The primary focus of the City of Boulder's Industrial Pretreatment Program is to reduce the amount of toxic and hazardous waste that enters Boulder's wastewater utility.

By pre-treating their waste, Boulder industries can help reduce the amount of pollutants that are discharged to the city's wastewater utility.


The goals of the Industrial Pretreatment Program are to:

  • promote the general health, safety and welfare of all who use Boulder's wastewater system;
  • protect city personnel who work with wastewater and biosolids;
  • prevent pollutants from entering the wastewater treatment system;
  • minimize pollutants that may interfere with the operation of the wastewater treatment system;
  • maximize opportunities to recycle and reclaim wastewaters and biosolids from the system;
  • distribute costs for the wastewater utility equally among Boulder customers; and
  • prevent the introduction of wastes that may adversely affect the environment or cause a violation of the city's National Pollution Discharge Elimination System (NPDES) permit, which is issued by the Colorado Department of Public Health and Environment.

The Industrial Pretreatment Program is located at the city's wastewater treatment facility.

Requirements for Food Service Establishments

The Boulder Revised Code 11-3-11 (b) (Grease Interceptors at Food Service Establishments) applies to facilities including restaurants, caterers, and food production facilities that discharge fats, oils and grease (FOG) from kitchen plumbing fixtures, or that serve menu items that generate grease waste.

If your food service business uses kitchen equipment such as deep fryers, woks, grills and cooking pots, your kitchen wastewater likely contains FOG. Food or menu items that contain FOG include cooking oil, salad dressing, butter, cream, sauce, gravy, and meat drippings.

The Boulder Revised Code addresses the installation and maintenance of grease interceptors to control FOG in wastewater discharged to the city sewer. While many food service businesses already meet the code requirements, others may need to install grease removal equipment or make operational changes.

If your business has the potential to discharge FOG in wastewater, a wastewater grease interceptor is required. Existing businesses that generate FOG will have until December 31, 2026 to install a grease removal device.

Fats, oils, and grease (FOG) cause serious problems in the wastewater collection system and in the plumbing lines of a food service establishment. FOG accumulating in sewer lines can result in raw sewage overflows due to blockages and cause odors, contact with disease causing micro-organisms, and costly cleanup and repair of damaged property.

A hydromechanical grease interceptor (HGI) connected to a plumbing fixture(s) that discharges greasy wastewater is acceptable to meet the code requirements under certain conditions. HGI’s are smaller units typically located inside a building. HGI’s use a flow control device and baffles to slow wastewater flow, allowing solids and FOG to separate.

A hydromechanical grease interceptor needs to be sized correctly to work effectively. Since these units are sized according to flow, make sure the HGI is large enough to accommodate inflow during peak or busy periods. These units should be installed with an indirect connection or air gap. The lid should be easily accessible with enough clearance to remove for cleaning. Make sure your plumber reviews the manufacturer’s instructions for installation since flow control or venting may be required. Food grinders should not connect to HGI’s. Because of their small size, HGI’s need frequent cleaning.

Gravity grease interceptors are large vaults typically made of precast concrete, located outside of a building. Gravity interceptors have one or two compartments that are accessed by manholes. Because of their size and expense, gravity grease interceptors are usually installed during new construction, or when a building undergoes a significant remodel. Multi-tenant buildings may have more than one restaurant that connects to a single gravity interceptor. Cleaning costs are usually divided among tenants.

Depending on interceptor size, menu type, and number of meals served, exterior grease interceptors may require cleaning at least once every 3 months, or when the solids and floating grease contents reach 25% capacity. Business owners may request a waiver from the quarterly pumping requirement based on conditions of use.

Hydromechanical grease interceptors are smaller and need more frequent cleaning. These units should be cleaned monthly or according to manufacturer’s specifications. Menu type and number of meals served will affect the cleaning frequency. Solids and floating FOG should not exceed 25% of the interceptor’s capacity. Business owners with HGI’s may request a waiver from the monthly pumping requirement based on conditions of use.

The code identifies several Best Management Practices to control FOG in wastewater. Food solids that accumulate in grease interceptors leave less room for FOG removal. To keep solids out of wastewater, install strainers or solid separators on all plumbing fixtures including floor drains and sinks. Make compost bins available in dishwash areas and train staff to scrape plates and cookware before washing.

The code also addresses the use of emulsifiers or degreasers. These products are a short-term solution since the dissolved grease will solidify downstream. Emulsifiers and degreasers are not a substitute for regular grease interceptor maintenance.

The Boulder Revised Code gives city staff the authority to request grease interceptor pumping records. The records are used to verify that the interceptor is being pumped on a regular basis. Business owners or property managers should keep records on file for a period of three years.

If possible, observe the pumper at work and make sure the contents of your interceptor are completely emptied. The pumper should check and note any missing parts, such as missing or broken inlet/outlet PVC T’s on a gravity interceptor. The T’s are important since the T on the inlet pipe keeps grease from floating back into your building and the T on the outlet pipe keeps grease from escaping into the city sewer.

If you have an interior interceptor, the pumper should empty the contents and scrape the sides and baffles. All baffles and fittings should be put back in place as per manufacturer specifications.

The pumper should provide a manifest form stating the amount of grease removed, the date, and the grease disposal location.

Permitted Industries

Certain types of industrial and commercial industries with the potential to discharge pollutants are regulated through an industrial discharge permit system. A discharge permit is required for significant industrial users.

Businesses are considered as significant industrial users if they:

  • Discharge an average of 25,000 gallons or more of processed wastewater per day;
  • Have the potential to adversely affect the city's wastewater utility; or
  • Are categorical users subject to the Environmental Protection Agency's Categorical Pretreatment Standards (categorical users, such as metal finishers and pharmaceutical manufacturers, receive increased scrutiny due to their potential to pollute).

Permitted industries must pay an annual permit fee, monitor their wastewater discharges on a routine basis, submit to city monitoring and inspections, and develop a spill control plan for their facility.

Register for a Discharge Permit


  • Please contact the Industrial Pretreatment Program for more information regarding permits at 303-413-7362.


Get a Grease Removal Device or Permit


For information and approval of grease removal device installation, call:

  • City of Boulder Industrial Pretreatment Program, 303-413-7360; or,
  • City of Boulder Building Services Center, 303-441-1880.


For information and approval of grease removal device installation, email Industrial Pretreatment