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. All reasonable opportunities for using ESD planning techniques
and treatment practices must be evaluated before any structural BMP
is proposed. 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 necessary.
(2)
The Department may require more than the minimum control requirements
specified in this chapter including quantity control, if hydrologic
or topographic conditions warrant it or if flooding or stream channel
erosion exists downstream from a proposed project.
B.
Stormwater management and development plans, where applicable, shall
be consistent with adopted and approved Watershed Management Plans
or Flood Management Plans as approved by MDE in accordance with the
Flood Hazard Management Act of 1976, and any subsequent revisions
thereof.
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 with 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 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 § 14:4-14 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 permeable pavement, reinforced turf, and other alternative
surfaces;
(g)
Limiting soil disturbance, mass grading, and compaction;
(h)
Clustering development; and
(i)
Other practices approved by the Administration.
(2)
The following ESD treatment practices shall be evaluated according to the Design Manual to satisfy the applicable minimum control requirements established in § 14:4-14 of this chapter:
(a)
Disconnection of rooftop runoff;
(b)
Disconnection of non-rooftop runoff;
(c)
Sheet flow to conservation areas;
(d)
Permeable pavement;
(e)
Reinforced turf;
(f)
Rainwater harvesting;
(g)
Submerged gravel wetlands;
(h)
Landscape infiltration;
(i)
Infiltration berms;
(j)
Dry wells;
(k)
Micro-bioretention;
(l)
Rain gardens;
(m)
Swales;
(n)
Enhanced filters; and
(o)
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 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 character of the site.
C.
ESD planning techniques and treatment practices and structural stormwater
management measures used to satisfy minimum control requirements of
this chapter must be recorded in the land records of Queen Anne's
County and remain unaltered by subsequent property owners. Prior approval
from the Department shall be obtained before any stormwater management
practice is altered.
D.
Alternative ESD 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 applicant 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 shall be established
with the concurrence of the Department.
