A.
Stormwater runoff is collected and conveyed in closed conduit systems
(inlets and pipe culverts) and in open channel systems (ditches, channels,
streams and rivers). Instructions and design criteria for the design
of these systems are included herein. The information and data contained
herein shall be supplemented by the use of acceptable nomographs,
charts, tables, flood routing techniques, etc., published by the United
States Department of Agriculture/Natural Resources Conservation Service,
and MSHA.
B.
The use of rural open storm drainage and open section roadways is
encouraged for new development in the County. Preliminary study of
possible problem areas, as well as predesign consultation with the
Director shall lead to timely solutions of storm drainage problems.
C.
Drainage plans with calculations, signed and sealed by an engineering
professional representative, shall be submitted to the Director for
review and approval.
D.
All drainage structures are to be built according to the current
edition of the Calvert County Construction Standards for Roads, Streets,
and Incidental Structures, or as otherwise approved. A structure schedule
specifying the Calvert County or MSHA detail number shall be provided
on the plans.
E.
Where a subdivision is traversed by a watercourse, stream, or other
natural drainagecourse, the Director shall require the permittee to:
(1)
Dedicate an easement area of sufficient width to adequately dispose
of the surface drainage water expected in a fifty-year storm, and
conforming substantially to the lines of such natural watercourse;
or
(2)
Furnish by dedication sufficient easement or construction, or both,
to safely dispose of such stormwater.
A.
It is the County's policy to require that all public or private
storm drainage facilities, whether natural or improved, surface or
subsurface, including stormwater management facilities, be within
an easement or right-of-way. No structures other than those of the
storm drainage system are allowed within the storm drain easements,
and access to these areas shall not be restricted.
(1)
Subsurface drainage facilities that convey drainage flow from a public
right-of-way shall be located within a drainage easement. This easement
shall be conveyed to the County unless the County stipulates other
limits of maintenance responsibility.
(2)
Surface drainage facilities that convey drainage flow from a public
right-of-way shall be located within a drainage easement. For flow
into natural drainagecourses or open ground, a right to discharge
shall be established. These easements shall not be conveyed to the
County unless the County stipulates other limits of maintenance responsibility.
(3)
On-site surface drainage facilities conveying stormwater shall have
easements and stipulate limits of maintenance responsibility.
(4)
Stormwater management facilities shall be located within an easement.
They shall include an access strip of a minimum of 20 feet leading
to and surrounding the facility.
(5)
All easements shall include area sufficient for maintenance of the
accompanying system.
(6)
All existing or proposed surface drainage facilities, such as swales,
streams, unpaved and paved channels, etc., located within private
drainage easements shall be the legal responsibility of the property
owner or, if established by agreement, a homeowners' association
for operation and maintenance.
(7)
For natural drainage systems, the one-hundred-year floodplain shall
be delineated by a drainage and utility easement or, unless the County
stipulates other limits of maintenance responsibility, conveyed to
the County.
(8)
Improved channels within the one-hundred-year floodplain shall be
within a drainage and utility easement extending beyond the floodplain
on both sides of the channel for purpose of access and maintenance.
The limit of the easement shall be defined by bearings and distances
and coordinate value, be tied to property lines, and show the floodplain
elevations at all bearing changes and at intervals not exceeding 200
feet between bearing changes.
B.
Right-to-discharge for drainage systems, excluding individual residential
lots, shall be required from upstream property owners when one or
more of the following conditions occur:
(1)
The point at which the flow crosses the property lines is altered
in location or the rate of flow is increased above the predevelopment
condition rate, or as approved by the Engineering Division Chief.
(2)
Any other situations which might adversely impact the upstream or
downstream property as determined by the Engineering Division Chief.
C.
The standard storm drain easement width shall be a minimum of 20
feet.
