A.
The minimum control requirements established in this section and
the Design Manual are as follows:
(1)
All counties and their incorporated municipalities shall require
that the planning techniques, nonstructural practices, and design
methods specified in the Design Manual be used to implement ESD to
the MEP. The use of ESD planning techniques and treatment practices
must be exhausted before any structural BMP is implemented. Stormwater
management plans for development projects subject to this chapter
shall be designed using ESD sizing criteria, recharge volume, water
quality volume, and channel protection storage volume criteria according
to the Design Manual. The MEP standard is met when channel stability
is maintained, predevelopment groundwater recharge is replicated,
nonpoint source pollution is minimized, and structural stormwater
management practices are used only if determined to be absolutely
necessary.
(2)
Control of the two-year and ten-year frequency storm event is required
according to the Design Manual and all subsequent revisions if the
Town of Bel Air determines that additional stormwater management is
necessary because historical flooding problems exist and downstream
floodplain development and conveyance system design cannot be controlled.
(3)
The Town of Bel Air may require more than the minimum control requirements
specified in this chapter if hydrologic or topographic conditions
warrant or if flooding, stream channel erosion, or water quality problems
exist downstream from a proposed project.
B.
Alternate minimum control requirements may be adopted subject to
Administration approval. The Administration shall require a demonstration
that alternative requirements will implement ESD to the MEP and control
flood damages, accelerated stream erosion, water quality, and sedimentation.
Comprehensive watershed studies may also be required.
C.
Stormwater management and development plans where applicable, shall
be consistent with adopted and approved watershed management plans
or flood management plans as approved by the Maryland Department of
the Environment in accordance with the Flood Hazard Management Act
of 1976.
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 § 405-9 of this chapter:
(a)
Preserving and protecting natural resources;
(b)
Conserving natural drainage patterns;
(c)
Minimizing impervious area;
(d)
Reducing runoff volume;
(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 § 405-9 of this chapter:
(a)
Disconnection of rooftop runoff;
(b)
Disconnection of nonrooftop runoff;
(c)
Sheetflow to conservation areas;
(d)
Rainwater harvesting;
(e)
Submerged gravel wetlands;
(f)
Landscape infiltration;
(g)
Infiltration berms;
(h)
Dry wells;
(i)
Microbioretention;
(j)
Rain gardens;
(k)
Swales;
(l)
Enhanced filters; and
(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 law or local
ordinances, regulations, or policies. Counties and municipalities
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 § 405-9 of this chapter:
(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 state.
C.
ESD planning techniques and treatment practices and structural stormwater management measures used to satisfy the minimum requirements in § 405-9 of this chapter must be recorded in the land records of the Town of Bel Air and remain unaltered by subsequent property owners. Prior approval from the Town of Bel Air 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
Town of Bel Air.
E.
For the purposes of modifying the minimum control requirements or
design criteria, the owner/developer shall submit to the Town of Bel
Air 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 streamflow. The point of investigation is to be
established with the concurrence of the Town of Bel Air, 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 Town of Bel Air and the Administration,
shall be those of the Design Manual.
