[HISTORY: Adopted by the City Commission
of the City of Royal Oak 8-12-1991 by Ord. No. 91-8; amended in its entirety 11-15-2004 by Ord. No.
2004-20. Subsequent amendments noted where applicable.]
This chapter shall be known and cited as the
"Stormwater Detention Ordinance of the City of Royal Oak" and will
be referred to herein as "this chapter."
This chapter is intended to specifically apply
to stormwater detention which is a prevailing need and which the absence
of detention could endanger the property, health, safety and general
welfare of the residents and property owners of the City.
As used in this chapter, the following terms
shall have the meanings indicated:
Any addition to an existing building.
Written approval by the City Engineer of the City of Royal
Oak, Michigan, or by his duly authorized agents, assistants, or representatives,
limited to the specific duties assigned or entrusted to them.
All designated or specified areas or devices where stormwater
is detained to meet the requirements of this chapter.
The City of Royal Oak, Michigan. When used in this chapter
in connection with any filing, submittal, delivery or payment to,
or review, approval or other action, refers to the City Engineer.
Any and all public rights-of-way, streets, highways, roads,
sidewalks, alleys, thoroughfares, public easements and public places
located within the City, including within any curbs, shoulders, landscaped
areas and/or other areas incidental and/or appurtenant.
Any new building, or paved driveway, parking lot or sidewalk,
not including public roadways.
City Engineer of the City of Royal Oak, Michigan, or his
duly authorized agents, assistants or representatives, limited to
the specific duties assigned or entrusted to them.
Any area of land which has been granted or dedicated to the
City or to public use, including, but not limited to, road or right-of-way,
utility, water main, sewer line, access, drainage, recreation, conservation
and other public areas, whether in easements or in fee.
Any existing building converted to other use or structurally altered, and which requires a City building permit and/or site plan for City Plan Commission review and approval as described in § 770-12, Site plan review, or any similar ordinance. Also, any paved parking lot, private street, drive or sidewalk removal and replacement. Renovation shall also include the pulverizing and/or crushing of existing pavement for use as a new pavement base material.
Additions, developments and renovations proposed for a specific
property as defined.
All features that comprise the requirements of this chapter,
including but not limited to storm detention basins and their required
components and finishes, restrictors, pumps and freeboard structures;
and all collection and outlet piping, drainage structures and conveyance
features, including curbing, swales, ditches; and all fences, gates
and signage.
Any development, renovation or addition to an
existing development within the City, excluding property in the Central
Business District Zones and properties used for one- and two-family
residential purposes, must detain the stormwater runoff from the improvement
on-site.
A.
Developments, renovations or additions less than 0.14
acre or 6,100 square feet in area will not require stormwater detention
at the time of the improvement. For such case, a recordable lien to
the City must be executed by the property owner. The recordable lien
shall state that when the next future improvement occurs on the property
which will make the accumulated area of the recorded lien(s) and the
future improvement greater than 0.14 acre or 6,100 square feet, the
property owner will make the stormwater detention improvements as
specified in this chapter on the accumulated area.
B.
Renovations and additions that do not involve parking
lot, private street, drive or sidewalk removal and replacement will
not require stormwater runoff detention at the time of the improvement,
unless adequate undeveloped land is available for detention on the
property. If stormwater detention is not included as part of the renovation,
a recordable lien to the City must be executed by the property owner.
The recordable lien shall state that when the next future improvement
occurs on the property, the property owner will make the stormwater
detention improvements as specified in this chapter on the accumulated
area.
C.
Lien(s) shall be prepared by the property owner using
the standard form available from the City Engineering Department.
The Oakland County Method of Detention Basin
Design, as made available by the Oakland County Drain Commissioner's
office, shall be utilized in determining the volume of detention required.
Basins with orifice or pumped outlets will be required to hold the
volume for a ten-year storm while basins with no outlets will be required
to hold two one-hundred-years storms. Discharge on an orifice or pumped
outlet must be throttled to a restricted rate of 0.2 cfs per acre,
or throttled to a restricted flow of 0.3 cfs if the total property
area requiring detention is 1.5 acres or less.
For City approval of stormwater detention, the
applicant shall furnish the City Engineering Department three sets
of detention plans, 24 inches by 36 inches, with detention calculations
shown on the plans.
A.
A professional engineer, licensed in the State of
Michigan, shall affix his or her seal on the plans.
B.
The plans shall not be drawn to a scale smaller than
one inch equals 30 feet. The City Engineer shall review the plans
and calculations for conformity to the standards set forth in this
chapter, and certify that they are consistent with the overall utility
plans of the City, after which he will return a letter of review with
appropriate comments. The applicant, after making any changes requested,
shall resubmit three sets of the revised plans to the Engineering
Department for approval. The applicant may be required to obtain approval
of the City of Royal Oak Building Department, Oakland County Drain
Commissioner, the Road Commission for Oakland County or the Michigan
Department of Transportation when the outlet discharges to facilities
under their jurisdiction.
C.
The detention plans shall clearly indicate the perimeter
of all acreage contributing to the detention basin. The perimeter
of the water surface for the volume of detention provided shall also
be indicated on the plans including the water surface elevation.
D.
The plans shall include the calculation of an overall
coefficient of runoff for the acreage contributing to the detention
basin. The range of this coefficient shall vary from 0.15 for completely
grassed areas to 0.90 for completely paved areas.
E.
The detention calculations for each site shall include
the number of total acres calculated to the nearest hundredth contributing
to the detention basin. The total cumulative volume of required detention
shall be calculated using all areas of proposed site improvements
and shall include previous site improvement areas covered by this
chapter.
F.
The detention calculations shall include the sizing
of the restricting orifice or structure cover. The calculations for
the restricting orifice size or restricted structures cover openings
shall be made using a coefficient for a sharp-edged orifice entrance.
Details for the restrictor are to be clearly indicated on submitted
plans. The smallest pipe orifice size allowed is 2.5 inches in diameter.
The orifice size shall be rounded down to the nearest one-half inch
from the actual calculated size.
G.
Calculations for the volume of detention provided
shall be included on submitted plans. The volume calculations shall
be made using standard geometric formulas to determine the volume
between appropriate contour elevations. For irregular-shaped basins,
the geometric formula for the volume of a frustum of a cone or pyramid
shall be used to estimate the volume between appropriate contour elevations.
H.
Plan approval constitutes conformance with this chapter
in regards to calculations and method used to control runoff and achieve
the required detention. Plan approval does not infer sanction or approval
of construction governed by any other permit or subsequent approvals.
I.
After approval of plans, any change to the storm detention
system shall be submitted to the City Engineer for approval prior
to its construction.
A.
All basin design shall incorporate components that
allow for visual inspection and maintenance by mechanical means of
all areas designated for stormwater storage or restricted outflow.
B.
Acceptable means of detention can be achieved through
standing water in parking areas, landscaped ponds, or buried vaults,
chambers, pipes or other approved buried device. Either one or any
combination of these designs may be utilized to achieve the required
detention.
C.
All components of storm detention systems shall be
constructed entirely on the private property of the proposed development,
except for discharge piping and connections to public sewers. No portion
of a basin shall be installed within a publicly owned utility easement.
Connections to public sewers shall be at locations as approved by
the City Engineer.
D.
Basins with orifice or pumped outlets must be constructed
to drain entirely unless designed to retain a permanent water level
that conforms to a Plan Commission approved landscape plan.
E.
Basins with no outlets must be constructed in soils
that have a saturated hydraulic conductivity of at least 0.004 feet
per minute.
F.
A minimum of 12 inches of freeboard must be provided
above the retained water surface of all detention basins and below
the finished floor of all adjacent buildings. A minimum of six inches
of freeboard must be provided above the maximum water surface created
by the required positive nonerodable overflow to both adjacent buildings
and adjacent properties.
G.
A positive nonerodable overflow capable of handling
the capacity of a one-hundred-year storm must be provided and clearly
identified on the plans, which shall not discharge onto abutting private
property.
H.
Drainage from a development, renovation and addition
shall not be diverted onto abutting private property. Drainage from
a development, renovation and addition requiring detention shall be
directed to the detention basin. Discharge from the basin and overflow
shall not be diverted onto abutting private property.
I.
The City requires a building permit for all piping
and drainage structures for compliance with other codes and ordinances
including the current Michigan Plumbing Code requirements for approved
materials and drainage pipe cleanouts. Section P-708 of the code requires
that manholes be provided as cleanouts at each major change of direction
for underground piping over 10 inches in diameter.
J.
All storm detention systems shall be maintained in
proper working order, free of debris, trash or anything else that
may adversely affect the operability of the system, the required volume
and outlet capacity. The storm detention systems shall be kept free
of vermin and any creatures that may cause the system to become inoperable
or harm the public. Maintenance of the storm detention system also
requires treatment to prevent and control insects and microbes.
A.
A paved open channel must be provided along the bottom
of all detention basins designed to drain entirely. The open channel
shall begin at the outlet for the basin and shall run the entire length
of the basin with the channel extending to all pipes discharging into
the basin. The channel shall be sized to equal the capacity of the
outlet for the basin when flowing full with no pressure head. The
channel shall provide a minimum velocity of two feet per second when
the basin outlet is flowing full with no pressure head.
B.
The entire basin must be either sodded, paved, or
have some other City approved method of stabilization. The maintenance
of all stabilization and fencing in and around the detention basin
shall be the responsibility of the property owner.
C.
All grass and noxious weeds growing in or around the basin shall be maintained in accordance with Chapter 757, Weeds, as amended, or other similarly adopted property maintenance code.[1] No hydrophilic plants such as rushes, reeds, water iris,
willow or cattails shall be allowed to grow or thrive within an open
basin, or any tree, shrub or plant not specifically shown and approved
on the required plans.
D.
Minimum grade on the bottom of the detention basin
shall be 1.2% when sodded. For paved open channels in basins, the
minimum grade shall be 0.5%.
E.
All pipes entering a detention basin shall have either
a headwall or end section at the end of the pipe. Bar screens must
be installed on all open ends of pipe 12 inches or larger in diameter.
Restricting orifices shall be located in an accessible structure outside
of the basin limits.
F.
Fencing.
(1)
All open pond detention basins must be fenced if the
side slopes exceed one vertical to six horizontal, or if the basin
is designed to hold water to a depth of more than 18 inches when filled
to capacity. This requirement may be waived by the City Plan Commission
when the design is an integral part of the landscaping and the location
and depth does not present a potential hazard.
(2)
A three-foot minimum shoulder shall be provided between
the fence and the side slopes for the basin. The side slopes shall
not exceed one vertical to three horizontal.
(3)
Fences shall be a minimum of four feet high chain
link or other fencing material of comparable durability and safety
as approved by the City Plan Commission with a locked access gate,
10 feet wide with double opening. A key for a City Engineer approved
lock shall be supplied to the City Public Service Department.
(4)
Depending upon location in relation to adjoining properties
or rights-of-way, the City Plan Commission may require a landscape
screen in front of the fencing.
(5)
All gates constructed directly in front of a paved
roadway are to have an end of roadway marker (ER-1) and a "road ends"
sign (W-14-2-a) securely fastened to the gate in accordance with the
"Michigan Manual of Uniform Traffic Safety Control Devices." The sign
material shall be high intensity reflectorized Scotchlite on 0.080
aluminum.
In cases where the drain outlet for the detention
basin is not deep enough to completely dewater the basin by gravity,
pumps must be installed. The pumps shall be installed in duplicate
with each pump capable of handling the flow. Controls shall be set
in the receiving water to regulate the flow.
A.
The controls may be electrodes placed inside a galvanized
pipe stilling well at a location adequately protected from the backwater
curve during discharge.
B.
A bubbler system in a stilling well protected as in Subsection A above. The operating controls and pumps shall be set in a fully designed pump house with adequate dimensions for working area. The pump house and west well must be located inside the fenced area.
C.
Pump controls shall be designed in a manner that accounts
for the water level in the receiving sewer.
D.
Complete specifications for the pumps and controls
and performance curves for the pumps called for must be submitted
to the City Engineer for approval, including two operation manuals
provided from the manufacturer.
E.
The City requires a building permit for all piping,
electrical work and concrete structures for compliance with other
codes and ordinances.
F.
A manhole with inside diameter of six feet is required
between the lift station and the outlet. The twin discharge lines
shall be ductile iron. They shall enter the manhole and a storm sewer
shall be installed from the manhole to the outlet. The manhole cover
shall be East Jordan Iron Works (EJIW) No. 8247A hinged type or equivalent.
G.
The pump house and gate to the detention basin shall
be locked at all times. A key for a City Engineer approved lock to
the pump house shall be supplied to the City Department of Public
Service and Recreation.
A.
Easement for discharge piping. The property owner
of any development, renovation or addition that contains a detention
basin, excluding surface basins within vehicular parking areas, shall
grant the City an easement for the detention basin discharge piping
and all discharge piping appurtenances. The easement shall be a minimum
12 feet wide, unless otherwise determined by the City Engineer. The
grant of easement shall provide the City the rights to access, inspect,
and to rectify any City ordinance violation within the easement if
the property owner fails to commence work on compliance within 21
days from the date of written notification by the City of a violation
unless emergency circumstances dictate immediate compliance. All costs
incurred by the City in rectifying an ordinance violation shall be
assessed to the property owner.
B.
Easement for basin. The property owner of any development,
renovation or addition that contains a detention basin, excluding
surface basins within vehicular parking areas, shall grant the City
an easement encompassing the detention basin. The limits of the easement
shall be a minimum three feet outside any fencing, or six feet from
the tip of the side slope for the detention basin and shall include
a minimum twelve-foot width to access the gate for the basin. The
grant of easement shall provide the City the rights to access, inspect,
and to rectify any City ordinance violation within the easement if
the property owner fails to commence work on compliance within 21
days from the date of written notification by the City of a violation
unless emergency circumstances dictate immediate compliance. All costs
incurred by the City in rectifying an ordinance violation shall be
assessed to the property owner.
C.
Easement grants. The property owner shall be responsible
for providing the City Engineering Department with all property and
easement descriptions. All grants of easement shall be executed by
the property owner prior to City issuance of occupancy permits for
the development.
A.
Prior to formal written acceptance by the City of
the storm detention system, all turf must be established in open basins.
In addition, a licensed professional engineer must furnish the City
Engineer two sets of sealed as-built detention plans. As-built plans
shall verify that the required detention volume has been provided
using calculations based on newly constructed elevations within and
surrounding the basin(s). Newly constructed elevations within and
surrounding the basin shall be shown on the plans in sufficient quantity
and interval to verify and correspond to the calculations. The required
outlet, pump or restrictor installation, grading that conforms to
the approved plans, and freeboard features constructed with overflow
provided shall also be indicated on the as-built plans.
B.
All differences and deficiencies shall be noted. Plans
to correct deficiencies in detention volume, outlet, pump or restrictor,
freeboard and overflow features shall be submitted for City Engineer
approval and included with the as-built plans. All deficiencies in
detention volume, outlet, pump or restrictor, freeboard and overflow
features shall be corrected prior to City issuance of occupancy permits
for the development.
A permit will be required from the City for
the installation of all parking lot pavements as addressed under this
chapter. The permit allows for one post construction site inspection
by the City Engineer upon submittal of the required as-built plans
to verify compliance with the permit provisions. The City Commission
shall establish the permit fee by resolution.
[Amended 8-20-2007 by Ord. No. 2007-13; 6-15-2015 by Ord. No. 2015-13]
A.
The City
Engineer is charged with the enforcement of this chapter. The City
Engineer shall have the authority to grant variances from the stormwater
detention regulations contained in this chapter upon a showing of
practical difficulty by a property owner. A property owner requesting
a variance shall submit a written request specifically stating which
provision a variance is being requested from and describing the practical
difficulty involved in strict compliance.
B.
The City
Engineer shall have the authority to promulgate rules to allow for
pilot projects that may vary from the stormwater detention regulations
contained in this chapter as long as any development, renovation or
addition to an existing development within the City, excluding property
in the Central Business District Zones and properties used for one-
and two-family residential purposes, detains stormwater runoff from
the improvement on site. The City Commission shall adopt the rules
before they become effective.
A.
Any person, permittee, owner, developer or subsequent
property owner who violates any provision of this chapter, including
failure to submit plans, obtain permits, pay any fees, charges or
surcharges imposed, or any condition or limitation of a permit issued
pursuant or who knowingly makes false statements, representations
or certification in any application, record, report or plan or other
document filed or required to be maintained pursuant to this chapter
or who tampers with, alters or fails to maintain, or knowingly renders
inoperable any detention basin, restrictor, fence or freeboard required
under this chapter is guilty of a civil infraction and shall, upon
conviction, be punished by the following:
(1)
A person violating this chapter for the first time
is responsible for a municipal civil infraction and subject to payment
of a civil fine of not less than $100 for each day of the violation,
plus costs.
(2)
A person violating this chapter for the second time
is responsible for a municipal civil infraction and subject to payment
of a civil fine of not less than $250 for each day of the violation,
plus costs.
(3)
A person violating this chapter for the third time
is responsible for a municipal civil infraction and subject to payment
of a civil fine of not less than $500 for each day of the violation,
plus costs.
B.
The City Engineer, Royal Oak Building Official and
City of Royal Oak Code Enforcement are hereby authorized to seek,
through any authorized prosecutorial official, prosecution of charges
against any person violating any provision of this chapter.
Ownership of a storm detention system and its
subsequent maintenance and liability fall to the legal ownership of
the property. In the case of condominiums or other development where
shared ownership of the storm detention system is owned by multiple
property owners, associations or entities, the association or joint
owners of the detention system shall register the legal owner's name(s),
contact representative, current address and telephone numbers with
the City Clerk office annually before January 30 or 30 days after
any change in ownership.
