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In an effort to curb sanitary sewer overflows (SSOs) from grease accumulations in its sanitary sewer mains, the Town of Cary City Council adopted, at its public meeting on December 10, 1998, a Fats, Oils, and Greases Control Ordinance. Any nonresidential facility connected to the Town sanitary sewer collection and treatment system involved in the preparation or serving of foods will be subject to the conditions of the ordinance.

Adopted by Town Council: December 10, 1998

A. Scope and Purpose

To aid in the prevention of sanitary sewer blockages and obstructions from contributions and accumulation of fats, oils, and greases into said sewer system from industrial or commercial establishments, particularly food preparation and serving facilities.

B. Definitions

1. Fats, Oils, and Greases. Organic polar compounds derived from animal and/or plant sources that contain multiple carbon chain triglyceride molecules. These substances are detectable and measurable using analytical test procedures established in 40 CFR 136, as may be amended from time to time. All are sometimes referred to herein as "Grease" or "Greases".

2. Grease Trap or Interceptor. A device for separating and retaining waterborne Greases and Grease complexes prior to the wastewater exiting the trap and entering the sanitary sewer collection and treatment system. These devices also serve to collect settlable solids, generated by and from food preparation activities, prior to the water exiting the trap and entering the sanitary sewer collection and treatment system. Grease Traps and Interceptors are sometimes referred to herein as "Grease Interceptors".

3. Cooking Establishments. Those establishments primarily engaged in activities of preparing, serving, or otherwise making available for consumption foodstuffs and that use one or more of the following preparation activities: cooking by frying (all methods), baking (all methods), grilling, sautéing, rotisserie cooking, broiling (all methods), boiling, blanching, roasting, toasting, or poaching. Also included are infrared heating, searing, barbecuing, and any other food preparation activity that produces a hot, non-drinkable food product in or on a receptacle that requires washing.

4. Non-Cooking Establishments. Those establishments primarily engaged in the preparation of precooked foodstuffs that do not include any form of cooking. These include cold dairy and frozen foodstuffs preparation and serving establishments.

5. Minimum Design Capability. The design features of a Grease Interceptor and its ability or volume required to effectively intercept and retain Greases from grease-laden wastewaters discharged to the public sanitary sewer.

6. User. Any person, including those located outside the jurisdictional limits of the Town, who contributes, causes or permits the contribution or discharge of wastewater into the POTW, including persons who contribute such wastewater from mobile sources, such as those who discharge hauled wastewater.

C. Grease Interceptor Maintenance, Record Keeping, and Grease Removal

1. Grease Interceptors shall be installed by Users as required by the Director or his designee. Grease Interceptors shall be installed at the User's expense, when such User operates a Cooking Establishment. Grease Interceptors may also be required in non-cooking or cold dairy and frozen foodstuffs establishments and other industrial or commercial establishments when they are deemed necessary by the Director for the proper handling of liquid wastes containing Grease. No User shall allow wastewater discharge concentration from subject Grease Interceptor to exceed 325 milligrams per liter, as identified by method EPA Method 1664 or 275 milligrams per liter, as identified by EPA method 413. All Grease Interceptors shall be of a type, design, and capacity approved by the Director or his designee and shall be readily and easily accessible for User cleaning and Town inspection. All such Grease Interceptors shall be serviced and emptied of accumulated waste content as required in order to maintain Minimum Design Capability or effective volume of the Grease Interceptor, but not less often than every thirty (30) days. Users who are required to pass water through a Grease Interceptor shall:

  1. provide for a minimum hydraulic retention time of twenty-four (24) minutes at actual peak flow or 12 minutes at the calculated theoretical peak flow rate as predicted by the Uniform Plumbing Code fixture criteria, between the influent and effluent baffles with twenty (20) percent of the total volume of the Grease Interceptor being allowed for sludge to settle and accumulate, identified hereafter as a "sludge pocket".
  2. remove any accumulated Grease cap and sludge pocket as required, but at intervals of not longer than thirty (30) days at the Users expense. Grease Interceptors shall be kept free of inorganic solid materials such as grit, rocks, gravel, sand, eating utensils, cigarettes, shells, towels, rags, etc., which could settle into this pocket and thereby reduce the effective volume of the Grease Interceptor.
  3. accept the following conditions: If any skimmed or pumped wastes or other materials removed from Grease Interceptor are treated in any fashion onsite and reintroduced back into the Grease Interceptor as an activity of and after said onsite treatment, the User shall be responsible for the attainment of established Grease numerical limit consistent with and contained in (C)(1) on all discharges of wastewater from said Grease Interceptor into the Town of Cary sanitary sewer collection and treatment system.
  4. operate the Grease Interceptor in a manner so as to maintain said device such that attainment of the grease limit is consistently achieved. "Consistent" shall mean any wastewater sample taken from said Grease Interceptor shall be subject to terms of numerical limit attainment described in (C)(1). If an establishment desires, because of documented space constraints, an alternate to an out--of--building Grease Interceptor, the request for an alternative location shall contain the following information:
    1. Location of Town sewer main and easement in relation to available exterior space outside building
    2. Existing plumbing at or in a site that uses common plumbing for all services at that site.
  5. understand and agree that: The use of biological additives as a Grease degradation agent is conditionally permissible, upon prior written approval by the Director. Any establishment using this method of Grease abatement shall maintain the trap or interceptor in such a manner that attainment of the Grease wastewater discharge limit, as measured from the trap's outlet, is consistently achieved.
  6. understand and agree that: The use of automatic Grease removal systems is conditionally permissible, upon prior written approval by the Director, the Lead Plumbing Inspector of the Town of Cary, and the Wake County Department of Health. Any establishment using this equipment shall operate the system in such a manner that attainment of the Grease wastewater discharge limit, as measured from the unit's outlet, is consistently achieved.
  7. understand and agree that: The Director reserves the right to make determinations of Grease Interceptor adequacy and need, based on review of all relevant information regarding Grease Interceptor performance, facility site and building plan review and to require repairs to, or modification or replacement of such traps.
2. The User shall maintain a written record of trap maintenance for three (3) years. All such records will be available for inspection by the Town at all times.

3. No non-grease laden sources are allowed to be connected to sewer lines intended for Grease Interceptor service.

4. Except as provided herein, for a period of one year following adoption of this Ordinance, although installation of Grease Interceptors will be required to be installed, no enforcement actions will be taken under this Ordinance for failure to achieve limits on Grease discharges from Grease Interceptors. If, during this one year period an obstruction of a Town sewer main(s) occurs that causes a sewer overflow to the extent that an impact on the environment is realized and that said overflow or failure of the sanitary sewer collection system to convey sewage can be attributed in part or in whole to an accumulation of Grease in the Town's sewer main(s), the Town of Cary will take appropriate enforcement actions, as stipulated in the Town's Industrial Pretreatment Enforcement Plan and Sewer Use Ordinance, against the generator or contributor of such Grease.

5. Access manholes, with a minimum diameter of 24 inches, shall be provided over each chamber and sanitary tee. The access manholes shall extend at least to finished grade and be designed and maintained to prevent water inflow or infiltration. The manholes shall also have readily removable covers to facilitate inspection, Grease removal, and wastewater sampling activities.

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