Stormwater management shall be accomplished for all new development
according to the minimum requirements established in this section
and the Design Manual as follows:
A.
All planning techniques, nonstructural practices, and design methods
specified in the Design Manual shall be used to implement ESD to the
MEP. The use of ESD planning techniques and treatment practices shall
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.
B.
Control of the ten-year frequency storm event is required according
to the Design Manual if the Town determines that additional stormwater
management is necessary because historical flooding problems exist
and downstream floodplain development and conveyance system design
cannot be controlled.
C.
Galena 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.
D.
Alternate minimum control requirements may be adopted subject to
approval by the Maryland Department of the Environment. The Maryland
Department of the Environment 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.
E.
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. The applicant 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 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 § 146-12 of this chapter:
(2)
The following ESD practices shall be designed according to the Design Manual to satisfy the applicable minimum control requirements established in § 146-12 of this chapter:
(a)
Disconnection of rooftop runoff.
(b)
Disconnection of non-rooftop runoff.
(c)
Sheetflow to conservation areas.
(d)
Rainwater harvesting, including rain barrels, rainwater tanks,
and cisterns.
(e)
Submerged gravel wetlands.
(f)
Landscape infiltration.
(g)
Infiltration berms.
(h)
Dry wells.
(i)
Microbioretention.
(j)
Rain gardens.
(k)
Swales.
(l)
Enhanced filters.
(m)
Any practice approved by the Maryland Department of the Environment.
(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. The Town shall modify ordinances
and 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 § 146-12 of this chapter:
(2)
When selecting structural stormwater management practices, the applicant
shall consider the performance criteria specified in the Design Manual
with regard to general feasibility, conveyance, pretreatment, treatment
and geometry, environment and landscaping, and maintenance.
(3)
Structural stormwater management practices shall be selected to accommodate
the unique hydrologic or geologic regions of the state.
C.
Alternative practices and measures. Alternative ESD planning techniques
and treatment practices and structural stormwater measures may be
used for new development runoff control if the practices and measures
meet the performance criteria in the Design Manual and all subsequent
revisions and are approved by the Maryland Department of the Environment.
Practices used for redevelopment projects shall be approved by the
Town.
D.
Recordation of practices and measures. ESD techniques and treatment practices and structural stormwater management measures used to satisfy the minimum requirements in § 146-12 of this chapter must be recorded in the land records of Kent County and remain unaltered by subsequent property owners. Prior approval from the Town shall be obtained before any stormwater management practice is altered.
E.
Modification. For purposes of modifying the minimum control requirements
or design criteria, the applicant shall submit an analysis to the
Town of the impacts of stormwater flows downstream in the watershed.
The analysis shall include hydrologic and hydraulic calculations necessary
to determine the impact of hydrographic timing modifications of the
proposed development upon a dam, highway, structure, or natural point
of restricted stream flow. The point of investigation shall be established
with the concurrence of the Town downstream of the first downstream
tributary whose drainage area equals or exceeds the contributing area
to the project or stormwater management facility.
F.
Specific design criteria. The basic design criteria, methodologies,
and construction specifications, subject to the approval of Galena
and the Maryland Department of the Environment, shall be those of
the Design Manual.
