[R.O. 2012 §420.050; Ord. No. 2827 §1, 5-12-2003]
A.
Storm water management plans shall be submitted to the City Engineer or his/her designated representative by the owner of any proposed residential, commercial or industrial development, excluding therefrom any land use, change or development, which does not create more than one (1) CFS differential runoff as determined by Section 420.070 of this Article, unless the City Engineer waives such requirement in writing for one (1) of the following reasons:
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.
Off-site facility by City. If an off-site storm water management system has been either constructed or programmed or identified for construction by the City or if, as a result of the topographical conditions present at the development site, there exists in the opinion of the City Engineer a suitable natural retention area and the applicant has agreed to either constitute to a storm water management fund or participate in the construction of an off-site system as part of a City project. The applicant must agree in writing to constitute to the City fund in accordance with Subsection (4) hereof.
3.
Other management techniques. Management techniques
other than detention facilities may be utilized by the development
provided 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.
4.
Storm Water Management Fund. A Storm Water Management
Fund is hereby created and established by City. Said fund shall be
used exclusively by City for programs and projects designed to help
control the effects of storm water within the City limits. Any contribution
made by an applicant in lieu of constructing an on-site facility shall
be deposited into said fund with any interest income on such funds
to remain a part of such fund. In order to participate in such find,
the following shall apply:
a.
Eligibility. It is determined that no immediate
adverse effects will result to adjacent property, and a contribution
is made to the Storm Water Management Improvements Fund. Residential
development of four (4) acres or less and commercial/industrial developments
of two (2) acres or less will be considered as prime candidates for
a contribution in lieu of on-site detention. It is the City's desire
that regional detention storage be utilized to accommodate these smaller
developments.
b.
Contribution. The contribution shall be an amount
equal to a cost estimate prepared by a professional engineer for site
specific improvements necessary to provide detention as provided herein.
All cost estimates for site specific detention facilities shall be
subject to review and approval by the City Engineer. The cost estimate
must include the value of the land which otherwise would have been
used as part of the system with the value of the subject land determined
by an independent appraiser paid for by the developer.
[R.O. 2012 §420.060; Ord. No. 4460, 7-12-2021[1]]
A.
Purpose.
The purpose of this Chapter is to control soil erosion on land that
is undergoing development for non-agricultural uses and to preserve
the natural terrain and waterways of land within the City. Soil erosion
scars the land and creates sediment that clogs storm sewers and road
ditches, chokes streams, and creates silt lakes, all of which pose
a threat to public health and safety. The provisions in this Chapter
are intended to provide a natural community environment, to prevent
soil erosion and to reduce costly repairs to gullies, washed out fills,
water conveyance systems, roads, and embankments. Application of the
regulations in this Chapter will effectively control soil erosion
and sedimentation.
B.
Scope
Of Authority. Any person, firm, corporation, or business proposing
to develop land within the City shall apply to the City Engineer for
approval of required erosion control plans and issuance of a grading
permit as specified in this Chapter.
C.
Performance
Guarantee. Upon approval of the erosion and sediment control plan,
but before the issuance of a grading permit, the City Engineer shall
require the applicant to post a performance bond, cash escrow, certified
check, or other acceptable form of performance guarantee in an amount
sufficient to ensure the execution of the plan. After determination
by the City Engineer that all erosion control measures and disturbed
surfaces have been constructed and stabilized in compliance with the
approved plan and provisions of this Section, the performance bond
or other securities shall be released.
D.
Control
Plan.
1.
Required Erosion And Sediment Control Plan Content. Grading plans,
site plans, preliminary plat or subdivision, or the subdivision improvement
plans for land disturbance sites that disturb twenty thousand (20,000)
square feet or more or disturb less than twenty thousand (20,000)
square feet when part of a larger common plan of development or sale
that will disturb a cumulative total of twenty thousand (20,000) square
feet or more, shall include the following additional information:
a.
Erosion and sediment control plans submitted to the designated official
shall include three (3) sets of maps and plans with specifications
showing proposed excavation, grading, or filling and will include
the following:
(1)
Full name and address of property owner;
(2)
Designation of property address and a location map;
(3)
Portion of the property that is to be excavated, graded, or
filled with excavated material;
(4)
Location of any sewerage disposal system or underground utility
line, any part of which is within fifty (50) feet of the proposed
excavation, grading or filling area and the location of any pipeline
operated at a maximum service pressure in excess of two hundred (200)
p.s.i.g., any part of which is within one hundred (100) feet of the
proposed excavation, grading or filling area;
(5)
Existing grade and topography of the premises and the proposed
finished grade and final contour elevation at a contour interval of
not more than two (2) feet on United States Geological Survey datum;
(6)
Location and present status of any previous permitted grading
operations on the property;
(7)
Details of any temporary drainage system proposed to be installed
and maintained by the applicant and a comprehensive drainage plan
designed to safely handle surface water, streams or other natural
drains following heavy rains during grading operations;
(8)
Details of proposed water impoundment structures, embankments,
sediment or debris basins, grass or lined waterways and diversions
with the details and locations of proposed stable outlets and the
location of any downstream impoundments which could be affected by
the proposed grading;
(9)
Details and locations of structural or non-structural BMPs;
(10)
Details of soil preparation and revegetation of the finished
grade and of other methods of soil erosion control;
(11)
Proposed truck and equipment accessways to the work site;
(12)
Delineation of the 100-year floodplain and floodway; and
(13)
A statement from the property owner or his/her agent assuming
full responsibility for the performance of the operation as stated
in the application. This statement shall also contain assurance that
all City property or roads will be adequately protected.
b.
The proposed phasing of development of the site, including clearing,
rough grading and construction, and final grading and landscaping.
Phasing should identify the expected date on which clearing will begin,
the estimated duration of exposure of cleared areas and the sequence
of clearing, installation of temporary sediment control measures,
installation of storm drainage, paving streets and parking areas,
and establishment of temporary and permanent vegetative cover. The
designated official may waive specific requirements for the content
of submissions upon finding that the information submitted is sufficient
to show that the work will comply with the objectives and principles
of these regulations.
2.
Erosion And Sediment Control Plan Approval. The erosion and sediment
control plan must define the measures that shall be taken to meet
erosion control principles and standards as defined in these regulations.
a.
Erosion and sediment control measures shall be designed to, at a
minimum, accommodate flows from a twenty-five-year, twenty-minute
storm. Approved erosion and sediment control measures shall be implemented
to prevent the flow or runoff of mud, dirt, rocks and other materials
onto sidewalks, streets, or other rights-of-way or into creeks, streams,
drainage ditch or any stormwater system or facility.
b.
The erosion and sediment control plan must be implemented before
grading operations begin. Collection of runoff containing mud, dirt,
rocks, and other materials, at permitted locations and quantities
and as detailed within an active MoDNR Land Disturbance Permit, is
permissible and not in violation of City ordinances.
c.
When a plan is submitted, the City Engineer may make comments and
recommendations. All such comments and recommendations shall be made
within thirty (30) days of receipt. Such comments, may pertain to,
but may not be limited to:
d.
All plans and specifications submitted for review and/or approval
shall be prepared by or under the direct supervision of a registered
professional engineer in the State of Missouri and shall be dated
and bear his/her original seal and signature.
e.
When applicable, the developer must also apply for the Missouri Department
of Natural Resources (MoDNR) land disturbance permit. A copy of the
MoDNR application or approved permit must be included with this submittal.
A copy of the approved MoDNR permit must be submitted to the City
when obtained.
f.
Grading permit approval shall confer upon the permittee, for a period
of one (1) year from date of approval, the conditional right that
the general terms and conditions under which the approval was granted
will not be changed by the City Engineer. Following approval of the
grading permit, the permittee may proceed with the grading operations
upon the final direction of the City Engineer.
3.
Principles And Standards Of Erosion And Sediment Control Plan.
a.
All excavations, grading, or filling shall have a finished grade
not to exceed a thirty-three percent (33%) [three (3) horizontal to
one (1) vertical] slope. Steeper grades may be approved by the City
Engineer if the excavation is through rock or if the excavation or
the fill is adequately protected (a designed head wall or toe wall
may be required). (BMP) designs may be utilized for slopes in excess
of thirty-three percent (33%), but must be designed by a qualified
geotechnical engineer hired by the developer and approved by the City
Engineer prior to and/or during installation.
b.
Erosion and sediment control plans for land disturbance sites that
disturb twenty thousand (20,000) square feet or more or disturb less
than twenty thousand (20,000) square feet when part of a larger common
plan of development or sale that will disturb a cumulative total of
twenty thousand (20,000) square feet or more, shall provide BMPs for
land disturbance. BMPs are a schedule of activities, practices or
procedures that reduce the amount of soil available for transport
or a device that reduces the amount of suspended solids in runoff
before discharge to waters of the State. Types of BMPs from stormwater
control, include, but are not limited to:
(1)
State-approved standard specifications and permit programs;
(2)
Employee training in erosion control, material handling and
storage and housekeeping for maintenance areas;
(3)
Site preparation such as grading, surface roughening, topsoiling,
tree preservations and protection, and temporary construction entrances;
(4)
Surface stabilization such as temporary seeding, permanent seeding,
mulching, sodding, ground cover, including vines and shrubs, riprap,
and geotextile fabric. Mulches may be hay, straw, fiber mats, netting,
wood cellulose, corn or tobacco stalks, bark, corn cobs, wood chips
or other suitable material which is reasonably clean and free of noxious
weeds and deleterious materials. Grasses used for temporary seeding
shall be a quick-growing species such as rye grass, Italian rye grass
or cereal grasses suitable to the area and which will not compete
with the grasses sown later for permanent cover;
(5)
Runoff control measures such as temporary diversion dikes or
berms; permanent diversion dikes or berms, right-of-way or perimeter
diversion devices, and retention and detention basins; and sediment
traps and barriers, sediment basins, sediment (silt) fences and staked
straw bale barriers;
(6)
Runoff conveyance measures such as grass-lined channels, riprap
and paved channels, temporary slope drains, paved flumes, or chutes;
and slope drains may be constructed of pipe, fiber mats, rubble, Portland
cement concrete, plastic sheets or other materials that adequately
will control erosion;
(7)
Inlet and outlet protection;
(8)
Streambank protection such as a vegetative greenbelt between
the land disturbance and the watercourse. Also, structural protection
which stabilizes the stream channel;
(9)
A critical path method analysis or a schedule for performing
erosion control measures;
(10)
Other proven methods for controlling runoff and sedimentation
as approved by the City Engineer.
c.
Land disturbance sites with grading area less than twenty thousand (20,000) square feet are exempt from the requirement of submitting an erosion and sediment control plan. This does not preclude the preventative measures that must be taken to prevent any materials, including, but not limited to, pollutants or waters containing any pollutants that cause or contribute to a violation of applicable water quality standards, other than stormwater, as set forth in Section 220.010(A)(15), to discharge, or cause to be discharged, into the municipal storm drain system or watercourses.
d.
All BMP designs are to be approved by the City Engineer. Temporary
siltation control measures (structural) shall be maintained until
at least seventy-five-percent vegetative cover of area disturbed is
established at a sufficient density to provide erosion control on
the site, as determined by the City Engineer.
e.
Where natural vegetation is removed during grading, vegetation shall
be reestablished in such a density (at least seventy-five-percent
vegetative cover of area disturbed) as to prevent erosion. Permanent-type
grasses shall be established as soon as possible or during the next
seeding period after grading has been completed.
f.
Land disturbance activities shall be scheduled as provided in the
table below:
|
Surface Stabilization Schedule
| |
|---|---|
|
Soil Disturbance Activity or Condition
|
Required Stabilization Time
|
|
Soil disturbance has ceased in areas greater than 2,000 square
feet
|
14 days
|
|
After construction of dikes, swales, diversions, and other concentrated
flow areas
|
5 days
|
|
When slopes are steeper than 3 horizontal to 1 vertical
|
7 days
|
|
When slopes are greater than 3% and longer than 150 feet
|
14 days
|
|
Perimeter controls around soil stockpiles
|
End of workday
|
|
Stabilization or covering of inactive stockpiles
|
30 days
|
|
When land disturbance is completed, permanent soil stabilization
must be installed
|
30 days
|
g.
Provisions shall be made to accommodate the increased runoff caused
by changed soil and surface conditions during and after grading. Unvegetated
open channels shall be designed so that gradients result in velocities
of two (2) feet per second (fps) or less. Open channels shall be designed
so that gradients result in velocities of two (2) fps or less. Open
channels with velocities more than two (2) fps and less than five
(5) fps shall be established in permanent vegetation by use of commercial
erosion control blankets or lined with rock riprap or concrete or
other suitable materials as approved by the designated official. Detention
basins, diversion, or other appropriate structures shall be constructed
to prevent velocities above five (5) fps.
h.
The ground adjoining development sites shall be provided with protection
from accelerated and increased surface water, silt from erosion, and
any other consequences of erosion. Runoff water from developed areas
(parking lots, paved sites, buildings, etc.) above the area to be
developed shall be directed to diversion ditches, detention basins,
concrete gutters and/or underground outlet systems.
E.
Enforcement.
1.
Inspections. By applying for a grading permit, the applicant consents
to the City inspecting the development of a site and all work in progress.
Additionally, the property owner, his/her agent or applicant shall
inspect all erosion and sediment control facilities weekly and following
a rain event producing more than one-half (1/2) inch of rain at the
project site. A log of each inspection and copy of the inspection
report shall be kept readily accessible and must be available upon
request by the City.
2.
Corrections. Repair, replacement, restoration, or cleaning of damaged
or failed BMPs identified during inspection shall be accomplished
within seven (7) calendar days of the inspection. Identified corrections,
can include, but are not limited to the following:
3.
Violations — Nuisance. It shall be unlawful for any person to violate any provision or fail to comply with any of the requirements of this Section. Any failure to adequately correct a deficiency in erosion and sediment control measures within the time period stated herein shall be a violation of City ordinances. Any failure to comply with an active MoDNR Land Disturbance Permit for a site that results in sediment entering streets or the stormwater system shall be considered a violation of City ordinances. For storms exceeding the design storm (twenty-five-year, twenty-minutes), any silt or debris leaving the site and affecting public rights-of-ways or stormwater drainage facilities shall be cleaned up within forty-eight (48) hours after the end of the storm. Any condition caused or permitted to exist in violation of any of the provisions of this Section is a threat to public health, safety and welfare and is declared and deemed a nuisance. The administration of violations and nuisances shall follow the City's ordinances related thereto and specifically Chapters 100 (General Provisions) and 220 (Nuisances).
a.
Each incident of failure shall be deemed a separate violation of
City ordinances, and each day where violations are not corrected shall
be considered separate additional violations.
b.
The City shall have the right to issue stop work orders to projects/sites
not complying with the requirements of this Section.
4.
Penalty. In addition to the other remedies set forth in this Section,
any person found to have violated this Section shall be guilty of
a misdemeanor punishable by a fine not less than ten dollars ($10.00)
and not more than five hundred dollars ($500.00) or imprisonment for
a period of not more than ninety (90) days. After the Board of Aldermen
has declared by ordinance that the conditions constitute a nuisance,
each day that the owner fails to abate the nuisance shall constitute
a separate offense.
[1]
Editor's Note: Ord. No. 4460 also changed the title of this
Section from "Sediment and Erosion Control" to "Erosion and Sediment
Control."
[R.O. 2012 §420.070; Ord. No. 2841 §1, 7-14-2003]
A.
Purpose. A development's storm water drainage system shall
be designed to:
B.
Rainfall Frequency. All facilities shall be designed to
carry a 25-year 20-minute storm of a duration which produces the maximum
peak flow rate of storm water runoff, without inundation or surcharging.
All hydraulic structures shall be designed to allow for a 100-year
storm to pass through the subdivision without destroying or damaging
property or inundating dwellings. Design information which substantiates
both conditions shall be provided.
C.
Calculation Of Runoff.
1.
The method of calculating and routing storm water runoff shall be
a generally accepted storm water management practice. The drainage
area shall consider all on- and off-site lands contributing to the
proposed development's drainage system. Capacity for such facilities
shall be based on the maximum potential water shed development permitted
by this Chapter.
2.
The rational method for calculating storm water runoff may be used
for developments up to one hundred fifty (150) acres. Other common
rainfall runoff calculation methods that may be utilized include graphical
peak discharge, tubular, and the synthetic unit hydrograph for development
greater than one hundred fifty (150) acres.
3.
The minimum percentage of imperviousness to be used in design shall
be based on the zoning district, as shown in the following table:
|
District
|
Minimum percent impervious
|
|---|---|
|
"R-1", Single-family
|
45
|
|
"R-2", Single-family
|
50
|
|
"R-3", Multiple-family
|
70
|
|
"R-4", Planned Mobile Home Park
|
60
|
|
"B-1", Central Business
|
90
|
|
"B-2", Highway Business
|
90
|
|
"B-3", Neighborhood Business
|
75
|
|
"I-1", Industrial
|
90
|
|
"NU", Non-Urban
|
5
|
|
Parking, Streets, Roofs
|
100
|
4.
Special uses, such as schools, churches, etc., shall have the differential
runoff computed and approved by the City Engineer.
5.
Special circumstance may dictate that the developed impervious area
may differ from that shown in the above table. An example may be single-family
lots of larger than ten thousand (10,000) square feet. Calculations
prepared by a registered professional engineer may be submitted to
the City Administrator or his/her designated representative for his/her
evaluation to determine if a minimum impervious area which differs
from that shown in the above table may be utilized. Likewise, the
City Administrator or his/her designated representative may determine
that the percent of impervious area for a particular development differs
from that shown in the above table.
D.
Open Channels. Open channels consist of swales, ditches,
or depressions, both natural and manmade, that convey water. Channels
shall be protected from scour and erosion by providing a channel lining
adequate to sustain the velocity of the 25-year design storm. If velocities
in channels exceed three and one-half (3.5) feet per second during
25-year design storms, then erosion control other than vegetation
shall be provided in channel construction. Channels shall have the
hydraulic capacity to carry the 25-year design storm runoff within
the channel bed and banks. Out of bank flow may be permitted on land
slopes parallel to the channel where it can be shown that no erosion
damage or serious property damage will result. Channels function as
part of the major drainage system and shall be evaluated for the 100-year
design storm to determine the impacts of runoff on adjacent property.
The channel's hydraulic capacity shall be increased where adjustments
to channel geometry provide significant protection to adjacent properties
during the 100-year event.
E.
Closed Conduit Storm Sewers.
1.
Pipe sizes for closed conduit flow shall be based on the 25-year
design storm runoff and minimum allowable velocities. The system shall
provide for the clearing of sediment and other deposits by maintaining
a minimum velocity of two (2) feet per second during the 25-year storm.
2.
Manning's Equation is the most common method of estimating the capacity
and flow resistance in closed conduits, although the Kutter, Hazen-Williams,
and Darcy Weisbach formulas are also acceptable.
3.
Closed conduit storm sewer systems shall convey the 25-year design
storm to a point of discharge by gravity or pressure flow. In gravity
flow conditions, the hydraulic grade line shall be calculated to reflect
losses in pipes and structures and shall not rise to an elevation
greater than the sewer structure tops during the design storm.
4.
Generally, pressure flow occurs where the capacity of pipe run exceeds
the design flow and the outfall point does not control discharge.
Storm sewer systems may be designed for pressure flow when the hydraulic
grade line is above the crown of the pipe. The decision to design
a pressure flow system may be based on aesthetics, the need to submerge
outfalls, economics, limitations associated with reduced pipe sizes,
or grade constraints in outfalling the system.
F.
Inlets. Calculations shall be submitted to demonstrate the
capacity of all inlets, such calculations must consider the cross-slope
of the pavement, depth of water at the curb face, size of opening,
and the longitudinal grade of street. Street inlets and inlets in
parking areas shall reduce the spread and depth of flow to acceptable
levels during the 25-year design storm. The acceptable level of flow
for a minor access or local access street would maintain an eight
(8) foot travel lane with a maximum one (1) inch depth. One (1) clear
ten (10) foot travel lane must be maintained for a collector street,
and two (2) clear ten (10) foot travel lanes must be maintained for
a major street. Any area inundated by water ponding at an inlet during
the 25-year storm event shall be located within an easement or right-of-way.
The effects of the 100-year storm event shall also be analyzed to
insure no property damage or dangerous conditions result. Inlets located
on continuous grades may be designed to permit a portion of flow to
bypass the structure; however, calculations for the downstream structure
must consider the bypass.
G.
Plans And Calculations.
1.
A drainage map shall be developed from a base reproduction of the
site plan or grading plan. The existing and proposed contours shall
be shown, of suitable scale and two (2) foot contour interval for
the subject property, extending off-site one hundred (100) feet or
less, as determined by the City for proper design of the proposed
improvements. Contour intervals other than the above shall be used
as determined by the site topography.
2.
The location of existing and proposed property lines, streets, sinkholes,
railroads, areas within the tract subject to inundation by storm water
and other significant natural features, such as wooded areas and rock
formations, etc., shall be included on the map. All existing and proposed
storm water facilities, such as inlets, manholes, pipes, culverts,
bridges, channels, etc., and all existing and proposed improvements
required for property design review, such as pavement, buildings,
etc., shall be included on the map.
3.
The location of streams and other floodwater runoff channels, calculations
supporting the method and capacity needed for the safe and temporary
storage of increased runoff resulting from the proposed development.
4.
Basic information regarding the receiving watercourse into which
the proposed storm water system will discharge. This information should
include a general cross section, and existing downstream culverts,
bridges, and other waterway openings.
5.
The runoff details shall be required, showing individual flows for
each existing and proposed structure and cumulative flows in pipes
and gutters, including "Q" and area. The map shall show all bodies
of water, such as ponds or lakes (including surface area and elevation),
and all waterways (including their names or the names of creeks or
rivers they flow into).
6.
Lots shall be laid out so as to provide positive drainage away from
all buildings. Individual lot drainage shall be shown and coordinated
with the drainage pattern for the area and designed so that runoff
from one (1) lot will not adversely affect an adjoining lot. All necessary
grading to direct storm water runoff shall be located within a drainage
easement. A layout of the proposed storm water management system including
the location and size of all drainage structures, storm sewers, channels,
channel sections, detention basins, and analysis regarding the effect
said improvements will have upon the receiving channel and its high
water elevation.
7.
All computations, plans and specifications, related to the implementation
of this Chapter must be prepared and sealed by a professional engineer
registered in the State.
[R.O. 2012 §420.080]
A.
The
rates (pre-developed and post-developed) of runoff shall be determined
for the 2-, 25- and 100-year rainfall frequencies. The minimum storm
duration shall be twenty (20) minutes.
B.
Storm
water shall be detained on site or on adjacent property under agreement
and metered out at the rate of an undeveloped site for the above frequencies
and minimum duration to prevent possible flooding and erosion downstream.
C.
In
the event the natural downstream channel or storm sewer system is
inadequate to accommodate the release rate provided above, then the
allowable release rate shall be reduced to that rate permitted by
the capacity of the downstream channel or storm sewer system.
D.
Detention
basin volume will be based on routing each post-developed runoff through
the detention facility while satisfying the appropriate allowable
release rate. The routing computation shall be based on an application
of the continuity principle. The discharge rate shall be based on
the maximum head conditions in the detention facility.
[R.O. 2012 §420.090]
A.
Dry Bottom Basins. Dry bottom basins may be constructed
to temporarily detain the storm water runoff so that the rate at which
it is released is the same rate as before development. The following
features shall be incorporated into the design of any detention basin:
1.
Freeboard. Detention storage areas shall have adequate
capacity to contain the storage volume of tributary storm water runoff
with at least two (2) feet of freeboard above the water surface for
a 100-year storm event.
2.
Outlet control works. Outlet works shall be designed
to limit peak outflow rates from detention storage areas to below
peak flow rates that would have occurred prior to the proposed development.
Outlet works shall not include any mechanical components or devices
and shall function without requiring attendance or control during
operation, unless specifically approved by the City Administrator
or his/her designated representative.
3.
Emergency overflow/spillway. Emergency structures
shall be provided to permit the safe passage of runoff generated in
excess of the design storm event. Antivortex measures shall be provided
along with the design plan.
4.
Maximum depth. The maximum planned depth of storm
waters stored shall not normally exceed five (5) feet.
5.
Side slopes. The maximum side slopes for grassed
basins shall not normally exceed one (1) foot vertical for three (3)
feet horizontal.
6.
Limits of ponding. In no case shall the limits of
maximum ponding be closer than thirty (30) feet horizontally from
any building and less than two (2) feet vertically below the lowest
sill elevation.
7.
Interior drainage. The basin bottom should be designed
to drain expeditiously. Flows through the detention basin should be
handled by paved ditch from inflow structure to outflow structure
to minimize erosion.
8.
Multipurpose basins. If the detention basin is to
have other uses, the design of the basin bottom should include underdrains
to expedite drying of the bottom between runoff events.
9.
Aesthetics. Designs should result in aesthetically
pleasing configurations which will enhance public acceptability.
B.
Retention Basins. All such privately owned and maintained
systems shall be subject to periodic inspection by the City Administrator
or his/her designated representative. Wet bottom basins may also be
used to temporarily detain the differential runoff from the development.
In addition to the general design features enumerated above for dry
bottom basins, the following features should also be incorporated
into the design of any wet bottom basin:
1.
Normal pool depth. In order to manage weed growth,
the normal pool depth should be four (4) feet minimum.
2.
Depth for fish. If fish are to be kept in the pond,
at least one-quarter (¼) of the area of the permanent pool
should have a minimum depth of ten (10) feet.
3.
Facilities for emptying. In order to ease cleaning
of the pond or shoreline maintenance, the pond design should include
provisions for emptying the pond.
4.
Low flow bypass. The design of any pond may include
a low flow bypass channel or pipeline to divert runoff that can be
accommodated by downstream drainageways.
5.
Side slopes below normal pool. The side slopes below
the normal pool elevation may exceed the maximum side slope permitted
above normal pool (3:1 slope). The design shall, however, include
provisions for a safety ledge having a depth of water not greater
than three (3) feet immediately adjacent to the shoreline.
6.
Permanent pool volume. The permanent pool volume
in a wet basin at normal depth should be equal to the runoff volume
from its watershed for the 2-year event.
C.
Detention In Flood Fringe Areas. The placement of a detention basin in a flood fringe area shall require compensatory storage for one and one-half (1.5) times the volume below the base flood elevation occupied by the detention basin including any berms. The release rate from the detention storage provided shall still be controlled consistent with the requirements of Section 420.080. The applicant shall demonstrate its operation for all streamflow and floodplain backwater conditions. Excavations for compensatory storage along streams and watercourses shall be opposite or adjacent to the area occupied by detention. All floodplain storage lost below the 25-year flood elevation shall be replaced below the 25-year flood elevation. All floodplain storage lost above the existing 25-year flood elevation shall be replaced above the proposed 25-year flood elevation. All compensatory storage excavations shall be constructed to drain freely and openly to the watercourse.
D.
Rooftop Storage. Detention storage may be met in total or
in part by detention on roofs. Details of such design, which shall
be included in the building permit application, shall include the
depth and volume of storage, details of outlet devices and downdrains
and elevations of overflow provisions. Direct connection of roof drains
to sanitary sewers is prohibited.
E.
Parking Lot Storage. Paved parking lots may be designed
to provide temporary detention storage of storm water on all or a
portion of their surfaces. Outlets will be designed so as to slowly
empty the stored waters and depths of storage must be limited so as
to prevent damage to parked vehicles.
F.
Other Detention Methods. All or a portion of the detention
storage may also be provided in underground or surface detention facilities,
to include basins, tanks, or swales, etc. Emergency overflow conditions
shall be considered in all methods.
G.
Detention Basins In Floodways. Detention basins shall not
be placed in the floodway.
[R.O. 2012 §420.100; Ord. No. 4354, 3-9-2020]
A.
Storm
pipes shall be protected from excessive bearing pressures by placing
them outside the forty-five degree (45°) influence zone of building
structures unless an engineer's calculations show the pipe material
or soil condition to be adequate for the subjected load.
B.
Pipes
on twenty percent (20%) slopes or greater shall be anchored securely
with concrete anchors or their equal to prevent the pipe from creeping
downhill.
C.
Pipes
or structures constructed on fill shall be stable and protected against
settlement by compacting fill material to ninety-five percent (95%)
of the modified proctor maximum dry density.
D.
Pipes
thirty-six (36) inches or larger may be placed on a curved alignment
utilizing alignment radii established by the pipe manufacturer.
E.
The
receiving surface where pipes discharge shall be protected from erosion
by evaluating the discharge velocity for the 25-year design storm.
The use of energy-dissipating devices may be necessary to reduce the
velocity to acceptable levels for the receiving surface. The energy-dissipating
device used shall be a minimum length of ten (10) times the diameter
of the discharge pipe.
F.
A manhole,
inlet, or junction box shall be located at changes in pipe size, grade,
alignment, or material.
G.
The
angle between influent and effluent pipes shall be not less than ninety
degrees (90°), and the drop between inverts shall be not less
than one-tenth (0.1) foot.
H.
Manhole
and inlet castings located in travelways shall be capable of withstanding
traffic loads and shall be constructed flush with the finished surface.
I.
All
materials and appurtenances for storm water management systems shall
conform to current standards of the American Society for Testing and
Materials (ASTM).
J.
(Reserved)
K.
A new
drainage channel or pipe shall intersect an existing drainage channel
at a maximum angle of sixty degrees (60°).
L.
All
trenches under roadway pavement shall be backfilled with MHTD Type
I aggregate in six (6) inch layers and compacted to ninety-five percent
(95%) of the modified proctor maximum dry density.
M.
All
piping shall be bedded per the manufacturer's requirements.
N.
Grated
inlets will not be allowed without special approval by the City Administrator.
O.
All
materials used in the construction of storm sewers shall be subject
to inspection and approval of the City Administrator or his/her designated
representative.
P.
Storm
Sewers.
1.
Description. Storm sewer construction shall consist of furnishing
all labor, materials and equipment for the complete installation of
sewers and appurtenances in accordance with the standards, drawings,
general conditions, and detail specifications. Unless indicated otherwise
in these specifications, the word "sewer" shall refer to pipe sewers,
box culvert sewers, or paved channels.
2.
Standards. Whenever any reference is made to ASCE, ASTM, AASHTO,
AWWA, and ASA Standard Specifications, the specification referred
to shall be understood to mean the latest revision of said specifications
or standards as amended to date of letting of contract. RCP, HP, HDPE,
and CMP shall be the only pipe material used in the right-of-way.
Only RCP and HP shall be used under arterials, collectors, and cul-de-sacs.
|
Pipe
|
Arterials, Collectors, Cul-de-sac
|
Acceptable Location Right-of-Way (other than arterials, collectors,
cul-de-sacs)
|
Easements
|
|---|---|---|---|
|
RCP
|
X
|
X
|
X
|
|
HP
|
X
|
X
|
X
|
|
HDPE
|
X
|
X
| |
|
VCP
|
X
| ||
|
DIP
| |||
|
CMP
|
X
|
X
|
3.
3.0 Materials.
a.
3.2 Reinforced Concrete Pipe (RCP). All reinforced concrete pipe
shall conform to ASTM Designation C 76-62T. RCP shall be Class III
with a D-load of 1350. This specification covers reinforced concrete
pipe of twelve (12) to one hundred eight (108) inches, depths of fill
of up to thirteen (13) feet above pipe, and is intended for use in
conveyance of storm water and for the construction of culverts. All
other installations shall be approved by the Engineer. The interior
surfaces of the pipe shall be a smooth true cylindrical surface free
from undulations or corrugations. Each pipe shall be marked by the
manufacturer with a "Q Cast" stamp to certify the pipe was produced
by an American Concrete Pipe Association (ACPA) certified plant. The
following additional information shall be clearly marked on the inside
of each section of pipe by indenting on the pipe section or by painting
thereon with waterproof paint:
b.
3.3 High Density Poly Ethylene Pipe (HDPE). All HDPE pipe shall conform
to ASHTO M294. HDPE pipe to be ADS N-12 WT IB (water tight, integral
bell) smooth interior, dual wall or approved equal. For forty-eight
(48) inch diameter pipe and smaller, minimum cover shall be one foot.
For fifty-four (54) inch and sixty (60) inch diameter pipe, minimum
cover shall be two (2) feet. All HDPE pipe shall contain a minimum
content of two percent (2%) carbon black as required by ASTM D3350.
Pipe shall be furnished with an integral reinforced bell with a bell
tolerance device and elastomeric gasket to meet ASTM D477 and ASTM
D3212.
c.
3.4 Cast Iron Pipe and Castings.
(1)
Cast Iron Pipe: All cast iron pipe shall conform to ASA A21.6
or A21.8 and shall be furnished with standardized mechanical joints
and accessories conforming to ASA A21.11.
(2)
Cast Iron: All iron castings used in connection with storm sewers
and their appurtenance, structures (manhole and catch basin rings
and covers, catch basin castings, inlet plates and grating, manhole
steps or ladder irons, etc.) shall be made from tough, gray iron of
even grain and tensile strength of not less than thirty-five thousand
(35,000) pounds per square inch, conforming to ASTM Designation A
48, Class No. 35B. The castings shall conform to the shapes and dimensions
shown on the standard drawings, be clean and whole, and without blow
or sand holes or other defects, and all parting fins and pouring gates
shall have been removed. No plugging or filling in of holes will be
permitted and all such castings, except the buried portion of manhole
steps or ladder rungs shall be cleaned and painted with one (1) coat
of coal tar before being delivered to the site.
d.
3.5 Vitrified Clay Pipe (VCP). All VCP shall conform to AASHTO M65.
Provide extra strength pipe under roadways.
e.
3.6 Corrugated Metal Pipe (CMP). Wherever shown on the plans and
profiles, or required by the Engineer, corrugated metal storm sewer
culvert pipe, complete with connecting bands, elbows, and fittings,
may be used. CMP shall be aluminized type 2 (AASHTO M36 & M274)
or polymeric precoated (AASHTO M36, M245 & M246) galvanized (AASHTO
M36 & M218) sheet or coils. Polymeric coating shall be Dow "TRENCHCOAT"
or approved, equal, 10 mils-thick on both inside and outside of pipe.
Corrugated metal culvert pipe gage requirements shall conform to the
specifications of the following table unless otherwise specified by
the plans and specifications or by the Engineer. Where zinc coated
sheets and coils (M218) are to be used, the gage requirements of the
following tables shall be increased to the next heaviest gauge.
|
Circular Culvert Pipe
| |||
|---|---|---|---|
|
Diameter (inches)
|
Gage
|
Diameter (inches)
|
Gage
|
|
12
|
16
|
42
|
14
|
|
15
|
16
|
48
|
14
|
|
18
|
16
|
54
|
12
|
|
24
|
16
|
60
|
12
|
|
30
|
16
|
72
|
10 up to 16 feet
|
|
36
|
16
| ||
|
Arch Culvert Pipe
| |||
|---|---|---|---|
|
Equivalent Diameter (inches)
|
Gage
|
Span (inches)
|
Rise (inches)
|
|
15
|
16
|
18
|
11
|
|
18
|
16
|
22
|
13
|
|
21
|
16
|
25
|
16
|
|
24
|
14
|
29
|
18
|
|
30
|
14
|
36
|
22
|
|
36
|
14
|
43
|
27
|
|
42
|
12
|
50
|
31
|
|
48
|
12
|
58
|
36
|
|
54
|
12
|
65
|
40
|
|
Wherever corrugated metal culverts are installed on railroad
property which is occupied by tracks or which may be occupied by tracks
at any time in the future, then it shall conform to the A.R.E.A. "Specifications
for Corrugated Metal Culverts."
|
|
Diameter of Pipe (inches)
|
Minimum Gage of Metal
|
|---|---|
|
12 to 18
|
14
|
|
20 to 24
|
12
|
|
26 to 36
|
10
|
|
38 to 60
|
8
|
|
Pipes larger than sixty (60) inches require special considerations
and special specifications.
|
|
Corrugated metal storm sewer pipe shall be handled in such a
manner that it is not chipped, dented or bent. If in handling the
culvert the base metal is exposed in any way then it shall be rejected
or repaired to the satisfaction of the Engineer.
|
f.
3.7 High Performance Polypropylene Pipe (HP). HP pipe shall have
a smooth interior and an annular corrugated exterior. Twelve (12)
inch through thirty (30) inch HP pipe shall meet or exceed ASTM F2736
and AASHTO M330. Thirty-six (36) inch through sixty (60) inch HP pipe
shall meet or exceed ASTM F2881 and AASHTO M330. The HP pipe is intended
for use in conveyance of storm water and for the construction of culverts.
The minimum depth of fill above the pipe shall be one (1) foot for
twelve (12) inch through forty-eight (48) inch HP pipe. The minimum
depth of fill above the pipe shall be two (2) feet for sixty (60)
inch HP pipe. The maximum depth of fill above pipe shall be nine (9)
feet. Backfill for minimum and maximum applications shall meet manufacture'
s specifications. All other installations shall be approved by the
Engineer. Polypropylene compound for pipe and fitting production shall
be impact modified copolymer meeting the material requirements of
ASTM F2736, Section 4.
(1)
All drainage structures used with HP pipe, including inlets,
junction boxes, and flared end sections, shall be precast concrete,
as specified for RCP pipe.
g.
3.8 Encasement Pipe. When circular corrugated iron lineal plate or
structural plate pipes or tunnels are installed on railroad property
which is occupied by tracks or by tracks at any time in the future,
then it shall conform to American Railway Engineering and Maintenance
of Right of Way Association (A.R.E.M.A.) "Specifications for Corrugated,
Structural, Plate Culverts and Arches." The minimum gage of the metal
shall be as follows:
|
Neutral Axis Diameter (inches)
|
Minimum Gage
|
|---|---|
|
48
|
8
|
|
60
|
8
|
|
62
|
7
|
|
72
|
7
|
|
74
|
5
|
|
84
|
5
|
4.
4.0 Joints for Reinforced Concrete Pipe.
a.
Flexible Compression Joints. Flexible compression joints may be made
with rubber gasket, rubber "0" rings, preformed plastic compound,
mastic, or butyl sealants. Rubber gasket and rubber "0" rings which
shall conform with ASTM C 443-59T. Preformed plastic compound shall
be either rope form or flat tape form conforming to ASTM C990. Primer,
as recommended by the manufacturer, shall be used to maintain the
material in position while pipe sections are being joined. Mastic
and butyl sealants may be used in accordance with ASTM C990-96. Mastic
shall be applied to the bottom half of the bell or groove and the
top half of the spigot or tongue.
b.
4.1 Joints for High Density Poly Ethylene Pipe. Pipe shall be joined
using a bell & spigot joint meeting AASHTO M252, AASHTO M294 or
ASTM F2306. The joint shall be water-tight and gaskets, when applicable,
shall meet the requirements of ASTM F477. Gaskets shall be factory
installed with a removable wrap to ensure gasket is free from debris.
A joint lubricant supplied by the manufacturer shall be used on the
gasket and bell during assembly. Field joints shall provide circumferential
and longitudinal strength to maintain the pipe alignment, prevent
separation of pipe and prevent infiltration of fill material.
c.
4.2 Joints for Cast Iron Pipe.
(1)
Open Bell Joints. The greatest care must be exercised in handling
the jointing compound so that the best possible joint may be obtained.
Each must be poured at one (1) pouring. If one (1) ladle will not
hold enough, two (2) or more ladles must be used, so that the pouring
is done in an absolutely continuous stream until the joint is filled.
The jointer shall not be removed until the gate has had time to harden.
For melting the jointing materials a gasoline furnace shall be used,
because a closer control of the heat than can be obtained than by
a coke or coal furnace is essential. The melting pot shall be at all
times within easy reach of the joint at a distance of not over twenty-five
(25) feet so that the jointing compound shall, under no circumstances,
be chilled in being carried from the melting pot to the pipe. The
contents of the kettle shall be well stirred before taking out each
ladle full. The interior of the pipe must be kept perfectly clean
during the progress of the work, and the end of the pipe and its branches
shall be closed with an iron or wooden plug whenever the work shall
temporarily cease. Where lead is used as a jointing compound, it shall
be thoroughly caulked after the jointer has been removed. The price
bid shall include the placing of all pipe fittings and plugs. All
joints shall be made in accordance with best practices.
(2)
Universal Joints. The tightness of the universal pipe joint
is dependent upon the perfection of the contact of the machined edge
of the spigot and with the tapered, machined surface of the bell end.
Before lowering the pipe into the ditch, the machined surfaces of
both ends of the pipe must be scraped with some tool such as a knife,
brushed with a wire brush and washed with a cloth saturated with kerosene,
then wiped clean and carefully examined for burrs or pits and other
imperfections. White lead which has been thinned so that it can be
applied with a brush, shall then be applied to the machined surface
contact with the bell of the pipe to be joined. After lowering the
pipe, the bell of the pipe in place shall be carefully cleaned by
wiping and white lead applied to the machined surface. Care is necessary
during this operation to have a perfectly clean surface at all times
as a small amount of sand may give trouble after the joint is made.
After inserting the pipe, the bolts are inserted with the heads in
reverse direction, to permit the use of both wrenches at the same
time, lock washers are applied and the nuts turned on as far as they
can be by using the wrenches with one (1) hand and without pipes or
other extensions to give greater leverage. Damage often is done to
the pipe by excessive tightening. Bolts, washers and nuts shall be
furnished by the installer.
(3)
Mechanical Joints. Mechanical joints specification shall conform
to ASA Designation ASA-A21.11.
d.
4.3 Joints for Vitrified Clay Pipe.
(1)
Flexible Compression Joint. Factory made vitrified clay pipe
gasket may be used conforming with ASTM Designation C 425-60T.
(2)
Hot Poured Joints. Hot poured joints may be allowed, if the
material used and the pipe jointing procedures are approved by the
Engineer prior to construction. The joint compound shall be heated
to a temperature of three hundred fifty degrees to four hundred degrees
Fahrenheit (350° to 400° F.) as may be necessary to provide
a smooth and rapid pour.
e.
4.4 Joints for High Performance (HP) Polypropylene Pipe.
(1)
Pipe shall be joined with a gasketed integral bell and spigot
joint meeting the requirements of ASTM F2736, for applicable diameters.
HP pipe shall be watertight according to the requirements of ASTM
D3212. Spigots shall have gaskets meeting the requirements of ASTM
F477. Gasket shall be installed by the pipe manufacturer and covered
with a removable, protective wrap to ensure the gasket is free from
debris. A joint lubricant available from the manufacturer shall be
used on the gasket and bell during assembly. HP pipe shall have a
reinforced bell with a polymer composite band installed by the manufacturer.
Fittings shall conform to ASTM F2736, for applicable diameters. Bell
and spigot connections shall utilize a spun-on, welded or integral
bell and spigot with gaskets meeting ASTM F477. Fitting joints shall
meet the watertight joint performance requirements of ASTM F2736 or
ASTM D3212. To assure water tightness, field performance verification
may be accomplished by testing in accordance with ASTM F2487. Use
manufacturer's recommendation for leakage rates.
5.
Storm Sewer Construction.
a.
5.1 Excavation and Backfill. All excavation for structures, trench
excavation, and backfilling for storm sewer construction and all related
work shall be performed in accordance with manufacturers suggested
installation practices. RCP, VCP, and DIP shall be considered rigid
pipes. HDPE and CMP shall be considered flexible pipe.
b.
5.2 Pipe Bedding.
(1)
RCP pipe shall be bedded according to the Type 3 installation
as recommended by the American concrete Pipe Association and details
bound in this manual.
(2)
CMP and HDPE. Pipe shall be bedded according to manufacturer's
recommendations and the details for flexible pipe bound in this manual.
Should any excess material be removed from the ditch bottom, the space
shall be filled with the approved material and thoroughly tamped,
with a pneumatic tamper to the satisfaction of the Engineer, or replaced
with a six (6) inch thick layer of approved granular material on top
of other approved compacted materials. Regardless of the method used
to transfer the line and grade from the stakes to the sewer, each
pipe shall be checked for line and grade using a method approved by
the Engineer.
c.
5.3 Laying the Pipe. All pipe shall be protected during handling
against shock and free fall. RCP shall, at the installer's option,
be furnished with factory cast lift holes. Lift holes shall be two
and one-half (2.5) inches in diameter or less for pipes with inside
diameter of sixty (60) inches or less. Lift holes shall be three and
one-half (3.5) inches in diameter or less for pipes with inside diameter
greater than sixty (60) inches. No more than two (2) holes will be
allowed in any one (1) piece of pipe. Drilling of lift holes on site
is not acceptable. Any rebar visible in a lift hole shall be cause
for rejection. Lift holes shall be plugged with a pre-manufactured
plug designed specifically for plugging RCP holes Popit or equal)
or grouted full. The filled hole shall then be covered with an adhering
sheet Membrane (Grace Ice and Water Shield or equal) or a coat of
bituminous material. Regardless of the method used, installer shall
be responsible for the final water tightness of the pipe. The laying
of pipe in finished trenches shall be commenced at the lowest point
and installed with the bell end forward or upgrade. All pipe shall
be laid with ends abutting and true to line and grade established
with a laser. They shall be carefully centered so that when laid they
will form a sewer with a uniform invert. Each piece of pipe shall
be checked for vertical and horizontal alignment immediately after
being laid. Preparatory to making pipe joints, all surfaces of the
portions of the pipe to be jointed, or of the factory made jointing
materials, shall be clean and dry. Lubricants, primer, adhesives,
etc., shall be used as recommended by the pipe or joint manufacturer's
specifications. The joints shall be wiped inside, removing all surplus
joint compound and dirt from the interior of the pipe. Twelve (12)
inch pipe and smaller shall be wiped by means of a disc attached to
a rod not less than four (4) feet long worked continuously through
the line of pipe. When cement mortar, Kalktite or other approved joint
compounds are used to make the joint in reinforced concrete pipe,
it shall be made as follows:
In the bottom half of the bell shall be placed a sufficient
amount of joint compound to thoroughly fill the annular space, and
the next pipe inserted into place. The remainder of the annular space
shall be completely filled on the inside and outside of the joint,
around the circumference of the pipe, and the joint wiped on the inside
of the pipe to remove all excess joint material.
No pipes may be trimmed unless by order of the Engineer. Pipes
having defects that do not cause their rejections shall be so laid
as to place these defects where they will be of least consequence.
Trenches shall be kept water-free and as dry as possible during bedding,
laying and jointing and for as long a period as required to protect
the pipe joints and concrete in structures. As soon as possible after
the joint is made, sufficient material shall be placed alongside each
side of the pipe to offset conditions that might tend to move the
pipe off line and grade.
d.
5.4 Manholes and Junction Chambers.
(1)
Precast Manholes. Precast manholes shall be constructed as shown
on the approved design plans, and as directed by the Engineer.
(2)
Manhole Base and Invert. The manhole base and invert shall be
constructed in accordance with the Missouri Department of Transportation,
Engineering Policy Guide. All bases and inverts shall be poured individually
in one (1) continuous pour for each, unless otherwise specified and
particular care taken to make channels smooth and perfect. All manhole
inverts and bases shall conform to the applicable manhole standards.
Precast manhole bases may be used with precast manholes provided the
design of the base has been approved.
(3)
Manhole Rings and Covers. The rings and covers of all manholes
shall be set at the elevation shown on the drawings and solidly built
into place. Concrete rings shall be grouted with cement mortar. Plastic
adjusting rings shall be injection molded-recycled HDPE as manufactured
by LADTECH, Inc., or approved equal and installed as per manufacturer's
recommendations. The manhole adjusting rings shall be molded from
high density polyethylene as defined in ASTM Specification D-4976.
The annular space between the rings and cone basin, the rings, and
the rings and cover frame shall be sealed utilizing an approved butyl
sealant. The installer shall utilize flat and sloping units to match
the required slope and or grade of the structure.
e.
5.5 Inlets.
(1)
Precast inlets shall be constructed in accordance with the standards
or approved equal. Concrete for precast concrete inlets shall conform
to the applicable Sections of these specifications for Class D concrete.
(2)
Reinforced concrete inlets shall conform to the standard drawings
and the applicable Sections of these specifications for Class D and
Class E concrete. Concrete cover over steel reinforcement shall be
not less than one (1) inch for covers and one and one-half (1 1/2)
inches for walls and floors. All exposed concrete shall have smooth
steel trowel or brushed finish. Interiors of structures shall have
the forms removed and surface voids filled.
f.
5.6 Reinforced Concrete Box Culverts.
(1)
General. Reinforced concrete box culverts shall be constructed
in accordance with the Missouri Department of Transportation Engineering
Policy guide.
(2)
Composition of Concrete. To determine the actual mixed proportions
of cement, aggregates and water proposed for use on the project, the
Installer shall furnish all the information required by the testing
laboratory retained by the Engineer. The testing laboratory will proportion
a concrete mix based upon the requirements of these specifications
and will determine the compressive breaking strength of these specimens
at seven (7) days and will determine that the mix is in strict compliance
with the specifications.
(3)
Paved Ditches and Rip-Rapping. Paving concrete for paved ditches
shall conform to Class E concrete specifications herein described
and shall correspond with the standard drawings or approved equal.
The material for rip-rap shall consist of a predominantly one-sized,
durable stone, shot rock or broken concrete. Acceptance by the Engineer
may be made by visual inspection. Rip-rap material shall be either
Type 1 or 2 per below. Type 1 Rip-rap shall consist of at least forty
percent (40%) of the mass being pieces having a volume of one (1)
cubic foot or more. Type 2 Rip-rap shall consist of at least sixty
percent (60%) of the mass being pieces having a volume of one (1)
cubic foot or more. A geotextile material shall separate the subgrade
from the rip-rap. Geotextile material shall be AASHTO M288-96 Class
2 with a minimum permittivity of 1.0 sec-i and an apparent opening
size of 0.22 mm MARV. Lap seams per manufacturers recommendations.
Rip-rap shall be placed to the approximate shape and thickness shown
on the plans for the specified ditch or as directed by the Engineer.
The rock shall be dumped on a subgrade of reasonably uniform density
and left in a rough condition meeting the approval from the Engineer.
Grouted rip-rap shall not be allowed unless approved by the Engineer.
g.
5.7 Toewalls. A toewall or extension plate shall be provided where
any pipe daylights,
h.
5.8 Headwalls, Wing walls and End walls. Design of these structures
shall conform to the standards attached or to the approved details
as submitted by the Engineer.
i.
5.9 Railroad Crossings. Wherever a railroad crossing is being constructed
beneath or at grade the necessary permit for the construction will
have been previously secured by the installer. It shall also be the
responsibility of the installer to contact the railroad company prior
to beginning of such crossings, and to proceed with the construction
as directed by the railroad company. All railroad crossings shall
be made at right angles to the railroad tracks wherever possible,
and shall be laid by jacking or tunneling.
j.
5.10 Traffic Control. Installer shall provide traffic control in
accordance with the Manual of Traffic Control Devices, latest edition.
Installer shall protect installed material from damage from construction
loads.
k.
5.11 Existing Utilities. The installer shall take all precautions
necessary to avoid conflict with and or damage to existing utilities.
l.
5.12 Replacement of Pavement. All pavement, surfacing, driveways,
curb, walks, buildings, utility poles, guy wires, and other surface
structures affected by construction operations in connection with
the performance of the contract, together with all sod and shrubs
in yards, parks, and parking lots, shall be maintained and if removed,
or otherwise damaged, shall be restored to the original condition
thereof, as determined and approved by the Engineer, unless otherwise
specified on the plans. The installer shall be responsible for, including
any damage caused by settlement of backfill placed beneath pavements,
street, road, and driveway surfacing, and drainage and other structures,
and beneath sod in yards, parking lots, and parks, which may occur
at any time prior to, and during the correction period after the date
of final acceptance of the work covered by the contract; during such
period the installer shall at his/her own cost and expense refill
all excavations where backfill damage to structures, pavements, surfacing,
and sod caused by such settlement, to the satisfaction of the City.
Should the installer fail to repair settlement which may occur as
described above within thirty (30) days after being given notice thereof,
the owner shall have the right to repair such settlement and charge
the cost of such repairs to the installer. The installer will be held
responsible for all damage to roads, highways, shoulders, ditches,
embankments, bridges, culverts and other property, caused by him or
any of his/her sub-installers in hauling or otherwise transporting
materials to and from the, several sites of the work, regardless of
the location of such damage. The installer shall make arrangements
relative to the payment for, or repair or replacement of such damage
or damaged surfaces or structures which are satisfactory and acceptable
to the owners or owner of such damaged surfaces or structures, or
to their legally responsible officers, agents or other representatives,
at the installer's own cost and expense.
m.
5.13 Video Inspection. All storm drains including pipes, inlets,
junction boxes, etc., shall be inspected using a video camera. Immediately
prior to video inspection all storm drain facilities must be flushed
with clean water, debris flushed from the facilities must be removed
and properly disposed. The installer shall provide and run a video
camera to check for the presence of sags or other evidence of improper
construction. The video shall show the restoration of all surface
areas disturbed during construction as well as document that the tops
of all inlets and junction boxes are properly adjusted to grade.
(1)
Furnish one (1) copy of the video to the Public Works Director.
Video shall comply with the following requirements:
(a)
Full color (Not black and white).
(b)
Date and time of inspection.
(c)
Inlet and Junction Box labels.
(d)
Real time stationing of camera in pipe.
(e)
Inspection of all joints, fittings, and lateral connections.
(f)
Locations of observed deficiencies (i.e. bad joints, breaks,
leaks, infiltration, etc.).
(g)
Pipe ponding in excess of three-fourths (3/4) inches identified
by location.
(h)
Minimum resolution of 800 x 600 pixels.
(i)
Single sided DVD or CD utilizing MPEG compression.
(j)
DVD/ CD and box shall be labeled with manhole numbers, project
title, and date.
(2)
The City of Union reserves the right to reject storm drains
based upon the video inspection, and complete own video inspection.
(3)
Faulty sections of storm drains, junction boxes or inlets rejected
by the City shall be repaired or replaced at the installers expense
to produce a like new product in a manner acceptable to the Engineer.
(4)
The installer shall provide the City a video inspection to document
the repair or replacement of any rejected work.
(5)
Camera speed shall not be greater than thirty (30) feet per
minute.
(6)
Payment. There will be no direct payment for testing and inspections.
The cost and expense of such work to the installer must be included
in the price of the bid for storm drains and concrete structures.
Q.
(Reserved)
R.
(Reserved)
S.
(Reserved)
T.
All
construction details pertaining to storm water drainage shall be in
accordance with the City and State requirements, unless otherwise
noted herein.
[Ord. No. 4461, 7-12-2021]
A.
Purpose.
Detention facilities can be located in residential, commercial, and
industrial developments, helping to offset the downstream effects
of stormwater flows and improving water quality to levels near to
pre-developed conditions. Detention facilities are a structural BMP
and require routine maintenance to ensure continued design function.
Poorly constructed and maintained detention facilities lose their
ability to control stormwater, potentially allowing contaminants to
enter creeks and streams. It is the policy of the City to protect
and promote the health, safety, and general welfare of the public.
Continuing design function of detention facilities will reduce the
erosion on land and creek channels, preserve the quality of water
in natural streams, and preserve and enhance the environmental quality
of watercourses in the City.
B.
Detention
Facility Permits.
1.
Every person who owns, operates, or maintains a detention facility
shall obtain a permit from the City to operate and maintain a detention
facility. Applications for permits required pursuant to this Section
shall be submitted on forms prepared by the City, and shall include
the following:
a.
The name, address, and telephone number of the applicant;
b.
The name of the owner of the property containing the detention facility;
c.
An address or description of the property containing the detention
facility;
d.
The name of the subdivision in which the detention facility is located,
if any;
e.
A statement granting the City authority to enter upon the property
containing the detention facility for purposes of conducting an inspection;
and
2.
All permits issued pursuant to this Section shall be valid for a
period of three (3) years. Permits shall be issued if, upon inspection
by the City, the detention facility is found to be in compliance with
the provisions of this Chapter.
C.
Maintenance And Inspection Of Detention Facilities. Maintenance and inspection of detention facilities shall be per Section 420.130.
D.
Alteration
Of Detention Facility.
1.
Native Vegetation/Natural Facilities. Should the owner(s) of a privately
owned detention facility want to alter original construction to convert
the system to provide increased water quality benefits and have a
more natural appearance, such alternatives must be submitted by permit
process to the City Engineer for review of detention facility functionality
and approval.
a.
Conversion examples, include, but are not limited to, native grasses,
wildflowers, removal of concrete swales, or alteration of outfall
structures.
b.
If approved, the owner(s) shall prepare and submit a maintenance
schedule for the conversion. Modifications will be subject to inspection
during conversion and continue after acceptance.
c.
If approved, converted areas shall be excluded from mowing requirements as stated in Section 220.020 Weeds, High Grass or Other Vegetation, but an alternative mowing/maintenance schedule shall be submitted and followed.
(1)
Annual mowing will be required in efforts to prevent the vegetation from becoming excessive and facilities from getting overgrown. All conversion-permitted facilities shall be mowed by November 1 of each year. Failure to meet this requirement will result in enforcement in accordance with Section 220.020.
d.
Maintenance of such systems will continue to be the responsibility of the property owner(s) as stated in Section 420.130.
e.
Under no circumstances does the alteration from a detention facility
to a native vegetation area waive the requirements for detention.
E.
Violations
And Corrections.
1.
If the privately owned detention facility is found to be deficient and in need of compliance measures or maintenance, the property owner(s) will be notified and correction of such requested. Any corrections will be the responsibility as identified in Section 420.130. Any cost incurred by the City, as a result of the City's actions, shall be assessed against the owner(s) of the system.
2.
After notification is provided to the owner(s) of any deficiencies
discovered from an inspection of a privately owned detention facility,
the owner(s) shall have thirty (30) days or other time frame mutually
agreed to between the City and the owner(s) to correct the deficiencies.
The City shall then conduct a subsequent inspection to ensure completion
of the repairs. If repairs are not complete during this subsequent
inspection, then enforcement procedures following this Section shall
be followed.
3.
If, after inspection by the City, the condition of a privately owned
detention facility presents an immediate danger to the public health
or safety, because of an unsafe condition or improper maintenance,
the City shall take such action as may be necessary to protect the
public and make the facility safe. Any cost incurred by the City,
as a result of the City's actions, shall be assessed against the owner(s)
of the system.
a.
No modifications shall be made to any privately owned detention facility,
without a permit or other approval from the City.
F.
Declaration Of Nuisance And Abatement. Any violation of the performance and maintenance standards set forth in this Chapter is hereby declared a public nuisance. The City is hereby authorized to declare a public nuisance pursuant to the provisions of this Chapter and may abate the same after providing notice and conducting a hearing consistent with the procedures set forth in Section 220.010(D) of this Code.
G.
Violation
And Penalty.
1.
Each incident of failure shall be deemed a separate violation of
City ordinances, and each day where violations are not corrected shall
be considered separate additional violations.
2.
Penalty. In addition to the other remedies set forth in this Section,
any person found to have violated this Section shall be guilty of
a misdemeanor punishable by a fine not less than ten dollars ($10.00)
and not more than five hundred dollars ($500.00) or imprisonment for
a period of not more than ninety (90) days. After the Board of Aldermen
has declared by ordinance that the conditions constitute a nuisance,
each day that the owner fails to abate the nuisance shall constitute
a separate offense.
[R.O. 2012 §420.110]
Where detention, retention, or depressional storage areas are
to be used as part of the drainage system for a property, they shall
be completed before general property grading begins. This is to ensure
that if soil erosion and sediment control practices are not adequately
implemented, the eroded sediment will be captured in these areas and
will have to be removed by the applicant before project completion.
[Ord. No. 4462, 7-12-2021]
A.
Purpose.
Vegetated buffers adjacent to natural watercourses provide numerous
environmental protection and resource management benefits that can
include the following:
1.
Reducing flood impacts by absorbing peak flows and slowing the velocity
of floodwaters;
2.
Benefitting the community economically by minimizing encroachment
on natural watercourses and the need for costly engineering solutions;
by reducing property damage and threats to safety of watershed residents;
by contributing to the scenic beauty and environment of the community,
and thereby preserving the character of the community, improving the
quality of life of its residents, and increasing the value of their
property;
3.
Providing infiltration of stormwater and runoff, and reducing impervious
surfaces;
4.
Stabilizing banks of natural watercourses;
5.
Reducing sediment and erosion along natural watercourses;
6.
Removing pollutants from stormwater;
7.
Restoring and maintaining the chemical, physical and biological integrity
of the water resources;
8.
Maintaining base flows of natural watercourses;
9.
Contributing organic matter that is a source of food and energy for
the aquatic ecosystem;
10.
Providing tree canopy to shade natural watercourses;
11.
Providing habitat to a wide array of wildlife by maintaining diverse
interconnected riparian vegetation;
12.
Furnishing recreational opportunities; and
13.
Allowing areas for natural watercourses to meander naturally reducing
infrastructure and property damage.
B.
Requirements
Of Vegetated Buffer.
1.
For streams depicted as a solid blue line on the U.S.G.S. map, an
undisturbed natural vegetative buffer shall be maintained for fifty
(50) feet, measured horizontally, on both banks (as applicable) of
the stream as measured from the top of the stream bank. For all other
streams subject to this Section, an undisturbed natural vegetative
buffer shall be maintained for twenty-five (25) feet, measured horizontally,
on both banks (as applicable) of the stream as measured from the top
of the stream bank.
2.
Permanent vegetation and existing ground elevation and grades within
the above-mentioned vegetated buffer shall be left intact and undisturbed,
except as permitted by this Article.
3.
All developments requiring a construction permit that necessitates
excavation or also requires a foundation, shall maintain the minimum
undisturbed vegetated buffers. Commercial and industrial areas shall
have creek areas dedicated as drainage easements. Notwithstanding
the foregoing setback requirements, an applicant may obtain a variance
to develop within the vegetated buffer area from the City, provided
the applicant is able to demonstrate that the water quality and stream
morphology will not be adversely affected or adequate mitigation is
provided to offset such adverse effects. Mitigation, may include,
but not be limited to, the following:
C.
Management
And Maintenance Of Vegetated Buffer.
1.
The vegetated buffer shall be managed to enhance and maximize its
value and effectiveness. Management includes specific limitations
on altering the natural conditions of the buffer. The following practices
and activities are permitted only with the express written approval
of the City:
2.
The following structures, practices and activities are permitted
in the vegetated buffer, with specific design or maintenance features,
subject to the review by the City Engineer:
a.
Roads, bridges and utilities (including sanitary and storm sewers).
(1)
The right-of-way shall be the minimum width needed to allow
for maintenance access and installation.
(2)
The angle of the right-of-way or utility crossing shall be perpendicular
to the natural watercourse or vegetated buffer in order to minimize
clearing requirements.
(3)
Plats and site plans shall include only the minimum number possible
of such crossings.
b.
Paths, including hard-surfaced trails.
c.
Buffer restoration projects approved by the City.
d.
Water quality monitoring and stream gauging.
e.
Removal of trash and debris and individual trees within the vegetated
buffer that are in danger of falling, causing damage to dwellings
or other structures, or causing blockage of the natural watercourse.
3.
Material dredged or removed during development authorized under this
Section shall be stored outside the vegetated buffer.
D.
Violations
And Enforcement.
1.
Declaration Of Nuisance And Abatement.
a.
Any violation of the performance and maintenance standards set forth in this Chapter is hereby declared a public nuisance. The City is hereby authorized to declare a public nuisance pursuant to the provisions of this Chapter and may abate the same after providing notice and conducting a hearing consistent with the procedures set forth in Section 220.010(D) of this Code.
2.
Requirement To Remediate. Whenever the City Engineer finds that unpermitted work within the vegetated buffer is taking place or has occurred, the City Engineer may require by written notice to the owner of the property that the affected property be restored within a specified time pursuant to the provisions of Section 220.010(D).
3.
Abatement By City. As set forth in Section 220.010(D).
4.
Charging Cost Of Abatement/Liens. As set forth in Section 220.010(D).
5.
Emergency Abatement. As set forth in Section 220.010(C).
6.
Violations. As set forth in Section 220.010(D)(4).
