Grease Trap Regulations in North Dakota

Overview of North Dakota FOG Compliance Framework

Food service establishments across North Dakota must control fats, oils, and grease (FOG) in the public sewer. The legal framework starts at the federal level. Local city rules build on top of that foundation. 40 CFR Part 403 bans pollutants that cause obstructions in a Publicly Owned Treatment Works (POTW). The specific clause is 40 CFR §403.5(b)(3). Congealing kitchen grease is a classic obstruction-causing pollutant. This federal clause is the basis for every local FOG ordinance in the state. Cities use it to justify their own grease trap rules.

When restaurant grease cools inside a sewer main, it hardens. It binds with debris. This blocks flow and causes overflows. The U.S. EPA's 2004 Report to Congress found that 47 percent of reported sanitary sewer overflow blockages were caused by grease. This covers grease from restaurants, homes, and industrial sources. The report estimated 23,000 to 75,000 sanitary sewer overflows per year nationwide EPA-833-R-04-001. These numbers drive the enforcement that restaurant operators see in inspection letters and permits.

For North Dakota operators, this creates a layered system. Federal rules set the floor. The North Dakota Department of Environmental Quality (NDDEQ) Division of Water Quality runs the state's pretreatment program. It is the Control Authority for facilities outside cities that have their own programs. Cities with their own treatment plants adopt local sewer use ordinances, FOG fees, and discharge permits. Restaurants, hotels, grocery stores with prep areas, and other FOG-generating operations all fall under these rules.

Governing Authorities

The North Dakota Department of Environmental Quality (NDDEQ) protects the state's air, land, and water. Within NDDEQ, the Division of Water Quality runs the NPDES and the state pretreatment program. The Division's address is 4201 Normandy Street, Bismarck, ND 58503-1324. Call (701) 328-5210 for pretreatment and NPDES questions NDDEQ public notice.

The federal framework is 40 CFR Part 403. Part 403 directs each Control Authority to identify Industrial Users, set local pretreatment limits, and enforce reporting. When a POTW has had interference or pass-through that is likely to recur, 40 CFR §403.5(c) requires it to develop specific local limits. That is why North Dakota cities with their own plants publish FOG ordinances. They cannot rely solely on state oversight.

Several North Dakota cities run their own pretreatment programs. West Fargo administers its FROG (Fats, Rags, Oil, and Grease) program under ordinance 8-0102 West Fargo FROG guidelines. Jamestown is taking over Industrial Pretreatment Program authority directly. NDDEQ public notices document that transition NDDEQ Jamestown notice. The list of cities with delegated programs changes. Confirm the current Control Authority for your address. Do not assume who has jurisdiction. Always verify before you act. Call NDDEQ Division of Water Quality at (701) 328-5210 NDDEQ contact.

Also contact the public works or wastewater utility for your city. NDDEQ, West Fargo Public Works, and Grand Forks Public Works all publish current contact information on their websites. Phone numbers and staff change over time. Use the agency's own website for current contacts. Do not rely on secondary directories. They may be out of date. When in doubt, call NDDEQ at (701) 328-5210 to confirm who has jurisdiction over your address.

Installation and Sizing Requirements

North Dakota plumbing follows model plumbing code rules for grease interceptors. The 2024 Uniform Plumbing Code (UPC) and the 2024 International Plumbing Code (IPC) both require pretreatment for fixtures that produce grease-laden waste. IPC §1003.3.1 requires a grease interceptor or automatic grease removal device in all food prep areas. This applies to all commercial kitchens. This covers restaurants, hotel kitchens, hospitals, school kitchens, bars, and similar facilities. Fixtures that must discharge into the interceptor include pot sinks, prerinse sinks, soup kettles, wok stations, floor drains, and sinks used to drain kettles IPC §1003.3.1.

Hydromechanical grease interceptors (HGIs) are small indoor units. They are typically installed under or near three-compartment sinks. They are sized by certified flow rate in gallons per minute (gpm). Under UPC §1014.2.1, no hydromechanical interceptor may have a certified flow rate above 50 gpm or below 20 gpm. Exceptions require approval from the Authority Having Jurisdiction. The total fixture capacity discharging into the unit may not exceed two and one-half times the certified gpm flow rate. Larger fixtures require special approval. Units outside this range must be specially approved.

The UPC also publishes pipe-based sizing tables. Under UPC Table 1014.2.1(1), the pipe size sets the minimum interceptor rating:

• A 2-inch grease waste pipe carries up to 20 gpm and pairs with a 20 gpm interceptor (one-minute drain) or a 10 gpm interceptor (two-minute drain).
• A 3-inch pipe carries up to 60 gpm and pairs with a 75 gpm interceptor (one-minute) or a 35 gpm interceptor (two-minute).
• A 4-inch pipe carries up to 125 gpm and pairs with a 150 gpm interceptor (one-minute) or a 75 gpm interceptor (two-minute).

The two-minute period applies when the unit sits more than roughly 20 feet from the discharging fixtures. At that distance, friction has slowed the influent. Use the two-minute sizing column in those cases.

Gravity grease interceptors (GGIs) are larger, multi-compartment vaults. They are usually installed outside. The IPC defines a GGI as a plumbing unit of not less than 500 gallons. It is installed in the sanitary drainage system to catch free-floating fats, oils, and grease IPC Chapter 2 Definitions. Under UPC §1014.3.4, GGIs must be installed outside. The Authority Having Jurisdiction may approve an indoor exception. The UPC sizing table at UPC §1014.3.6 ties minimum interceptor volume to drainage fixture units (DFUs):

Where the actual DFU count is unknown, UPC §1014.3.6 requires sizing to the maximum DFU capacity of the inlet pipe. This prevents undersizing. It also protects you if you add fixtures later. Third-party benchmarks for hydromechanical units sold in North Dakota are PDI G-101 and ASME A112.14.3. ASME A112.14.4 covers automatic grease removal devices.

A North Dakota-specific reference comes from the University of North Dakota. Its Facilities Management Division 22 plumbing specs set a floor of 750 gallons and a cap of 2,000 gallons for grease interceptors on UND projects UND Division 22. That is not a state code. But it shows how local authorities apply the UPC framework in practice. It is a useful benchmark for new construction on or near institutional campuses.

Cleaning and Maintenance Frequency

Cleaning frequency in North Dakota is set by local ordinance and discharge permit. There is no single statewide rule. Two styles of enforcement appear in the state's published guidance. One is the numeric "25% Rule" used in many municipal codes. The other is the performance-based standard used in West Fargo. Both styles aim for the same result: keep grease out of the public sewer. One uses a number. The other uses performance.

The "25% Rule" is the widely cited threshold. Pump the interceptor before the combined depth of floating FOG and settled solids reaches 25% of the unit's total liquid depth. Above that point, the clear-water zone becomes too thin. Grease starts to pass through to the sewer. Do not wait until you can see grease in the drain. The Massachusetts Health Officers Association FOG guidelines say to inspect monthly. Clean when grease reaches 25% of effective depth, or at least every three months MHOA FOG guidelines. CSA B481.4 uses the same threshold for Canadian installations.

The City of West Fargo uses a performance-based standard. There is no fixed percentage. The FROG program considers a facility out of compliance if it fails to clean or maintain its FOG device. The result must be that grease passes through to the sewer. This is defined under ordinance 8-0102(H). The city also charges a monthly surcharge to high-strength dischargers. This covers extra inspection effort West Fargo FROG guidelines. West Fargo operators must clean often enough to keep the device working. There is no fixed 90-day calendar in the ordinance.

The City of Grand Forks adds a FOG utility fee on top of its sewer use rules. Monthly amounts vary by facility type Grand Forks Public Works:

• Gas stations with grease removal devices and churches: $5.00/month
• Hotels: $15.00/month
• Commercial restaurants, schools, and childcare facilities: $20.00/month

This fee recovers infrastructure costs from FOG-generating users. It is separate from any pumping schedule. Check your discharge permit for that schedule.

North Dakota also regulates grease disposal. NDDEQ solid waste guidance limits land application of septage and restaurant grease trap waste. The limit is four dry tons per acre per year. This protects groundwater NDDEQ solid waste guidance. Confirm that your licensed hauler tells you where the material will be taken. The disposal location is a required entry on the service manifest. Ask your hauler for the disposal site name and address. Write it on the manifest before signing.

Record-Keeping and Manifest Requirements

Federal pretreatment record-keeping sets the baseline for every North Dakota food service establishment classified as an Industrial User. Under 40 CFR §403.12(o)(2), monitoring records must be kept for at least 3 years. That period extends if there is unresolved litigation about pollutant discharge. Always keep records beyond the minimum if a dispute is open. The Control Authority must also keep records supporting any monitoring waiver for 3 years after it expires under 40 CFR §403.12(e)(2)(iv).

Self-monitoring must follow the sample collection rules of the pretreatment program under 40 CFR §403.12(g). In practice, this means grab or composite samples. The method is set by the Control Authority. Log the results and keep them alongside pumping manifests.

A complete service manifest from a licensed hauler typically includes:

• Date and time of service
• Facility name and address
• Gallons of waste removed
• Pre-pumping measurements of the FOG and solids layers
• Total interceptor capacity
• Hauler company name and license number
• Technician signature
• Disposal facility
• Any observations about interceptor condition

Keep these manifests on site so they are ready for inspection. Most inspectors ask to see at least the last three years of records. Missing manifests are treated as a compliance violation.

Local rules may require shorter retention than the federal 3-year floor. Always follow the longer of the two requirements. The City of West Fargo FROG program requires grease interceptor repair and maintenance records to be kept for 1 year West Fargo FROG guidelines. Falsifying records is a direct compliance violation. When both federal and local rules apply, the longer retention period controls. This protects you under either program.

Fines and Penalties

North Dakota does not publish a single statewide grease trap fine schedule. Penalties run through municipal courts. They follow the limits set in city ordinances and state law. The City of Bismarck publishes a non-criminal procedures schedule for ordinance violations. It uses tiered amounts capped at $500, with steps for repeat offenses Bismarck non-criminal procedures. Operators in Bismarck should check that schedule. Also check the sewer use ordinance for the exact FOG citation amount. Do not rely on out-of-state fine tables.

The City of West Fargo handles FOG non-compliance through cost recovery. If a discharge causes an obstruction, the cost of removal and repair is charged to the establishment that caused the blockage West Fargo FROG guidelines. High-strength dischargers also pay a monthly surcharge. This funds extra inspections. Ordinance 8-0102(H) defines the core violation: failing to clean or maintain a FOG control device so that grease passes through to the sewer.

Federal penalties run on a separate track. 40 CFR Part 403 requires each Control Authority to enforce its pretreatment standards. The Clean Water Act allows much higher civil penalties. These apply to direct NPDES permit violations. They also apply when a discharge causes pass-through or interference. Operators whose discharge causes a documented sewer overflow can face cleanup and repair costs. That exposure is on top of any city fine.

The practical message for North Dakota operators is simple. The dollar amounts vary by city, but the triggers are consistent. Any of these will open you to enforcement. All of these expose you to enforcement under both city ordinance and the federal pretreatment program:

• Failing to install a properly sized interceptor
• Failing to pump before the device passes FOG to the sewer
• Falsifying or losing service records
• Discharging pure fryer oil ("yellow grease") into a trap designed only for wash-water FOG ("brown grease")

Get the exact penalty schedule from your city's published code. For facilities outside delegated cities, contact NDDEQ Division of Water Quality at (701) 328-5210 NDDEQ contact. Ask specifically about FOG enforcement procedures and local limits for your facility type. Get the answer in writing if you can.