Managing fats, oils, and grease in collection systems
Fats, oils, and grease (FOG) are among the most persistent operational threats in wastewater collection systems. When cooking oils, animal fats, and grease enter sewer lines, they can cool, harden, and attach to pipe walls. Over time, deposits restrict flow, increase pumping demands, trigger odors, and contribute to sanitary sewer overflows.
A successful FOG program reaches beyond routine cleaning. It combines source control, inspections, maintenance data, customer education, enforcement, and coordination among collection system staff, treatment plant personnel, food service establishments, and local regulators. The strongest programs focus on preventing grease from entering the network in the first place.
For water and wastewater professionals in the Los Angeles Basin, these practices also create valuable opportunities to share field experience. Organizations such as LABS of CWEA connect agency staff, engineers, operators, consultants, and other specialists through technical programs that can turn recurring problems into practical, regionally informed solutions.
Why grease deserves systemwide attention
FOG-related blockages often develop gradually. A sewer may continue to carry normal flows while grease accumulates at bends, low points, siphons, pump station wet wells, and areas with reduced velocity. A sudden increase in flow during a storm or peak-use period can then dislodge material and create a blockage downstream.
The consequences extend beyond emergency response. Repeated line cleaning consumes labor, equipment, fuel, and contractor budgets. Blockages can cause property damage, traffic disruption, odor complaints, environmental impacts, and regulatory scrutiny. Grease entering a pump station may also foul level sensors, interfere with pumps, and increase the frequency of wet-well cleaning.
Operators should evaluate FOG as a risk-management issue rather than a single maintenance task. Mapping blockage locations, comparing them with commercial dischargers, and reviewing cleaning frequency can reveal whether the problem is isolated or systemic.
Build a reliable source-control program
Restaurants, food processors, institutional kitchens, hospitals, schools, and residential neighborhoods can all contribute FOG. Commercial kitchens typically require the greatest attention because cooking processes produce concentrated waste streams. A source-control program should identify regulated establishments, document grease interceptor and grease trap requirements, and maintain current contact information for owners and managers.
Inspection schedules should reflect risk. A large restaurant with a history of overflows may need frequent inspections and documented maintenance, while a low-volume facility with consistent compliance may require less intensive oversight. Inspectors should examine interceptor condition, access, baffle configuration, wastewater flow, cleaning records, and evidence of bypassing or improper discharge.
Education is most effective when it is specific. Businesses need clear instructions on scraping food waste into trash containers, collecting used cooking oil for recycling, maintaining grease control devices, and avoiding detergents or additives marketed as quick fixes. These products can move grease farther into the collection system, where it creates a larger downstream problem.
Design inspections around risk
Historical work orders are a valuable starting point for a FOG assessment. Agencies can rank sewer segments by the number of blockages, emergency callouts, repeat cleanings, complaints, and overflow incidents. Combining this information with pipe diameter, slope, age, material, and proximity to commercial kitchens helps staff identify critical areas.
Field inspections should verify what the data suggests. CCTV inspection can show whether deposits are attached along the crown, bench, or invert of the pipe. Manhole observations may reveal floating grease, congealed accumulations, or unusual wastewater characteristics. Pump station inspections can identify whether FOG is collecting in wet wells or damaging mechanical equipment.
The inspection record should capture enough detail to support decisions. Useful fields include the source location, estimated deposit thickness, cleaning method, labor hours, disposal destination, repeat history, and suspected cause. Consistent documentation makes it easier to measure whether a corrective action actually reduces recurrence.
Match controls to the source
Different sources require different controls. A small residential contribution may respond to community education, while a commercial kitchen may need a properly sized and maintained grease interceptor. Industrial facilities can require additional pretreatment, sampling, discharge limits, or process changes.
| Source or condition | Useful control | Performance indicator |
|---|---|---|
| Restaurants and commercial kitchens | Interceptor sizing, inspection, and scheduled pumping | Complete maintenance records and fewer downstream blockages |
| Residential neighborhoods | Public education and proper disposal campaigns | Reduced complaints and fewer grease-related service calls |
| Food processors | Pretreatment review and discharge monitoring | Compliance with local limits and stable wastewater characteristics |
| Pump stations with recurring deposits | Wet-well inspection and targeted cleaning | Lower pump fouling and reduced cleaning frequency |
| Sewer segments with repeat blockages | Root-cause investigation and optimized cleaning | Longer interval between corrective maintenance events |
A cleaning schedule should be based on measured accumulation, not simply a calendar date. If an interceptor is consistently less than one-quarter full at service, the interval may be longer than necessary. If grease returns rapidly after pumping, staff should investigate undersizing, hydraulic short-circuiting, poor baffle condition, excessive water use, or unauthorized discharge.
Disposal practices matter as well. Collected grease and interceptor waste should be transported and processed through approved channels. Tracking manifests or vendor documentation helps agencies confirm that material is handled responsibly and prevents an apparent solution from shifting the environmental burden elsewhere.
Use operations data to prevent recurrence
Work management systems can turn routine maintenance into a predictive tool. A department that records cleaning dates, blockage causes, equipment used, and post-cleaning conditions can compare results across crews and locations. Over time, this information supports more precise scheduling and better allocation of vacuum trucks, jetters, cameras, and staff.
Key performance measures may include FOG-related blockages per 100 miles of sewer, repeat incidents within 90 days, emergency response hours, interceptor compliance rates, and cost per cleaned segment. Tracking these measures by basin or service area can expose patterns that are hidden in systemwide averages.
Technology can supplement, rather than replace, operator judgment. Level sensors, pump current monitoring, remote cameras, and supervisory control data may help identify changing conditions. However, alarms must be configured carefully. A sensor that is poorly located or frequently fouled can generate nuisance alerts and cause staff to ignore a meaningful warning.
Training also supports better data quality. When operators use the same definitions for “grease blockage,” “FOG accumulation,” and “preventive cleaning,” managers can compare records over time. Workshops on automation and collection system practices can help agencies connect field observations with reliable operational information.
Coordinate people, policy, and compliance
FOG control works best when collection system, pretreatment, laboratory, customer service, and public information teams share responsibility. A restaurant inspection may identify a maintenance deficiency, but lasting improvement requires follow-through, technical assistance, and appropriate enforcement. Communication between field crews and inspectors is especially important when crews repeatedly find the same commercial source near a problem segment.
Local requirements should be easy for businesses to understand and practical for staff to enforce. Policies may address grease interceptor design, pumping frequency, record retention, prohibited discharges, sampling, administrative penalties, and corrective action timelines. Consistent enforcement protects compliant businesses from being disadvantaged by competitors that avoid maintenance costs.
Regulatory awareness is part of the broader picture. Agencies evaluating coastal discharges can use this permit requirements guide to connect collection system performance with changing environmental obligations. At the same time, professional networks preserve institutional knowledge; the LABS of CWEA leadership history reflects the continuity that helps water professionals learn from earlier programs and pass effective practices to the next generation.
Priorities for the next quarter
A focused work plan can produce measurable progress without waiting for a major capital project. Agencies should select a small number of high-risk areas, establish baseline conditions, and assign responsibility for each action. The following steps provide a practical starting point:
- Map FOG-related blockages, repeat cleaning locations, pump station deposits, and nearby commercial sources.
- Verify that high-risk food service establishments have accessible, correctly configured, and regularly maintained grease control devices.
- Standardize field documentation for deposits, cleaning results, labor hours, disposal records, and suspected sources.
- Use measured accumulation and incident history to adjust preventive cleaning intervals.
- Share concise disposal and maintenance guidance with businesses, residents, inspectors, and collection system crews.
The program should be reviewed after the first quarter using both operational and compliance measures. A decrease in emergency blockages is valuable, but so is a longer interval between cleanings, better inspection completion, improved maintenance records, or fewer recurring deposits at pump stations.
Strong FOG management is built through steady attention to sources, assets, data, and people. LABS of CWEA members can advance that work by bringing real collection system cases to technical presentations, workshops, facility tours, and peer discussions. Register for an upcoming professional development opportunity or connect with fellow water professionals to turn recurring grease problems into durable system improvements.