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Why Not Approve DIY Grease Interceptors?

Recently, while googling something related to grease interceptors, I came across a YouTube video showing viewers how to build their own grease interceptor. I watched the video with a feeling of queasiness. I got the same feeling when I watched a video of someone walking and texting at the same time and they walked straight into a fountain pool at a mall. It's awful to imagine, but you can't tear away from watching it. 

A do-it-yourself (DIY) grease interceptor seems a lot like this idea for a riding lawnmower. Maybe it's genius, but is it really a good idea?


If you've used YouTube before then you know that when you click on a video you are taken to that video, but also on the side of the screen, assuming you haven't maximized the video for a completely immersive experience, on the side panel you will find related videos. 


In this case, there are a bunch of videos that all boast a DIY method of building your very own grease interceptor. These are jaw-dropping foray's into "innovation" and entrepreneurship. Here are just a few examples:

What's your initial reaction?


Are you thinking, "hey, those are clever solutions that we should approve." Perhaps you are thinking, "complying with wastewater pretreatment requirements is hard, at least this FSE is trying, so let's let this slide." Instead what we should be thinking is, "what in the world is that?" or, "does that thing even work?", or "no way is that acceptable!"


But, why exactly would we reject these DIY grease interceptors? I doubt any reader of this blog took longer than about five seconds to conclude that none of these homemade designs has been tested or rated for performance. While these kinds of 'innovative' solutions may work in some third-world countries, they most certainly are not acceptable here in North America. Right?


Really? Before we climb on board our proverbial soap box too quickly perhaps we ought to check out that "plank" in our own eye before we go after the speck in the other guys eye. 


What is a gravity grease interceptor (GGI)? Is it not an alternative grease interceptor design that has NOT been tested and rated for performance? What is the difference between taking a plastic storage container and calling it a 'grease trap' and taking a residential septic tank and calling it a commercial 'grease interceptor'? If neither one is performance tested then what really is the difference?


I will remind readers that the lack of a performance test requirement for GGIs in approved standards (i.e. IAPMO Z1001) has reached a sufficient level of concern among wastewater authorities to have caused IAMPO to take action in forming a new performance based standard, titled IAPMO Z1001.1. Before we get too excited, you should know that there has only been one meeting (9/23/16) of the technical committee responsible for drafting this new standard. 


Perhaps one reason for the lack of progress in drafting a performance based standard for GGIs is that it is very difficult to gather a consensus on how to test these devices. For example, some want them tested to an maximum effluent concentration limit. Others argue that there is no technical basis for developing a maximum effluent concentration limit. Still others argue that there isn't any consensus among wastewater authorities for what that limit should be.


For those that conceded the arguments against effluent concentration limits, the only option remaining is to mimic, at least in part, the test protocols in PDI G101 and/or ASME A112.14.3. Yet, there is much debate on the cost/benefit of testing 1,000, 1,500, or 2,000 gallon tanks with lard. Then there is the debate over what flow rate to use and how to calculate that flow rate. That of course depends upon the retention time that is used as the basis for sizing GGIs. 


Regardless of the difficulty in gathering a consensus, the benefit of testing any type of grease interceptor for performance must necessarily outweigh the arduous task of drafting the minimum acceptable performance criteria any approved interceptor should be expected to meet. Otherwise, what's the point of having a product standard in the first place? 

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