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;
(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;
(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 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:
(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 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.