Solid waste disposal/weights and measures question

Factual Questions
1

I’m in the process of getting bids for waste removal. We have a 30 yd container that gets pulled about twice a month at a fixed cost per pull.

Of course the only competing bid I’m getting has a flat rate + an amount per ton. So I do not have a comparable quote. (Of course!!) I do not have any info from my current company on how many tons they pull and if I ask, well, they’re gonna know something is up and I don’t want to go down that road just yet.

So, here’s what I need to know: If I know the compactor is full for the two pulls a month, what (even a WAG would do) would be the weight of a full 30 yd compactor?

I believe that the 30 yd compactors have a fixed PSI that they compact at but I don’t know what it is. If I find that info, I’ll post it.

As usual, thanks in advance.

2

Depends what kind of setting this container is in. Are you getting rid of household waste, restaurant, industrial, construction, etc.? Different industries generate waste with different densities. This page has uncompacted waste densities broken down by industry - you can check there to get a rough idea. I don’t know where to find the compacted density - maybe guess how much the compactor reduces the waste volume and scale the uncompacted density up?

3

Looking at some test data I have from a commercial waste management company, there is considerable variation.

I’m looking at scale tickets for trucks hauling the dumpsters into the landfill, with the tare weight of the truck and dumpster subtracted out. I haven’t been at the landfill enough to tell you if the variation is mostly from how full the dumpsters are, or from other factors.

But here is what I’m seeing: The 20 and 30 yard dumpsters (oddly, there doesn’t seem be a lot of difference between them in the weight of the trash on the tickets I’m looking at) run as light as about 3000 pounds, and up to about 12,000 pounds non-compacted, although there are a couple of tickets that show as high as 20,000 non-compacted. These are probably construction waste, things like drywall, piping, etc, that runs heavy and you don’t compact anyway.

Compacted it looks like they run about 2 to 3 times that, although there is still variation. I see tickets for as little as 6,000 pounds, and for as much as around 24,000 pounds (2 to 12 tons). Most of the 30 yard compactor tickets I see seem to be in the 12,000 to 20,000 range, which would 6 to 10 tons.

I wouldn’t bet the farm on these numbers, as they are from a new system where the bugs are still being worked out, and there seem to be a lot of variables. But they are actual tickets from a system in use, and I think are probably good numbers, at least in the right ballpark.

Question: Can’t you ask the bidding company what their average weight per yard is, or what the average weight of a 30 yard compactor is? Seems like they should have a feel for it.

4

Thanks for the sight Enginerd. I thought about the different densities, but I also figured of everything was being compacted at the same PSI, the density wouldn’t matter, it gets compacted anyway, right? See, that’s why I’m an accountant and not an engineer.

RJKUgly I am going to call the bidding company this a.m. and ask them if they have some ballpark figures, I just always feel like I am getting the big screw when I have to deal with bidding out contracts. If I had some numbers to compare it to, I would know whether they are full of crap or not.

When I went out to the dumpster last night to look for a pressure gauge, I saw that the dumpster is attached to a contraption that measures something. We call for pick up when the gauge gets to about 2,200 (psi I believe - the gauge said PSI but it also said kpa/100, so I have no idea, really.)

Thanks again for the input.