(a)
Grease traps, interceptors, separators, or holding tanks shall be
provided for the proper handling of wastes containing grease, oil,
sand, and other harmful pollutants which may interfere with the operation
and maintenance of the POTW and shall be constructed and maintained
in accordance with the provisions outlined in the city Code of Ordinances.
(b)
All restaurants, institutions, cafeterias, or other establishments
preparing or serving food to the general public shall be required
to install and maintain a grease trap for the efficient removal of
oil and grease from the waste stream. The design and installation
of such devices shall be subject to review and approval by the director.
(c)
All vehicle wash areas shall be equipped with interceptors and oil
separators for the removal of oils, grease, and sand and other solids.
The design and installation of such devices shall be subject to review
and approval by the director.
(d)
It shall be the responsibility of the user to furnish, operate and
maintain such pretreatment devices as necessary to produce an effluent
in compliance with this article or other applicable ordinances.
(e)
Holding tanks shall be provided for waste oils and other objectionable
waste that is prohibited from being discharged into the POTW, such
as phosphates and vegetable debris. Such holding tanks shall be constructed
to prevent leakage and splashing and shall be equipped with secondary
containment to prevent spills during operation and cleaning. Such
tanks shall be maintained to preclude odor and other nuisances and
shall not be connected to the POTW or in any other way allowed to
be discharged to the POTW.
(Ordinance 05-0503-2 adopted 5/3/05)
(a)
Existing facilities required by this article or other applicable
ordinances to maintain a grease trap, interceptor or separator not
equipped with an adequately sized treatment unit shall, within eighteen
(18) months of the effective date of this article (ordinance adopted
May 3, 2005), install an adequately sized grease trap, interceptor
or separator in accordance with the specifications of this article.
(b)
Existing facilities required by this article or other applicable
ordinances to maintain a grease trap, interceptor or separator not
equipped with the required pretreatment device for the type of business
shall, within nine (9) months of the effective date of this article
(ordinance adopted May 3, 2005), install an adequately sized grease
trap, interceptor or separator in accordance with the specifications
of this article.
(c)
In any circumstance where, in the opinion of the director, the existing
grease trap, separator, or interceptor or the absence of a grease
trap, separator, or interceptor poses a serious threat or an ongoing
problem to the sanitary sewer, is a public nuisance, or poses a threat
to public health or to the environment, the director shall require
the grease trap, interceptor, or separator to be installed or replaced
as and when necessary to remediate the threat.
(d)
If a food establishment or any other facility requiring a grease
trap, interceptor, or separator shall cease operation and shall be
required to come into compliance with other city codes, then such
establishment or facility shall be required to comply with this article
before reopening.
(Ordinance 05-0503-2 adopted 5/3/05)
New businesses required by this article or other ordinance to
maintain a grease trap, interceptor or separator shall install such
unit prior to commencement of discharge to the POTW.
(Ordinance 05-0503-2 adopted 5/3/05)
(a)
All nondomestic users shall request a determination from the director
whether a new or upgraded grease trap, interceptor or separator will
be required for his facility. The director may approve alternate treatment
technologies for some types of wastes normally treated by a separator.
(b)
Where a user requests his facility not be required to install a grease
trap, interceptor or separator, the director shall require data demonstrating
the user is able to comply with the limitations outlined in this article
or other applicable ordinances. The user may be subject to periodic
monitoring to demonstrate continued compliance. Requests not to install
a grease trap, interceptor or separator must be approved by the city
manager.
(c)
Where a user requests the use of alternate technology, the director
shall require data demonstrating the user is able to comply with the
standards contained herein and in other applicable ordinances. The
user may be subject to periodic monitoring to demonstrate continued
compliance.
(d)
Such approvals shall be made on a case-by-case basis.
(e)
The decision of the director can be appealed to the city manager.
The decision of the city manager is final.
(Ordinance 05-0503-2 adopted 5/3/05)
(a)
Specifications outlined in this article shall be considered minimum
requirements only. It shall be the responsibility of each user to
have a grease trap, interceptor, or separator designed and installed
and maintained that will produce an effluent in compliance with the
requirements of this article or other applicable ordinances.
(1)
Grease traps, interceptors, and separators shall meet or exceed the
more stringent of specifications and requirements set forth in this
article and other applicable local, state, or federal requirements.
(2)
An existing grease trap, interceptor, or separator which is upgraded
or replaced shall meet or exceed the specifications set forth in this
article and other applicable local, state, or federal requirements.
(3)
Where a nondomestic user required under this article to have a grease
trap, interceptor, or separator will occupy an existing building,
the grease trap, interceptor, or separator shall meet or exceed the
requirements in this article and other applicable local, state, or
federal requirements.
(b)
Grease traps, interceptors, and separators shall be constructed of
impervious materials capable of withstanding abrupt and extreme changes
in temperature and capable of withstanding the traffic load where
installed.
(c)
Grease traps, interceptors, and separators shall be installed outside
the building wherever possible. Where it is impossible to locate a
grease trap outside the building, the trap shall be located in a mechanical
room or other separate area where no food is stored or processed.
(d)
Grease traps, interceptors, and separators shall be located so as
to be readily and easily accessible for cleaning and inspection of
the pretreatment device and shall be equipped with easily removable
covers.
(1)
Manhole rings and covers, not less than twenty-four (24) inches in
diameter, shall be installed in the lid of each compartment to facilitate
easy access for cleaning and inspection. The manholes shall be placed
so that all internal piping is accessible for maintenance and inspection.
The cover shall be at or near, but not below, the finished grade.
(2)
Where an existing interceptor or separator is located inside a vehicle
wash bay, the first chamber shall be preceded by a grated catchbasin
with openings not greater than one-half (1/2) inch in diameter or
shall be equipped with a grated cover with openings not greater than
one-half (1/2) inch in diameter so that no solid material greater
than one-half (1/2) inch in diameter may enter the chamber. The cover
on the secondary chamber shall be watertight. Where the interceptor
or separator is preceded by a grated catchbasin, all covers on the
separator shall be watertight.
(e)
Grease traps shall have a total liquid capacity of not less than
five hundred gallons unless he user has demonstrated and received
approval from the director for a smaller capacity. Interceptors shall
have a total liquid capacity of not less than fifty (50) gallons.
Separators shall have a total liquid capacity of not less than five
hundred (500) gallons. Grease traps and separators shall be constructed
with a minimum of two (2) compartments.
(f)
Plans for new grease traps, interceptors, and separators or modifications
to existing grease traps, interceptors, and separators shall be submitted
to the director and the city plumbing inspector for review.
(1)
A description of plumbing fixtures draining to the trap, the number
of fixture units as determined by the plumbing inspector and the calculations
used to determine the proposed capacity shall be included in the submittal.
(2)
The director and the plumbing inspector shall be in agreement for
approval of the final plans prior to the issuance of any required
plumbing or construction permits and subsequent construction.
(g)
All grease traps, interceptors and separators shall be equipped with
an approved sampling port immediately downstream of the treatment
facility. Existing facilities without an approved sampling port shall
be equipped with an approved sampling port within twenty-four (24)
months of the effective date of this article (ordinance adopted May
3, 2005).
(1)
Sampling ports shall be easily accessible and safely located and
shall be constructed in accordance with plans approved by the director.
Sampling ports shall be inspected by the director prior to use.
(2)
Sampling ports shall be installed by the owner at his expense and
shall be maintained by him so as to be safe and accessible at all
times.
(3)
Sampling ports shall be constructed to exclude the entry of stormwater
and groundwater and the exit of wastewater (prevention of infiltration/inflow,
exfiltration/exflow).
(h)
Grease traps, interceptors, separators and sampling ports shall be
installed by a licensed plumber. Completed grease traps, interceptors,
and separators shall be subject to inspection by the director and
the plumbing inspector prior to connection to the POTW.
(Ordinance 05-0503-2 adopted 5/3/05)
(a)
All liquid waste lines in food preparation and dishwashing areas,
except lines from restroom facilities, cooling unit condensate, icemakers,
and soft drink dispenser drain lines, shall discharge through the
grease trap.
(b)
The minimum size of grease traps shall be determined according to
the number of fixture units draining through the trap, but shall,
in no case, have a total liquid capacity of less than five hundred
(500) gallons unless the user has demonstrated and received approval
from the director for a smaller capacity. If the director has not
approved a small capacity then the capacity will be determined by:
(1)
The total number of fixture units multiplied by one hundred and fifty
(150) gallons shall determine the minimum total liquid capacity of
the trap.
(2)
The primary chamber shall occupy three-fourths (3/4) of the total
liquid capacity of the trap.
(3)
The dividing wall between each chamber shall completely divide the
chambers (shall extend top to bottom) except where the specific design
of the separator provides for underflow, in which case the wall shall
not be greater than twelve (12) inches from the bottom between the
chambers rather than the flow traveling through a pipe.
(c)
Grease traps shall be equipped with double cleanouts on the outside
of the trap in both the influent (prior to the trap) and effluent
(after the trap) pipes.
(d)
The influent shall enter each chamber below the static water level
in accordance with the specifications outlined in this section. The
effluent shall discharge from below the static water level of the
chamber in accordance with the specifications outlined in this section.
(1)
The influent line into all chambers shall terminate no greater than
eighteen (18) inches from the bottom of the chamber.
(2)
The effluent from all chambers shall discharge from the lower twelve
(12) inches of the chamber.
(3)
There shall be no openings in any influent or effluent pipe that
will allow liquid to enter or exit the chamber at any point other
than the intake or discharge point of the pipe.
(4)
The static water level shall be maintained throughout the entire
trap.
(Ordinance 05-0503-2 adopted 5/3/05)
(a)
Automatic car or truck washes and coin-operated wash bays, drive-in
or drive-through wash bays, hand wash bays and other areas where vehicles
are washed shall be equipped with an interceptor and a two-stage separator.
The interceptor and the separator shall function as separate units.
(1)
An adequately sized interceptor shall be provided for the removal
of sand, grit and other objectionable solids from the waste stream.
(2)
An adequately sized two-stage separator shall be provided for the
removal of oil and grease from the waste stream.
(3)
Interceptors and separators shall be minimally sized in accordance
with the specifications outlined in this article. Minimum sizing for
any interceptor or separator may be increased at the discretion of
the director when necessary to protect health, safety and property
or to carry out the purposes and intents of this article.
(b)
Interceptors shall have a minimum detention time of not less than
five (5) minutes. The minimum size shall be in accordance with the
specifications outlined in this article.
(1)
Interceptors may be located inside the wash bay and may be equipped
with a grated cover provided the openings in the cover are not greater
than one-half (1/2) inch in diameter or per side of a rectangle. When
located inside the wash bay, the director may require a larger capacity
interceptor be installed to facilitate efficient sand and grit removal.
Covers shall be easily removable for cleaning and inspection.
(2)
Where located outside the wash bay, the interceptor shall be equipped
with solid watertight covers on each chamber and shall be preceded
by a catchbasin, located inside the bay, equipped with a grated cover
with openings not greater than one-half (1/2) inch in diameter or
per side of a rectangle. Covers shall be easily removable for cleaning
and inspection.
(3)
The inlet and outlet lines shall be designed and installed to provide
uniform flow and stilling in the interceptor and to preclude sand
from passing through the interceptor.
(A)
Where a down pipe is provided at the inlet, the pipe shall extend
into the interceptor a distance not less than one-third (1/3) from
the static water level to the bottom.
(B)
The discharge pipe shall extend into the interceptor a distance not
less than one-third (1/3) from the static water level to the bottom.
(c)
Separators shall be located outside the wash bay and shall be equipped
with solid watertight covers on all chambers. Covers shall be easily
removable for cleaning and inspection. The influent shall enter each
chamber below the static water level in accordance with the specifications
outlined in this section. The effluent shall discharge from below
the static water level of the chamber in accordance with the specifications
outlined in this section.
(1)
The influent line into all chambers shall terminate no greater than
eighteen (18) inches from the bottom of the chamber.
(2)
The effluent from all chambers shall discharge from the lower twelve
(12) inches of the chamber.
(3)
There shall be no openings in any influent or effluent pipe that
will allow liquid to enter or exit the chamber at any point other
than the intake or discharge point of the pipe.
(4)
The static water level shall be maintained throughout the entire
trap.
(d)
Minimum sizing for interceptors shall be fifty (50) gallons per fixture
unit (F.U.) draining into the interceptor, but not less than the minimum
sizes outlined below:
(e)
(1)
Minimum sizing for separators shall be one hundred and fifty (150)
gallons per fixture unit draining into the separator, but not less
than the minimum sizes outlined below:
(A)
Portable washer: Greater of 500 gallons or 150 gallons/F.U.
(B)
Single coin-operated wash bay: Greater of 500 gallons or 150 gallons/F.U.
(C)
Manual hand wash, single bay only: Greater of 500 gallons or 150
gallons/F.U.
(D)
2 to 4 coin-operated or manual hand wash bays: Greater of 1000 gallons
+ 200 gallons/bay or 150 gallons/F.U.
(E)
[More than] 4 coin-operated or manual hand wash bays: Greater of
1000 gallons + 200 gallons/bay or 150 gallons/F.U.
(F)
Drive-through wash bay: Greater of 500 gallons/bay or 150 gallons/F.U.
(2)
The primary chamber of the separator shall occupy three-fourths (3/4)
of the total liquid capacity of the separator.
(3)
The dividing wall between each chamber shall completely divide the
chambers (shall extend top to bottom) except where the specific design
of the separator provides for underflow not greater than twelve (12)
inches between the chambers rather than the flow traveling through
a pipe.
(Ordinance 05-0503-2 adopted 5/3/05)
(a)
Holding tanks shall be constructed and maintained to prevent discharge
of waste cooking oils, motor oils and other oils and fluids that are
prohibited from being discharged to the POTW.
(b)
Holding tanks shall not be connected to the sanitary sewer or in
any other way be allowed to discharge to the POTW.
(c)
Holding tanks shall be provided with secondary containment and such
containment shall be capable of containing not less than one hundred
and ten (110) percent of the capacity of the holding tank or the capacity
of the largest tank plus water from a maximum 24-hour/10-year rainfall
event if exposed to rainwater, whichever is greater.
(1)
Secondary containment shall be constructed so as to control spills
or splashes during operation and maintenance and leaks.
(2)
Secondary containment shall not be connected to any POTW or storm
drain and shall not be allowed to drain onto public or private property
or to the waters of the United States.
(Ordinance 05-0503-2 adopted 5/3/05)
(a)
General requirements.
(1)
Grease traps, interceptors, separators and holding tanks shall be
operated in a safe and secure manner at all times.
(2)
Areas surrounding grease traps, interceptors, separators and holding
tanks shall be maintained to facilitate immediate access to the unit
for cleaning and for inspection by the director at all times.
(3)
Grease traps, interceptors and separators shall be maintained in
continuously efficient operation by the owner or operator at his expense
and shall produce an effluent in compliance with this article and
other applicable ordinances.
(4)
A user shall not remove any down pipes or otherwise alter a grease
trap, interceptor or separator in any way which may allow oil, grease,
sand, or other objectionable materials to pass through the device
into the POTW.
(5)
Where the city must clean associated public sewers caused by inappropriate
operation or maintenance, inadequate design or installation, or inappropriate
alteration of a grease trap, interceptor or separator, costs of such
cleaning shall be billed to the user.
(A)
In a case where several users are discharging to the same sewer line,
all the users shall be equally liable except where the user provides
written proof his discharge could not have been a contributing factor.
(B)
Proof shall consist of demonstration of adequate sizing and installation;
appropriate cleaning (as documented by manifests and inspection documentation)
and valid analysis of a sample of the discharge collected within one
(1) week of the sewer cleaning activities. Analysis of samples collected
after sewer line cleaning will be accepted only where the grease trap,
interceptor or separator has been properly maintained and was not
cleaned within thirty (30) days of the sewer cleaning activities.
(6)
A user shall not increase the use of water or in any other way attempt
to dilute the waste stream in lieu of adequate treatment.
(7)
The addition of hot water or the use of emulsifiers, chemicals, or
other agents or devices that may cause oil, grease, or sand to pass
through a treatment facility or into the POTW sewer collection system
is strictly prohibited.
(8)
Areas surrounding a grease trap, interceptor, separator or holding
tank shall be kept clean and free of grease and odors and other materials
at all times.
(A)
Materials shall not be splashed, spilled, allowed to overflow, or
otherwise placed on the area surrounding a grease trap, interceptor
or separator.
(B)
In the event materials are spilled, splashed, overflowed, or otherwise
placed on the surrounding area, the generator or owner shall assure
the materials are promptly cleaned from the area and properly disposed.
(9)
Grease traps, interceptors, separators and holding tanks shall be
fully evacuated of all contents during cleaning. If the capacity of
the trap, interceptor, separator or holding tank is greater than the
capacity of the transport vehicle where full evacuation is not possible
in a single load, then the transporter and the generator shall assure
the contents are fully evacuated within twenty-four (24) hours.
(A)
No liquid waste shall be returned to the trap, interceptor, separator
or holding tank after or during cleaning, either from the same or
other trap, interceptor, separator or holding tank.
(B)
During cleaning, grease residue shall be removed from piping and
walls and the piping and walls shall be inspected to assure the integrity
of the device is maintained.
(10)
Materials removed from traps, interceptors, separators and holding
tanks shall be utilized by industry, recycled, or disposed at a facility
designated by or acceptable to the generator where the owner or operator
agrees to receive the wastes and the disposal facility has documentation
showing the facility meets all requirements of the state and federal
authorities. All wastes shall be disposed in a suitable manner in
accordance with applicable federal, state, and local laws.
(11)
Users required to maintain grease traps, interceptors, separators,
or holding tanks shall establish a system of training designed to
provide employees with appropriate instruction on the proper use of
such facilities.
(A)
Such training system shall provide employees at all levels of
responsibility with a complete understanding of the operation and
maintenance of the pretreatment device and the relation between appropriate
waste disposal and efficient operation of the pretreatment device.
Such system should include:
(i)
The importance and methods of good housekeeping practices;
(ii)
Acceptable waste disposal practices, including proper disposal
of different types of wastes;
(iii)
Procedures for preventing prohibited discharges;
and
(iv)
The proper response to and notifications in case of spills or
other accidental discharges.
(B)
Periodic training sessions shall be conducted to assure the
employee understands the essential elements of the system. New employees
shall be trained immediately upon employment.
(C)
Users required to maintain grease traps, interceptors, separators
or holding tanks shall keep documentation of training available for
inspection.
(b)
Use of grease trap treatment products.
(1)
Use of grease trap treatment products, including bacteria, designed
to digest the grease, is specifically prohibited without prior written
consent of the director.
(A)
Acceptance of such products for use may be considered only where
a valid screening test, showing the product’s ability to treat
the waste and to produce an effluent in compliance with this article,
has been performed in accordance with the methods outlined by the
director.
(B)
Screening tests for grease trap treatment products shall be designed
by the director.
(C)
The results of screening tests shall be subject to technical review
by the director.
(D)
All costs of screening tests shall be borne by the user whether or
not the product is accepted for use.
(E)
If a product is accepted for use, each user shall obtain written
permission from the director to use the product.
(F)
The director may revoke permission to use such products where the
effluent from the trap or basin in which the product is used fails
to meet the requirements of this article.
(2)
Use of accepted grease trap treatment products shall not relieve
the user of minimum cleaning requirements set forth in this article.
(3)
Use of accepted grease trap treatment products may subject the user
to monthly surcharge fees where such usage causes the effluent concentrations
to exceed the definition of normal domestic wastewater. Surcharge
fees may be levied for biochemical oxygen demand, chemical oxygen
demand, total suspended solids, or ammonia.
(c)
Inspection and cleaning schedule.
(1)
Inspection, cleaning, and other necessary maintenance of such facilities
shall be conducted as often as needed to assure the discharge is in
compliance with the provisions of this article or other applicable
ordinances, but not less than once per ninety (90) days.
(A)
The trap, interceptor or separator shall be cleaned as often as necessary,
up to and including daily, to assure compliance with this article
or other applicable ordinances.
(B)
In no case shall the accumulated grease, oil, or sand be allowed
to occupy more than twenty-five (25) percent of the capacity of the
first stage.
(2)
The physical condition of the trap, interceptor, or separator (piping,
internal walls, side walls, etc.) shall be inspected by the user each
time the facility is cleaned. Repairs, if needed, shall be made prior
to further use.
(A)
Repairs or modifications shall be approved by the plumbing inspector
and shall not be made without the appropriate city permits.
(B)
Inspection shall be conducted by the plumbing inspector after repair
and prior to refilling or use. A copy of the inspection tag issued
by the plumbing inspector shall be maintained on-site by the user
and a copy shall be sent to the director.
(C)
Documentation of repairs shall be submitted to the director within
thirty (30) days of the date of repair, or earlier if specified in
a notice of deficiency or other director-issued document.
(3)
Grease traps, interceptors, and separators shall produce an effluent
in compliance with this article at the user’s pumping schedule.
Schedules inadequate to produce such effluent shall be upgraded to
as often as necessary, up to and including daily, or the trap, separator,
or interceptor shall be upgraded. Upgraded traps, separators, or interceptors
shall meet all requirements set forth in this article or other applicable
ordinances.
(4)
A user shall have any trap, interceptor, or separator cleaned when
ordered to do so by the director. Failure to comply within forty-eight
(48) hours after the request shall be cause for the director to precipitate
the cleaning and to bill the user for such costs plus any added costs
incurred by the city.
(d)
Cleaning schedule extensions.
(1)
The user may apply to the director for an extension of the required
cleaning frequency set forth in this article. A user who wishes to
apply for a cleaning schedule extension shall notify the director,
in writing, of the intent to apply for an extension.
(2)
The director may grant an extension on a required cleaning frequency
on a case-by-case basis where the user has demonstrated, with defensible
analytical results, the specific trap will produce an effluent in
consistent compliance with this article if such an extension is granted.
(3)
The notification of intent to apply for an extension shall include:
(B)
Treatment unit information:
(i)
The type of treatment unit and the capacity in gallons;
(ii)
A brief description of the treatment unit;
(iii)
The time(s) of day the greatest hydraulic and organic loadings
to the treatment unit normally occur;
(iv)
The date of the most recent cleaning and inspection of the unit;
(v)
A statement of the physical condition of the unit; and
(vi)
Where applicable, the name of any treatment products used and
a copy of the director’s approval letter for the use of the
product;
(C)
A proposed sampling schedule, including:
(D)
Other information as may be requested by the director.
(4)
The user shall obtain approval of the proposed sampling schedule
prior to initiation of the sampling and analyses. The user shall certify
the sampling schedule will be carried out as submitted or as approved.
The director shall reserve the right to modify a sampling schedule
as deemed necessary.
(5)
The user shall be required to provide analytical results for not
less than four (4) oil and grease analyses for samples collected during
peak flow periods through the unit during the normal working hours
of a twenty-four-hour period.
(A)
Samples shall be collected at an approved sampling port and shall
be collected by a qualified person properly trained in the collection
and handling of wastewater samples.
(B)
Samples shall be collected seventy (70) to seventy-five (75) days
after the most recent cleaning.
(C)
Samples shall be analyzed, separately, by a reputable laboratory
using approved analytical procedures.
(D)
The user shall submit a written request for a cleaning schedule extension,
including:
(6)
The director may grant extensions to the cleaning schedule as follows:
(A)
A thirty-day extension may be granted where the average oil and grease
concentration of the analyses is less than seventy (70) percent of
the concentration limit and no single concentration exceeded eighty
(80) percent of the concentration limit.
(B)
A sixty-day extension may be granted where the average oil and grease
concentration of the analyses is less than fifty-five (55) percent
of the concentration limit and no single concentration exceeded sixty-five
(65) percent of the concentration limit.
(C)
A ninety-day extension may be granted where the average oil and grease
concentration of the analyses is less than forty (40) percent of the
concentration limit and no single concentration exceeded fifty (50)
percent of the concentration limit.
(D)
In no case shall an extension greater than ninety (90) days be granted.
(7)
Extensions granted shall begin on the date the samples for which
results were submitted were collected as documented on the chain of
custody.
(8)
Where an extension has been granted, the unit shall consistently
produce an effluent in compliance with the terms of this article or
other applicable ordinances. The director shall reserve the right
to collect and analyze samples of any user’s discharge and may
revoke, without notice, any extension where the director believes
it is in the best interest of the proper operation of the POTW.
(A)
Where an extension has been granted and the results of any sample
analysis exceed the oil and grease limitation by twenty-five (25)
percent or more, the user shall immediately clean and inspect the
trap and shall return to the original cleaning schedule. Where the
user has been required to return to an original cleaning frequency,
the user shall be required to submit a new request for extension if
desired.
(B)
Where an extension has been granted and the results of any sample
analysis exceed the oil and grease limitation by any magnitude but
less than twenty-five (25) percent, the user shall immediately clean
and inspect the trap and shall increase the established cleaning frequency
by at least thirty (30) days.
(C)
Where an extension has been granted and the city must clean associated
public sewer lines and the stoppage is traceable to or known or suspected
to be caused by the user’s facility, the user shall immediately
clean and inspect the trap and shall return to the original cleaning
schedule. The user will be required to submit a new request for extension
if desired.
(Ordinance 05-0503-2 adopted 5/3/05)
(a)
All fixtures with a potential to carry grease-bearing waste shall
be plumbed to the grease trap. The first step in determining the appropriate
size of the grease trap is to calculate the total number of fixture
units connected to the trap. The following fixture unit counts shall
be assigned to each different kind of fixture:
|
Kind of Fixture
|
Trap and Trap Arm Size
|
Fixture Units
|
|---|---|---|
|
3-compartment sink
|
1-1/2", 2"
|
3, 4
|
|
2-compartment sink
|
1-1/2"
|
2
|
|
Dishwasher
|
2"
|
4
|
|
Garbage grinder
|
2"
|
4
|
|
Wok stove
|
2"
|
4
|
|
Hand sink
|
–
|
0
|
|
Mop sink
|
–
|
0
|
|
Floor drains (2", 3", 4")
|
2", 3", 4"
|
2, 3, 4
|
|
Floor sinks (3", 4")
|
3", 4"
|
3, 4
|
Notes: Hand sinks and mop sinks are not required to
be plumbed to the grease trap. For indirect waste systems where hub
drains and floor sinks are used as receptors for dishwashers, 2- and
3-compartment sinks, etc., the fixture unit shall be twice (2x) the
floor sink or hub drain fixture unit count. In such cases the fixture
count for the indirect waste source is not counted.
(b)
The next step is to determine the minimum flow rating of the grease
trap. This is done by multiplying the total fixture unit count times
three gallons/minute:
Grease trap flow rating = Total fixture unit count x 3 gallons/minute
(c)
The minimum liquid holding capacity of the trap is calculated by
multiplying the grease trap flow rating (in gallons per minutes) times
twelve minutes:
Grease trap liquid holding capacity (gallons) = Grease trap
flow rating x 12 minutes
(d)
Facilities using dishwashers, wok stoves, or garbage grinders are
required to install 2-compartment traps with a 12-minute total retention
time.
(e)
Upon approval from the director, fixtures receiving non-grease-bearing
wastes may be drained through a grease trap, but shall not be included
for grease trap sizing (i.e., condensate for coolers).
(Ordinance 05-0503-2 adopted 5/3/05)
(a)
The approved design for grease traps shall be as follows:
(1)
The grease trap must be constructed in accordance with the current
plumbing codes adopted by the city, as amended, and installed in a
manner acceptable to the director (no exceptions).
(2)
The grease trap shall have two compartments.
(3)
While operating at the trap’s rated flow capacity, the first
compartment must provide a retention time of no less than seven minutes,
and the second compartment must provide a retention time of no less
than five minutes, for a minimum total of twelve minutes.
(4)
Trap inverts and vents shall be external to the compartments.
(5)
The flow line to the trap (upstream of inlet invert) must be at least
3 inches above the static water level of the tank.
(6)
Similarly, the trap vent must be at least 3 inches above the static
water level of the tank.
(7)
The trap inlet must be at least 24 inches below the static water
level of the tank, and the trap outlet must be at least 12 inches
above the floor of the tank.
(8)
Adequate flow diffusion features must be provided to evenly distribute
flow throughout the grease trap. Examples of such features would include
a flow diverter plate in the primary compartment and “tee”
piping on the tank outlet.
(9)
Each trap compartment shall be accessible for cleaning and inspection
purposes (no exceptions).
(b)
Exceptions to certain of these criteria may be considered for approval
in conjunction with the plan review process. In such cases, engineering
drawings and supporting performance data must be submitted to and
approved by the director of public works prior to grease trap installation.
Metal grease traps of alternative designs may be approved for those
sites needing grease traps of 250 gallons or less.
(c)
View a conceptual drawing of a typical grease trap design.
(d)
View contact information for grease trap manufacturers that are familiar
with these criteria. However, do not purchase any grease trap without
first verifying with the city office that the specific model will
be approved for installation.
(Ordinance 05-0503-2 adopted 5/3/05)
