7.4 Interceptors and Separators: Grease, Sand, Oil, Laundry, & Bottling (UPC 1009–1017)

When Interceptors Are Required (UPC 1009)

• 1009.1: The AHJ requires interceptors (clarifiers) where needed to handle wastes containing grease, flammable wastes, sand, solids, acid or alkaline substances, or other ingredients harmful to the drainage system, sewer, or sewage disposal.
• 1009.2: The AHJ approves size, type, and location. Only wastes that need treatment go into an interceptor.
• 1009.3: Interceptors for sand and heavy solids have a water seal of at least 6 inches and must be readily accessible for cleaning.
• 1009.4: Interceptors must not become air-bound where closed covers are used; each is properly vented.
• 1009.5: Covers must be readily accessible. Needing a ladder or removing bulky equipment to service an interceptor is an accessibility violation. The location appears on the approved plans.
• 1009.6: Interceptors are maintained by periodic removal of grease, scum, oil, and solids.
• 707.7: The cleanout for an interceptor is outside the interceptor.

Grease Interceptors (UPC 1014)

When the AHJ requires pretreatment, fixtures and equipment producing grease-laden waste in food-preparation areas discharge into an approved grease interceptor. It must meet ASME A112.14.3, ASME A112.14.4, CSA B481, PDI G-101, or PDI G-102, and be sized per 1014.2.1 or 1014.3.6.

Hydromechanical grease interceptors (HGI)

• 1014.2.1 Capacity: The total capacity in gallons of the fixtures discharging into an HGI may not exceed 2.5 times the interceptor's certified gpm flow rate (Table 1014.2.1).
• 1014.2.2: A vent is installed downstream of the HGI.
• Fixture capacity method (Example 1014.2.1): gallons = length × width × depth (in inches) ÷ 231. Multiply by a 0.75 fill factor, then divide by the drain period (1 or 2 minutes) to get gpm.
  • One 24 × 24 × 12-inch compartment holds 6,912 ÷ 231 ≈ 29.9 gallons. At a 0.75 fill, that is about 22.4 gallons, and two compartments about 44.9 gallons.
  • At a 1-minute drain period, the load is about 45 gpm, so the code example selects a 50 gpm unit. At a 2-minute drain period, the load is about 22.4 gpm, so a 25 gpm unit.
• Table 1014.2.1 (gravity flow rates at 1/4 inch per foot): 2-inch pipe, 20 gpm full flow; 3-inch, 60 gpm; 4-inch, 125 gpm; 5-inch, 230 gpm; 6-inch, 375 gpm.

Gravity grease interceptors (GGI)

• Serve the commercial kitchen; toilets, urinals, and similar fixtures may not drain through them (1014.3.2.1). Waste enters through the inlet pipe.
• Scullery and pot sinks, dishwashers, soup kettles, and floor drains in grease areas may drain through the interceptor where the AHJ approves (1014.3.2).
• Located as close as practical to the fixtures, accessible to pumping equipment. An IAPMO Z1001 interceptor may not be installed inside a building where food is handled (1014.3.4).
• Each business establishment needing one has its own, unless the AHJ approves otherwise.

Table 1014.3.6, gravity grease interceptor sizing:

When DFU are unknown, size from the maximum horizontal DFU of the inlet pipe in Table 703.2. For equipment with no DFU value, add the known flow in gpm multiplied by 30 minutes.

Code example 1014.3.6: three floor drains (2 DFU each = 6), a mop sink (3), and a food-prep sink (3) total 12 DFU. That exceeds 8, so the next row applies: a 750-gallon interceptor.

Abandoned gravity interceptors are pumped and filled like abandoned sewers (1014.3.7). FOG disposal systems must produce effluent of no more than 100 mg/L FOG, per ASME A112.14.6 (1015.4).

Other Interceptors