This document provides a practical, industry-based guideline for sizing, designing, and installing grease traps and grease interceptors for commercial food service establishments. Developed by the Fort Worth Water Department’s Pretreatment Services Division, the guide consolidates standards from the International Plumbing Code (IPC) Commentary, the Uniform Plumbing Code (UPC), and local environmental ordinances.
The guidance applies to all types of commercial kitchens — including new construction, renovations, changes of ownership, and facilities that struggle with compliance due to excessive grease discharge. Its purpose is to help business owners, engineers, and contractors ensure that wastewater entering the municipal sewer system meets regulatory requirements and prevents blockages caused by fats, oils, and grease.
Key Contents of the Guideline
1. Applicability and General Requirements
The guide outlines when grease traps are required and emphasizes that proper sizing and installation are essential for protecting the city’s sanitary sewer system. While formulas help determine capacity, the minimum recommended size for restaurant applications is 750 gallons, and no exterior trap smaller than 500 gallons is allowed.
2. Sizing Methods
Two industry-standard methods are presented:
• Method 1: Uniform Plumbing Code (UPC), Appendix H
A formula based on peak meal volume, waste flow rate, retention time, and storage factors. This method includes safety factors that may result in very large traps, though the city caps its requirement at 4,000 gallons.
• Method 2: Five-Hour Detention / Peak Flow Method
This method calculates trap volume based on water usage, graywater flow, peak flow factors, and detention time.
The guide also allows alternate sizing proposals, but only if supported by engineering justification and approved by city authorities.
3. Construction & Installation Standards
The document details specific technical requirements, including:
- Minimum two-baffle design
- Installation at least 10 feet from sinks and dishwashers to allow cooling
- Routing all grease-bearing waste streams through the interceptor
- Doubling the calculated size when garbage disposals are used
- Requirements for sample wells and flow regulators
- Compliance with local plumbing codes during installation
4. Responsibilities of the Waste Generator
Business owners must maintain grease traps in proper working condition at all times. The guide highlights:
- Mandatory pump-out and cleaning every 90 days (or more frequently as needed)
- Keeping maintenance records for five years
- Avoiding the use of enzymes, solvents, or emulsifiers
- Ensuring dishwashers and hot water do not reduce the trap’s effectiveness
- Ensuring compliance with discharge requirements at all times
5. Other Interceptor Types
Beyond restaurant grease traps, the document also provides requirements for:
• Laundries
Formulas for sizing lint interceptors based on gallons per cycle, cycles per hour, retention time, and storage factors.
• Car Washes
Minimum separator capacities and construction requirements to prevent stormwater infiltration.
• Automotive Repair Facilities
Sizing of oil/water separators based on drainage area.
6. Illustrations & Vendor Information
The guide includes diagrams of typical plumbing layouts, grease interceptors, and sampling wells, along with a list of known vendors supplying approved equipment and alternative grease removal systems.
Conclusion
This guideline serves as a comprehensive reference for anyone involved in the design, installation, or maintenance of grease traps and interceptors. By following the recommended formulas, construction standards, and maintenance requirements, commercial facilities can ensure proper wastewater pretreatment, reduce environmental impact, and remain in compliance with municipal regulations.
You can download and review the full document for detailed formulas, diagrams, and technical specifications.
0 Comments