Grease interceptors and grease traps, when required, shall be installed as follows:
(A) Grease interceptors and grease traps shall be installed at the expense of the owner or operator of the FSE or owner of the building or facility in which the FSE is located which is contributing wastewater to the POTW.
(B) All wastewater streams containing FOG or reasonably likely to contain FOG within FSEs or other FOG generating operations shall be directed into one or more appropriately sized grease interceptor before discharge to the POTW. Grease interceptors shall be either sized by adding the peak design flow rates for all fixtures leading to the grease interceptor and allowing a minimum retention time of 30 minutes or as follows:
Grease Interceptor Sizing | |
(1) Peak meals per hour | |
(a) Seating capacity of FSE | ___________ |
(b) Occupancy of FSE | ___________ * |
(c) Seating or occupancy x meal factor of 1.3 (45 minute meal) or 1.0 (intermittent-use FSEs) = Peak meals per hour | |
* Church: include all area(s) used for meal service ** Assisted Living / nursing facility: equal to maximum number of residents (per state license) | |
(2) Waste flow rate, gallons of flow | |
(a) Commercial, equipped kitchen with dishwasher and one garbage disposal* | 7 |
(b) Commercial, equipped kitchen with dishwasher, no garbage disposal | 6 |
(c) Commercial, equipped kitchen with no dishwasher, one garbage disposal* | 6 |
(d) Commercial, equipped kitchen with no dishwasher, no garbage disposal | 5 |
(e) Single service kitchen** | 2 |
* Each additional garbage disposal, add one gallon ** Single service kitchen = no garbage disposal, no dishwasher and all service is single use | |
(3) Retention time, hours | |
(a) Commercial kitchen | 2.5 |
(b) Single service kitchen | 1.5 |
(4) Storage factor | |
(a) Commercial Kitchen up to 8 hours of operation | 1 |
(b) Commercial kitchen up to 12 hours of operation | 1.5 |
(c) Commercial kitchen up to 16 hours of operation | 2 |
(d) Commercial kitchen up to 20 hours of operation | 2.5 |
(e) Commercial kitchen up to 24 hours of operation | 3 |
(f) Single service kitchen | 1.5 |
Peak meals per hours x Waste Flow Rate x Retention Time x Storage Factor = Calculated Interceptor Size | |
(C) Concrete grease interceptors whether precast or poured in place, shall be designed and manufactured in accordance with ASTM C 1613-08 Standard Specification for Precast Concrete Grease Interceptor Tanks or IAPMO/ANSI Z1001 Grease Interceptors and shall be installed in accordance with the codes adopted by the jurisdiction in which the FSE is located. Where no code is adopted, the construction and installation shall be in accordance with the Iowa State Plumbing Code and this division. Grease interceptors using materials other than concrete require approval by the Director, and shall comply with the conditions of such approval, if any.
(D) The building official or other designated official of the governmental subdivision within which the FSE is located shall inspect each grease interceptor installation made pursuant to this section, shall review all relevant information regarding the rated performance of the grease interceptor, and the building plan and facility site plan for the building and site where the grease interceptor has been installed, and shall approve such grease interceptor installation upon determination that the grease interceptor meets all applicable standards and requirements.
(E) Grease interceptors shall have a minimum capacity of 1,000 gallons and shall not exceed 5,000 gallons for a single unit. Where a capacity greater than 5,000 gallons is required, several smaller units shall be installed in series, however the capacity shall not exceed 10,000 gallons for any single series of interceptors without approval of the Director.
(F) Grease interceptors shall be installed outside the building housing the FSE and below surface grade, and shall have access manholes, with a minimum diameter of 24 inches, over each chamber and sanitary tee. Access manholes shall extend from the grease interceptor to at least the finished surface grade and be designed and maintained to prevent storm or surface water inflow and groundwater infiltration. The manholes shall also have readily removable covers to facilitate inspection and grease removal.
(G) Sewer lines which are not grease laden, which are not likely to contain FOG, or which contain sanitary wastes shall not be connected to a grease interceptor.
(H) Grease interceptors shall be equipped with an accessible discharge sampling port with a minimum six-inch diameter, which shall extend from the grease interceptor to at least the finished surface grade.
(I) Where grease interceptors are shared by more than one FSE, the building owner shall be the responsible party for record keeping and cleaning of the interceptor.
(Ord. 2010-09, passed 7-13-2010; Am. Ord. 2019-03, passed 2-26-2019; Am. Ord. 2022-09, passed 8-23-2022)