As used in this chapter, the following terms shall have the
meanings indicated:
ACCELERATED EROSION
The removal of the surface of the land through the combined
action of man's activity and the natural processes at a rate greater
than would occur because of the natural process alone.
ACCESS EASEMENT
A right granted by a landowner to a grantee, allowing entry
for the purpose of inspecting, maintaining and repairing SWM facilities.
ACT 167 PLAN
A plan prepared under the authority of the Stormwater Management
Act.
AGRICULTURAL ACTIVITY
Activities associated with agriculture such as agricultural
cultivation, agricultural operation, and animal heavy use areas. This
includes the work of producing crops and raising livestock including
tillage, land clearing, plowing, disking, harrowing, planting, harvesting
crops, or pasturing and raising of livestock and installation of conservation
practices. Construction of new buildings or impervious areas 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; earth disturbance activity.
ANIMAL HEAVY USE AREAS
A barnyard, feedlot, loafing area, exercise lot, or other
similar area on an agricultural operation where due to the concentration
of animals, it is not possible to establish and maintain vegetative
cover of a density capable of minimizing accelerated erosion and sedimentation
by usual planting methods. The term does not include entrances, pathways
and walkways between areas where animals are housed or kept in concentration.
APPLICANT
A landowner and/or developer, as hereinafter defined, including
his heirs, successors and assigns, who has filed an application to
the Borough for approval to engage in any regulated activity at a
development site located within the Borough.
BMP (BEST MANAGEMENT PRACTICE)
Activities, facilities, control measures, planning or procedures used to minimize accelerated erosion and sedimentation and manage stormwater to protect, maintain, reclaim, and restore the quality of waters and the existing and designated uses of waters within this commonwealth before, during and after earth disturbance activities. (NOTE: See §
315-97A.) See also "nonstructural BMP" and "structural BMP."
BMP MANUAL
The Pennsylvania Stormwater Best Management Practices Manual
of December 2006, or most recent version thereof.
BOROUGH
The Borough of Millersville, Lancaster County, Pennsylvania.
BUILDING
Any enclosed or open structure, other than a boundary wall
or fence, occupying more than four square feet of area and/or having
a roof supported by columns, piers, or walls.
CARBONATE GEOLOGY
Limestone or dolomite bedrock. Carbonate geology is often
associated with karst topography.
CERTIFICATE OF COMPLETION
Documentation verifying that all permanent SWM facilities
have been constructed according to the plans and specifications and
approved revisions thereto.
CHAPTER 102
25 Pa. Code Chapter 102, Erosion and Sediment Control.
CHAPTER 105
25 Pa. Code Chapter 105, Dam Safety and Waterway Management.
CISTERN
A reservoir or tank for storing rainwater.
CLEAN WATER ACT
The 1972 Amendments to the Federal Water Pollution Control
Act, P.L. 92-500 of 1972, 33 U.S.C. § 1251 et seq.
CONSERVATION PLAN
A plan written by an NRCS certified planner that identifies
conservation practices and includes site-specific BMPs for agricultural
plowing or tilling activities and animal heavy-use areas.
CONSERVATION PRACTICES
Practices installed on agricultural lands to improve farmland,
soil and/or water quality which have been identified in a current
conservation plan.
CONVEYANCE
A.
(n) Any structure that carries a flow.
B.
(v) The ability of a pipe, culvert, swale or similar facility
to carry the peak flow from the design storm.
CULVERT
A structure with appurtenant works which can convey a stream
under or through an embankment or fill.
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.
DCNR
The Pennsylvania Department of Conservation and Natural Resources
or any agency successor thereto.
DEP also PA DEP or PADEP
The Pennsylvania Department of Environmental Protection or
any agency successor to the Pennsylvania Department of Environmental
Protection.
DESIGNEE
The agent of Millersville Borough involved with the administration,
review or enforcement of any provisions by Borough Council action.
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 SWM systems.
DETENTION BASIN
An impoundment structure designed to manage stormwater runoff
by temporarily storing the runoff and releasing it at a controlled
rate.
DEVELOPER
A person who undertakes any regulated activity of this chapter.
DEVELOPMENT SITE (SITE)
The specific area of land where regulated activities in the
Borough are planned, conducted or maintained.
DISAPPEARING STREAM
A stream in an area underlain by limestone or dolomite that
flows underground for a portion of its length.
DISTURBED AREA
A land area where an earth disturbance activity is occurring
or has occurred.
DRAINAGE CONVEYANCE FACILITY
A SWM facility designed to transmit stormwater runoff, including
streams, channels, swales, pipes, conduits, storm sewers, etc.
DRAINAGE EASEMENT
Rights to occupy and use another person's real property for
the installation and operation of SWM facilities, or for the maintenance
of natural drainageways to preserve and maintain a channel for the
flow of stormwater therein, or to safeguard health, safety, property,
and facilities.
E&S
Erosion and sediment.
E&S MANUAL
The Erosion and Sediment Pollution Control Program Manual,
Number 363-2134-008, prepared by DEP.
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; operation of animal heavy use areas; timber harvesting activities; road maintenance activities; oil and gas activities; well drilling; mineral extraction; building construction; and the moving, depositing, stockpiling, or storing of soil, rock, or earth materials. (NOTE: See §
315-97A.)
ENVIRONMENTALLY SENSITIVE AREA
Slopes greater than 15%, shallow bedrock [located within six feet of ground surface (NOTE: See §
315-97B.)], wetlands, natural heritage areas and other areas designated as conservation or preservation in Greenscapes, the Green Infrastructure Element of the County Comprehensive Plan, where encroachment by land development or land disturbance results in degradation of the natural resource.
EROSION
The natural process by which the surface of the land is worn
away by water, wind, or chemical action. See also "accelerated erosion"
as defined above.
EXISTING CONDITIONS
The dominant land cover during the five-year period immediately
preceding a proposed regulated activity.
FEMA
The Federal Emergency Management Agency and any agency successor
thereto.
FLOOD
A general but temporary condition of partial or complete
inundation of normally dry land areas from the overflow of streams,
rivers, and other waters of this commonwealth.
FOREST MANAGEMENT/TIMBER OPERATIONS
Planning and activities necessary for the management of forest
land. These include conducting a timber inventory and preparation
of forest management plans, silvicultural treatment, cutting budgets,
logging road design and construction, timber harvesting, site preparation
and reforestation.
FREEBOARD
A vertical distance between the elevation of the design high
water and the top of a dam, levee, tank, basin or diversion ridge.
The vertical distance is required as a safety margin in a pond or
basin.
FREQUENCY
The probability or chance that a given storm event/flood
will be equaled or exceeded in a given year.
GRADE
A.
(n) A slope, usually of a road, channel or natural ground specified
in percent and shown on plans as specified herein.
B.
(v) To finish the surface of a roadbed, top of embankment or
bottom of excavation.
GREEN INFRASTRUCTURE
Systems and practices that use or mimic natural processes
to infiltrate, evapotranspire, or reuse stormwater on the site where
it is generated.
[Added 9-27-2022 by Ord. No. 2022-04]
GROUNDWATER RECHARGE
The process by which water from above the ground surface
is added to the saturated zone of an aquifer, either directly or indirectly.
HYDROLOGIC SOIL GROUP (HSG)
Refers to soils grouped according to their runoff-producing
characteristics by NRCS. There are four runoff potential groups ranging
from A to D.
A.
(Low runoff potential) Soils having high infiltration rates
even when thoroughly wetted and consisting chiefly of deep, well to
excessively drained sands or gravels. These soils have a high rate
of water transmission (greater than 0.30 inches/hour).
B.
Soils having moderate infiltration rates when thoroughly wetted
and consisting chiefly of moderately deep to deep, moderately well
to well drained soils with moderately fine to moderately coarse textures.
These soils have a moderate rate of water transmission (from 0.15
to 0.30 inches/hour).
C.
Soils having slow infiltration rates when thoroughly wetted
and consisting chiefly of soils with a layer that impedes downward
movement of water, or soils with moderately fine to fine texture.
These soils have a slow rate of water transmission (from 0.05 to 0.15
inches/hour).
D.
(High runoff potential) Soils having very slow infiltration
rates when thoroughly wetted and consisting chiefly of clay soils
with a high swelling potential, soils with a permanent high water
table, soils with a clay pan or clay layer at or near the surface,
and shallow soils over nearly impervious material. These soils have
a very slow rate of water transmission (from 0 to 0.05 inches/hour).
ILLICIT CONNECTION
Any man-made physical connection or prohibited connection
to the MS4 that conveys an illicit discharge.
[Added 9-27-2022 by Ord. No. 2022-04]
ILLICIT DISCHARGE
Any discharge to the MS4 that is not composed entirely of stormwater or polluted stormwater, except for discharges allowed under an NPDES permit, discharges conditionally allowed under the MS4 permit, and discharges authorized by this chapter as set forth in §
315-81E.
[Added 9-27-2022 by Ord. No. 2022-04]
IMPERVIOUS SURFACE (IMPERVIOUS AREA)
Surfaces which prevent the infiltration of water into the
ground. All structures, buildings, parking areas, driveways, roads,
streets, sidewalks, decks, and any areas of concrete, asphalt, stone,
and compacted soil shall be considered impervious surface if they
prevent infiltration.
IMPOUNDMENT
A retention or detention facility designed to retain stormwater
runoff and infiltrate it into the ground (in the case of a retention
basin) or release it at a controlled rate (in the case of a detention
basin).
INFILTRATION STRUCTURES
A structure designed to direct runoff into the ground (e.g.,
french drains, seepage pits, seepage trench, rain gardens, vegetated
swales, pervious paving, infiltration basins, etc.).
INLET
A surface connection to a closed drain. The upstream end
of any structure through which water may flow.
INTERMITTENT
A natural, transient body or conveyance of water that exists
for a relatively long time, but for weeks or months of the year is
below the local water table and obtains its flow from both surface
runoff and groundwater discharges.
INVASIVE VEGETATION (INVASIVES)
Plants which grow quickly and aggressively, spreading, and
displacing other plants. Invasives typically are introduced into a
region far from their native habitat. See Invasive Plants in Pennsylvania
by the DCNR.
KARST
A type of topography or landscape characterized by features
including but not limited to 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
Any activity meeting the definition of "land development" in Chapter
325, Subdivision and Land Development Ordinance.
LAND DISTURBANCE
Any activity involving grading, tilling, digging or filling
of ground or stripping of vegetation or any other activity that causes
an alteration to the natural condition of the land.
LANDOWNER
The legal or beneficial owner or owners of land including:
the holder of an option or contract to purchase (whether or not such
option or contract is subject to any condition), a lessee if he is
authorized under the lease to exercise the rights of the landowner,
or other person having a proprietary interest in land.
LIMITING ZONE
A rock formation, other stratum, or soil condition which is so slowly permeable that it effectively limits downward passage of effluent. (NOTE: See §
315-97L.) Seasonal high-water tables, whether perched or regional, also constitute a limiting zone.
LINEAMENT
A linear feature in a landscape which is an expression of
an underlying geological structure such as a fault.
MANNING'S EQUATION
An equation 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. Manning's
Equation assumes steady, gradually varied flow.
MAXIMUM EXTENT PRACTICABLE (MEP)
Applies when the applicant demonstrates to the Borough's satisfaction that the performance standard is not achievable. The applicant shall take into account the best available technology, cost effectiveness, geographic features, and other competing interests such as protection of human safety and welfare, protection of endangered and threatened resources, and preservation of historic properties in making the assertion that the performance standard cannot be met and that a different means of control is appropriate. (NOTE: See §
315-97E.)
MPC
The Pennsylvania Municipalities Planning Code, Act of 1968,
P.L. 805, No. 247, as reenacted and amended, 53 P.S. § 10101
et seq.
MUNICIPALITY
The Borough of Millersville, Lancaster County, Pennsylvania.
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), which is all of the
following:
A.
Owned or operated by a state, city, town, borough, township,
county, district, association or other public body (created under
state law) having jurisdiction over disposal of sewage, industrial
wastes, stormwater or other wastes;
B.
Designed or used for collecting or conveying stormwater;
C.
Not a combined sewer; and
D.
Not part of a publicly owned treatment works as defined at 40
CFR 122.2.
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)(18), or designated as regulated under 40 CFR 122.26(a)(1)(v).
NATIONAL POLLUTION DISCHARGE ELIMINATION SYSTEM (NPDES)
A permit issued under 25 Pa. Code Chapter 92a (relating to
National Pollutant Discharge Elimination System permitting, monitoring
and compliance) for the discharge or potential discharge of pollutants
from a point source to surface waters.
NATIVE VEGETATION
Plant species that have evolved or are indigenous to a specific
geographical area. These plants are adapted to local soil and weather
conditions as well as pests and diseases.
NATURAL GROUND COVER
Ground cover which mimics the infiltration characteristics
of predominant hydrologic soil group found at the site.
NONPOINT SOURCE POLLUTION
Any source of water pollution that does not meet the legal
definition of "point source" in Section 502(14) of the Clean Water
Act.
NONSTRUCTURAL BMPs
Planning and design approaches, operational and/or behavior-related
practices which minimize stormwater runoff generation resulting from
an alteration of the land surface or limit contact of pollutants with
stormwater runoff.
NRCS
Natural Resources Conservation Service (previously Soil Conservation
Service, or SCS).
OPEN CHANNEL
A drainage element in which stormwater flows with an open
surface. Open channels include, but shall not be limited to, natural
and man-made drainageways, swales, streams, ditches, canals, and pipes
flowing partly full. Open channels may include closed conduits so
long as the flow is not under pressure.
OUTFALL
Point where water flows from a conduit, stream, pipe, or
drain.
PEAK DISCHARGE
The maximum rate of stormwater runoff from a specific storm
event.
PENNDOT
The Pennsylvania Department of Transportation or any agency
successor thereto.
PERSON
An individual, partnership, public or private association
or corporation, or a governmental unit, public utility or any other
legal entity whatsoever which is recognized by law as the subject
of rights and duties.
PERVIOUS AREA
Any material/surface that allows water to pass through at
a rate equal to or greater than natural ground cover.
PIPE
A culvert, closed conduit, or similar structure (including
appurtenances) that conveys stormwater.
PLANNING COMMISSION
The Planning Commission of Millersville Borough, Lancaster
County, Pennsylvania.
PLANS
The SWM and erosion and sediment control plans and narratives.
PMF (PROBABLE MAXIMUM FLOOD)
The flood that may be expected from the most severe combination
of critical meteorologic and hydrologic conditions that are reasonably
possible in any area. The PMF is derived from the probable maximum
precipitation (PMP) as determined on the basis of data obtained from
the National Oceanographic and Atmospheric Administration (NOAA).
PROCESS WASTEWATER
Water that comes in contact with any raw material, product,
by-product, or waste during any production or industrial process.
PROJECT SITE
The specific area of land where any regulated activities
are planned, conducted, or maintained.
[Added 9-27-2022 by Ord. No. 2022-04]
QUALIFIED PERSON
Any person licensed by the Pennsylvania Department of State
or otherwise qualified by law to perform the work required by this
chapter.
RATE CONTROL
SWM controls used to manage the peak flows for the purposes
of channel protection and flood mitigation.
REDEVELOPMENT
Any physical improvement to a previously developed lot that
involves earthmoving, removal, or addition of impervious surfaces.
REGIONAL STORMWATER MANAGEMENT PLAN
A plan to manage stormwater runoff from an area larger than
a single development site. A regional stormwater management plan could
include two adjacent parcels, an entire watershed, or some defined
area in between. Regional stormwater management plans can be prepared
for new development, or as a retrofit to manage runoff from already
developed areas.
REGULATED ACTIVITIES
Activities, including earth disturbance activities, that
involve the alteration or development of land in a manner that may
affect stormwater runoff. Regulated activities shall include, but
not be limited to:
[Amended 9-27-2022 by Ord. No. 2022-04]
A.
Land development subject to the requirements of Chapter
325, Subdivision and Land Development;
B.
Removal of ground cover, grading, filling or excavation;
C.
Construction of new or additional impervious or semi-impervious
surfaces (driveways, parking lots, etc.) and associated improvements;
D.
Construction of new buildings or additions to existing buildings;
E.
Installation or alteration of stormwater management facilities
and appurtenances thereto;
F.
Diversion or piping of any watercourse;
G.
Any other regulated activities where the Borough determines
that said activities may affect any existing watercourse's stormwater
management facilities or stormwater drainage patterns; and
H.
Any activities where the Borough determines that said activities
may affect the water quality of stormwater discharges or generate
nonstormwater discharges to the MS4 and/or receiving water bodies.
RELEASE RATE
For a specific design storm or list of design storms, the
percentage of peak flow rate for existing conditions which may not
be exceeded for the proposed conditions.
RELEASE RATE MAP
A graphical representation of the release rates for a specific
area.
RETENTION BASIN
A SWM facility that includes a permanent pool for water quality
treatment and additional capacity above the permanent pool for temporary
runoff storage.
RETENTION VOLUME/REMOVED RUNOFF
The volume of runoff that is captured and not released directly
into the surface waters of the commonwealth during or after a storm
event.
[Added 9-27-2022 by Ord. No. 2022-04]
RETURN
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 another way, the probability
of a twenty-five-year storm occurring in any one year is 0.04, i.e.,
a 4% chance.
[Added 9-27-2022 by Ord. No. 2022-04]
RIPARIAN
Pertaining to a stream, river or other watercourse. Also,
plant communities occurring in association with any spring, lake,
river, stream or creek through which waters flow at least periodically.
RIPARIAN BUFFER
A BMP that is an area of permanent vegetation along a watercourse.
RIPARIAN CORRIDOR
A narrow strip of land, centered on a stream or river that includes the floodplain as well as related riparian habitats adjacent to the floodplain. (NOTE: See §
315-97F.)
RIPARIAN FOREST BUFFER
A type of riparian buffer that consists of permanent vegetation
that is predominantly native trees, shrubs and forbs along a watercourse
that is maintained in a natural state or sustainably managed to protect
and enhance water quality, stabilize stream channels and banks, and
separate land use activities from surface waters.
RISER
A vertical pipe extending from the bottom of a pond that
is used to control the discharge rate from the pond for a specified
design storm.
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.
ROOFTOP DETENTION
Temporary ponding and gradual release of stormwater falling
directly onto roof surfaces by incorporating controlled-flow roof
drains into building designs.
RUNOFF
Any part of precipitation that flows over the land surface.
SCS
United States Department of Agriculture, Soil Conservation
Service (now known as NRCS).
SEDIMENT
Soils or other materials transported by stormwater as a product of erosion. (NOTE: See §
315-97A.)
SEDIMENTATION
The action or process of forming or depositing sediment in waters of this commonwealth. (NOTE: See §
315-97A.)
SEDIMENT BASIN
A barrier, dam, retention or detention basin located and
designed to retain rock, sand, gravel, silt, or other material transported
by water.
SEDIMENT POLLUTION
The placement, discharge or any other introduction of sediment
into the waters of the commonwealth occurring from the failure to
design, construct, implement or maintain control measures and control
facilities in accordance with the requirements of this chapter.
SEEPAGE PIT/SEEPAGE TRENCH
An area of excavated earth filled with loose stone or similar
coarse material, into which surface water is directed for infiltration
into the ground.
SHEET FLOW
Runoff which flows over the ground surface as a thin, even
layer, not concentrated in a channel.
SMALL PROJECT
Regulated activities that do not create more than 2,000 square
feet of impervious area or involve the removal of ground cover, grading,
filling, or excavation of more than one acre, and do not require the
submission of a subdivision or land development plan.
SMALL STORM EVENT
A storm having a frequency of recurrence of once every two
years or smaller.
SOIL-COVER COMPLEX METHOD
A method of runoff computation developed by the SCS (now
NRCS) that is based on relating soil type and land use/cover to a
runoff parameter called "curve number (CN)." For more information,
see "Urban Hydrology for Small Watersheds," Second edition, Technical
Release No. 55, SCS, June 1986 (or most current edition).
STATE WATER QUALITY REQUIREMENTS
The regulatory requirements to protect, maintain, reclaim,
and restore water quality under Title 25 of the Pennsylvania Code,
the Clean Streams Law and the Clean Water Act.
STORAGE
A volume above or below ground that is available to hold
stormwater.
STORM EVENT
A storm of a specific duration, intensity, and frequency. (NOTE: See §
315-97G.)
STORM SEWER
A system of pipes and/or open channels designed to convey
stormwater.
STORMWATER
Drainage runoff from the surface of the land resulting from
precipitation or snow or ice melt.
STORMWATER MANAGEMENT FACILITY (SWM FACILITY)
Any structure, natural or man-made, that, due to its condition,
design, or construction, conveys, stores, infiltrates/evaporates/transpires,
cleans or otherwise affects stormwater runoff. Typical SWM facilities
include, but are not limited to, detention and retention basins, open
channels, watercourses, road gutters, swales, storm sewers, pipes,
BMPs, and infiltration structures.
STRUCTURAL BMPs
Physical devices and practices that capture and treat stormwater
runoff. Structural stormwater BMPs are permanent appurtenances to
the development site.
STRUCTURE
Any man-made object having an ascertainable stationary location on or in land or water, whether or not affixed to the land. (NOTE: See §
315-97H.)
SWALE
A low-lying stretch of land which gathers or carries surface
water runoff.
SWM
Stormwater management.
TIME OF CONCENTRATION (Tc)
The time for surface runoff to travel from the hydraulically
most-distant point of the watershed to a point of interest within
the watershed. This time is the combined total of overland flow time
and flow time in pipes or channels, if any.
TOP OF STREAMBANK
First substantial break in slope between the edge of the
bed of the stream and the surrounding terrain. The top of streambank
can either be a natural or constructed (that is, road or railroad
grade) feature, lying generally parallel to the watercourse.
TREATMENT TRAIN
The sequencing of structural best management practices to
achieve optimal flow management and pollutant removal from urban stormwater.
USDA
United States Department of Agriculture or any agency successor
thereto.
VOLUME CONTROL
SWM controls, or BMPs, used to remove a predetermined amount
of runoff or the increase in volume between the pre- and post-development
design storm.
WATERCOURSE
A channel or conveyance of surface water having defined bed
and banks, whether natural or artificial, with perennial or intermittent
flow.
WATERSHED
The entire region or area drained by a watercourse.
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 Pennsylvania.
WETLAND
Those areas that are inundated or saturated by surface water
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, ferns, and similar areas.
WOODLAND
Land predominantly covered with trees and shrubs. Without
limiting the foregoing, "woodlands" include all land areas of 10,000
square feet or greater, supporting at least 100 trees per acre, so
that either:
A.
At least 50 trees are two inches or greater in diameter at breast
height (DBH); or
B.
Fifty trees are at least 12 feet in height.