[Ord. No. 11042013 §II, 11-4-2013]
No development shall increase the quantity and rate of stormwater
emanation from said land areas except in accordance with an approved
stormwater management plan as provided in these regulations. The stormwater
management plan shall be prepared by a licensed professional engineer
in the state where the development occurs. No building permits shall
be issued until and unless the stormwater management plan has been
approved by the City Engineer.
[Ord. No. 11042013 §II, 11-4-2013]
A.
The preliminary stormwater management plan for any proposed development
shall contain but not be limited to the following information and
data:
1.
Topographic map outlining the limits of the contributing area.
Topographic maps should be the best available. U.S.G.S. 7.5 minute
quandrange topographic maps with a ten-foot contour interval will
be accepted as a minimal requirement;
2.
Site plan of suitable scale or contour interval, showing the
land to be developed and such adjoining land whose topography may
affect the layout or drainage patterns for the development;
3.
The location of streams and other flood water runoff channels,
the extent of floodplains at the established high-water elevations,
the limits of the floodway, if pertinent, and any additional information,
all of which shall be properly identified;
4.
The normal shoreline of lakes, ponds, swamps and detention basins,
including their floodplains and inflow and outflow structures if such
structures exist;
5.
The location and calculated flow rates of other existing storm
drains, inlets and outfalls;
6.
The location and calculated flow rates of any existing storm
sanitary and combined sewers which occur within the proposed project
site or adjacent thereto within a distance of approximately five hundred
(500) feet from the perimeter of said site;
7.
The location and observed flow rates of any flowing springs,
existing wells or any existing seepage areas as determined by means
of a field inspection of the property;
8.
General information regarding the type and characteristics of
soils which will be encountered within the project;
9.
Concepts which will be considered within the development to
handle safely all stormwater runoff, including the methods for detention
or control of increased stormwater runoff generated by the project
development;
10.
A general plan showing the extent and nature of the storm drainage
facilities which will be planned to serve the proposed project, including
preliminary calculations indicating the runoff which must be handled
by such facilities, the methods and criteria which have been utilized
in calculating such runoff, and basic information regarding the receiving
stream channel into which such drainage facilities will discharge;
11.
Calculation supporting the method and capacity needed for the
sale and temporary storage of increased runoff resulting from the
proposed development, if temporary storage is needed;
12.
Basic information regarding the receiving stream or channel
into which proposed storm drainage facilities will discharge, including
the channel location, general cross section, existing downstream culverts
and bridges and other waterway openings, any existing detention basins
or lakes and other information required to determine, in preliminary
form, the effect which the proposed development will have on downstream
drainage conditions;
13.
A general plan indicating the exterior perimeter of the site,
the general development proposed for the project, and an indication
by means of rough contours showing the terrain after grading the site.
[Ord. No. 11042013 §II, 11-4-2013]
Following receipt of the preliminary stormwater management plan,
and information to be included with such plan, the general drainage
concepts and planning proposals will be reviewed by the City Engineer
with representatives of the developer, including the developer's
engineer, to review the overall concepts included in the preliminary
stormwater management plan. The purpose of this review shall be to
jointly agree upon an overall stormwater management concept for the
proposed development and to review criteria and begin design parameters
which shall apply to final design of the project.
[Ord. No. 11042013 §II, 11-4-2013]
A.
Following review of the preliminary stormwater management plan and
after the concept review meeting and general approval of the preliminary
plan by the City Engineer, a final stormwater management plan shall
be prepared for each phase of the proposed project as each phase is
developed. The final plan shall constitute a refinement of the concepts
approved in the preliminary stormwater management plan with preparation
and submittal of the following additional detailed information unless
specifically excluded during the preliminary concept review meeting:
1.
A topographic map of the project site and adjacent areas, of
suitable scale and contour interval, which shall define the location
of streams, the extent of floodplains, and calculated high-water elevations,
the shoreline of lakes, ponds, swamps and detention basins, including
their inflow and outflow structures, if any;
2.
The location and flowline elevation of all existing sanitary,
storm, or combined sewers, and the location of any existing sewage
treatment facilities, which fall within the project limits and within
a distance of two hundred fifty (250) feet beyond the exterior boundaries
of said project;
3.
Detailed determination of runoff anticipated for the entire
project site following development indication design volumes and rates
of proposed runoff of each portion of the watershed tributary to the
storm drainage system, the calculations used to determine said runoff
volume and rates and restatement of the criteria which have been used
by the project engineer throughout his/her calculations;
4.
A refined layout of the proposed stormwater management system,
including the location and size of all drainage structures, storm
sewers, channels and channel sections, detention basins, and analyses
regarding the effect said improvements will have upon the receiving
channel and its high-water elevation;
5.
The slope, type, size and flow calculations for all existing
and proposed storm sewers and other waterways;
6.
For all detention basins, if any, a plot or tabulation of storage
volumes with corresponding water surface elevations and of the basin
outflow rates for those water surface elevations;
7.
For all detention basins, if any, design hydrographs of inflow
and outflow for the one-hundred-year differential runoff from the
site under proposed development conditions;
8.
A refined grading plan for the entire project site drawn at
a suitable scale and contour interval, or the terrain within the proposed
project site, including contours of the existing terrain along with
contours indicating final grades which will be established during
completion of the project. The grading plan shall also include a plotting
of the line defining the high-water elevation to be expected under
one-hundred-year peak flow conditions produced by the projected development
of the contributing watershed based on the best available land use
information;
9.
A profile and one (1) or more cross sections of all existing
and proposed channels or other open drainage facilities, showing existing
conditions and the proposed changes thereto, together with the high-water
elevations expected from stormwater runoff under the controlled conditions
called for by these regulations and the relationship of structures,
streets, and other utilities to such channels.
[Ord. No. 11042013 §II, 11-4-2013]
A.
Final stormwater management plans shall be reviewed by the City Engineer.
If it is determined according to present engineering practice that
the proposed development will provide control of stormwater runoff
in accordance with the purposes, design criteria and performance standards
of these regulations and will not be detrimental to the public health,
safety and general welfare, the City Engineer shall approve the plan
or conditionally approve the plan, setting for the conditions thereof.
If approved, a drainage permit for the development shall be granted.
B.
If it is determined that the proposed development will not control
stormwater runoff in accordance with these regulations, the City Engineer
shall disapprove the final stormwater management plan.
C.
If disapproved, the application and date shall be returned to the
applicant for resubmittal.
D.
Time frames for filing, review and approval of stormwater management
plans shall coincide with time periods applicable in existing subdivision
regulations.
