Fixture Unit Conversion

[ccbuilding]

UPC 2009

I am being asked to convert gallons into fixture units.

This is in order to determine fees to be paid on unmetered, treated industrial waste water, that will be trucked to our wastewater treatment plant for final treatment.

Our ordinance reads that the user charge is based on fixture units per the UPC, not gallons.

I found 702.3 which shows 2 fixture units shall be allowed for each gallon per minute, but I'm not sure if that will work, as this is going to be delivered in batches of 6,000 gallons a day.

Any suggestions, ideas?

 

[mark handler]

How do I convert Water Supply Fixture Units to GPM?

 

[Dr. J]

The same way you would covert apples to oranges. Fixture unit is a rate, while gallons is a quantity. One could dump the 6000 gallons over an entire day, and it would be 6000/24/60 = 4 gpm = 2 fixture units. Or it could be dumped in one minute then the rate would be 6000 gpm = 12,000 FU. Fixture units is a dumb way to charge for sewer. Some buildings have a lot of rarely used convenience fixtures, some buildings use their limited fixtures heavily. The right way to charge (I know it does not help you) is based on the water meter in the non-irrigation months - what goes in does out. It sounds to me like this is a special circumstance that needs a special rate. What is the daily cost to treat the normal gallons per day? What is the normal gallons per day in the WWTP? What percentage is 6000 gallons? Charge the same percentage.

 

[Yikes]

On a separate but related note, do think there will ever be a change in the measurement of fixture units, based on the reduced flow rates of water conserving kitchen faucets, bath faucets, shower heads, etc.?

I have multifamily developers who re-pipe affordable housing and replace fixtures for water conservation. Occasionally we get a building official who says the old water service is undersized per current code (though legal at time of installation), and they want us to change the service as well.

 

[peach]

probably not; what's the problem with oversizing the drainage pipe (DFU is drainage fixture unit). Really has nothing to do with sizing water piping.

 

[zigmark]

Well the simplest thing to do would be just use the 2 FU per gallon. By comparison how does 6000 gallons per day stack up against other industrial facilities? What are they being charged? How quickly does this company expect to turn their truck around? 6000 gallons over 24 hours results in a fairly low rate, I would presume, which is why the question is being asked? If they want to pull up and dump the truck as quickly as possible just time it and redo the math. I would guess it would take 30-60 minutes.

ZIG

 

[ccbuilding]

Zig - Interesting idea.

FYI, we have no other industrial facilities on the system.

The company wanting to bring the wastewater in has now informed us that it will be 4 trucks on Monday, 4 trucks on Friday, 6,000 gallons each truck.

The powers to be still haven't come up with how they want to base the charges, but are working on it.

I have given them both Zigmark and Dr. J's suggestions.

This circumstance has lead to the whole ordinance being questioned and looks like it's going to be completely redone in some fashion. Whether that means we won't be using FU's anymore or what we will be using is still up in the air.

My job gets interesting around here sometimes, lots of juggling going on.