Hello, In my area there was a project called Proctor & Gamble Distribution Center. They had to get "good" clay about 40 ft deep out of a retention pond on site for the pad of the building so it would compact. I was also down to the new Honda Plant in Greensburg, Indiana where they are moving 7.5 million CY of earth. They were getting "good" clay for compaction on the pad. The example for my question is the Proctor & Gamble job. My first question is: Do the engineers state that the pad need to be compacted so many % and then estimator is responsible to have tests done to see if it will compact?? If not how does it work?? Next question is: If they need clay for the job does the engineer say..."Get the borrow from this retention pond"?? Or is the estimator/contractor responsible for finding the borrow pit that has clay that will compact. Next question: On highway ramps and overpasses, does the engineer state where the borrow should come from or is the contractor/estimator responsible for the borrow pit?? Final question: For example on Proctor & Gamble where the clay on the pad won't compact, do they take an x amount of clay off that won't compact, or just pile the good clay on top of it?? I know I have a lot of questions, but I want to learn a lot when it comes to earthwork and soil.
Ive only worked on much smaller jobs, but i would imagine the idea is the same. We have a soils engineer take samples of the borrow and test it in the lab. Then we know what we are working with, what the best moisture content for compaction is, etc. We have a soils engineer on site testing the compacted fill to make sure we are hitting our compaction numbers, usually 95% or more. They will take more soil samples as the job goes on incase the soil changes slightly, as it would throw all the tests off. contractor is the one who gets the soils engineer to aprove of the borrow and do all compaction testing. If you arent reaching desired compaction you cant/shouldnt just cover it and hope for the best, its either got to be removed or figure out why it isnt up to snuff. weather it be you just need a new test, different moisture content, different way of compacting, smaller lifts, etc.
Thanks for the info. Then the contractor needs to figure out how much spoil they may have how much borrow is needed?? So a lot of the winning bidder will come from who gets the nearest borrow and calculates the quantities correctly??
Yeah... whoever says they can move X amount in Y time for Z costs will ususally win the bid, if they don't get it done in time or run into unforseen problems, such as sinkholes (around here anyway) then that can eithre be a profit cutting problem or a Time and Money job. pretty much all cut/fill works on the same basic lines as the clay on your P&G job, like Tyler said, they will go and dig test pits and take the soil samples back to a lab and determine ahead of time what is the best method to reach the required specs. At least thats how it's been explained to me:wink2
Thank you for the info. On this P&G Job they got the borrow from the retention pond, they took around 200,000 CY out of it. So do you all think that the engineers stated there had to be a retention pond there of that size, and then the contractor figured to just use that soil as there borrow??
The retention pond was probably part of the Erosion and Sediment control and final plans. SO, in a sense, yes they did, but the contractor and the engineers probably got together and agreed that the material excavated from the pond could be used in a structural fill (two words that will become your friend and enemy in this business). In some cases, borrow pits are in nonstructural areas and can be back filled later with "bad fill", muck, topsoil or broken concrete culverts. ANother fun thing you can sometimes do, depending on what is stated in the contract is what is called undercutting. For example, lets say that digging this pond to grade you got 40,000 Cubic yards of good fill, but you're 5,000 short, as long as you're allowed to do this in the contracts you decided to dig X feet below final grade in the pond to get your extra 5k, then you'd have to use the topsoil or bad fill to bring the pond back up to grade. Like I said though, undercutting retention ponds isn't always approved, sometimes you have to find a part of the job that is to remain open or not built on. Sorry, rambled a bit there... hope that made sense.
Thank you Jim. That made a lot of sense to me, better understanded. Anyone else have any input??
I was thinking and came up with another question. If the building pad needs to have borrow put onto it does the contractor have the engineer or soils engineer determine how many ft/inches of "bad" dirt they will have to take off?? I was wondering how that was determined??
Your welcome, I always enjoy trying to help, when I think I know what I'm talking about. Course I love to learn about stuff I dont know about or when I'm wrong too, so any time. I'm sure one day you'll be teachin me a few things:thumbsup On our jobs, they will roll the area, Nuke it and then determine if it passes or fails and has to be undercut. How deep is determined along the same lines, sometimes it can even go until you hit a different phase of soil.
Thank you, that cleared a lot up with me. Nolan