Automotive Repair Facilities (Garages and Service Stations)

(Excerpted from the City of Fort Worth, Texas Water Guidance Document for sizing and installation of grease traps and interceptors - to see the whole document in PDF form, click here).

Where automobiles are serviced, greased, or repaired or where gasoline is dispensed, oil/water separators shall have a minimum capacity of 500 gallons for the first 1000 square feet of area to be drained, plus 250 gallons for each additional 1000 square feet of area to be drained into the separator.

An effluent sampling well is required, per specifications listed in Part 1, Section F, Subsection d.
Note: Parking garages in which servicing, repairing, or washing is not conducted, and in which gasoline is not dispensed, shall not require a separator. Areas of commercial garages utilized only for storage of automobiles are not required to be drained through a separator.
Figure 1, Typical plumbing layout
Figure 2, Typical Grease Interceptor Schematic
Figure 3, Typical Sampling Well, Courtesy Park Env. Equipment Co.
Figure 4: Typical Grease Trap / Sample Well Installation, Courtesy Park Env. Equipment Co.