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Not in facts.json. Verbatim, 10.09(1)(b)2.f: "Interceptors shall be located not more than 25 feet of the most remote fixture being served." 5: "Interceptors shall have a capacity of not less than two pounds of grease for each gallon-per-minute (GPM) of flow." 2.b: "A vent shall be installed downstream of all interceptors". 3.b: "The waste discharge from a commercial food waste disposer shall not discharge into the sanitary drainage system through an interceptor."
Grease goes down the drain as a hot liquid, cools in the pipe, and solidifies, sticking to the walls and building up until the sewer backs up or overflows. EPA's report to Congress found grease was the most common cause (47%) of reported sewer blockages.
An interceptor slows the flow and gives it time to cool, so grease, which is lighter than water, floats and is held back while the clearer water leaves. Federal pretreatment rules also bar discharges of 'solid or viscous pollutants in amounts which will cause obstruction' in the public sewer.
Nathaniel T. Whiting of San Francisco patents a grease trap (US 306,981, Oct. 21, 1884).
Source: https://patents.google.com/patent/US306981
BMS 66 leaves grease interceptors to local authority, and allows an interceptor plus a fixture trap if a vent intervenes.
Source: https://archive.org/stream/plumbingmanual66subc/plumbingmanual66subc_djvu.txt
EPA Report to Congress on CSOs and SSOs (EPA-833-R-04-001), as quoted in EPA's 2012 food-service fact sheet.
Source: https://www.hampton.gov/DocumentCenter/View/50257/EPA-pretreatment-food-service-PDF
EPA fact sheet (EPA-833-F-12-003) citing the pretreatment prohibition at 40 CFR 403.5(b)(3).
Source: https://www.hampton.gov/DocumentCenter/View/50257/EPA-pretreatment-food-service-PDF
Mnemonic: 'Hot down the drain, hard in the main.' Grease is liquid in the sink and solid in the sewer, so the interceptor has to catch it in between.
Hot water and dish soap flush grease safely away.
They only move it downstream, where it cools and solidifies. EPA's point is that grease 'solidifies, reduces conveyance capacity, and blocks flow.'
An interceptor is a second fixture trap, so it's prohibited double trapping.
In 1940 BMS 66 allowed an interceptor in addition to a fixture trap if a vent was between them. MA today says interceptors 'shall not be considered traps unless they meet' the 2-to-4-inch seal rule (10.09(1)(b)1.a), and 'a vent shall be installed downstream of all interceptors' (10.09(1)(b)2.b).
A grease interceptor (grease trap) is required for:
Fats, oils and grease flow as liquids when hot but congeal as they cool in the building drain and public sewer, forming blockages. A grease interceptor slows and cools the flow so grease separates and is held back before it leaves the building; commercial kitchens produce that load continuously, while laundries need lint interceptors, not grease interceptors.
A grease interceptor is rated at 25 GPM flow-through. What minimum grease retention capacity does 248 CMR require?
Interceptors must hold not less than 2 pounds of grease for each GPM of flow: 25 GPM x 2 lb/GPM = 50 lb. Table 2 in 10.09 lists the same 25 GPM = 50 lb pairing.
An inside grease interceptor must be located not more than how far from the most remote fixture it serves?
248 CMR requires interceptors within 25 feet of the most remote fixture served, so grease does not congeal in a long branch before reaching it. If an exterior interceptor is within 25 feet of the most remote fixture, no inside interceptor is needed.
pressuretest.me/learn/grease-interceptors/