Interceptor Whisperer Blog has Moved

Change is inevitable and in this case it's a good thing. The blog has been moved to its permanent new home at https://www.interceptorwhisperer.com/iw-blog.

The move is effective immediately. Old content will still reside here, but all new posts will be found at the new location.

Cheers and see you at the new location!

Accuracy should trump easy-peasy

In January the ASME A112.14.3 sub-committee will once again meet to try to update the standard, which has remained unchanged since its publication in 2000.

One of the issues that the committee has struggled to come to consensus on is the incremental test cycles and the skim tank procedure.

At the risk of boring the reader to death - something I normally try to avoid - let me explain the procedure and the inherent problem that I believe needs to be addressed.

This is what the ASME A112.14.3 test apparatus looks like, conceptually anyway.

Once the flow rate is calibrated from the test sinks to the desired flow rate for the interceptor being tested, the testing procedure involves opening the drain valve on the test sinks and "let 'er rip".

The flow from the test sinks will pass through the grease interceptor and into the skim tank, after which any accumulated lard found in the skim tank is skimmed off (hence the clever and sophisticated name of the tank), dewatered and weighed. The weight of the lard taken from the skim tank is deducted from the weight of the lard introduced into the test sinks and the difference representing the efficiency of the interceptor during that specific test cycle.

Now, the skim tank is supposed to have a waste outlet connected to the bottom of the tank at one end and be trapped to retain approximately 18 inches of water in the tank. The tank is also provided with a four (4) inch bottom drain to permit draining and cleaning.

The purpose of the waste outlet being trapped to retain 18 inches of water in the tank is so that the tank volume does not drop below 18 inches during a test cycle.  In practice what this means is that the flow from the grease interceptor can actually pass through the skim tank during a test cycle since the waste outlet is typically not closed off during testing.

Is this a problem?

Perhaps not, but since the point of the testing procedure is to determine with the greatest accuracy possible the efficiency of a grease interceptor, this doesn't seem right to me.

In case you didn't quite follow all that, allow me to clarify the issue.

The skim tank is just that a tank intended to capture the effluent from the grease interceptor during a test run in order to measure the amount of lard that escaped the interceptor which will determine the efficiency of the interceptor.

If the tank is open during a test run it is possible for some of the lard that enters the skim tank to escape the skim tank.  Any lard which escapes the skim tank is automatically counted as lard that must be in the grease interceptor, which has the potential of reporting a higher than actual efficiency of the interceptor for a given test cycle.

Since the interceptor will be tested over a minimum of 13 cycles, the problem can be compounded resulting in a potentially significant higher than actual average efficiency for a certified grease interceptor.

The solution would seem to be a simple one; keep the skim tank closed during each test cycle.

I have proposed just such a radical idea to the committee before but have received resistance from some who cite the benefit of the "automatic" nature of the testing when the tank is allowed to remain open during each test cycle.

I take the term "automatic" to basically mean, "easy-peasy", which is actually short for "easy-peasy-lemon-squeezy", which means "very easy" and makes me think about vodka and a drink called a Lemon Drop...

I doubt that the proponent of the argument intended committee members to conjure up images of
alcoholic drinks, but I did anyway.

Further arguments have been proposed that at higher flows and a two-drop series (allowed by the standard) that a lack of  human intervention at the required time would cause the skim tank to overflow, invalidating the test.

It's hard to not respond with a bit of sarcasm to that argument, but I'll abstain and simply say, "hogwash".

The committee has already agreed to enlarge the size of the skim tank for testing grease interceptors at flow rates over 50 gpm.  The size of the larger skim tank will allow for two complete drops (test increments) at 100 gpm, which is 400 total gallons of water. There is no risk of overflowing the skim tank unless the "human interaction" fails to drain the skim tank prior to another test cycle.

If testing personnel fail to drain the skim tank down between two successive two-drop tests at 100 gpm, then I would agree that the test results would be invalid, requiring the interceptor to be tested over from the beginning - and the testing personnel fired for incompetence (after they clean up the mess, of course).

Anyways, it seems to me that accuracy in testing should be the most important issue - definitely more important that what's easy-peasy.

I'll update this post if any progress on the issue is made at the next committee meeting.

Clean Water - something to be thankful for

This week here in the US we celebrate Thanksgiving. It's a nationally recognized holiday originally set aside for the nations' citizens to give thanks for the blessings we have received individually and collectively.

One of the ways we show our thankfulness is by consuming copious amounts of turkey, stuffing, homemade mashed potatoes with gravy, corn on the cob, butternut squash, candied yams, green been casserole, cranberry sauce, and pumpkin pie.

For Thanksgiving in 2014, Americans spent $2.9 billion, ate 51 million turkeys, and gained a collective 765 million pounds. Hey, what can you say, we're a grateful people.

This year I thought I might share one of the things I am truly thankful for...

Change.

I suppose you could consider how much weight you gained over the holiday as "change" but that's not the kind of change that I'm talking about.

There can be no growth without change. I think we all know and understand this principle intellectually, but I think it's also important to consider what it means literally.

Why is it that we don't like change?

Is it that we don't like change or the idea of what the change represents?

I found the following letter to the editor from the Spokesman-Review newspaper in Spokane Washington dated December 8, 1967 titled, "Change Feared":

Clearly the former Governor had some very valid concerns especially regarding the "breakneck speed" of 15 miles per hour at which these early locomotives traveled and the terrifying nature of these "engines" which will frighten women and children. One wonders how we managed to adapt to the enormous speeds and frightening nature of trains.

Despite the fears of some, consider a few examples of what the introduction of the railroad actually meant to this country:

• After the completion of the transcontinental railroad on May 10, 1869, for the first time the nation was connected from east coast to west coast. Before the railroad, travel from New York to California took up to six months at a cost of around $1000. The railroad reduced the travel time to one week and the cost to $150.
• Within just 10 years of its completion the railroad moved $50 million in freight from coast to coast every year.
• The transcontinental railroad opened up vast new areas for settlers to populate as roads spider webbed out from rail lines across the US.

The point is that there is no growth without change.

While I think its easy for us to look at progress in terms of those things that benefit us all collectively such as:

• Indoor plumbing - hey who isn't happy they don't have to use an outhouse everyday or thankful to have running water indoors?  
• Electricity - unless you are from an Amish community you have to be thankful for this. I'm not picking on the Amish, I'm just sayin'.
• Automobiles - enough said.

You get the point. 

One area we are all effected by is clean water. 

I'm no fan of unchecked government that attempts to govern every aspect of American lives.  

But you know, I'm also no fan of unchecked industry that can and has wreaked havoc on our environment.

Do you remember the Cuyahoga River Fire of 1969? That was just the last one and the one that finally drew enough attention to the issue of water pollution to drive congress to pass legislation that would later become known as the Clean Water Act.

There were actually 13 fires on the Cuyahoga river, the first of which happened in 1868, followed later by the largest and most expensive in 1952. 

While these fires were unfortunate, they did lead to change. Important and necessary change. But, over 100 years passed from the first fire to the last before change happened.  

Why did it take so long?

The obvious answer would seem to be that, for whatever reason, we just don't like change.

But I can honestly say that I am thankful for this kind of change which has benefited us all collectively with clean rivers and lakes and arguably the best wastewater collection and fresh water delivery systems in the world. 

While we all express our appreciation for the many blessings we have individually and collectively, this Thanksgiving one of the blessings I'm adding to my list is clean water.

Happy Thanksgiving.

The Baffling Requirement for Baffles

I am always baffled when I see a requirement for baffles in an interceptor. Why are they required and do they actually improve performance?

If you are a pretreatment professional, may I ask you to consider the following question:

What is the role of manufacturers of grease interceptors?

Let me ask the question differently:

Are there pretreatment programs, basically anywhere in the country, that staff a research and development department that is capable of developing and testing primary pretreatment device technologies in order to justify policy requirements regarding these devices?

Cue Jeapordy theme...

I come back to this line of thinking from time to time when I come across requirements that mandate an interceptor have internal baffles. I simply do not understand why baffles are required.

Remember that all grease interceptors, regardless of type, operate based on gravity-differential separation. The principle is simple, reliable and is based on laws that are immutable. Fats, oils and grease (FOG) are lighter than water and therefore float.

Turbulence inside of an interceptor, any interceptor, is bad. Turbulence negatively effects velocity which decreases the amount of time FOG has to separate since the FOG has to break free from the turbulent flow path before it can ascend to the surface.

Creating a laminar (turbulence free) flow path in an interceptor is of paramount importance in an effective design.

Baffles inside an interceptor create turbulence.

Allow me to illustrate my point like this...

Here are some typical HGIs - same basic designs that have been around since the 1940's:

Notice the vertical baffles that are intended to enhance the performance of these designs.

Facts:

• 90% average efficiency
• Maximum grease storage capacities are 2 times the flow rate
• Grease storage capacities range from 25% to 30% of total liquid volume

It has only been in the last decade or so that manufacturer's began introducing high-efficiency, high-capacity HGIs and you may notice something these devices have in common:

Schier GB-250 (100 gpm, 1076 lbs) - Canplas XL 100 (100 gpm, 1058 lbs) - Thermaco TZ1826 (100 gpm, 1826 lbs)

All of these designs are open with no vertical baffles.

Facts:

• Efficiencies range from 93% to 99%
• Maximum grease storage capacities range from 10 to 18 times the flow rate
• Grease storage capacities range from 50% to 90% of total liquid volume

Okay, so what about gravity grease interceptors (GGI)?

Many seem convinced that somehow a 30 minute retention time and two-chambers ensure that these devices work correctly as commercial grease interceptors.

What most people may not be aware of is that GGIs are really residential septic tanks adapted for a different purpose.

A comparison between IAPMO/ANSI Z1001 (the standard that governs GGIs) and IAPMO/ANSI Z1000 (the standard that governs septic tanks) reveals little if any real difference between the two tanks.

But, it turns out that even in a septic tank, a vertical baffle forming two chambers is not a good idea!

Image scanned from textbook

According to the same book that the UPC derives the 30 minute retention time from titled Small and Decentralized Wastewater Management Systems (McGraw-Hill, 1998),  "Two compartments have been used to limit the discharge of solids in the effluent from the septic tank. Based on measurements made in both single and double compartments, the benefit of a two-compartment tank appears to depend more on the design of the tank than the use of two compartments."

Under the heading Tank Configuration the textbook notes, "Although a divider is used, the rationale for its use is historical more than scientific. Both Seabloom et al. (1982) and Winneberger (1984) have found, on the basis of field measurements, that the performance of a single-compartment tank is equal to or exceeds the performance of a two-compartment tank of the same liquid volume."

When it comes to GGIs, the WERF report titled Assessment of Grease Interceptor Performance (2008) confirmed with bench testing, that the inclusion of a vertical baffle had a negative effect on the performance of the tank. The tank design that performed the best had an open design with no vertical baffle.

Now you know why I'm baffled when I see requirements mandating the inclusion of internal baffles.

Instead of telling us what you want an interceptor to look like, consider telling us what you want it to do and leave the design, research and development to those best able to create something that will do what you want.

Is there FOG in Food Waste?

I recently submitted an article to PM Engineer Magazine asking the question, "is there FOG in food waste?" which was published in the September 2015 issue.

If you would like to read the article as published, click here: http://digital.bnpmedia.com/publication/?i=272248&p=14

I came under some criticism for my position in objecting to having food waste disposers routed directly to sanitary under two proposed changes to the 2018 International Plumbing Code.

This article attempts to explain, based upon very basic research I conducted on the subject, why I believe food waste disposers should be routed through a grease interceptor, by means of a solids interceptor (as the IPC currently requires) to intercept the food waste in order to prevent the solids from prematurely filling up the interceptor.

Those in favor of routing FWDs directly to sanitary have attempted on multiple occasions to make their case. This article simply attempts to present an opposing position for readers to consider.

Please leave a comment below and join the conversation.

Where did the 30 minute retention time come from?

It seems today that it is universally agreed to that gravity grease interceptors (GGI) are supposed to be sized based on a 30-minute retention time.

Have you ever wondered where the 30-minute retention time came from? Is there a technical justification for its use? If not then what?

Commercial GGIs are actually residential septic tanks. The reason they work as septic tanks is because they are sized for very long retention times (typically 24 hours) and only have to deal with relatively low flow rates.

The genesis of their use as commercial grease interceptors is difficult to pinpoint, however we do know that beginning with the 1982 edition of the Uniform Plumbing Code (UPC) a methodology for sizing commercial kitchen grease interceptors was developed and placed within Appendix H. The method of sizing calculated meals per peak hour, waste flow rate, retention time and a storage factor. Appendix H was included with each subsequent edition of the UPC through 2003.

In 2006 the UPC removed Appendix H and changed the way GGIs were sized to be based on Drainage Fixture Units. A table was created that assigned a liquid volume amount for the interceptor to predetermined DFU loads. These loads were developed to try to ensure that the liquid amount would provide at least a 30 minute retention time.

The 30 minute retention time was taken from a textbook titled Small and Decentralized Wastewater Management Systems, published in 1998. The authors of that textbook provided the following technical argument for a minimum 30-minute retention time when using a septic tank as a commercial grease interceptor, "Typically, skimming or interceptor tanks are used to trap oils by flotation and grease by cooling and flotation. The contents of the tank serve as a heat exchanger cooling the incoming liquid, which helps to solidify the greases. For flotation to be effective, the interceptor tank must detain the fluid for an adequate period of time (typically greater than 30 minutes)."

That's it.

No research.

No studies.

No evidence that 30 minutes is the right amount of time.

No investigation into the effectiveness of a septic tank as a commercial grease interceptor. Just a statement that 30 minutes or more is adequate to allow for greases to separate in the tank.

Here are some questions to ponder:

How does a 30-minute retention time account for differing flow rates throughout the day? What effect do higher temperature surges have on velocity and flow pattern within the tank? At what point does the accumulated grease and solids effect the separation efficiency? If you travel past the horizon will you fall off the earth? Can you breathe through your nose and mouth at the same time?

You just tried that didn't you?

Since there has never been a technical justification for the use of GGIs, the Water Environment Research Foundation funded a study and published a report titled Assessment of Grease Interceptor Performance in 2008 to investigate the performance of these devices in real world installations.

The study found that GGIs were generally not sized correctly, regardless of whether using the older Appendix H or the newer DFU sizing method, and that they frequently suffered from short circuiting. You can read the report yourself by following this link: Assessment of Grease Interceptor Performance

The problem with the Appendix H sizing method is that it often resulted in over-sized interceptors leading to the generation of lethal amounts of H2S gas as well as elevated BOD and TSS in interceptor discharges.

The problem with the current DFU sizing method is that it often leads to undersized interceptors that short circuit frequently, especially during periods of high flow rates.

If we don't test these devices to understand exactly how they work, the things that negatively effect efficiency and how much actual capacity they have for storing grease and solids, how can we possibly deduce that a 30-minute retention time is adequate for any particular GGI?

The point is that before we go all-in with mandating the use of GGIs, shouldn't we at least do some basic testing to ensure they actually work?

I for one think you can breathe through your nose and mouth at the same time, though I admit that I've only been trying it for the last few minutes.

A Big Dirty Secret in Facilitator Magazine

In order for a food service establishment to maintain a grease interceptor properly they need to understand how much grease they produce and how much grease their interceptor can efficiently separate and store.

Schier's Corporate Accounts Manager, Traci Ismert, was given the opportunity to write an article for Facilitator magazine (the official magazine of the Restaurant Facility Management Association) where she was able to address this important topic with restaurant facility managers across the country.

Click here to read Traci's article

We believe our grease production sizing method is the most accurate and reliable method for sizing grease interceptors. Rather than sizing by flow rate alone, this method focuses on what a grease interceptor does to ensure an FSE gets the right interceptor with enough capacity to allow for a reasonable and affordable pumpout schedule.

For more information, check out these past blog posts:

Grease Production Sizing
The 25% Rule; where did it come from?
Understanding Rated Grease Capacity versus Maximum Grease Capacity
Kitchen fixtures and grease interceptors; does it matter?

Trapping and Venting for Grease Interceptors

From time to time I will get an email that contains a schematic of a grease interceptor installation with the question, "does this look right?"

Usually the email-sender wants to know if the trapping and venting is shown correctly.

The answer requires a knowledge of both the applicable plumbing code and the installation requirements of the specific grease interceptor.

Model plumbing codes require each fixture discharging into a grease interceptor be individually trapped and vented, and require the installation of a vent downstream of the grease interceptor.

Standards also come into play when it comes to determining the type and location of vents upstream of a grease interceptor.

PDI G101 mandates the installation of an vented external flow control. The vent on the flow control is an air intake.  As the waste stream flows through the orifice in the flow control device negative pressure is created, drawing in air from the air intake which is intended to mix with the waste water as it enters the grease interceptor aiding in separation efficiency.

ASME A112.14.3 allows four types of ratings as follows:
  Type A - units with external flow control, with air intake (vent): directly connected
  Type B - units with external flow control, without air intake (vent): directly connected
  Type C - units without an external flow control: directly connected
  Type D - units without an external flow control: indirectly connected

Manufacturer's are required to identify which Type their interceptor is rated to when certifying to the ASME standard. 

PDI G101 and ASME A112.14.3 Type A certified interceptors are required to have a vented external flow control installed upstream of the interceptor.

Okay, so lets take a look at some drawings and see what works and what doesn't.

What's wrong with this installation?

It depends on which model plumbing code applies to the installation.

The International Plumbing Code (IPC) 1002.1 (exception 3) allows a grease interceptor to serve as a fixture trap - where it is intended by the manufacturer to serve as a trap - for a single fixture or a combination sink of not more than three compartments so long as the vertical distance from the outlet of the fixture to the inlet of the interceptor is not more than 30 inches and the developed length of the waste pipe from the most upstream fixture outlet to the inlet of the interceptor does not exceed 60 inches.

This drawing for a PDI G101/ASME Type A grease interceptor appears to be compliant with the IPC.  Assuming the interceptor is intended to serve as a fixture trap, there is no requirement to install an additional trap and vent between the fixture and the interceptor. 

The Uniform Plumbing Code (UPC) does not permit a grease interceptor to serve as a fixture trap and also prohibits the installation of a vent between the air intake on the flow control and the grease interceptor. The above diagram would not be compliant with the UPC. There needs to be a trap and vent between the fixture and the vented flow control fitting.

What's wrong with this installation?

Actually, nothing!

The drawing shows a PDI G101/ASME Type A grease interceptor connected to a the three compartment sink that is trapped and vented, an external flow control with air intake and a vent on the downstream side of the grease interceptor.

This installation would be compliant with both the IPC and the UPC.

What's wrong with this installation?

The drawing shows a PDI G101/ASME Type A grease interceptor with an external flow control with air intake, however it also shows a trap on the fixture but no vent for the trap.

This is not compliant with the IPC since the code does not allow double trapped fixtures. The code does allow the interceptor to serve as a trap - assuming that this interceptor is intended to serve as a fixture trap - thus adding a trap to the fixture upstream of the interceptor creates a double trapped fixture installation. Either adding a vent to the trap or removing the trap on the fixture altogether would solve the problem.

The only solution for compliance with the UPC is to add a vent for the trap on the fixture upstream of the vented flow control fitting.

What's wrong with this installation?

This drawing shows a semi-automatic draw-off type grease interceptor but without a vented external flow control.

Since all semi-automatic draw-off grease interceptors are certified to either PDI G101 or ASME A112.14.3 Type A (that I am aware of) an external vented flow control must be shown for compliance with the IPC.

For compliance with the UPC this drawing would have to show both a vented external flow control and a trap and vent for the fixture.

What's wrong with this installation?

Again, there is nothing wrong with this installation, though it may not be immediately obvious as to why.

The unit shown is certified to ASME A112.14.3 Type C (without external flow control) with a built-in or integral flow control and does not require an air intake.

That being the case the interceptor does not require a vented external flow control - jurisdictions unfamiliar with this type of interceptor often question drawings like this and understandably so.

This installation is compliant with both the IPC and the UPC since it shows a trapped and vented fixture discharging through an approved interceptor without external vented flow control with a vent installed downstream.

Air Admittance Valves (AAV)

The UPC does not include provisions for AAVs except as a part of an "Engineered Vent System" under section 912.0, much to the chagrin of engineers around the country. Many states that adopt or adapt the UPC have added an allowance for AAVs so you will have to check with your state to see if they are approved.

The IPC approves the use of and installation requirements for AAVs under section 918.0.

What's important to remember about AAVs is that they only allow for the relief of negative pressure in the drainage system. Therefore, when using an AAV to vent a grease interceptor, it's important that the drainage system has provision for the relief of positive pressure to ensure proper flow.

Boilerplate drawings can be trouble

To be honest, much of the confusion over whether a drawing shows a code compliant installation of a grease interceptor or not, can be the result of boilerplate drawings provided by manufacturers in submittals or installation instructions. Manufacturer's want to provide guidance for a broad range of installations without providing detailed drawings for every single installation variable that can exist. 

When it comes to traps and vents for grease interceptors and the fixtures discharging to them, it's incumbent upon an engineer or contractor to identify and comply with local code requirements regardless what a manufacturer's drawing shows. 

Hopefully after reading this post you will find it easier to identify a drawing that is right for your installation or one that needs to be corrected. 

Steel grease interceptor's costly but last tearout and replacement

Steel grease interceptor's corrode and fail over time.  That's a fact that's generally not in dispute.

How long it can take can vary of course,  but is influenced by restaurant menu, frequency of pumpouts and thoroughness of cleaning.

A corroding steel interceptor feeds FOG deposit formation in collection systems with lots of iron oxide, and when it fails it leaches it's contents and contaminates the surrounding soil.

The average life expectancy for a steel interceptor is roughly five years.

The cost to replace a failed steel interceptor runs in the thousands of dollars, which is why we put together a video; we wanted to show just what it takes to tearout and replace a corroded steel interceptor.

The best long term strategy to prevent the problems associated with failing steel interceptors, of course, is to mandate or approve only interceptors made with non-corrosive materials such as heavy duty thermoplastics or fiberglass. 

Eliminating steel interceptors will benefit all stakeholders including restaurant owners, wastewater authorities and the rest of us.

Check out the video here: https://vimeo.com/130551325

Regulatory compliance manager; fancy title or job description?

Recent activities I have been involved in have made me think that people really don't understand what it is that I do for a living.

There's no secret that I work for a grease interceptor manufacturer, But, what do I do for Schier?

Am I in sales?  No.

Wait, let me correct that.  I believe everyone is a sales person in one way or another.  For example, my wife would say that she is absolutely not cut out to be in sales.  But when she really wants something, she seems to have no problem presenting me with all of the features and benefits that would justify her request - which usually boil down to me having a happy and contented wife.

Hey, who doesn't want a happy and contented wife?

I generally find that preferable to just about anything else in the entire universe as it tends to provide a much "safer" environment at home.

My kids are some of the best sales people I know, with their mom and dad anyway.  They can be very creative in their justifications for why we should do this thing, or buy that thing, or go to such and such a place, all the while hammering home the features of this or that and the benefits that either they specifically would enjoy or that we all would collectively enjoy together.

Sales is really just the art of persuasion.  Some are naturally more gifted at it than others', and they typically end up selling for a living, but everyone has sold someone something at some point in their life.

Okay, so in the sense of doing "sales" for a living, no, I don't do that anymore. In other words, Schier does not pay me to sell anything.  I can't even tell you what our sales look like anymore because I am very much out of that loop.

So what do I do?

You might say that I am an advocate.

Merriam-Webster's dictionary defines advocate as, "one that defends or maintains a cause or proposal", or "one that supports or promotes the interests of another."

Who or what do I advocate for?

I am an advocate for fats, oils and grease (FOG) abatement in wastewater collection systems to reduce or eliminate sanitary sewer overflows (SSO) and their resultant risks to human health and safety.

That is my job description.  It has taken a while for it to come into clear focus, even for me.

What it means is that, while I am paid to do what I do by Schier Products, I am not paid to promote or sell for Schier Products.

I am in fact paid by Schier Products to advocate for what I think is right for FOG abatement in wastewater collection systems.

The advocacy I do is both internal and external to Schier.

When working with Schier I may advocate for some specific product improvements to make field inspections by pretreatment personnel easier or I might advocate for a new product to solve problems I am seeing in the field.

When working with pretreatment programs I may advocate for improving the requirements in an ordinance, or to remove some restrictive language that will hurt enforcement efforts, or to stop mandating products that are untested for performance.

When working with plumbing codes I may advocate for improved less-confusing-language regarding which fixtures should be routed to an interceptor, or I might take a stand against proposed changes that might lead to conflicts with pretreatment requirements or would loosen restrictions that would, in my opinion, be harmful to wastewater collection systems.

When working with standards such as ASME A112.14.3, I might advocate for more accountability in the standard and less prescriptive design requirements that shackle manufacturers and stifle innovation - something very much needed in grease interceptor design and operation, in my opinion.

I think it's important to understand that I see what I do, not as a job, but as a calling.

I believe in the "cause" of FOG abatement.

When you passionately believe in something you are willing to fight for it. You are willing to take actions that you believe in your heart will make a difference for your cause.

I guess that means that you might ruffle a few feathers. You might not "go along" to get along - if getting along means compromising what you believe in.

That being said, I love engaging with the pretreatment community and others who are equally interested in the issues surrounding FOG deposit formation and the exploration of solutions that might mitigate its deleterious effects.

My job title sure can be confusing, but I take my role in the cause seriously and I welcome the challenges, debates, and struggles that are necessary to make a real difference for us all.

The 2015 IPC Committee Action Hearings - food waste disposer proposed changes

In case you are wondering why I haven't posted an article in like over a month, allow me to divulge my recent activities so you will understand and perhaps sympathize with how I set my priorities.

Well if not sympathize, perhaps you could at least feel some pity.  If its not asking too much.

Or not.  Hey, I'm not going to beg.

Anyways...
 
The 2015 Group A Committee Action Hearings for the International Building, Existing Building, Residential-Mechanical and Plumbing, Plumbing, Private Sewage Disposal, Mechanical, Fuel Gas, Swimming Pool and Spa, and Property Maintenance and Zoning Codes were held this past week in Memphis Tennessee (April 19 - 28, 2015).

I was privileged to serve on the International Plumbing Code committee during the hearings in which some 280 proposed code changes were heard.

Now, before going to Memphis to sit on the dais for two very long days, each committee member was given copies of all of the proposed code changes.  

While it would have been nice to just read them through on the fly in Memphis, we were informed in advance that we were required to put in just a bit more effort than that. 

They actually wanted us to review all 280ish proposals in advance.  Yeah.  Like actually read them.

That forced me to weigh my priorities because on the one hand I wanted very much to blog about something interesting, even if only to me.

On the other hand I felt obligated to wade through each proposal and the significant amount of supporting documentation that warranted at least a cursory glance if not an outright perusal.  

Feeling overwhelmed, I put all projects on hold and spent around three weeks methodically going through each proposal in the hope that my efforts would be rewarded later.

Rewarded I was.

Thanks to the preparation and hard work of each of the committee members we were able to get through every single proposal in just two days of sitting on the dais.

That's about 16 proposals per hour or less than four minutes per proposal.

That is a fast pace.

By fast, of course, I mean like Speedy Gonzales on Red Bull running downhill being chased by a herd of cats.

That being said, there were two proposals regarding food waste disposers that you might want to be aware of.

P 231-15 (abbreviated here by me to focus on the relevant portions of the proposal)
1003.3.1
Proponent: Julius Ballanco, JB Engineering and Code Consulting, P.C., representing InSinkErator (JBENGINEER@aol.com)
2015 International Plumbing Code

Revise as follows:
1003.3.1 Grease interceptors and automatic grease removal devices required. A grease interceptor or automatic grease removal device shall be required to receive the drainage from fixtures and equipment with greaseladen waste located in food preparation areas, such as in restaurants, hotel kitchens, hospitals, school kitchens, bars, factory cafeterias and clubs. Fixtures and equipment shall include pot sinks, prerinse sinks; soup kettles or similar devices; wok stations; floor drains or sinks into which kettles are drained; automatic hood wash units and dishwashers without prerinse sinks. Commercial food waste disposers shall not be required to discharge to a grease interceptor or to an automatic grease removal device. Grease interceptors and automatic grease removal devices shall
receive waste only from fixtures and equipment that allow fats, oils or grease to be discharged. Where lack of space or other constraints prevent the installation or replacement of a grease interceptor, one or more grease interceptors shall be permitted to be installed on or above the floor and upstream of an existing grease interceptor.

The part above that is underlined was added by the proponent to the original text.

Basically, this proposal simply attempts to eliminate perceived requirements that a food waste disposer should be routed to a grease interceptor.

While this proposal was disapproved, the second proposal dealing with food waste disposal units was not:

P 233-15 
1003.3.2 
Proponent: Julius Ballanco, JB Engineering and Code Consulting, P.C., representing InSinkErator (JBENGINEER@aol.com) 
2015 International Plumbing Code 

Revise as follows: 
1003.3.2 Food waste disposers restriction. WhereA food waste disposers connect to grease interceptors, a solids interceptor shall separate the discharge before connecting to the grease interceptor. Solids interceptors and grease interceptors shall be sized and rated for the discharge of the food waste disposers. Emulsifiers, chemicals, enzymes and bacteriadisposer shall not discharge into the food waste disposer.to a grease interceptor.

This proposal mandates that food waste disposers be routed directly to sanitary and removes any requirements for a solids interceptor between the food waste disposer and either a grease interceptor or the sanitary.

Testimony in support of both proposals centered around three issues:

1. That food waste disposers prematurely fill up grease interceptors with solids that require the interceptor to be maintained more often than would otherwise be necessary.

2. That a solids interceptor capturing the effluent from a food waste disposer prior to it entering a grease interceptor exacerbates FOG deposit formation. 

3. That effluent from food waste disposers does not have a deleterious effect on collection systems.

While I think testimony from supporters of the proposal may have been confusing to committee members, regardless the committee approved the proposal as submitted (in a narrow vote).  

Look, if I have to be honest about it, I don't mind this proposed change.  Food waste does fill up a grease interceptor prematurely.

So why am I bringing this up?  Because I think some of you may care about this issue and may not agree that the effluent from a food waste disposer is "good" for the system, at least not your collection system or POTW anyway.

So what can you do?

Join the Public Comments Process and make your voice be heard.  The Public Comments Process is open to the public (that's you and me) and it's the next step.

You have just as much right to object to a proposal as a proponent does to support it.

To follow the current code development cycle here's the link: http://www.iccsafe.org/current-code-development-cycle/

It was very obvious to me during the hearings that manufacturer's were represented in proposals, owners were represented in proposals, building officials were represented in proposals, even installers were represented in proposals...

The one group that appeared to lack representation in proposals is the pretreatment community. 

But, it's not too late to get involved if you want to have a say regarding proposals that may effect your jurisdiction down the road.

The Inherent Problems with CSA B481.2

You may be familiar with Canadian Standards Association's (CSA) standard B481 which governs hydromechanical grease interceptors.

What you may not know is that B481 contains two alternative ratings designated as B481.1 and B481.2

All passive hydromechanical grease interceptors currently certified to CSA B481 are all listed to B481.1, which is basically the CSA version of ASME A112.14.3 and PDI G101.

By now you must be dying to know what B481.2 is, right?

By "dying to know" what I mean, of course, is that you have at least a mild curiosity if not a feigned interest; something more than an out right I-could-care-less feeling about the subject.

Hey, I'll take what I can get.

Anyway, assuming that you are in fact curious or at least feigning interest in the topic, lets take a look at this alternate rating and notice some inherent problems with it.

B481.2 uses effluent concentration sampling for testing the interceptor. The test requires the interceptor to be filled with water first, then have crushed granite added up to the interceptors maximum solids capacity (unless the interceptor is not designed to capture and contain solids), then  the interceptor is filled with sunflower oil to the point at which 5 test cycles of 12,000 mg/L will fill the interceptor to its rated capacity.

The interceptor is then tested 5 cycles with the oil mixture in the prescribed concentration and the interceptor’s effluent is sampled multiple times during the cycle. The average concentration of the oil in the effluent grab samples is recorded as the efficiency for the interceptor in mg/L.

Here are the problems with this rating:

Problem 1
5.3.3 Flow calibration - the standard does not specify any particular flow rates for testing, but instead, refers to B481.0 which specifies a range of flow rates with a lower limit of 7 gpm (26 L/m) and an upper limit of not more than 100 gpm (380 L/m). Thus a manufacturer can simply pick any flow rate for any interceptor and having tested to that flow rate, report the results of the effluent testing without regard to the flow rate at which the interceptor achieved the rating.

Here's the problem...

B481.0 requires the interceptor be marked with its flow rate according to either B481.1 or B481.2, but not both. Therefore a manufacturer can have an interceptor certified to B481.1 at 100 gpm (380 L/m) and can list that flow rate on its label but it doesn't have to list the flow rate used to achieve the effluent testing results under B481.2.

It's one or the other.

For example, let's say a manufacturer tests and certifies their interceptor to B481.1 at 100 gpm.  They can then list that flow rate on their label.  Now lets say they want to test to B481.2 and they discover that the interceptor's effluent concentration is 300 mg/L at 100 gpm. Now lets say they want to show 100 mg/L as their results but can only achieve that threshold at 20 gpm.

They can show the 100 mg/L test results, but are not required to label the interceptor with the lower flow rate used to achieve these test results.

How will anyone know that the interceptor didn't meet the effluent concentration at the flow rate listed on the label?


Problem 2
5.3.1 Solids preloading - B481.2 requires the interceptor to have solids (in the form of crushed granite) preloaded up to the interceptors maximum solids capacity unless the interceptor is not designed to capture and contain solids.

Here's the problem...

B481.2 does not provide a test protocol to determine a grease interceptors maximum solids capacity. 

Problem 3
5.3.4 Oil preloading - B481.2 requires the interceptor to have oil (in the form of sunflower oil) preloaded, according to section 6.2.3, based on the interceptors total rated oil storage capacity minus the amount of oil that will be added during testing.

Here's the problem...

B481.2 does not provide a test protocol to determine a grease interceptors total rated oil storage capacity.

Problem 4
The test protocol under B481.2 mandates that the water and the oil used to conduct the test be at room temperature. We would expect to find lower effluent concentration results from cooler temperature oil water mixtures owing to higher viscosity and flocculation which would be more resistant to mechanical sheering forces and turbulence inside the interceptor. This undermines the credibility of the test results as a predictor of real world installation performance.

Aside from these inherent problems there are two other issues to note:

1. No approved testing facility in North America has ever conducted the testing protocol under B481.2.

2. We are aware of only one jurisdiction in the US or Canada that actually requires compliance with B481.2. This apparent lack of jurisdictional support only serves to undermine the viability of this rating which dampens the incentive for manufacturers' to certify interceptors to this rating on their own.

As you can see there are a number of problems with certification to CSA B481.2 and these problems are serious enough that jurisdictions should avoid policy decisions that would include mandating compliance with this rating until these problems are adequately addressed in future amendments to the standard.

YouTube Video - Grease Production Sizing Method

I realize that I recently blogged about the topic of Schier's Grease Production Sizing Method (here), but as I travel around the country visiting with pretreatment professionals I repeatedly see the need for a better sizing approach for grease interceptors.

Schier created a video to provide another tool to help jurisdictions, specifiers and contractors to not only understand how to size by grease production but also to be able to quickly explain the method to anyone else.

Flow rate or liquid volume based sizing for grease interceptors is inaccurate and inadequate, having led to thousands and thousands of incorrect installations across North America.

Grease Production Sizing is the only method that considers how much grease a restaurant will produce to ensure that the grease interceptor selected has enough capacity for a consistent and affordable pumpout schedule.

Here is a link to the video if you want to check it out:

http://youtu.be/c3HLV3dF89c

Schier's Owner's Manual - fostering partnerships for the environment

When you scour the pretreatment program landscape it's not hard to see that many jurisdictions spend a fair amount of resources on marketing materials or campaigns designed to communicate the need for restaurants to reduce the discharges of fats, oils and grease (FOG) to help mitigate their destructive effects on collection systems.

Why do some restaurant owners see pretreatment requirements as the enemy when in reality both desire a healthy environment?

Wouldn't it be great if more restaurants viewed themselves as partners to the pretreatment community?

I'm not suggesting that there is some kind of magical elixir that will act like a love potion creating an instant bond and lifelong partnership between restaurants and pretreatment programs, but I do think that manufacturer's can help.

We believe most restaurant owners see themselves as part of the communities where they live and work and that, if they understood the serious environmental hazard that sanitary sewer overflows create, they would want to do their part to help eliminate this very real threat to human health and safety.

Schier created the Great Basin^TM Series Owner's Manual to help restaurant owners understand the need for a grease interceptor, how to properly maintain their new Great Basin and how to mitigate the amount of FOG they discharge during normal kitchen operations, so they can feel good about doing their part in the fight against SSOs.

The environment is all of our responsibility and we all need to work together to eliminate SSOs and the danger they pose to our collective health and safety.

The partnership between grease interceptor manufacturer's, pretreatment authorities and restaurants is a potent force in this critical fight.

You can view the new owner's manual here: http://www.schierproducts.com/GI/gb_redesign/GBOM-0215.pdf

2015 IPC Expands Approved Grease Interceptors

The 2015 International Plumbing Code (IPC) has been out since the summer of 2014 and for the first time it has expanded the approved types of grease interceptors to include gravity grease interceptors (GGI) and fats, oils and grease (FOG) disposal systems.

Lets take a look at what's changed and note some problems that will have to be addressed.

Section 1003.3.6 was added to the code as a distinct new category for grease interceptors titled, "Gravity grease interceptors and gravity grease interceptors with fats, oils and greases disposal systems."

Note that these are actually two different categories for gravity interceptors with different requirements for approval.

• GGIs are required to comply with IAPMO/ANSI Z1001
• GGIs with FOG disposal systems are required to comply with ASME A112.14.6. 

I have covered all of the recognized standards for grease interceptors previously here: http://theinterceptorwhisperer.blogspot.com/2014/03/the-standards-that-govern-grease.html

As I explain in the post linked above, IAPMO/ANSI Z1001 doesn't have a performance test protocol, but rather only mandates leak testing.

Another problem with the standard is that it doesn't provide any sizing guidelines, which forces specifiers to look elsewhere for help sizing these devices.

The problem with the 2015 IPC is that it doesn't adequately address sizing of GGIs in the new section. Here is what it says, "the required capacity...shall be determined by multiplying the peak drain flow into the interceptor in gallons per minute by a retention time of 30 minutes."

Okay, so which method is approved for determining the peak drain flow into the interceptor?

It doesn't say.

I can outline the options for you though:

Fixture volume
The formula for determining the flow rate from a fixture is as follows: (((LxWxH)/231)*0.75)/1 (1 minute) or (((LxWxH)/231)*0.75)/2 (2 minute).

Calculate the flow rate from each fixture connecting to the interceptor and sum them together and then add the flow rates from any other fixtures, such as dishwashers or woks, etc. This is the maximum flow rate to the interceptor.

Pipe diameter
Using pipe diameter is another method for determining the peak flow rate into an interceptor. Pipe diameters in gravity drainage systems are determined by drainage fixture units (DFU) according to chapter 7 of the code. Maximum DFUs are calculated to ensure that the pipe will never be more than 50% full during peak flow periods. Maximum flow rates in horizontal drainage piping is calculated by Manning's Formula with the following results:



The design flow or half pipe flow values should be selected for sizing GGIs since they represent the peak horizontal flow for each pipe diameter.

The real fun begins when you actually take the peak flow rate you have selected and multiply it by a 30 minute retention time.

This will raise all kinds of interesting questions that your local plumbing inspector may have to answer:

• When using fixture volume sizing, if the jurisdiction requires a one minute drainage period calculation, how do you account for intermittent use of all of the connected fixtures, since the calculation doesn't account for it?
• Are you allowed to use a two minute drainage period for fixture volume calculations?
• Are you allowed to use a two minute drainage period for pipe diameter calculations?
• What if the jurisdiction mandates 6" diameter drainage piping outside of the building, requiring 6" connections on the interceptor; do you use pipe diameter or fixture volume sizing?

There is another area of the 2015 IPCs new section that bears consideration and that is regarding GGIs with FOG disposal systems.
ASME A112.14.6 does not mandate gravity grease interceptors as the required type of interceptor.  In fact the standard requires separation/retention efficiency in accordance with ASME A112.14.3 which GGIs are not required to be tested and rated to.

The last area of concern in the 2015 IPC is section 1003.3 which states, "Grease Interceptors shall comply with the requirements of sections 1003.3.1 through 1003.3.5, leaving out the new section 1003.3.6.

This oversight leaves the specifier with unclear and vague requirements as stated under 1003.1 and 1003.2 only.  Thus while hydromechanical grease interceptors and automatic grease removal devices have clear requirements spelled out regarding which fixtures are to be routed to them and how to handle food waste disposers and dishwashers, GGIs have no stated requirements.

Hey, even if you get all of that down for your project, regardless how you determine the size of the grease interceptor, how does an owner know that the interceptor is the right one for his facility?

Oh yeah, that's why we developed the Grease Production Sizing Method!

The 25% Rule; where did it come from?

Have you heard of the 25% rule?

In case you are unaware or have been off-planet for a while let me explain.

The 25% rule is used primarily by pretreatment authorities to determine when a grease interceptor (or oil separator) is full. A fairly universal definition would be:

"The total depth of the floating grease layer plus the settle-able solids layer cannot exceed 25% of the total liquid depth of the interceptor."

Determination is made by taking a core sample with something like a Sludge Judge or Dipstick Pro (I know of a few jurisdictions that use florescent light covers (clear plastic tubes) from Home Depot or Lowe's, with a rubber stopper).  The device is lowered slowly through the fats, oils and grease layer all the way to the bottom through the solids layer of the interceptor and then capped or plugged and slowly removed and set aside to rest.  This allows the captured FOG to collect at the top of the device while the solids settle at the bottom.

A measurement is taken, typically in inches, from the top of the FOG layer to the bottom of the device, which represents the tanks total water column.  Then the FOG and solids layers are each measured, also typically in inches, and added together.  If the combined FOG and solids layers are equal to or greater than 25% of the total water column then the interceptor is considered full.

For example lets take a typical gravity interceptor in the field like the one pictured here on the left. 

The technician is using a Dipstick Pro which appears to be showing a 48" water column and the technician is showing by the spread of his fingers a FOG depth of about 6" (okay, I'm guessing on that, but I have fairly large hands - not like Wilt Chamberlains, but I wear a large golf glove - and when I spread my fingers like his against a ruler its about 4.5" and adding a bit for the extra FOG above and below his fingers its about 6" or so, give or take).  If the solids layer at the bottom of the device is also 6" that would be a combined 12" of FOG and solids.  When you divide 12 by 48 you get 25%.

This particular interceptor is full, hence the stunned demeanor from the restaurant owner/manager as the technician gives him the bad news.

But wait, there appears to be quite a bit of space left in the interceptor for collecting even more FOG and solids, so how do we know that this interceptor is actually full (a question this restaurant owner/manager probably asked the technician)?

Here's the thing, it's not that the rule is a scientifically based determination of efficiency breakdown, or that the EPA has mandated it, it's more like a generally accepted rule-of-thumb that many jurisdictions have adopted.

Where did it come from?

Good question.

I've been looking for the answer for a while now and no one seems to know.

Seriously.

In 2011, while preparing for a presentation at the Pacific Northwest Grease Summit in Bellevue Washington, I wondered if there was a correlation between the capacities of certified hydromechanical grease interceptors and the 25% rule.

I took all of the major manufacturers certified units (JR Smith, Zurn, Mifab, Watts, Josam, and Wade) and did some very basic math.  For example, if a unit was certified at 20 gpm with 40 lbs grease capacity using lard, I converted the amount of lard in the interceptor, when it was full, into gallons and then divided that by the amount of water the unit could hold.

It didn't matter which manufacturer's unit I checked, the results were very similar and all within a narrow range.  The maximum capacity for storing grease before failure in each unit I checked was between 25% and 35%.

This is further supported by the Plumbing and Drainage Institutes 1998 (R-2010) paper Guide to Grease Interceptors - Eliminating the Mystery, in which they stated that PDI-G101 certified interceptors may need maintenance when as little as 25% of their rated capacity has been reached.

Fast forward to my more recent research in which I have been emailing jurisdictions, googling the internet and searching all available forums for any clue as to the origins of the 25% rule.

Honolulu appears to be one of the early if not earliest users of the rule.  A post on the Yahoo Pretreatment Coordinators forum said that the jurisdiction did the same calculations as far back as 1995 as they were developing their FOG program.  It was stated that the jurisdiction chose 25% to be conservative and it became the rule for grease interceptor maintenance enforcement in their new FOG program.

Many of the jurisdictions in Orange County California use the 25% rule based on a recommendation in the Orange County FOG Control Study which was not based on any science, but rather on a survey of FOG control programs around the US, many of which were using the 25% rule or similar standard such as maximum inches of accumulation of FOG or solids.

The 25% rule appears to be ubiquitous in FOG programs and ordinances, not because of any scientific or technical merit, but rather it seems to have its footing in the idea that 'everyone else is doing it' so it must be right.

The problem now is that the rule is well entrenched in these FOG programs and ordinances making it difficult for jurisdictions to be flexible with newer technologies that hold more grease in comparable foot prints to traditional designs, in some cases matching the storage capacities of much larger gravity style interceptors.

Schier Products Great Basin, Thermaco Trapzilla and other products looming on the horizon are capable of storing grease and solids to well over 50% of their liquid volume, but jurisdictions are challenged to figure out a way to allow an owner to actually benefit from these higher capacities, owing to limitations set on themselves through enacted policy.

Hopefully by understanding how we got where we are, jurisdictions can gain insight into how to either avoid the pitfalls in setting universal capacity limits and/or perhaps, correct any problems that may have been created in enacted policies that inadvertently punish owners who would choose to use newer more efficient higher capacity technologies.

Anyone out there that has more information on the history of the 25% rule please message me and I'll update this post. 

Grease Production Sizing

Although sizing grease interceptors, whether gravity or hydromechanical, has always been based solely on flow rate, this strategy falls short in that it does not consider how much grease a specific food service facility could produce.

There are many times when volume or flow rate sizing would lead to the same size interceptor for a subway sandwich shop as for a Mexican grill, however it is well understood by inspectors that these two types of restaurants produce significantly different amounts of fats, oils and grease (FOG).

Schier recommends using a grease production calculation to determine how much grease a particular restaurant is likely to produce in order to ensure that the specified grease interceptor has sufficient grease storage capacity to allow for a realistic and affordable pump out frequency.


 

We developed the above categories for restaurants based on feedback from jurisdictions and pumper contractors around the country, combined with reports such as the Brown Grease Study (Kennedy Jenks 2011) which gives detailed information about restaurant types and menu's as well as grease and solids production data.

The formula for calculating grease production requires three bits of information:
1. Grease production per meal - you simply have to decide by menu type which category (low, medium or high) that the restaurant falls under and then whether the restaurant uses flatware or disposable (plastic or paper) forks, knives, spoons, plates, cups, etc.

2. Meals or customers per day - if this is a franchise they typically have this information available. Independent start-ups may not know this information up front, in which case you may have to make an educated guess or phone a friend or consult a medium. Most of the time you can get close enough that the calculation makes sense.  Just remember that its better to err on the high side.

3. Days per pump-out cycle - this is simply the maintenance cycle you plan to use for pumping out the interceptor.  Most people will not maintain an interceptor that is sized to be cleaned out more often than once per month and most jurisdictions won't let an interceptor be maintained less often than once every 90 days.  Somewhere in between is the sweet spot for your project.

The formula for calculating grease production is very straight forward. You simply take the amount of grease expected per meal (a,b,c,d,e, or f), times the number of meals expected per day, times the number of days between pump outs to arrive at the grease capacity required for the interceptor.

Lets take a couple of real-world examples:

Example 1
McDonalds (medium grease producer, no flatware - category "c")
400 meals per day X 0.025 lbs per meal = 10 lbs FOG per day, or 300 lbs every 30 days, or 600 lbs every 60 days, or 900 lbs every 90 days.

You can also take a grease interceptors' certified capacity and divide it by the amount of grease production per day, to determine the pump out frequency as follows:

10 lbs per day would require:

Schier GB-75, 75 gpm, 616 lbs = 61 days between pump-outs
Schier GB-250, 100 gpm, 1076 lbs = 108 days between pump-outs
Trapzilla TZ-400, 75 gpm, 400 lbs = 40 days between pump-outs
Trapzilla TZ-600, 75 gpm, 600 lbs = 60 days between pump-outs
Mifab BigMax 750, 75 gpm, 150 lbs* = 15 days between pump-outs
Mifab BigMax 1150, 100 gpm, 200 lbs* = 20 days between pump-outs

*based on grease interceptors' actual third party certification (not based on the manufacturer's claims of performance, which cannot be proven).

Example 2
Buffalo Wild Wings (high grease producer with flatware, category "f")
642 meals per day X 0.455 lbs per meal = 29.2 lbs per day, or 876 lbs every 30 days, or 1,752 lbs every 60 days, or 2,628 lbs every 90 days.

29.2 lbs per day would require:

Schier GB-75, 75 gpm, 616 lbs = 21 days between pump-outs
Schier GB-250, 100 gpm, 1076 lbs = 36 days between pump-outs
Trapzilla TZ-400, 75 gpm, 400 lbs = 14 days between pump-outs
Trapzilla TZ-600, 75 gpm, 600 lbs = 20 days between pump-outs
Mifab BigMax 750, 75 gpm, 150 lbs* = 5 days between pump-outs
Mifab BigMax 1150, 100 gpm, 200 lbs* = 7 days between pump-outs

Of course you can increase capacity by increasing the number of interceptors in order to lengthen the pump-out cycle, i.e:

Schier GB-250 (2), 100 gpm, 2152 lbs = 74 days between pump-outs

Using the grease production sizing method is not limited to any specific manufacturer, you can use it for any interceptor.

The only thing to watch out for is the funny-business some manufacturers' play in making unsubstantiated claims of capacity that they want to be used in determining a pump-out frequency.

Sorry Charlie, that's just not going to work.

When in doubt ask them for their certified test reports to see what their actual/real/genuine/true/factual capacity is, then base the pump-out cycle on that.

High Capacity Hybrid HGI Replacement of 1000 Gallon GGI

Replacing a large volume gravity grease interceptor is expensive and time consuming.

Owners like Chipotle Mexican Grill are opting for better performing high-capacity hybrid hydromechanical (HGI) grease interceptors such as Schier's Great Basin series to replace failing concrete gravity interceptors at locations such as this in Belton MO.

This 1000 gallon concrete interceptor is just 11 years old:



https://www.youtube.com/watch?v=Y6Cz3KL838o&feature=youtu.be

Grease interceptors are not called traps anymore

Every now and again the question of whether a grease interceptor is still considered a trap comes up. 

Grease interceptor...grease trap...you say tomayto, I say tomahto - does it really matter?

The distinction is important enough that you should be on the lookout for a fearsome predator known as a lawyer.  These anal-retentive-jot-and-tittle-semantics-fanatics have already picked up the scent of blood in the water on this subject.

Disclaimer: the sharks in suits pictured here are not intended to represent any particular lawyer or lawyers; any similarity to actual individuals is purely coincidental.

Anyways...

It's interesting to see how the Uniform Plumbing Code (UPC) and the International Plumbing Code (IPC) have evolved on this issue over time.

UPC
Through the year 1997, the UPC mandated that grease traps have a 2" water seal (the minimum required for a fixture trap), allowed a maximum connection of four fixtures and allowed the grease trap to be used as a fixture trap for a single fixture provided that the distance between the fixture outlet and the grease trap did not exceed 4 feet and the vertical tailpipe or drain did not exceed 2-1/2 feet. 

In 1994 the UPC added or clarified a restriction by stating that, "no fixture shall be double trapped," which created a conundrum. Since the code prohibited double trapping fixtures, and since a grease trap was allowed to serve up to 4 fixtures, if the grease trap is considered a "trap" owing to its 2" water seal, and it can serve as a fixture trap for a single fixture, and it can receive the discharge of up to 4 fixtures, and each of those fixtures must be individually trapped, and each of those fixtures is then routed to a grease trap, then all 4 fixtures are double trapped, which is a violation of the code.

The 2000 UPC eliminated some confusion by removing the language that allowed a grease trap to serve as a fixture trap as had been previously approved and eliminated the requirement for a minimum 2" water seal. Yet this really only added confusion since a grease trap would no longer be required to have a water or trap seal but it was still called a trap.

The 2006 UPC eliminated the term grease trap and introduced a new term, hydromechanical grease interceptor (HGI), to define passive grease interceptors. By eliminating the term grease trap and all references to it, and by not allowing a HGI to serve as a fixture trap for even a single fixture, the UPC eliminated the confusion that had existed over whether a grease trap was a trap.

It's not.

IPC
Prior to 2006 the IPC defined grease interceptors and grease traps, which were distinguished from each other only in that a grease trap had a rated flow of 50 gpm or less while a grease interceptor had a rated flow exceeding 50 gpm. A grease trap intended to serve as a fixture trap in accordance with the manufacturer's installation instructions was permitted to serve as the trap for a single fixture or a combination sink of not more than three compartments so long as the vertical distance from the fixture outlet to the inlet of the interceptor did not exceed 30 inches and the developed length of the waste pipe from the furthest compartment outlet to the inlet of the interceptor did not exceed 60 inches (1002.1 Exception 3).

In 2006 the IPC removed the definition for grease trap and changed the definition of grease interceptor, removing any reference to rated flow, making it the term for a passive grease interceptor.  The code language under 1002.1 Exception 3 from previous codes was not amended, retaining the term grease trap, a term which was no longer defined in the code.

The 2009 IPC removed all references to the term grease trap. The code language under 1002.1 Exception 3 was amended, changing the term grease trap to grease interceptor.

The 2012 IPC introduced a new definition of grease interceptor adding two new terms; hydromechanical and gravity.  The term hydromechanical grease interceptor (HGI) was introduced as the new term for a passive grease interceptor while the term gravity introduced a liquid volume-retention time based type of interceptor.  Beyond simply defining the term, the code made no further reference to gravity grease interceptors.  Section 1002.1 Exception 3 remained unchanged.

The 2015 IPC added another subcategory for grease interceptors called fats, oils and grease (FOG) disposal systems and added section 1003.3.6 governing gravity grease interceptors and the new FOG disposal systems. Section 1002.1 Exception 3 remains unchanged. 

The problem I see with the IPC is in the misapplication of a HGI because the section doesn't require the interceptor to have a 2" water seal.  Instead it relies on the manufacturer to stipulate that the interceptor is intended to be used as a fixture trap in compliance with the language of the section. 

That's dangerous to me. 

By dangerous of course I mean like wearing tuna-laced swim trunks and swimming in shark infested waters.

The IPC could eliminate the confusion by simply requiring a 2" water seal for any interceptor approved for installation under section 1002.1 Exception 3.

Time for someone to submit a code change proposal for the next code cycle...anyone?