Engineering Fact Sheet - Design for .Engineering Fact Sheet For Grease Interceptors ® Grease Interceptor
Engineering Fact Sheet - Design for .Engineering Fact Sheet For Grease Interceptors ® Grease Interceptor
Engineering Fact Sheet - Design for .Engineering Fact Sheet For Grease Interceptors ® Grease Interceptor
Engineering Fact Sheet - Design for .Engineering Fact Sheet For Grease Interceptors ® Grease Interceptor
Engineering Fact Sheet - Design for .Engineering Fact Sheet For Grease Interceptors ® Grease Interceptor

Engineering Fact Sheet - Design for .Engineering Fact Sheet For Grease Interceptors ® Grease Interceptor

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  • Inlet

    Cast IronAccess Hatchway

    Double TeeManifold


    Service AlertSensors




    Grease Trooper Performance Schedule

    Model Number

    Capacity Gal

    Flow Rate GPM Max Grease Capacity

    GalMax Solids

    Capacity GalDimensions

    InchesEmpty Wt.


    Average (1)

    Intermittent (2)

    GT-500 500 17 26 275 174 94x52x54 9,500

    GT-750 750 25 38 410 260 94x52x72 9,900

    GT-1000 1,000 33 50 545 350 104x60x72 13,350

    GT-1250 1,250 42 63 690 440 110x68x72 14,650

    GT-1500 1,500 50 75 820 530 110x68x84 16,050

    GT-2000 2,000 67 100 1,100 700 108x72x96 21,250

    GT-2500 2,500 83 125 1,375 875 156x84x84 27,050

    GT-3000 3,000 100 150 1,650 1,050 156x84x96 33,150

    GT-3500 3,500 1167 175 1925 1225 156x84x102 38,590

    GT-4000 4,000 1333 200 2200 1400 192x102x84 38,100

    GT-5000 5,000 1667 250 2750 1750 192x102x96 41,550

    GT-6000 6,000 2000 300 3300 2100 192x102x108 44,700

    GT-7000 7,000 2333 350 3850 2450 216x108x120 59,908

    GT-8000 8,000 2667 400 4400 2800 216x108x130 65,018

    GT-9000 9,000 3000 450 4950 3150 216x108x115 69,116

    GT-10000 10,000 3333 500 5500 3500 254x135x104 85,760

    GT-11000 11,000 3667 550 6050 3850 254x135x114 89,950

    GT-12000 12,000 4000 600 6600 4200 254x135x120 93,280

    GT-13000 13,000 4333 650 7150 4550 254x135x126 97,960

    GT-14000 14,000 4667 700 7700 4900 254x135x134 101,040

    GT-15000 15,000 5000 750 8250 5250 254x135x146 107,700

    1. Recommended for 100 mg/L (ppm) euent concentration of grease (most plumbing codes)2. Maximum intermittant ow rate3. Precast concrete model

    The Gravity Interceptor also allows for solids retention from food grinders. Gravity grease interceptors are generally located outdoors away from the kitchen areas. This eliminates the health department concerns regarding maintenance and disposal of FOGs.

    General InformationSewers back up an estimated 400,000 times each year in the United States causing approximately 40,000 municipal sanitary system overows (SSO). The EPA has determined that sewer pipe blockages are the leading cause of SSOs and grease is the primary cause of sewer blockages.Grease interceptors are devices designed to reduce the amount of FOG (Fats, Oil and Greases) in wastewater.

    Grease interceptors are used in establishments to remove excessive amounts of grease that may interfere with the proper drainage and treatment of wastewater. Even if accumulated FOG does not escalate into blockages and SSOs, it will disrupt wastewater treatment operations and increase costs. Most Local plumbing codes prohibit any industrial user from discharging FOG over 100 (mg/l) into the public sewer system.

    The general doctrine, of most Authorities Having Jurisdiction (AHJs), is one of user pay, especially when it comes to solid waste. Therefore, it makes sense for establishments that create FOG to be responsible for its collection and disposal. Otherwise, the burden is on the municipality and ultimately the taxpayer to pay for sewer blockages and grease overloads at sewer treatment plants. It is prudent for the consultant engineer to utilize a Best Management Practice (BMP) that includes adequate sizing for the grease interceptor.

    Typical applications include commercial and institutional kitchens and food processing plants. The waste discharge from these facilities usually contains high temperature water, high organic loads, FOG, suspended food particles, and detergents.

    New plumbing codes have eliminated the term grease trap from the code and now designated Hydromechanical Grease interceptor and Gravity Grease interceptor as the two types of grease interceptors. Park sells both units, but Gravity Grease interceptors are by far the design of choice by engineers and city ocials.

    Hydromechanical Grease Interceptors incorporate air entrapment, the buoyancy of grease in the water and hydromechanical separations with interior baing for FOG separation. Hydromechanical units incorporate a ow-control device that controls velocity as it enters the interceptor.These are typically smaller interceptors installed indoors in the oor or under-the-sink. Hydromechanical grease interceptors require cleaning every 2-4 days and are typically cleaned by kitchen personnel. City health departments have concerns regarding proper cleanout and accurate documentation of maintenance. Many major cities have prohibited the installation of hydromechanical interceptors within food preparation areas without special variances.

    Hydromechanical units are sized by determining ow-through rate (gpm) at peak demand for each xture draining into the unit.

    Check with the local AHJ before specifying Hydromechanical units to determine if the jurisdiction allows these type units.

    Gravity Grease Interceptors incorporate two or more compartments in series and use its inherent larger volume to maximize the pretreatment of the wastewater. By comparison, the Gravity Interceptor is more eective because of its larger volume that acts as a heat-sink. This allows for temperature dierential (cool down) and more retention timeof the greasy liquid to promote separation and coagulation of FOGs from the wastewater.


    Engineering Fact SheetFor Grease Interceptors

    EFSEdition 2016EFS-GT-WW

  • EFSEdition 2016EFS-GT-WW

    Recent ndings by EPA of SSOs in cities and accompanying nes have caused states and municipalities to require haulers of grease to be registered. Owners are required to maintain documentation of pump-out for review by the health department.

    MaintenanceOne of the most important features for the successful operation of the grease interceptor is the maintenance program. Regardless of the size or design, an interceptor is only as good as its maintenance program. The interceptor should be located so that it will be easily accessible for inspection, cleaning and removal of collected FOG. The interceptor should be located near the source of the wastewater for the protection of the piping system.

    There should be an adequate number of access manholes to permit access for cleaning all areas of the interceptor. Access manholes should be located near the inlet and the outlet. The manholes should not be less than 20 in size. All manholes should extend to grade and be suitable for trac loading for indoor and sensitive areas.

    The grease interceptor should be cleaned (or pumped out) routinely to insure grease detention performance. Cleaning should be performed when the interceptor is at 75% of grease retention. The frequency of cleaning at any given installation will vary depending on use. Pumping frequencies for restaurants range from 30 to 90 days. Most AHJs have minimum requirements for pump out and require pump out manifest records be maintained for review by local health departments. Typically, pump out companies are required to be registered with the states water quality agency.Types of Grease Interceptors

    Gravity Grease Interceptors manufactured by ParkUSA are available in several styles depending on the application.

    Typically, the ParkUSA GT Series Interceptor is the most economic and preferred choice over all other interceptor types. The Park GT Series Interceptor is manufactured of Class II 4500 PSI precast concrete oering superior structural strength and longevity. As an option, the interceptor can be equipped with a variety of interior chemical proof liners including PVC.

    The ParkUSA GTS Series Interceptor is a stainless steel unit and is recommended for applications where the grease interceptor is installed in a freestanding position, i.e., in a basement or on a slab.

    The ParkUSA GTF Series Interceptor is manufactured from berglass reinforced polyester (FRP) material and is corrosion resistant and lightweight for above or below ground installations.

    Engineering Fact SheetFor Grease Interceptors

    Gravity Grease Interceptors Application Matrix

    GT Model Grease Interceptor Style Applications Advantages

    GT Precast Concrete DesignBuried Below

    Grade OutdoorsStrength,

    Lowest Priced

    GTS Stainless Steel Design

    Free Standing Design, Indoors or


    Strength,Moderately Priced



    Buried or Free Standing in Hard to Reach Areas,

    Outdoors or Indoors

    Convenient Lightweight design

    Fig. 4 - Typical Precast Concrete GreasTrooperGravity Grease Interceptor Installation

    Fig. 4 - Typical Stainless Steel GreasTrooperGravity Grease Interceptor Installation

    Fig. 4 - Typical Composite GreasTrooperGravity Grease Interceptor Installation


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  • Engineering Fact SheetFor Grease Interceptors

    Grease Interceptor SizingGravity Grease Interceptors are recommended to be sized utilizing Best Management Practices (BMP). The commonly used BMP sizing methods are the Seating Method and the Drainage Fixture Unit Method (2012 UPC). All methods are based on sizing according to local plumbing codes and on years of eld performance testing with methods utilizing the relationship of the probable ow rate and retention time to estimate the grease interceptor size.

    Seating Method:The dierent variables include number of seats or beds, gallons of wastewater per meal, storage capacity factor, number of hours open and loading factor.

    (D) x (MF) x (GL) x (RT) x (ST) = Size of Grease Interceptor (gallons)

    Where: D = Total Number of Seats in Dining AreaMF = Meal Factor, based on establishment type & average time per meal: 1.33 Fast Food / Cafeteria (45min) 1.00 Restaurant (60min) 0.67 Fine Dining (90 min) 0.50 Banquet Hall & Commissaries