For the purpose of this chapter, the following documents are
incorporated by reference:
A. The 2000 Maryland Stormwater Design Manual, Volumes I and II (Maryland
Department of the Environment, April 2000), and the Carroll County
supplement to the 2000 Maryland Stormwater Design Manual (August 2010),
and all subsequent revisions, are incorporated by reference and shall
serve as the official guide for stormwater principles, methods, and
practices.
B. USDA Natural Resources Conservation Service, Maryland Conservation
Practice Standard Pond Code 378 (January 2000).
In this chapter, the following terms have the meanings indicated.
Any term not defined in this chapter shall have the meaning as defined
in any chapter of the Code. Any term not defined in the Code in any
chapter shall have its generally accepted meaning.
ADMINISTRATION
The Maryland Department of the Environment (MDE), Water Management
Administration (WMA).
ADVERSE IMPACT
Any deleterious effect on waters or wetlands, including the
quality, quantity, surface area, species composition, aesthetics or
usefulness for human or natural uses, which is or may potentially
be harmful or injurious to human health, welfare, safety or property
or to biological productivity, diversity, or stability or which unreasonably
interferes with the enjoyment of life or property, including outdoor
recreation.
AGRICULTURAL LAND MANAGEMENT PRACTICES
Those methods and procedures used in the cultivation of land
in order to further crop and livestock production and conservation
of related soil and water resources.
APPLICANT
Any person, firm, or governmental agency that executes the
necessary forms to procure official approval of a project or a permit
to carry out construction of a project.
AQUIFER
A porous water-bearing geologic formation generally restricted
to materials capable of yielding an appreciable supply of water.
BEST MANAGEMENT PRACTICES or BMPs
A structural device or nonstructural practice designed to
temporarily store or treat stormwater runoff in order to mitigate
flooding, reduce pollution, and provide other amenities.
CFR
The Code of Federal Regulations.
CHANNEL PROTECTION STORAGE VOLUME (CPV)
The volume used to design structural management practices
to control stream channel erosion. Methods for calculating the CPV
are specified in the 2000 Maryland Stormwater Design Manual.
CITY
The City of Westminster.
CLEARING
The removal of trees and brush from the land, but shall not
include the ordinary mowing of grass.
CODE
The Code of the City of Westminster.
COMAR
The Code of Maryland Regulations.
COMMISSION
The City of Westminster Planning and Zoning Commission.
CONCEPT PLAN
The first of three required plan approvals that includes
the information necessary to allow an initial evaluation of a proposed
project.
COUNTY
The Board of Commissioners of Carroll County.
DEPARTMENT
The Department of Public Works of the City of Westminster.
DESIGN MANUAL
The 2000 Maryland Stormwater Design Manual and all subsequent
revisions, together with the Carroll County supplement to the 2000
Maryland Stormwater Design Manual (August 2010), which collectively
serve as the official guide for stormwater management principles,
methods, and practices.
DETENTION STRUCTURE
A permanent structure for the temporary storage of runoff,
which is designed so as not to create a permanent pool of water.
DEVELOP LAND
To change the runoff characteristics of a parcel of land
in conjunction with residential, commercial, industrial, or institutional
construction or alteration.
DEVELOPER
A person who engages in development or who owns property
upon which a development is proposed or accomplished.
DEVELOPMENT
Any change to improved or unimproved real estate, including
but not limited to buildings and other structures, grading, dredging,
filling, paving, clearing, excavation, dumping, extraction or storage
of soil or minerals, and the storage of equipment or material; and
the subdivision of land, including off-conveyances.
DIRECTOR
The Director of the Department of Public Works of the City
of Westminster.
DRAINAGE AREA
That area contributing runoff to a single point, measured
in a horizontal plane, which is enclosed by a ridgeline.
EASEMENT
A grant or reservation by the owner of land for the use of
such land by others for a specific purpose or purposes, and which
must be included in the conveyance of land affected by such easement.
ENGINEER
A professional engineer licensed in the State of Maryland,
proficient in stormwater management design.
ENVIRONMENTAL SITE DESIGN (ESD)
Using small-scale stormwater management practices, nonstructural
techniques, and better site planning to mimic natural hydrologic runoff
characteristics and minimize the impact of land development on water
resources. Methods for designing ESD practices are specified in the
Design Manual.
EXEMPTION
Those land development activities that are not subject to
the stormwater management requirements contained in this chapter.
EXTREME FLOOD VOLUME (QF)
The storage volume required to control those infrequent but
large storm events in which overbank flows reach or exceed the boundaries
of the one-hundred-year floodplain.
FINAL STORMWATER MANAGEMENT PLAN
The last of three required plan approvals that includes the
information necessary to allow all approvals and permits to be issued
by the Department.
FLOODPLAIN
That land adjacent to a body of water or stream inundated
by the base flood.
FLOW ATTENUATION
Prolonging the flow time of runoff to reduce the peak discharge.
GRADING
Any act by which soil is cleared, stripped, stockpiled, excavated,
scarified, filled or any combination thereof.
IMPERVIOUS AREA
Any surface that does not allow stormwater to infiltrate
into the ground.
INFILTRATION
The passage or movement of water into the soil surface.
LAND SURVEYOR
A professional land surveyor registered in the State of Maryland,
proficient in drainage design.
MAXIMUM EXTENT PRACTICABLE (MEP)
Designing stormwater management systems so that all reasonable
opportunities for using ESD planning techniques and treatment practices
are exhausted and only where absolutely necessary a structural BMP
is implemented.
OVERBANK FLOOD PROTECTION VOLUME (Qp)
The volume controlled by structural practices to prevent
an increase in the frequency of out-of-bank flooding generated by
development. Methods for calculating the overbank flood protection
volume are specified in the Design Manual.
PERSON
Includes the federal government, the state, any county, municipal
corporation, or other political subdivision of the state, or any of
their units, or an individual, receiver, trustee, guardian, executor,
administrator, fiduciary, or representative of any kind, or any partnership,
firm, association, public or private corporation, or any other entity.
PLANNING TECHNIQUES
A combination of strategies employed early in project design
to reduce the impact from development and to incorporate natural features
into a stormwater management plan.
RECHARGE VOLUME (Rev)
That portion of the water quality volume used to maintain
groundwater recharge rates at development sites. Methods for calculating
the recharge volume are specified in the Design Manual.
REDEVELOPMENT
Any construction, alteration, or improvement performed on
sites where existing land use is commercial, industrial, institutional,
or multifamily residential and existing site impervious area exceeds
40%.
RETENTION STRUCTURE
A permanent structure that provides for the storage of runoff
by means of a permanent pool of water.
RETROFITTING
The implementation of ESD practices, the construction of
a structural BMP, or the modification of an existing structural BMP
in a previously developed area to improve water quality over current
conditions.
SCD
The Carroll County Soil Conservation District.
SEDIMENT
Soils or other surficial materials transported or deposited
by the action of wind, water, ice or gravity as a product of erosion.
SITE
Any tract, lot, or parcel of land, or combination of tracts,
lots, or parcels of land that are in one ownership, or are contiguous
and in diverse ownership, where development is to be performed as
part of a unit, subdivision, or project.
STABILIZATION
The prevention of soil movement by any of various vegetative
or structural means.
STORMWATER
Water that originates from a precipitation event.
STORMWATER MANAGEMENT SYSTEM
Natural areas, ESD practices, stormwater management measures,
and any other structure through which stormwater flows, infiltrates,
or discharges from a site.
STRIPPING
Any activity that removes the vegetative surface cover, including
tree removal, clearing, grubbing and storage or removal of topsoil.
VARIANCE
The modification of the minimum stormwater management requirements
for specific circumstances such that strict adherence to the requirements
would result in unnecessary hardship and not fulfill the intent of
this chapter.
WAIVER
The reduction of stormwater management requirements by the
Department for a specific development on a case-by-case review basis.
WATERCOURSE
Any natural or artificial stream, river, creek, ditch, channel,
canal, conduit, culvert, drain, waterway, gully, ravine or wash, in
and including any adjacent area that is subject to inundation from
overflow or floodwater.
WATER QUALITY VOLUME (WQv)
The volume needed to capture and treat 90% of the average
annual rainfall events at a development site. Methods for calculating
the water quality volume are specified in the Design Manual.
WATERSHED
The total drainage area contributing runoff to a single point.
WETLAND
An area that is inundated or saturated by surface water or
groundwater at a frequency and duration sufficient to support, and
that under normal circumstances does support, a prevalence of vegetation
typically adapted for life in saturated soil conditions, commonly
known as "hydrophytic vegetation." A wetland area is delineated according
to the 1987 United States Army Corps of Engineers Wetlands Delineation
Manual.
No person shall develop any land for residential, commercial, industrial, or institutional uses without providing stormwater management measures that control or manage runoff from such developments, except as provided within this section. Stormwater management measures must be designed consistent with the Design Manual, and constructed according to an approved plan, for new development or the policies stated in §
136-8 of this chapter for redevelopment, as appropriate.
The following development activities are exempt from the provisions
of this chapter and the requirements of providing stormwater management:
A. Agricultural land management practices.
B. Additions or modifications to existing single-family detached residential structures if they comply with Subsection
C of this section.
C. Any developments that do not disturb over 5,000 square feet of land
area.
D. Land development activities that the Administration determines will
be regulated under specific state laws which provide for managing
stormwater runoff.
A person may apply to the Department for a stormwater management
exemption by providing a written explanation which describes how the
proposed development qualifies for an exemption.
The Department may grant a written variance from any technical requirement of this chapter if there are exceptional circumstances applicable to the site such that strict adherence will result in unnecessary hardship and not fulfill the intent of this chapter. A written request, with adequate supporting documentation, for a variance shall be provided to the Department and shall state the specific variances sought and reasons for their granting. The Department shall not grant a variance unless and until sufficient justification is provided by the person developing land that the implementation of ESD to the MEP has been investigated thoroughly, when a variance is granted. The property owner must provide compensatory stormwater management provided in accordance with §
136-8D of this chapter.
The ESD planning techniques and practices and structural stormwater
management measures established in this chapter and the Design Manual
shall be used, either alone or in combination in a stormwater management
plan. A developer shall demonstrate that ESD has been implemented
to the MEP before the use of a structural BMP is considered in developing
the stormwater management plan.
A. ESD planning techniques and practices.
(1) The following planning techniques shall be applied according to the Design Manual to satisfy the applicable minimum control requirements established in §
136-10 of this chapter:
(a)
Preserving and protecting natural resources;
(b)
Conserving natural drainage patterns;
(c)
Minimizing impervious area;
(e)
Using ESD practices to maintain 100% of the annual predevelopment
groundwater recharge volume;
(f)
Using green roofs, permeable pavement, reinforced turf, and
other alternative surfaces;
(g)
Limiting soil disturbance, mass grading, and compaction;
(h)
Clustering development; and
(i)
Any practices approved by the Administration.
(2) The following ESD treatment practices shall be designed according to the Design Manual to satisfy the applicable minimum control requirements established in §
136-10 of this chapter:
(a)
Disconnection of rooftop runoff;
(b)
Disconnection of nonrooftop runoff;
(c)
Sheet flow to conservation areas;
(e)
Submerged gravel wetlands;
(m)
Any practices approved by the Administration.
(3) The use of ESD planning techniques and treatment practices specified
in this section shall not conflict with existing state or City law.
The City shall modify planning and zoning ordinances and public works
codes to eliminate any impediments to implementing ESD to the MEP
according to the Design Manual.
B. Structural stormwater management measures.
(1) The following structural stormwater management practices shall be designed according to the Design Manual to satisfy the applicable minimum control requirements established in §
136-10 of this chapter:
(a)
Stormwater management ponds;
(b)
Stormwater management wetlands;
(c)
Stormwater management infiltration;
(d)
Stormwater management filtering systems; and
(e)
Stormwater management open channel systems.
(2) The performance criteria specified in the Design Manual with regard
to general feasibility, conveyance, pretreatment, treatment and geometry,
environment and landscaping, and maintenance shall be considered when
selecting structural stormwater management practices.
(3) Structural stormwater management practices shall be selected to accommodate
the unique hydrologic or geologic regions of the City.
(4) All barrel pipes and risers in ponds shall be concrete pipe with
a minimum fifteen-inch diameter. Inlet and outlet structures shall
be made of concrete with a metal inlet or grate.
(5) A nonerosive flow velocity shall be provided at the principal spillway.
(6) All low-flow pipes shall have minimum twelve-inch-diameter orifices,
which shall be located inside the outlet structure.
(7) All publicly maintained surface stormwater management facilities
shall be designed with slopes no steeper than 4:1.
(8) All publicly maintained facilities shall have an in-fee access from
the bottom of the facility to a public right-of-way, unless an alternative
access is approved by the Department. This access shall be a minimum
of 20 feet in width, containing a twelve-foot-wide paved access road
constructed to minimum use-in-common drive standards. The access road
shall have a maximum slope of 17% with a maximum cross slope of 3%
and a maximum side slope of 4:1.
(9) In areas of public maintenance, no loose riprap may be left permanently
exposed.
(10)
Concentrated flows shall enter surface stormwater management
facilities through drop structures and pipes. Riprap inflow ditches
down facility slopes may not be allowed.
(11)
Pipes shall outfall at the facility bottom. End treatment shall
be headwalls.
(12)
All pipe outfalls shall have underdrained plunge pools or forebays.
(13)
All surface stormwater management facilities shall be underdrained.
(14)
Structural stormwater management practices for multi-lot residential
developments shall be deeded to the City in fee simple. For all other
developments containing structural measures, the measures shall be
protected by easement recorded in the Land Records of Carroll County
and remain unaltered by subsequent property owners. Prior approval
shall be obtained from the Department before structural stormwater
measures are altered.
C. ESD planning techniques and treatment practices and structural stormwater management measures used to satisfy the minimum requirements in §
136-10 of this chapter must be recorded in the Land Records of Carroll County and remain unaltered by subsequent property owners. Prior written approval from the Department shall be obtained before any stormwater management practice is altered.
D. Alternative ESD planning techniques and treatment practices and structural
stormwater measures may be used for new development runoff control
if they meet the performance criteria established in the Design Manual
and all subsequent revisions and are approved by the Administration.
Practices used for redevelopment projects shall be approved by the
Department.
E. For the purposes of modifying the minimum control requirements or
design criteria, the owner/developer shall submit to the Department
an analysis of the impacts of stormwater flows downstream in the watershed.
The analysis shall include hydrologic and hydraulic calculations necessary
to determine the impact of hydrograph timing modifications of the
proposed development upon a dam, highway, structure, or natural point
of restricted stream flow. The point of investigation is to be established
with the concurrence of the Department, downstream of the first downstream
tributary whose drainage area equals or exceeds the contributing area
to the project or stormwater management facility.
The basic design criteria, methodologies, and construction specifications,
subject to the approval of the Department and the Administration,
shall be in accordance with the Design Manual.
Nonrefundable review fees will be collected for the cost of
plan review, administration, and management of the permitting process,
for all projects subject to this chapter and for inspection of all
projects subject to this chapter, as well as inspection and maintenance
of City-owned facilities. A permit fee schedule shall be established
by the City based upon the relative complexity of the project and
long-term maintenance obligations and may be amended from time to
time.
Any grading or building permit issued by the Department may
be suspended or revoked after written notice is given to the permittee
for any of the following reasons:
A. Any violation(s) of the conditions of the stormwater management plan
approval;
B. Changes in site runoff characteristics upon which an approval or
waiver was granted;
C. Construction is not in accordance with the approved plan;
D. Noncompliance with a correction notice(s) or stop-work order(s) issued
for the construction of the stormwater management practice; or
E. Immediate danger exists in a downstream area in the opinion of the
Department.
In granting an approval for any phase of site development, the
Department may impose such conditions that it deems necessary to ensure
compliance with the provisions of this chapter and the preservation
of public health and safety.
The Department shall require from the applicant a surety or
cash bond, irrevocable letter of credit or other means of security
acceptable to the Department prior to the issuance of any building
and/or grading permit for construction of a development requiring
stormwater management. The amount of security shall not be less than
the total estimated construction cost of all stormwater management
facilities. The bond required in this section shall include provisions
relative to forfeiture for failure to complete work specified in the
approved stormwater management plan, compliance with all of the provisions
of this chapter and other applicable laws and regulations and any
time limitations. The bond shall not be fully released without a final
inspection of completed work by the Department or its authorized agent,
submission of as-built plans and a certification of completion by
the Department that all stormwater facilities comply with the approved
plan and the provisions of this chapter. A procedure may be used to
release parts of the bond held by the Department after various stages
of construction have been completed and accepted by the Department.
The procedures used for partially releasing performance bonds must
be specified by the Department in writing prior to stormwater management
plan approval.
All plans submitted for approval pursuant to this chapter shall
bear the engineer's title block required by Title 9, Subtitle
23, Chapter 3, of the Code of Maryland Regulations and the certifications
required by the supplement.
Any person convicted of violating the provisions of this chapter
shall be guilty of a misdemeanor and, upon conviction thereof, shall
be subject to a fine of not more than $5,000 or imprisonment not exceeding
one year, or both, for each and every violation, with costs imposed
in the discretion of the court and not to exceed $50,000. Each day
that the violation continues shall be a separate offense. In addition
thereto, the Mayor and Common Council may institute injunctive, mandamus
or other appropriate action or proceedings at law or equity for the
enforcement of this chapter or to correct violations of this chapter,
and any court of competent jurisdiction shall have the right to issue
restraining orders, temporary or permanent, injunctions or mandamus
or other appropriate forms of remedy or relief.
Any person aggrieved by the action of any official charged with
the enforcement of this chapter, as the result of the disapproval
of a properly filed application for a permit, the issuance of a written
notice of violation, or an alleged failure to properly enforce this
chapter in regard to a specific application, shall have the right
to appeal the action to the Circuit Court for Carroll County. Such
should be taken according to the Maryland Rules of Procedure as set
forth in Title 7, Chapter 200.