility.
STORM DRAINAGE PROBLEM AREAS
Areas which lack adequate stormwater collection and/or conveyance facilities. These areas are either documented in Appendix 23B-B of this Chapter
23B or identified by the Township or Township Engineer.
STORM SEWER
A system of pipes or other conduits which carries intercepted
surface runoff, street water and other wash waters, or drainage, but
excludes domestic sewage and industrial wastes.
STORMWATER
The surface runoff generated by precipitation reaching the
ground surface.
STORMWATER FILTERS
Any number of structural mechanisms such as multi-chamber
catch basins, sand/peat filters, sand filters, and so forth which
are installed to intercept stormwater flow and remove pollutants prior
to discharge. Typically, these systems require periodic maintenance
and clean out.
STORMWATER MANAGEMENT CONTROLS (aka STORMWATER MANAGEMENT FACILITY)
Any structure, natural or man-made, that, due to its condition,
design, or construction, conveys, stores, or otherwise manages stormwater
runoff. Typical stormwater management facilities include but are not
limited to: detention and retention basins; open channels; storm sewers;
pipes; and, infiltration facilities.
[Added by Ord. No. 2022-05, 10/6/2022]
STORMWATER MANAGEMENT PLAN
The plan for managing stormwater runoff adopted by Lehigh
County for the Perkiomen Creek Headwaters Watershed as required by
the Act 167 of October 4, 1978, P.L. 864, as amended, and known as
the "Stormwater Management Act," 32 P.S. § 680.1 et seq.
SUBAREA
The smallest unit of watershed breakdown for hydrologic modeling
purposes for which the runoff control criteria have been established
in the Stormwater management plan.
SUBDIVISION
The division or redivision of a lot, tract or parcel of land
by any means into two or more lots, tracts, parcels, or other divisions
of land including changes in existing lot lines for the purpose, whether
immediate or future, of lease, partition by the court for distribution
to heirs or devisees, transfer of ownership, or building or lot development;
provided, however, that the subdivision by lease of land for agricultural
purposes into parcels of more than 10 acres, not involving and new
street or easement of access or any residential dwelling, shall be
exempted.
SURFACE WATERS OF THE COMMONWEALTH
Any and all rivers, streams, creeks, rivulets, impoundments,
ditches, watercourses, storm sewers, lakes, dammed water, wetlands,
ponds, springs, and all other bodies or channels of conveyance of
surface water, or parts thereof, whether natural or artificial, within
or on the boundaries of this commonwealth.
SWALE
A low-lying stretch of land which gathers or carries surface
water runoff. See also "vegetated swale."
TOWNSHIP
Lower Macungie Township, Lehigh County, Pennsylvania.
TRASH/DEBRIS COLLECTORS
Racks, screens, or other similar devices installed in a storm
drainage system to capture coarse pollutants (trash, leaves, etc.).
VEGETATED BUFFERS
Gently sloping areas that convey storm water as sheet flow
over a broad, densely vegetated earthen area, possibly coupled with
the use of level spreading devices. As water quality BMPs, vegetated
buffers serve to filter pollutants from runoff and promote infiltration.
Vegetated buffers should be situated on minimally disturbed soils,
have low-flow velocities, and extended residence times. Vegetated
buffers may be, but are not restricted to, use in riparian (streamside)
conditions.
VEGETATED ROOFS
Vegetated systems installed on roofs that generally consist
of a waterproof layer, a root-barrier, drainage layer (optional),
growth media, and suitable vegetation. Vegetated roofs store and eventually
evapotranspirate the collected rooftop rainfall; overflows may be
provided for larger storms.
VEGETATED SWALES
Vegetated earthen channels designed to convey and possibly
treat stormwater. As water quality BMPs, these are broad, shallow,
densely vegetated, earthen channels designed to treat stormwater through
infiltration, evapotranspiration, and sedimentation. Swales should
be gently sloping with low flow velocities to prevent erosion. Check
dams may be added to enhance performance.
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.
[Added by Ord. No. 2022-05, 10/6/2022]
WATERCOURSE
Any channel of conveyance of surface water having defined
bed and banks, whether natural or artificial, with perennial or intermittent
flow.
WATER QUALITY INSERTS
Any number of commercially available devices that are inserted
into storm inlets to capture sediment, oil, grease, metals, trash,
debris, etc.
WET DETENTION PONDS
Basins that provide for necessary stormwater storage as well
as a permanent pool of water. To be successful, wet ponds must have
adequate natural hydrology (both runoff inputs as well as soils and
water table which allow for maintenance of a permanent pool of water)
and must be able to support a healthy aquatic community so as to avoid
creation of mosquito and other health and nuisance problems.
WATERSHED
The region or area drained by a river, watercourse, or other
surface water of this commonwealth.
[Amended by Ord. No. 2022-05, 10/6/2022]