[Ord. No. 1272-23-07, 4-13-2023]
A. It is the policy of the City to protect and promote the public health,
safety and general welfare. The management of stormwater will reduce
the possibility of damage to public and private property, will reduce
the erosion on land and creek channels, will assist in the attainment
and maintenance of water quality standards, and will preserve and
enhance the environmental quality of the watercourses in the City.
B. Stormwater management must be performed on a watershed basis. A stormwater
management plan for each watershed shall be prepared.
[Ord. No. 1272-23-07, 4-13-2023]
A. The administration of this Chapter shall be the responsibility of
the City Engineer, and/or the Building Inspector.
B. In the interpretation and application of this Chapter, the provisions
expressed herein shall be held to be the minimum requirements, shall
be liberally construed in favor of the City and shall not be deemed
a limitation or repeal of any other powers granted by State Statutes.
[Ord. No. 1272-23-07, 4-13-2023]
For the purposes of this Chapter, certain terms shall be used,
interpreted and defined as set forth in this Section. Unless the context
clearly indicates to the contrary, terms used in the present tense
include the future tense; terms used in the singular shall include
the plural, and vice versa; the term, "these regulations" means "this
Chapter," and the term "shall" is always mandatory:
10-YEAR STORM
Rainstorms of varying duration and intensities having a ten
percent (10%) probability of being equaled or exceeded in any given
year.
25-YEAR STORM
Rainstorms of varying duration and intensities having a four
percent (4%) probability of being equaled or exceeded in any given
year.
100-YEAR STORM
Rainstorms of varying duration and intensity having a one
percent (1%) probability of being equaled or exceeded in any given
year.
ADVERSE IMPACT
Any modifications, alterations, or effects on a feature or
characteristic of surface waters, including its quality, quantity,
hydrodynamics, surface area, species composition, living resources,
aesthetics or usefulness for human or natural uses which are or may
potentially be harmful or injurious to human health, welfare, safety
or property, to biological productivity, diversity, or stability,
or which unreasonably interferes with the enjoyment of life or property,
including outdoor recreation. The term "adverse impact" includes secondary
and cumulative, as well as direct impacts.
APPLICANT
The record owner, or his/her authorized representative, of
a tract of land that is the site of development, or development activity
within the scope of this Chapter.
BASE FLOOD
The flood having a one percent (1%) probability of being
equaled or exceeded in any given year (i.e., the 100-year flood).
BOND
Any form of security for the completion and performance of
a stormwater management plan or the maintenance of drainage improvements
in an amount and form satisfactory to the City Council.
DETENTION BASIN
Any manmade area which serves as a means of controlling and
temporarily storing stormwater runoff.
DETENTION STORAGE
The temporary detaining or storage of stormwater in reservoirs,
on rooftops, on parking lots and other areas under predetermined conditions.
DEVELOPMENT
Any change of land use or improvement on any parcel of land.
DIFFERENTIAL RUNOFF
The difference between the calculated volume or rate of stormwater
runoff discharged from a site after development, and the calculated
volume and rate of stormwater runoff discharged from a site prior
to development.
DRY BOTTOM BASIN
A facility designed for the temporary storage of stormwater
runoff.
FOREBAY
A device to trap silt before it enters a detention pond.
FREEBOARD
The difference in elevation between the top of the detention
basin dam and the design surface water elevation.
GREENWAY
Sodded or green area designed to carry stormwater flow.
MAINTENANCE
The act of maintaining or preserving, including, but not
limited to, operation, construction and reconstruction.
OVERFLOW ELEVATION
Design elevation of discharge structure at which point, or
above which point, water leaks out, or bleeds out through a control
device down to the control elevation.
PEAK FLOW
The maximum rate of flow of water at a given point in a channel
watercourse or conduit resulting from a predetermined storm or flood.
POST-DEVELOPMENT CONDITIONS
Those conditions which are expected to exist or do exist
after alteration, resulting from human activity, of the natural topography,
vegetation and rate, volume or direction of surface or subsurface
flow.
PREDEVELOPMENT CONDITIONS
Those conditions which existed at the time the ordinance
from which this Chapter is derived becomes effective in terms of topography,
vegetation and rate, volume or direction of surface or subsurface
flow, as indicated by the best available historical data.
PROFESSIONAL ENGINEER
An engineer duly registered or otherwise authorized by the
State to practice engineering.
RATIONAL METHOD
An empirical formula for calculating peak rates of runoff
resulting from rainfall.
SITE
The area to be developed or altered.
SITE PLAN
The plan, usually in map form, prepared pursuant to the City
Council's zoning, subdivision, building regulations and codes.
SOIL CONSERVATION SERVICE METHOD
A technique for calculating stormwater runoff volume and
peak flow described in Soil Conservation Service (SCS) Technical Release
55.
STORMWATER MANAGEMENT SYSTEM
Includes all means, natural or manmade, used for conducting
stormwater runoff to, through or from a drainage area to the point
of outlet.
STORMWATER RUNOFF
Water that results from precipitation, which is not absorbed
by the soil, evaporated into the atmosphere or entrapped by ground
surface depressions and vegetation.
STRUCTURE
Any object constructed above or below ground.
SWALE
A low-lying stretch of land either natural or manmade.
TIME OF CONCENTRATION
The elapsed time for stormwater to flow from the most distant
point in a drainage basin to the outlet or point in question.
TRIBUTARY AREA
All of the area that contributes stormwater runoff to a given
point.
WATERCOURSE
Any natural or artificial stream, river, creek, channel,
slough, gulch, ditch, canal, culvert, drain, waterway, gully, ravine,
street roadway, reservoir, lake, pond, or natural or manmade drainageway;
the swale or wash in which water flows, either continuously or intermittently,
and which has a definite channel, bed or banks.
[Ord. No. 1272-23-07, 4-13-2023]
A. Any person, business or government entity within the municipality
shall submit a site plan and stormwater management plan for the development
to the administrative officer for approval a stormwater management
plan before commencing any development or development activity in
any existing or proposed plat. Preliminary stormwater management plans
shall accompany any preliminary plats. Owners of individual residential
property for which a residence is being constructed on that property
are exempt from the stormwater management plan requirement.
B. Written notice of intent to commence development shall be delivered
to the administrative officer prior to undertaking any development
activity, whether exempt from plan provisions or not.
[Ord. No. 1272-23-07, 4-13-2023]
A. Every development or alteration of land for a subdivision, commercial
or industrial development, shall provide on-site stormwater management
unless the City Engineer waives such requirement for the following
reasons stated:
1.
Off-Site Facility, Two (2) Or More Developments. If two (2)
or more developments, including that of the applicant, have provided
for a common system.
2.
Contribution Or Participation By Applicant. If an off-site stormwater
management system has been either constructed or identified for construction
by the City, and the applicant has agreed to contribute to or participate
in the construction thereof.
3.
Other Management Techniques. Management techniques other than
detention facilities may be utilized by the developer, provided that
the techniques proposed meet the intent of this Chapter and provide
a benefit to the watershed that equals or exceeds the benefit that
a detention facility would provide. These may include wetlands, rain
gardens, bio-swales, and other environmentally friendly or natural
means of stormwater management.
4.
Drainage provisions for the project were previously approved
and remain valid as a part of a final plat.
5.
Isolated lots of record for single-family and two-family dwelling
purposes unless the development involves changing in any way existing
drainage facilities, degrades the quality of water, adversely affects
any wetland or adversely affects any sinkhole, watercourse or water
body.
6.
Building construction which will not increase the amount of
impervious area on the site and will not adversely impact an existing
drainage area or drainage on adjoining properties.
B. Any request for waiver of the stormwater management requirements
must be made in writing to the City Engineer with justification of
why the waiver is requested and how stormwater drainage will not be
adversely affected. Only the Planning and Zoning Commission may waive
the stormwater management requirement.
[Ord. No. 1272-23-07, 4-13-2023]
A. The purpose of the stormwater management plan is to provide an organized
framework for evaluating and acting upon proposals for development
as they relate to stormwater management issues.
B. The stormwater management plan shall be prepared for each phase of
the proposed project as each phase is developed.
C. It is the responsibility of an applicant to include sufficient information
in the stormwater management plan to enable evaluation of the environmental
quality of the affected area, the potential and predicted impacts
of the proposed activity on affected waters and the effectiveness
and acceptability of the measures proposed by the applicant for preventing
or reducing adverse impacts of stormwater runoff following the rainstorms
which exceed the maximum allowable release rate and the capacity of
the stormwater drainage system.
D. The applicant shall furnish the administrative officer with two (2)
hard copies and one (1) electronic copy of the stormwater management
plan sealed by a professional engineer registered in the State. The
plan shall include the following information:
1.
Preface Information. The plan shall include as a preface the
following information:
a.
The name, address, and telephone number of the applicant, and
the owner, if different from the applicant.
b.
Name and address of the professional engineer.
c.
The legal description of the property and its acreage.
2.
Predevelopment Site Information. The plan shall also include
maps at a minimum scale of one (1) inch equals one hundred (100) feet
and other descriptive materials including the basis of computation,
showing the following required predevelopment site information:
a.
Detailed location sketch showing the parcel and major adjacent
roads.
b.
Topographic map of the site with maximum five (5) feet contour
intervals, except in floodplains or other areas of low relief where
a smaller interval may be required.
c.
Where percolation or exfiltration systems are proposed, information
as to the location and type of vegetative cover and soil types and
characteristics representative of the design condition.
d.
Location of streams and other floodwater runoff channels, normal
channels and the extent of the floodplains at the established high-water
elevations, and the limits of the floodway.
e.
Location of lakes, ponds, swamps and detention basins indicating
normal shorelines, floodplains and lines of inflow and outflow.
f.
Location of farm drains, inlets and outfalls, storm sanitary
and combined sewers and outfalls, septic tank systems and outlets,
if any, and seeps, springs and flowing and other wells.
g.
Location and description of nearby existing off-site water management
facilities such as wells, lakes, drainageways, etc., which are potentially
directly affected by the proposed construction or development.
h.
Concepts which will be considered within the site to handle
all stormwater runoff, including the methods for detention or control
of increased stormwater runoff generated by the development.
i.
A general plan showing the extent and nature of the stormwater
system planned to serve the site including preliminary calculations
indicating the runoff which must be handled by such systems, the methods
and criteria which have been utilized in calculating such runoff,
and basic information regarding the receiving watercourse into which
such system will discharge.
j.
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 of the
site.
3.
For all existing drainage facilities which are to be maintained,
altered, or enlarged as part of the stormwater management system.
Provide information as to its size, slopes, depths, outfalls, receiving
waters, elevations, cross sections, profiles, construction materials
and other design details as applicable.
4.
Location of all new drainage facilities, including detention
basins, to be constructed. Provide design details on each facility
as applicable.
5.
Location and extent of existing and proposed impervious surfaces,
roads, parking lots, buildings, etc., and their elevations. Provide
grading and paving plans and specifications.
6.
Predevelopment and post-development location of 100-year flood
boundary, if applicable.
7.
Location and extent of rights-of-way and easements for the stormwater
management system, including all areas to be dedicated for water management
purposes. Rights-of-way and easements must be recorded and evidence
provided by the developer to the Department of Public Works.
8.
Identification and description of any special or required maintenance
procedures to keep the project functioning as designed.
9.
Provide stormwater management system design calculations as
follows:
b.
Calculated hydrographs of inflow and outflow of design storms
runoff for the project site under natural and undeveloped conditions.
c.
Hydrographs of the runoff from the design storm for the project
site under developed conditions.
d.
For all detention basins, a plot or tabulation of storage volumes
with corresponding water surface elevations and of the basin outflow
rates for those water surface elevations.
e.
Acreages and percentage of property proposed as:
(2) Pervious surfaces, green areas;
(3) Lakes, canals, detention areas, etc.;
(4) Total acreage of project.
f.
Runoff routing calculation showing discharge, elevations and
volumes retained and/or detained during applicable storm event.
g.
Calculation required for determination of minimum building floor
and road elevations.
10.
Identify the entity responsible for operation and maintenance
of the system.
11.
Basic information regarding the receiving watercourse into which
the proposed stormwater system will discharge including the watercourse
location, general cross section, existing downstream culverts and
bridges and other waterway openings within a reasonable distance;
any existing detention basins or lakes and other information required
to determine, in final form, the effect which the proposed development
will have on downstream drainage conditions.
12.
The stormwater management plan for minor development activities
may consist of a certification from a professional engineer that the
differential runoff equals zero (0).
E. Stormwater Management Plans Shall Be Reviewed By The City Engineer.
If it is determined 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 setting forth the conditions thereof. If it
is determined that the proposed development will not control stormwater
runoff in accordance with these regulations, the City Engineer shall
disapprove the stormwater management plan, and the plan shall be returned
to the applicant for resubmittal.
[Ord. No. 1272-23-07, 4-13-2023]
A. For purposes of evaluation, projects will be classified in three
(3) categories according to acreage:
Class
|
Review Fee
|
---|
A. Less than 25 acres
|
$100.00
|
B. 25 acres to 200 acres
|
$200.00
|
C. Over 200 acres
|
$400.00
|
B. The effective acreage for a project is not limited to a fractional
part of the total concept, rather if a project is developed in phases
or small plots, the total acreage of the conceptual project will be
considered.
C. The review fee shall be collected at the time the preliminary stormwater
management plan is submitted to the administrative officer and will
reflect the cost of the review process. These fees may be adjusted
from time to time by the City Council to reflect actual costs of administration
and review.
[Ord. No. 1272-23-07, 4-13-2023]
A. A stormwater management system shall be laid out in such a manner
as to reduce the velocity of overland flow and allow the maximum opportunity
for infiltration of stormwater into the ground, and to preserve and
utilize natural streams, channels and detention basins, and wherever
possible, to include streams and floodplains within parks or other
public grounds.
B. The maximum allowable release rate of stormwater after development
shall not exceed the before-development rate based on a ten-year frequency
storm. The total drainage area must be used in calculating the allowable
release rate. The required storage volume will be based on the project
area only, with extraneous flows from upland areas being bypassed
or discharged via overflow spillway or other devices.
C. The increased stormwater runoff resulting from the proposed development
shall be detained onsite by appropriate detention techniques. The
minimum volume of storage shall be sufficient to store the volume
from a twenty-five-year storm, under developed conditions. Control
devices shall limit the discharge from storage to a rate no greater
than the predevelopment rate. Downstream property, watercourses channels
or conduits shall not receive stormwater runoff from proposed development
at a higher peak flow rate than that which existed prior to the development
for the ten-year frequency storm.
D. Generally acceptable locations of the stormwater channels in the
design of a subdivision may include, but are not limited to, the following:
2.
In a depressed median of a double roadway, street or parkway,
provided the median is wide enough to permit slopes of one-foot drop
in six (6) feet horizontal or flatter.
3.
Centered on the rear lot lines in block, or entirely within
the rear yards of a single row of lots or parcels.
E. Systems such as curb and gutter, drop inlets and storm sewers shall
discharge through closed conduits, or paved ditches, into a detention
basin or natural drainageway. Suitable methods of reducing velocities
to limit erosion control shall be provided at the discharge of such
enclosed conduits, or paved ditches.
F. Drainage channels and swales forming the natural drainage system
near a watershed divide may be relocated or eliminated and incorporated
into the planned system of storm sewers and open channels.
G. Flow Toward Streets. Any concentration of surface water flow in excess
of two (2) cubic feet per second (cfs) for the ten-year frequency
rain shall be intercepted before reaching the street right-of-way
and shall be carried by an enclosed storm drain to connect with a
drainage structure at the low point in the street right-of-way or
to discharge to a watercourse.
H. Whenever the plans call for passage and/or storage of stormwater
runoff along lot lines, the utility drainage easement shall be at
least twenty (20) feet wide and no structure or vegetation which would
obstruct the flow of stormwater shall be allowed, nor shall any change
be made to prescribed grades and contours of the specified stormwater
channels. Easements must be written to prohibit buildings, fences,
or other obstructions to be erected on them.
I. All storm sewer outfalls shall be so designed, by reason of elevation
of the invert, or by other features, that when the receiving stream
is in full flood, the storm sewers continue to drain the areas they
are designed to serve, unless the provision is made for sewer backups
into planned storage locations.
J. Detention facilities shall release stormwater at a nonerosive velocity.
Calculations for the velocity and the erosion control feature's
ability to handle the velocity without eroding soil shall be provided
as part of the stormwater management plan submittal to the City Engineer.
Protected Channels receiving detention discharge shall incorporate
features to reduce velocity to none-erosive levels at the point where
such discharge enters the unprotected channel. If release is into
a subsurface conduit, the energy gradient in the receiving facility
shall not be increased beyond the slope of the conduit.
K. All utility sewer manholes constructed in an area designed for the
storage or passage of stormwater, shall be provided with either a
watertight manhole cover or be constructed with a rim elevation of
a minimum of one (1) foot above the high water elevation of the design
storm.
L. Projects that are to be developed in phases will require the submission
of a master plan of the applicant's contiguous land holdings.
Applications for individual project phases may be considered only
when the phases are totally independent of, or make sufficient provisions
for, adjacent lands.
M. Emergency Spillway. Emergency overflow facilities must be provided
in all instances so stored waters will not exceed the safe capacity
of the basin. At a minimum, the emergency spillway must be able to
pass, without damage, the 100-year storm.
N. Designs should result in aesthetically pleasing configurations which
will enhance public acceptability.
[Ord. No. 1272-23-07, 4-13-2023]
A. Design Storms. Stormwater systems will be designed with sufficient
hydraulic capacity as a minimum for the following frequencies and
durations:
Type of Facility Design
|
Frequency
(years)
|
---|
Detention basins
|
25
|
Primary drainage systems
|
25
|
Bridges and culverts
|
50
|
Secondary drainage systems (i.e., crossdrains and ditches for
internal subdivision drainage)
|
10
|
B. The administrative officer may require alternative designs or features
to reduce the cost of long-term maintenance.
C. In critical areas, the administrative officer may require additional hydraulic capacity above the minimums set forth in Subsection
(A) of this Section, up to the 100-year frequency design.
[Ord. No. 1272-23-07, 4-13-2023]
A. Differential runoff evaluation consists of the determination of required
volume of detention and verification of adequacy of discharge and
control structures.
1.
Differential Runoff Rates Shall Be Evaluated By The Rational
Formula. The runoff coefficients from U.S. Weather Bureau Technical
Paper No. 40, or other similar published documentation, shall be used.
The durations analyzed shall be the following:
a.
The duration approximately equivalent to the time of concentration
for the site, but as a minimum, twenty (20) minutes.
2.
Volumes of detention shall be evaluated according to the following
methods:
a.
Projects of less than two hundred (200) acres shall be evaluated
by the rational method or SCS TR-55.
b.
If the site is larger than two hundred (200) acres or if another
method is desired to be used, the applicant shall submit a proposed
method of evaluation for the calculations to the City Engineer for
review and approval.
[Ord. No. 1272-23-07, 4-13-2023]
A. Dry-detention facilities.
1.
Side slopes of the facility shall not be steeper than 3:1 (horizontal
to vertical).
2.
Provisions must be incorporated to facilitate complete interior
drainage to dry- bottom basins.
3.
Multipurpose features may be designed to serve secondary purposes
for recreation, open space or other types of use which will not be
adversely affected by occasional or intermittent flooding.
4.
In no case shall the limits of maximum ponding elevation be
closer than twenty-five (25) feet horizontally from any building and
less than two (2) feet vertically below the lowest sill elevation.
5.
The entire reservoir area shall be seeded, fertilized and mulched,
sodded or paved.
6.
Small flows through the detention basin should be handled by
lined ditches from inflow structure to outflow structure to minimize
erosion.
7.
The maximum planned depth of stormwater stored shall not normally
exceed five (5) feet.
8.
A plan describing the operation and maintenance required for
the detention basin shall be submitted with the detention basin design.
B. Wet-Detention Facilities. In addition to the general design features enumerated in Subsection
(A) of this Section for dry-bottom basins, the following features should also be incorporated into the design of any wet-bottom basin:
1.
Control elevations should be no higher than two and five tenths
(2.5) feet below the minimum road centerline elevation in the area
served by the control device in order to protect the road subgrade
when structures are constructed near roads.
2.
Side slopes shall not be steeper than a ratio of 3:1, horizontal
to vertical, out to a depth of three (3) feet below the control elevation,
then as steep as soils stability will allow.
3.
If fish are to be used to help keep the basin clean, at least
one-quarter (1/4) of an area of the permanent pool must be a minimum
depth of ten (10) feet.
4.
For emergency purposes, cleaning or shoreline maintenance facilities
shall be provided or plans prepared for the use of auxiliary equipment.
5.
In order to minimize weed growth, the normal pool depth shall
be four (4) feet minimum.
6.
The design of any pond may include a low flow bypass channel
or pipeline to divert runoff that can be accommodated by downstream
drainageways.
7.
In order to minimize the effects of waves or ice, some type
of bank stabilization such as riprap or concrete shall be placed along
the normal pool shoreline.
8.
In order to minimize siltation of the pond, a forebay shall
be included in the design.
9.
A plan describing the operation and maintenance of the detention
basin shall be submitted with the detention basin design.
C. Impervious Areas. Paved parking lots shall not be designed to provide
detention storage of stormwater on all or a portion of its surfaces.
D. Rooftop Storage. Detention storage requirements may be met in total
or in part by detention on flat roofs. Details of such designs to
be included in the stormwater management plan shall include the depth
and volume of storage, details of outlet devices and down drains,
elevations of overflow scuppers, design loadings for the roof structure
and emergency overflow provisions.
E. Underground Storage. All or a portion of the detention storage may
also be provided for in underground facilities, as long as all applicable
requirements of this Chapter are met. Details of such designs are
to include type of facility, depth and volume of storage, details
of inlet and outlet devices and locations, emergency overflow provisions,
measures to be used for surface and groundwater pollution control,
and operation and maintenance plans.
F. Design Alternatives. The listing of design criteria outlined in this
Section is not intended to preclude the use of other known state of
the art methods and available best management practices and should
not be construed as a mechanism to discourage innovative design concepts,
so long as the intent and requirements of this Chapter are met.
G. Installation Of Stormwater Runoff Control Measures. Positive stormwater
runoff control shall be provided for during development. Stormwater
management plans shall include a schedule for the installation, construction
or modification of all drainage facilities. Erosion control measures
and a schedule for their installation shall be shown on the stormwater
management plan. Installation of drainage facilities and erosion control
measures shall proceed as scheduled.
[Ord. No. 1272-23-07, 4-13-2023]
A. Where a development adjoins or encompasses a portion of a floodplain
for a 100-year flood, the following shall apply:
1.
The applicant shall show the floodplain and floodway on the
stormwater management plan.
2.
The applicant shall include in the stormwater management plan,
all other plans, plats, specifications, etc., required by Federal,
State, county and/or municipal law or regulations detailing such provisions
or restrictions as are necessary to comply with the following:
a.
All applicable zoning and subdivision requirements.
b.
All applicable building code requirements.
c.
All requirements of other Federal, State or local agencies exercising
jurisdiction over the area.
3.
The applicant shall not alter any channel in such a way that
would prohibit any section of the channel from conveying, in its post-development
state, the same amount of flow at the same or lower maximum water
elevation that it conveyed in its predevelopment state.
4.
The applicant shall furnish, for the administrative officer's
review and approval, the following information pertaining to proposed
channel modifications or detention basins:
a.
Typical cross sections of the existing and proposed channel.
b.
Plan view of the channel showing the location of existing constrictions,
obstructions and other non-typical areas.
c.
Hydrographs and/or flood routing calculations and backwater
curve profiles of the proposed waterway corresponding to a storm recurrence
interval of one hundred (100) years.
d.
Engineering evaluation of all potential increases in flood hazards
to the adjacent upstream or downstream private or public lands and
facilities located thereon, showing provisions for eliminating any
and all adverse impacts on said land and facilities at no public cost.
e.
Minimum finished floor elevations which shall be set at or above
the maximum water surface elevation as determined by either or both
of the following:
(1) The current Flood Insurance Rate Map published
by the Federal Emergency Management Agency.
(2) Backwater curve profiles of the proposed waterway
due to a 100-year storm recurrence interval.
f.
Designation on the final plan of all areas reserved for flood
routing, detention or storage, together with the required wording
pertaining to restrictions, dedications and maintenance responsibilities
of such areas.
g.
If detention storage is provided within a floodplain, only the
net increase in storage volume above that which naturally existed
on the floodplain shall be credited to the development. No credit
will be granted for volumes below the elevation of the regulatory
flood at that location unless compensatory storage is also provided.
h.
Verification of Adequacy. Analysis of all elements of design
is to be verified by the engineer of record submitting the plan.
(1) For all projects, regardless of size, submittal
of routing calculation or tabulated proof of adequacy of tributary
runoff for detention, including:
(a) Volume of detention for the total project.
(b) Tributary (Q) peak runoff to basin.
(c) Balanced maximum outflow rate from the low-flow
structure.
(d) Ratios of inflow to outflow rates.
(e) Sizing of the overflow facilities.
(f) Stability of detention dikes.
[Ord. No. 1272-23-07, 4-13-2023]
A. All stormwater management facilities shall be constructed within
an easement or right-of-way dedicated for stormwater management use
and connected to a public road or other location from which operation
and maintenance is legally available. Minimum right-of-way and maintenance
easements shall be provided by instrument or plat dedication for all
waterways used to convey or detain runoff. The minimum widths of rights-of-way
and easements shall be as follows:
Facility
|
Maintenance Access Width
|
---|
Open drainage channel or facility
|
15 feet each side from top of bank
|
Greenways
|
Width of greenway
|
Pipes and culverts
|
20 feet, centered
|
Detention areas
|
20 feet continuous around total area
|
Connecting access
|
20 feet
|
B. Easements must include the top of the bank width and the maintenance
access width.
C. The maintenance access width begins at the point of the bank or slope
of the facility.
D. Additional maintenance access width may be required by the administrative
officer in special circumstances.
[Ord. No. 1272-23-07, 4-13-2023]
A. Detention facilities, when mandatory, are to be built in conjunction
with the storm sewer installation and/or grading. Since these facilities
are intended to control increased runoff, they must be partially or
fully operational soon after the clearing of the vegetation. Silt
and debris connected with early construction shall be removed periodically
from the detention area and control structure in order to maintain
close to full storage capacity.
B. The responsibility for maintenance of stormwater management facilities
in single lot development projects shall remain with the owner, developer
and general contractor until final inspection is performed and approved.
After legal occupancy of the project, the maintenance shall be vested
with the owner of the project.
C. The responsibility for maintenance of stormwater management facilities
shall remain with the developer until such time as responsibility
is transferred, under appropriate legal arrangements, to the private
individual owners or such other maintenance entity.
D. The growth of noxious weeds, the creation of conditions which support
the growth of mosquitoes and other insects, and the decrease in available
storage by accumulated sediments shall be controlled. The cleanup
of accumulated debris, flotsam and other materials after runoff events
have subsided shall be ensured.
E. All privately owned detention storage facilities will be inspected
by the developer not less often than once every three (3) years. A
certified report will be submitted to the Board of Public Works covering
the physical conditions, required storage capacity and operational
conditions of key elements of the facility.
F. If deficiencies are found by the inspector, the owner of the detention
facility will be required to take the necessary measures to eliminate
nuisances and correct structural deficiencies. If the owner fails
to do so, the City may undertake the work necessary and recover all
expenses from the owner.
[Ord. No. 1272-23-07, 4-13-2023]
Upon approval of the final plans for any stormwater management
system, but before the issuance of any permits, the City Engineer
shall require the applicant to post an acceptable form of performance
security for the monetary value of the work to be done pursuant to
the approved stormwater management plans. This performance security
shall not be fully released by the City Engineer until a final inspection
has been made and the facility has been found to be in compliance
with the approved plans, and provisions have been made to ensure perpetual
maintenance in accordance with the operation and maintenance plan.
[Ord. No. 1272-23-07, 4-13-2023]
The applicant shall be required to adhere strictly to the stormwater
management plan as approved. Any changes or amendments to the plan
must be approved by the administrative officer in accordance with
the procedures set forth in this Chapter for obtaining stormwater
management plan approval. Enforcement officials shall be granted inspection
rights and right-of-entry privileges in order to ensure compliance
with the requirements of this Chapter.
[Ord. No. 1272-23-07, 4-13-2023]
A. Enforcement. If it is determined that the project is not being carried
out in accordance with an approved stormwater management plan, or
is being carried out without approval, the administrative officer
is authorized to do the following:
1.
Written Notice. Issue written notice to the applicant or owner,
specifying the nature and location of the alleged non-compliance,
with a description of the remedial actions necessary to bring the
project into compliance within ten (10) days.
2.
Stop Work Order. Issue a stop work order directing the applicant
or owner to cease and desist all or any portion of the work which
violates the provisions of this Chapter, if the remedial work identified
in the written notice is not completed within the specified time.
B. Revocation Of Approval. Should the applicant or owner not bring the project into compliance with the written notice and stop work order, he/she shall then be subject to immediate revocation of his stormwater management plan approval and to the penalties described in Section
430.180.
C. Appeal. Any notice, order or revocation issued pursuant to this Section
shall become final unless the person named therein requests, in writing,
no later than ten (10) days after the date such notice, order or revocation
is served, a hearing before the Planning and Zoning Commission.
[Ord. No. 1272-23-07, 4-13-2023]
A. Violation of the provisions of this Chapter or failure to comply
with any of its requirements, including conditions and safeguards
established in connection with variances or special use permits, shall
constitute a misdemeanor. Any person who violates this Chapter or
fails to comply with any of its requirements shall upon conviction
thereof, be fined not more than five hundred dollars ($500.00) or
imprisoned for not more than three (3) months, or both, and in addition,
shall pay all costs and expenses involved in the case. Each day such
violation continues shall be considered a separate offense.
B. Nothing herein contained shall prevent the City from taking such
other lawful action as is necessary to prevent or remedy any violation.
All such costs connected therewith shall accrue to the person responsible.
[Ord. No. 1272-23-07, 4-13-2023]
This Chapter shall not in any way limit or modify the vested
rights of any person to complete any development or improvements to
lands based upon prior law, where a previous permit or authorization
has been granted or applied for and where such previous permit or
authorization remains in effect. The City may acknowledge vested rights
in other circumstances where it is equitable and just.
[Ord. No. 1272-23-07, 4-13-2023]
In case of conflict with this Chapter or any part thereof, and
the whole or part of any other existing or future ordinance or code
of the City, the most restrictive in each case shall apply.
[Ord. No. 1272-23-07, 4-13-2023]
Before starting any work regulated by this Chapter, an applicant
shall comply with the requirements set forth in all other applicable
ordinances with respect to the submission and approval of preliminary
and final subdivision plats, site plans for construction and rezoning
improvement plans, and building, grading, and zoning permits, along
with those set forth in this Chapter and as may be required by State
Statutes and the regulations of any department of the State.
[Ord. No. 1272-23-07, 4-13-2023]
The performance standards and design criteria set forth herein
establish minimum requirements which must be implemented with good
engineering practices and workmanship. Use of the requirements contained
herein shall not constitute a representation, guarantee, or warranty
of any kind by the municipality or its officers and employees of the
adequacy or safety of any drainage management structure or use of
land. Nor shall the approval of a stormwater management plan and the
issuance of a permit imply that land uses permitted will be free from
damages caused by stormwater runoff. The degree of protection required
by these regulations is considered reasonable for regulatory purposes
and is based on historical records, engineering and scientific methods
of study. Larger storms may occur or stormwater runoff heights may
be increased by manmade or natural causes. Enforcement of these provisions,
therefore, shall not create liability on the part of the municipality
or any officer of the municipality with respect to any legislative
or administrative decision lawfully made hereunder, nor shall compliance
relieve an owner, developer, and/or permittee from responsibility
under any circumstances where liability would otherwise exist.