[Ord. No. 95-12 §3.1, 3-7-1995]
No development equal to or greater than ten thousand (10,000)
square feet shall increase the quantity and rate of stormwater emanating
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 Building Inspector.
[Ord. No. 95-12 §3.2, 3-7-1995]
A.
The
Preliminary Stormwater Management Plan for any proposed development
shall contain, but not be limited to, the following information and
date:
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 (10) foot contour interval will be accepted as a minimal
requirement;
2.
Site plan suitable scale and 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 flood plains 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 flood plains 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.
Calculations supporting the method and capacity needed for safe 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. 95-12 §3.3, 3-7-1995]
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 Building
Inspector. A review meeting then will be scheduled by the City Building
Inspector 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 design parameter which
shall apply to final design of the project.
[Ord. No. 95-12 §3.4, 3-7-1995]
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 Building Inspector, 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 streams,
the extent of flood plans 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 indicating design volumes and rates of
proposed runoff for each portion of the watershed tributary to the
storm drainage system, the calculations used to determine said runoff
volumes 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 waterway;
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 fifty (50) 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 (100) 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. 95-12 §3.5, 3-7-1995]
A.
Final
Stormwater Management Plans shall be reviewed by the City Building
Inspector. 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 Building Inspector shall approve
the plan or conditionally approve the plan, setting forth 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 Building Inspector
shall disapprove the Final Stormwater Management Plan.
C.
If
disapproved, the application and data shall be returned to the applicant
for resubmittal.
[1]
Note — Time frames for filing, review and approval of
Stormwater Management Plans should coincide with time periods applicable
in existing subdivision regulations.
