Frequently Asked Questions
Does the interceptor have to be concrete or is the use of non-concrete material allowed?
Per policy alternative materials are allowed.
What is a hydromechanical interceptor?
Hydromechanical interceptors (HGIs) can be specific to one manufacturer. HGIs are devices that use hydromechanical separation, interior baffling and air entrainment barriers, whether in combination or independently, to separate and retail oil and grease solids from wastewater.
Do you permit interceptor configurations with multiple interceptors?
Yes, however they must be in parallel not in series even if recommended or allowed by a specific manufacturer if your device is approved through a variance. A flow control valve will be required upstream of the interceptor configuration to ensure flow to all interceptors.
Are single point/at fixture interceptors allowed?
No, they are not allowed for any facility that is required to have an interceptor.
What if I install a size other than what my plans were approved for?
The approved interceptor is based upon the review completed and approval granted. If the mode of operation has changed, a supplemental review can be completed to update the required minimum size GI for the project. Otherwise, the original approved interceptor is to be installed.
I have a tenant finish that is proposing a grease interceptor, but I am being asked to remove it. Why?
In general, it is because the interceptor location or type is not approved for use. Projects that do not require an interceptor will be asked to remove it unless approved by variance.
How do I size for a future unknown restaurant use and I want to install the interceptor now under a core/shell permit?
Core/Shell installations of an interceptor come with an acknowledged risk. It is recommended to consult with your designer and determine the size of the space and possible fixtures for each space that will potentially use an interceptor. See the current interceptor policy for more information.
Can I share the same interceptor with another facility in the same building/strip mall? If so, how do I size it? If not, why?
Yes, an interceptor can be shared by multiple units. Sizing of the interceptor must account for all spaces. If the existing interceptor is at capacity, additional capacity or new interceptor will be required.
Do I need to install a solids interceptor?
One is not required but highly recommended downstream of a disposal/food grinder and for optimal use of the interceptor. If a hydromechanical interceptor is approved, the manufacturer's recommendations shall be followed for any solids interceptor.
Why do I have to install an interceptor?
- It was identified during review that the facility's proposed mode of operation requires an interceptor be installed to eliminate/remove fats, oils, and grease prior to discharging waste from the facility to the public main.
- The existing interceptor is undersized or not suitable for reuse as determined by the Right of Way Services inspection team.
- The existing interceptor is shared by multiple tenants and is at capacity.
Does my type of restaurant require a grease interceptor?
Final determination is made during review of the project. For those kitchen facilities that generate no or minimal amounts of grease/solid waste, a variance to a grease interceptor may be granted by the plan reviewer at their own discretion. The SUDP reviewer will determine if the project qualifies for an automatic variance during review. Possible examples include facilities that serve prepackaged food, drinks, etc. for sale or consumption. Some variances are reviewed by the variance committee only.
My facility uses milk in our process - is pretreatment required?
Pretreatment, including sampling, may be required depending on the volume of milk used or produced. A solids interceptor is recommended but final determination is made during review.
Is a sampling port required downstream of an interceptor?
In general no, but it may be required for locations with multiple tenants as determined by our Quality Control department during review. Installation is allowed if desired when not required.
How do I schedule inspections?
Please refer to your review comments, the inspections section of your issued SUDP, and the Wastewater Inspections Sections on this page. Inspections are not scheduled online through E-Permits, but by emailing dotipermitoperations@denvergov.org.
What is the minimum pipe size for the interceptor inlet and outlet pipes?
Four inch (4") is the minimum pipe size and must be consistent between both the inlet and outlet pipes.
Where can I install a grease interceptor?
Preferred locations are on the exterior of the structure, on private property and below grade. Interior locations to be approved by DDPHE but in general may not be in areas of food prep, cooking, or dish washing.
Can I use an ejector for my grease waste?
Ejectors are not allowed upstream of any interceptor, grease or solids. Ejectors downstream will need to provide justification as all fixtures that can drain by gravity must drain by gravity.