testing grit waste

[cherokee235]

My city just passed a tough grease/grit trap ordinance. Cleaning is now required 4 times a year by a licensed hauler and testing of the water discharge at least once annually. The ordinance says the test must be conducted for BOD/TSS concentrate according to 40 CFR Part 136 Tables 1B and II. code of Federal Registry. All previous testing I've done shows all the chemicals in the mud, not BOD/TSS as far as I can determine. The numbers make no sense to me other than all concentrations are below EPA limits for hazardous handling.

I think the city is asking for some other measurement than what I've done in the past. Anyone familiar with this? The ordinance just past, so the waste water dept head doesn't have a clue what they will require yet. I'm trying to be proactive and ahead of the curve. I don't want any surprises.

David

 

[Dirtychuck]

TSS = total suspended solids
BOD = Biochemical Oxygen Demand

BOD basicly is a test to determine how fast biological organisms use up oxygen in a body of water.

TSS is what can not be filtered from water using filter paper.

Both of these tests are usually sent out to a lab for analysis.

Have you asked how/ where they want you to sample this? Typically, this should be sampled at point of discharge into the sewer main at the edge of your property, but is difficult to get an accurate sample due to layout of most sewer piping.

Sounds like a lot of extra time and expense to me for a car wash. Typically these tests required of heavy industry.

 

[Jony82]

Not sure what you are asking exactly, but I'll give you what I know based on the sewer discharge testing I conducted while a chemist at a large industrial plant.

TSS- Total Suspended Solids can be measured by anybody with the right tools. Take a measured sample of your discharge water, filter it through a piece of preweighed filter paper. Let the filter paper and the resulting debris on the paper dry. Weigh this paper then do the calculation to determine the total amount of suspended solids you are sending to the city based on your sewer discharge numbers. Another way would be to take a measured sample and just let the suspended solids settle out and measure the amount of debris at the bottom, not as accurate but you might be far enough below your required TSS numbers to not worry about accuracy. If you want to do the filter paper method, you'll need a pretty accurate scale and would be better off sending it to an outside lab. We measured our TSS numbers to 4 decimal places and you'll need a pretty pricey analytical scale to do that.

The BOD (biological oxygen demand) is much harder to test for and will probably need to be sent to an outside lab unless you have access to a digestor. You are basically measuring the amount of organic carbon being discharged. Things such as leaves, some parts of the mud, grass, etc. Sand, salt, and other inorganic substances won't count against your BOD levels but the sand will show up on your TSS testing.

I don't think you have to worry about your BOD numbers, they should be low for a car wash unless someone is dumping organic waste into your pits. As for your TSS numbers, your pits should catch most of it.

Hope that answers your question. Again, not sure sure what information you were wanting.

 

[cherokee235]

You've answered the question about what TSS/BOD is, but this is a different test than I've done in the past. The Texas DEQ (TCEQ) requires a TCLP test on the mud biennally which from looking over my previous tests shows the elements, metals, flash point, etc. but nothing about TSS/BOD. Since my city just past this ordinance, I will just shove my TCLP test to them and see what happens. They won't know the difference, for a while anyway.

Regardless, this will be more expense for my wash than I'm paying now.

David