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Ordinance 2007-07

ORDINANCE NO. 2007-07
AN ORDINANCE ESTABLISHING MINIMUM SPECIFICATIONS AND REQUIREMENTS
FOR STORMWATER RUNOFF WITHIN THE CITY LIMITS OF THE CITY OF JOHNSON.
ARKANSAS AND AMENDING THE CITY CODE, PROVIDING FOR THE EMERGENCY
CLAUSE AND FOR OTHER PURPOSES.
WHEREAS, the City Council of the City of Johnson hereby finds it in the public interest.
and in the furtherance of the public health, safety, and welfare, that minimum specifications and
requirements relating to Stormwater Runoff within the corporate limits of the City of Johnson,
Arkansas, be adopted.
NOW, THEREFORE, BE IT ORDAINED by the City Council of the City of Johnson,
Arkansas:
Section 1 : General Provisions
A. JURISDICTION: The provisions of this Ordinance shall apply to all lands within the
City of Johnson, Arkansas and its planning area as defined on the official maps of the
City of Johnson.
Section 2: Applicability
Developers of land within the jurisdiction of the City of Johnson, Arkansas shall provide for
drainage improvements and the protection of the area, land and water resources as follows
herein. The principles and concepts of erosion and sedimentation control and watershed
protection apply to all projects and shall be instituted as required by the current Grading,
Erosion Control and Stormwater Pollution Prevention Ordinance.
Section 3: Project Control
All development shall comply with the following sections in preparing the project plan:
A. To the extent practical, all development shall conform to the natural contours of
the land and natural pre-existing man-made drainage channels shall remain
undisturbed. Approved clearing or enlargement of drainage channel will be
allowed.
B. To the extent practical, lot boundaries shall be made to coincide with natural and
pre-existing man-made drainage ways within subdivisions.
C. When the proposed project borders a subdivision with an existing storm drain
system, a storm drain system will be required and every effort shall be made to
make the system compatible.
D. Easements for drainage channel maintenance will be a minimum of 20 foot wide
unless approved in writing by the City Engineer.
E. All developments or any lot containing or adjacent to a drainage channel or
drainage structure must provide the finish floor elevation for any proposed
structure one (1) foot minimum above the 100 year flood elevation in the
drainage structure. For subdivisions, this minimum elevation shall be shown on
the Final Plat. For Large Scale Development Plans, this minimum elevation must
be shown on the approved plan.
F. Whenever practical, the drainage system of a development shall coordinate with
and connect to existing systems or drainage ways on surrounding properties or
streets.
G. Where offsite downstream improvements are required to control runoff resulting
in part from the improved area, it shall be the developer's responsibility to acquire
the necessary easement(s) from property owners for the construction and
operation of the necessary drainage improvements. If affected property owners
are not receptive to granting easements, the developer may petition the city for
assistance. All easements shall be dedicated to the city. In the event the
developer petitions the city for assistance, the procedure will be as follows:
1. The petition shall first be presented to the planning commission which shall
make its recommendation on the same to the city council.
2. The city council shall either approve or reject the petition and; if approved,
shall direct the city attorney to proceed with condemnation proceedings upon
the developer depositing the required funds with the city clerk.
3. The primary criterion to be used by the planning commission and the city
council hi deciding whether to proceed with the condemnation proceedings
shall be whether the taking is in the best interest of the affected drainage area
and not whether the taking is in the best interest of the developer or the project
being considered.
4. If the petition is approved, the developer shall deposit with the
recorder/treasurer the funds necessary to acquire the required easements to pay
appraisal and attorney fees and costs and any and all other funds reasonably
foreseeable to accomplish the taking. The engineer of record for the project
shall provide a cost estimate to determine the amount necessary to be
deposited.
5. The developer shall deposit additional funds as necessary from time to time
once the taking order has been issued and litigation has begun.
6. The condemnation suit shall be brought in the name of the city and shall be
directed and controlled by it.
H. Private roads, parking .lots, and access ways v excluding residential driveways),
within developments shall utilize curb, gutter, and storm drain systems to provide
f adequate drainage. The use of swales and sodding open side ditches are
acceptable only upon written approval of the City Engineer. All utilities must be a
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minimum of 24" below the flow line of an open ditch unless approved in writing
by the City Engineer and the respective utility company. Clearances may be
reduced for paved ditches.
I. Persons engaged in land alteration activities regulated by this chapter shall take
measures to protect public and private properties from damage by such activities.
J. All developments shall be constructed and maintained so that adjacent properties
are not unreasonably burdened with surface waters as a result of such
development. More specifically, new development may not unreasonably impede
water runoff from higher properties nor may it unreasonably channel water onto
lower properties.
K. Land shall be revegetated and restored as close as practically possible to its
original condition so far as runoff and erosion are concerned. All restoration
efforts must be to the satisfaction of the City Engineer.
L. A drainage report shall be submitted to the city at the time new subdivisions and
large scale developments are submitted for project approval. The drainage report
must be certified by a registered professional engineer licensed in the State of
Arkansas.
M. A grading permit shall be required as detailed in the current grading ordinance.
Section 4: Storm water management
All development shall be constructed and maintained so that adjacent properties are not
unreasonably burdened with surface waters as a result of such developments. More
specifically:
A. No development or other activity may be constructed or maintained so that such
development or activity unreasonably impedes the natural flow of water from
higher adjacent properties across such development, thereby unreasonably causing
avoidable damage to such higher adjacent properties; and
B.No development may be constructed or maintained that allows surface water to
flow onto lower adjacent properties to cause avoidable damage to such lower
adjacent properties.
C. All drainage design must be computed based on the total drainage basin or area,
including on and off site, being totally developed in accordance with the City of
Johnson's approved Master Land Use Map. Runoff coefficient values shall be used
in accordance with the Arkansas Highway and Transportation Department's
Drainage Manual.
D. Erosion control provisions shall be as set forth in the current Grading, Erosion
Control and Stormwater Pollution Prevention Ordinance.
E. A Drainage Report with complete hydraulic data showing all calculations shall be
performed by an Engineer licensed in the State of Arkansas and shall be completed
in accordance with the Arkansas Highway and Transportation Department's
Drainage Manual. The impact on downstream flows outside the project shall also
be addressed. The following requirements shall also apply:
1. Methods of calculating stream flows and runoff.
(The following is a general guideline; other methods may be used with
written approval from the City Engineer).
a. The Rational Method shall be used in determining peak storm water
runoff for areas up to 100 acres in size. To determine the intensity,
use the Intensity-Duration-Frequency curve from the City of
Fayetteville Drainage Manual.
b. The SCS TR-55 Method shall be used in determining peak storm
water runoff for areas from 100 to 2,000 acres in size.
c. The HEC-1 Method shall be used in determining runoff for areas
greater that 2,000 acres.
2. Storm Frequency
a. The following storm frequencies shall be used in all runoff
calculations: 2~year; 5-year, 10-year, 25-year, 50-year, and 100-year.
3. Storm water Detention:
a. If hydrologic and hydraulic studies reveal that the development would
cause increased flood stages so as to increase the flood damages to
existing developments or property, or increase flood elevations
beyond the vertical limits set for the floodplain districts, then the
grading permit shall be denied unless one or more of the following
mitigation measures are used:
1. Stormwater detention.
2. Improve the downstream drainage system.
b. Stormwater detention ponds shall be designed to limit the peak
Stormwater discharge rate of the 2, 10, 25; 50 and 100 year storm
frequencies after development to predevelopment rates.
c. Detention facilities shall be located within the parcel limits of the
project under consideration. No detention or ponding will be
permitted within public road right-of-ways.
d. Wet weather ponds or dry reservoirs shall be designed with proper
safety, stability, and ease of maintenance facilities, and shall not
exceed eight (8) feet in depth. Maximum side slopes for grass
reservoirs shall not exceed one (1) foot vertical for three (3) feet
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horizontal (3:1). In no case shall the limits of maximum ponding
elevation be closer than twenty (20) feet horizontally from any
building and less than one (1) foot vertically below the lowest sill or
floor elevation. The entire reservoir area shall be sodded as required
prior to final plat approval. The pond bottom shall have a slope of
1.0% or greater and a 4' trickle channel shall be supplied.
e. Detention is permitted in parking lots to maximum depths of 6 inches.
In no case should the maximum limits of ponding be designed closer
than ten (10) feet from a permanent structure unless waterproofing of
the building and pedestrian accessibility are properly documented and
approved.
f. Detention facilities shall be provided with effective control structures.
Plan view and sections of the structure with adequate details shall be
included in the construction plans.
g. All detention reservoirs with the exception of parking lot detention
shall be enclosed by a drainage/maintenance easement for public use
unless the basin is to be maintained by the property owner.
h. Finished floor elevations shall be set at one (1) foot minimum above
the calculated 100 year water surface elevation for the pond.
4. Floor elevations shall be set at a minimum of one (1) foot above the
calculated 100 year flood elevation on each lot or site that is located
adjacent to a primary drainage way. Floor elevations shall be shown at a
minimum of two (2) feet above the 100 year flood elevation in areas that
are in a designated floodplain.
5. All flow of water across continuous streets or alleys shall be through
culverts or bridges.
6. Bridges and culverts shall be sized to accommodate the total contributing C! O
drainage area involved and the frequency of rainfall event as follows:
Local Street: 10 year
Collector Street: 25 year
Arterial Street: 50 year
7. Design of bridges and culverts shall conform to the A.H.T.D. standards
and construction specifications.
8. Closed storm sewers shall be constructed of precast or prefabricated pipe
or cast-in-place conduit conforming to the A.H.T.D. standards and
specifications.
9. Open paved storm drainage channels shall be constructed in accordance
with the A.H.T.D. standards and specifications.
10. All side slopes of earth lined channe',3 shall be sodded unless approved
otherwise by the City Engineer.
11. It shall be understood that the minimum requirements outlined in these
standards are only minimum requirements and shall only be applied
when conditions, design criteria, and materials conform to the City
Specifications and are normal and acceptable to the City Engineer.
When unusual subsoil or drainage conditions are suspected, an
investigation should be made and a special design prepared in line with
good engineering practice.
12. Review and approval of drainage plans, reports and calculations by the
City or City personnel shall not relieve the developer of any
responsibility associated with the development of property.
13. The engineer of record shall certify that the risk of endangerment to
life or property damage downstream from the site has not been
increased.
F. The City Engineer, with the consent of the Planning Commission, may make
additional requirements for waterway improvement where the minimum
requirements for waterways do not adequately provide for the protection of life,
limb, and property.
G. Preservation of Existing Channels:
New construction shall not block existing channels. In constructing buildings or
making other improvements, the Developer shall not cause material of any sort to
block any drainage way. Should the Developer inadvertently block such drainage
channel, he or she shall immediately take action to restore the full channel capacity.
H. Fences and Structures:
Temporary or permanent structures and fences shall not be allowed within drainage
easements or open channels. Vehicular access to drainage ways shall not be
blocked by fences.
I. The City reserves the right to require improvements, drainage easements, and to
enter into agreements beyond the boundaries of the area being developed where
necessary to facilitate the flow of water through the area to be developed and to
avoid possible damages resulting from changed runoff in the area. The City also
reserves the right to provide for or require of the Developer, improvements of the
overall storm drainage system.
J. The City may exercise the power of eminent domain to assure proper operation of
flood control drainage channels, waterways and storm, sewers.
K. These requirements will not preclude the developer from acquiring a Storm Water
Pollution Prevention permit in accordance with the Arkansas Department of
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Environmental Quality's standards. A copy of the Storm Water Pollution
Prevention Plan shall be provided to the City Engineer.
Section 5: Administration of All Drainage Projects
A. Project Plan Required:
A developer of land shall cause to be prepared a Project Plan in accordance with
the provisions of this Ordinance. Prior to any construction or other improvement
being commenced upon the subject property, the Project Plan must be approved as
provided by this Ordinance.
B. Project Plan Submission Procedure:
1. The Developer shall file three (3) copies of the Project Plan and Drainage
Report with the Planning Commission for consideration 30 days prior to
the Planning Commission meeting.
2. Upon filing and consideration of the Project Plan and Drainage Report,
the Planning Commission may approve, disapprove, or approve with
conditions, the Project Plan and/or Drainage Report.
3. If the Planning Commission finds that they cannot determine if the
Project Plan and Drainage Report satisfies the requirements of the
Ordinance, due to a matter of interpretation, a question of engineering
opinion or supporting data, or the complexity of the project, the Planning
Commission may elect to retain an Engineer for technical counsel in
assisting to resolve an issue. The engineering fees for technical counsel
will be paid by the Developer.
C. Appeal:
1. Any decision of the Engineer retained for technical counsel, may be
appealed to the Planning Commission by the Developer provided the
Developer does so by filing his or her written appeal notice with the
Planning Commission Chairman within fifteen (15) days of the decision
from the Engineer.
2. Any decision of the Planning Commission, with the exception of a
variance decision under sub-part E. of this Section, may be appealed by
the Developer to the City Council provided the Developer does so by
filing his or her written appeal notice with the Mayor's office within
fifteen (15) days of the decision of the Planning Commission.
D. Approved Project Plan term:
The approval of a Project Plan shall be effective for an original term of six (6)
months from its date of approval. Thereafter, if construction of the
improvements or any portion thereof has no, been completed, the approval of
the Project Plan shall lapse. Provided, however, the Developer may obtain an
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extension of approval of the Project Plan for successive six (6) months terms
upon written request to the Planning Commission stating good cause therefore
and certifying that no change has occurred which would materially affect the
Project Plan.
E. Variance:
Upon application by a Developer, for good cause, the Planning Commission
shall have authority to vary the requirements of this Ordinance.
F. Enforcement:
1. No Building Permit shall be issued until the Project Plan has been
approved and the drainage system constructed and certified.
2. The City Engineer may authorize adjustments in the approved Plan
during construction provided the adjustments conform to the purpose and
intent of the Project Plan.
G. Warranty of Developer:
The Developer is required to provide routine maintenance of the drainage
system until structures have been built on 50% of the lots in the development or
after two years, whichever is longer, at which time the City accepts the system.
Upon acceptance of the drainage system, the Developer must warrant the
operation of the drainage system for a one-year period after acceptance by the
City. A bond equal to 50% of the cost of the drainage improvements wall be
required of the Developer. The bond shall be required until all project phases
are complete. No alteration of the drainage system will be allowed without
written approval by the City Engineer.
I. Penalty:
It shall be unlawful for any person, firm, or corporation to alter or tamper with
an approved public or private drainage system or detention basin or dispose of
trash or debris or other construction material into a private or public drainage
system. Any person, firm or corporation violating this ordinance shall be
subject to imprisonment not to exceed thirty (30) days or a fine not to exceed
$500.00 or both. Each day will be considered a separate violation.
Section 6: Conflicts:
Where the provisions stipulated herein conflict, the most stringent provision shall
govern, except as may otherwise be provided herein. In the event the provisions of
this Article are determined to conflict with the provision of other Chapters of the Code
of Ordinances of the City of Johnson, the more stringent provision shall govern.
Section 7: Emergency Clause:
This Ordinance is necessary to preserve the public peace, health, safety and welfare,
and because of such an emergency is hereby declared to exist and this ordinance shall
be in full force and effect from the date of its passage and approval.
PASSED THIS DAY 10th OF July, 2007.