A.
The minimum control requirements established in this section and
the Design Manual are as follows:
(1)
The 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, pre-development 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
Denton Town Engineer 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 Denton Town Engineer 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 by the Town
subject to Administration approval.
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 structural and nonstructural stormwater management measures
established in this chapter shall be used, either alone or in a combination,
in developing a 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 § 106-11 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 pre-development
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 § 106-11 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.
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 § 106-11 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.
Standard plans.
(1)
Compliance with any of the following Standard Plans is considered to satisfy the minimum control requirements established in § 106-11A of this chapter.
(2)
Standard plans. The following documents are incorporated by reference:
(3)
Compliance with an approved Soil Conservation and Water Quality Plan (SCWQP) is considered to satisfy the minimum control requirements established in § 106-11A of this chapter if the development:
(a)
Is an agricultural structure, or associated access roads and
parking areas;
(b)
Complies with USDA Natural Resources Conservation Service Maryland
Conservation Practice Standard Stormwater Runoff Control Code 570
(March 2013);
(c)
Is not located within the Chesapeake and Atlantic Coastal Bays
Critical Area; and
(4)
An approving agency may require more than the minimum control measures.
An approving agency may require that an engineered stormwater management
plan be submitted if:
D.
ESD planning techniques and treatment practices and structural stormwater management measures used to satisfy the minimum requirements in § 106-11 of this chapter must be documented and remain unaltered by subsequent property owners. Prior approval from the Denton Director of Planning and Codes shall be obtained before any stormwater management practice is altered.
E.
Alternative ESD planning techniques and treatment practices and structural
stormwater management practices 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
Denton Town Engineer.
F.
For the purposes of modifying the minimum control requirements or
design criteria, the owner/developer shall submit to the Denton Town
Engineer 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 Denton Town Engineer,
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 Denton and the Administration,
shall be those of the Design Manual.
