Bidding on this 8 acre pond 111K cu.yds, trouble is I don't know if our scrapers will run because the area is known for muddy conditions. Soil borings vary on the site from 16-25% moisture @ 11 ft (silty clay). We're going to backhoe a few test holes next week, I'd hate to end up with 50K yds my scrapers can't get. Material is to be used for compated fill. Always something to worry about
A silty clay with that much moisture is a difficult material to work. Any ground water observed in the bore holes? I would dig my own holes as well to see first hand what you could be dealing with.
Water was 40 ft. in 10-09 when the borings were taken however it is a tricky area because of farm irrigation there is a purged water table that is worse with 2nd or 3rd irrigations. We'll see what the hoe turns up, maybe have to put a clause in my bid stating ( material must be workable). Not sure what to do.
How far is the haul? Also I couldnt read the cuts of the excavation. There has been a lot of that going on around here for the last few yrs, because of all the levee work going on around here. Many times I have seen them have to top load the scrapers with an excavator or in extreme cases they have used off hwy haul trucks. Tough call, best of luck on the bid.
Maybe price per yard as long as we can get it with scrapers in normal mode, T&M after that. Mud in the cut is mud in the fill, slows everything down. It's a repeat good customer, my first time to deal with these conditions on a contract basis. Job is + or - 2700" in length
Up here in Oregons Willamette Valley contractors deal with silty clays and high moisture content pretty regular. Obviously, if scheduling permits, the best thing to do is try to wait until June or July when high temps and lower humidity create better conditions for using this type of material but even under the best conditions it can still be a fight to pass compaction tests. Short of that I have seen a number of different method employed. In really wet weather lime is literally tilled into the fill material after each one to two foot lift, really expensive and some counties have banned this. Most common method when using scrapers is to make the cut in short deep sections using open bowl scrapers and a push cat. As the cut develops it is best to limit the distance traveled by scrapers accross the finished cut areas. Weather permitting, if the fill area is quite large and shallow, the scrapers will ideally dump in thin lifts and a disc pulled by a tractor, preferably with some sort of knockdown blade is continuasly run throughout the fill to speed up the drying process. An old rubber tired log skidder does nicely. If the fill area is too small to facilitate discing and compaction without slowing production a seperate area is often used [called a farm] where the material is spread, disced and dried then reloaded prior to being placed in the fill. It is also common to find a selfloading scraper running around on the haul road or some other location on large sites carefully picking up any dust/loose fine material that is created by traffic or evaporation. This material is placed in the fill atop some of the moister areas and mixed in with the compactor. Works kind of like kitty litter helping to suck some of the moisture out. Really helps to have a sharp compactor and scraper operator for this. I understand that these methods go against the cardinal rule of having to move your dirt more than once and of course the price reflects the conditions most likely encountered based on the job schedule. Additionally it is quite common among contractors up here to look at mass ex as a break even necessary evil leading to more profitable pipe installation. We don't have many excavation contractors that specialize in any one type of excavation as you do down in California. May not be exactly what your looking for but I thought I would share what we do to give you some ideas. Keep us posted as you may come up with an even better idea!!!
Can't really tell but is that some sort of underground filtration structure to be constructed to the left of your retention pond?
I love jobs like that for my hoe and trucks. It is a pain in the fill. Spread it out, disc it, disc it again, dump elsewhere while it dries out, and hope it doesn't rain to make it worse. After this weekend I bet it is a little wetter now. Best of luck to you.
Up here we used well points to dewater sites. Would that be an option when giving the price for the job?
They dewater some places here to, for a borrow pits quite often. Lots of well points lower the water table enough that the material is dry enough to work with. Might be a way out of a sticky situation.
Rim ditch and hyd pump.
Hoe hit water about 9', soils report said 40' They sent the plans back to the engineer for redesign, bid postponed
That sucsk Dpete. All the money the owner spent on drills and geotechnical engineers and you find water with your hoe, to bad you couldn't have collected their fees...
DFC that is so right, pay big money and a guy with a hoe can find out in a few minutes. Hope you get another look at the job.
You just saved your repeat customer a bunch of money and headaches.... Here's hoping he realizes it and gives you a leg up on the rebid:notworthy