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(1) Applicability. The requirements specified herein apply to all new commercial facilities and any existing or new customer with a reasonable potential to discharge excessive levels of FOG (as solely determined by the district) into the district’s wastewater collection system. Excessive levels of FOG are levels defined as those that exceed 100 mg/L total FOG, have a visible sheen or cause build-up or obstructions in sewer systems.

(2) Fats, Oils and Greases (FOG) Standard. The discharge of more than 100 mg/L (combined polar and nonpolar FOG concentrations, EPA Method 1664) is prohibited. The discharge of FOG in amounts that cause a visible sheen on the discharge or in the public sewer system, a build-up of FOG in any public sewer facility, which accumulates either alone or in combination with other discharges to cause obstruction of the public sewer system is also prohibited.

(3) Variances From FOG Regulations. The district has the authority to approve any variances to the discretionary standards and/or other conditions of the requirements specified herein.

(4) Requirements for New and Existing Facilities.

(a) New Facilities. All new commercial facilities are required to install grease interceptors and/or oil/water separators unless the facilities will exclusively generate domestic wastewater and are provided a written exemption by the district. Constructed facilities with the potential to discharge FOG shall be required to continuously operate and maintain an approved type and adequately sized grease interceptor and/or oil/water separator designed to meet the district’s FOG regulation requirements within 180 calendar days from notification by the district. New facilities must be designed in accordance with this chapter and the current Uniform Plumbing Code (UPC).

(b) Existing Facilities With FOG Removal. Existing facilities with FOG removal devices shall be permitted to operate and maintain existing FOG removal devices; provided, that the equipment is in good operating condition and meets the effluent requirements. Any facilities that will be expanded or renovated (e.g., tenant improvements), or are known to cause violations of the FOG removal device effluent standards or FOG-related cleaning activities in the sanitary sewer, shall be required to install, operate, and maintain an approved type and adequately sized grease interceptor and/or oil/water separator designed to meet the district’s current FOG control requirements within 180 calendar days from notification by the district.

(c) Existing Facilities Without FOG Removal. Existing facilities without FOG removal devices that will be expanded or renovated (e.g., tenant improvements), or are determined by the district to cause violations of the FOG removal device effluent standards or FOG-related cleaning activities in the sanitary sewer, shall be required to install, operate, and maintain an approved type and adequately sized grease interceptor and/or oil/water separator designed to meet the district’s current FOG control requirements within 180 calendar days from notification by the district.

(5) Requirements for FOG Removal Devices.

(a) Responsibility. The owner of each facility is solely responsible for the cost of FOG removal, device installation, inspection, cleaning, and maintenance.

(b) General Design Requirements. No sanitary waste shall be conveyed to a FOG removal device.

A downstream monitoring manhole or sampling port shall be included on all GI and OWS installations, unless a variance is approved by the district (for instance, if there is insufficient space).

Grease interceptors and/or oil/water separators shall be installed at an exterior underground location where they are easily accessible for sample collection, inspection, cleaning, and removal of retained FOG, unless a variance is provided by the district. The location of the grease interceptor and/or oil/water separator must be approved by the district and may not be installed in any interior part of a building.

Grease interceptors and/or oil/water separators shall be located on the facility’s side sewer downstream of all fixtures which may introduce FOG into the sanitary sewer and upstream of the connection to the sanitary sewer collection system.

(c) Grease Interceptors. Grease interceptors (GIs) shall be designed, sized, constructed, and installed in accordance with district standards and the Uniform Plumbing Code (UPC), whichever is more stringent. For FSEs, the type (grease trap or GI) and size of the FOG removal device shall be based on the “Sizing of GIs” formula as defined in the currently adopted UPC or the table below, whichever is more stringent. All fixtures, equipment, and drain lines located in a facility’s food preparation and cleanup areas shall be connected to a GI, unless specifically approved by the district. The following types of equipment or fixtures have been identified as potential sources of fats, oils and grease and shall be connected to a GI per district or manufacturer’s instructions: pre-rinse and/or pre-wash sinks or sinks in dishwashing areas; two or three compartment sinks; wok stoves; self-cleaning stove ventilation/exhaust hood; kitchen floor drains; floor drains; floor sinks; mop sinks; food prep sinks; and hand sinks.

Minimum Grease Interceptor Sizing Requirements

Meter Size

Gallons per Minute 1 (GPM)

Drainage Fixture Units 2 (DFUs)

Grease Interceptor Size 3

5/8"

25

50

1,000

1"

70

140

1,250

1-1/2"

120

240

2,000

2"

170

340

2,500

3"

320

640

5,000

4"

500

1,000

7,500

6"

1,000

2,000

7,500

> 6"

DISCUSS WITH DISTRICT

1Source: AWWA Standards: Displacement C700-09 and Compound Class I C702-10.

2One gpm of flow is approximately equivalent to 2 DFUs.

3Source: Uniform Plumbing Code: Table 1014.3.6, Gravity Grease Interceptor Sizing.

Grease traps and hydromechanical grease interceptors are not allowed unless a variance is granted if grease interceptors are not feasible due to space or other considerations.

Hydromechanical grease interceptors, if allowed, must be sized, installed and maintained per the more stringent of UPC and the Plumbing and Drainage Institute (PDI) Standard PDI-G 101.

For grease traps, if allowed, manufacturer certifications, and sizing calculations utilizing the more stringent of IAPMO, UPC and district guidance must be provided for review and approval by the district.

The minimum size for an in-ground gravity grease interceptor shall be 1,000 gallons.

Dishwashers may only be directed to GIs per district or manufacturer instructions. District kitchen BMPs must be followed to minimize solids and grease from entering the dishwashers. Dishwashers or other fixtures discharging emulsifying agents, such as detergents, shall be located such that their potential to adversely impact the GI operation is minimized. All drain lines shall have permanently fixed screens with maximum one-quarter-inch openings to prevent the pass through of larger solids.

A grease interceptor shall only serve one building unless otherwise approved by the district. The district reserves the right to require more than one grease interceptor for large buildings or buildings with more than one significant FOG discharger.

Commercial food grinders and garbage disposals are not allowed.

(d) Oil/Water Separators. Oil/water separators are required for all customers that are potential dischargers of petroleum-based and/or nonpolar FOG. Businesses and facilities that require oil/water separators include, but are not limited to, car washes, quick-lube stations, loading docks/trash compactors, auto detail shops, parking garages, elevator sumps, gas stations, fuel pumps, automotive and equipment repair, service shops and any businesses using steam or pressure washers.

Exterior vehicle washing and/or service areas must be served by an oil/water separator and the area covered with a canopy or roof unless a variance is granted by the district.

Outside areas served by oil/water separators must be designed to meet district standards.

Indoor areas served by oil/water separators must be sized based on the table below, based on the UPC.

Service Area Drained to Separator (ft2)

# of Vehicles Stored/Serviced in Service Area

Oil/Water Separator Capacity (gal)

≤ 600

≤ 3

45

601 – 700

4

55

701 – 800

5

60

801 – 900

6

70

901 – 1,000

7

75

1,001 – 1,100

8

85

1,101 – 1,200

9

90

1,201 – 1,300

10

100

≥ 1,301

≥ 11

DISCUSS WITH DISTRICT

Source: Uniform Plumbing Code: Section 1017.2, Design of Interceptors. Find the row corresponding to the service area and number of vehicles for the facility. If these are different rows, then choose the row with the larger oil/water separator capacity.

Or use the formula in Uniform Plumbing Code: Section 1017.2, Design of Interceptors. Supporting sizing calculations shall be submitted to the district for review and approval.

(6) Maintenance Requirements.

(a) Twenty-Five Percent Rule and FOG Disposal. Grease interceptors and/or oil/water separators shall be considered out of compliance if the total volume of FOG and solids displaces more than 25 percent of the effective volume of the final chamber of the interceptor “25 Percent Rule.” Grease interceptors and/or oil/water separators must be serviced and emptied of accumulated waste content as required to maintain the accumulated grease and solids to less than 25 percent of the volume of the interceptor, but not less than once every 180 calendar days.

(b) If a facility determines that cleaning every 180 calendar days is unnecessary in order to remain in compliance with the district’s requirements, the facility may make a written application for a variance from the standard cleaning schedule. If a grease interceptor, oil/water separator, or other grease removal device requires repairs, they shall be performed within a minimum of 14 calendar days, or sooner for severe issues, as determined by the district.

(c) Any facility that has a gravity grease interceptor and/or oil/water separator shall utilize a licensed rendering and/or disposal company for maintenance. Wastes removed from a gravity grease interceptor and/or oil/water separator shall be disposed of at a facility permitted to receive such waste. FOG, solids or liquids removed from the gravity grease interceptors and/or oil/water separators shall not be returned to any gravity grease interceptor, oil/water separator, private sanitary sewer line, any portion of the sanitary sewer collection system, or any portion of the storm water system.

(d) It is the facility owner’s responsibility to inspect, monitor, maintain and report on all FOG facilities. The FOG removal device must be kept in intact condition and without leaking and/or lids that do not seal. Elements of the FOG removal device such as baffles shall not be allowed to be broken or missing. Other issues that impair the device’s ability to separate FOG from wastewater must be prevented.

(e) All facilities that have a reasonable potential to discharge FOG as determined by the district must follow district food service establishment or automotive service BMPs to ensure that excess concentrations of FOG are not discharged to the sewer system.

(f) All facilities shall maintain a written record of inspection and maintenance activities and the rendering/disposal company manifest (including date of activity). A copy of such records shall be submitted to the district within 15 calendar days following the inspection and maintenance activity.

(g) Facilities must retain maintenance records, covering at minimum the previous 12 months, for each FOG removal device located on the premises.

(7) Enzymes, Emulsifiers, Bacteria, and Other Agents. The direct addition into the building plumbing, grease interceptor, or oil/water separator of enzymes, chemicals, or other agents designed to biodegrade or emulsify the FOG compounds is prohibited. Any attempt to modify the interceptor into a biological reactor by adding bacterial or microbial agents is also prohibited.

(8) Inspection, Monitoring, and Reporting.

(a) Inspection. Authorized personnel from the district may inspect the FOG removal devices and other wastewater facilities and equipment of any user at any time during normal business hours to ascertain whether the applicable district pretreatment standards are being met. Maintenance records shall be made available for on-site inspection during all operating hours.

(b) Monitoring. Authorized personnel from the district shall have the right and access to set up on any user’s property devices necessary for conducting wastewater sampling inspection, compliance monitoring, and/or metering operations.

(c) Reporting. Facilities shall retain maintenance records, covering at minimum the previous 12 months, for each FOG removal device located on the premises. These records shall include the date, time, amount of waste emptied, hauler, and disposal site. Copies of all maintenance records (including cleaning receipts) shall be forwarded to the district using the form or portal designated by the district. Facilities shall also report compliance with maintenance requirements in a form or portal designated by the district and retain records of employee education/training and documentation of any BMPs. Facilities which properly report records and are compliant may receive district approval for fewer inspections. [Res. 830 § 1 (Exh. 1), 2022.]