holy SHIT !!!

TimBr

Official Well Known Greeter
Ground penetrating radar???
You beat me to it. This is exactly what I was thinking. I wonder if there is such a thing as a commercially available, reasonably priced machine that does this, or if it is only a hugely expensive military piece of hardware.

Edit: Found it, Bing search. http://penetradar.com/iris-gpr-systems.html. Look particularly at the man-portable units on this page.

Look at these guys, too. They were actually the first result, so maybe better, more popular? https://www.geophysical.com/products


Plus, the whole Bing results page. https://www.bing.com/search?q=ground+penetrating+radar+for+sale&qs=AS&pq=ground+pen&sk=ONR2AS2&sc=8-10&cvid=CDAB15DA791F4485BE790ACD552FD214&FORM=QBLH&sp=5&ghc=1
 
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ATH

Well-Known Member
Sounds expensive...until you are watching another crane pick your crane off of the neighbors house and the log off of the client's house.

Does anybody do that before setting outriggers? Even larger construction cranes? It would seem to be a very quick thing as I assume you'd just check a 4 or 5' x 4 or 5' area under each planned pad Relatively 'cheap' insurance in that you only have to buy once.
 

Adam07

New Member
Sounds expensive...until you are watching another crane pick your crane off of the neighbors house and the log off of the client's house.

Does anybody do that before setting outriggers? Even larger construction cranes? It would seem to be a very quick thing as I assume you'd just check a 4 or 5' x 4 or 5' area under each planned pad Relatively 'cheap' insurance in that you only have to buy once.
I am guessing that for larger construction cranes they have an engineered subgrade beneath the setup area
 

Stephen Moore

Well-Known Member
Client- hey your crane fell into my abandon shit hole! “ yeah Happens all the time... sorry I’ll pay to repair it for you?
 

theatertech87

Well-Known Member
You could also just use oversized outrigger pads. The company I work for does a bunch of work in cemetaries, and while they know where most of the graves are, there are a bunch of unknown and unmarked ones. (we've found them with bobcats and a bucket truck before). Any time the crane is heading to one, we bring along some 1 inch thick steel road plates for outrigger "pads" setup the crane on the road, set the plates where they need to be, then setup the crane in place
 

pctree

Well-Known Member
I don't have access to 1" steel plates which IMO would be somewhat unwieldy however I think Im going to mill some 6' 4x12" white oak timbers , 3 per outrigger.. We currently use 3" thick 3'x4' oak pads but as you saw they didn't hold up. I really think if we had some cribbing on it to spread load we might have been OK..

Life is a crap shoot
 

southsoundtree

Well-Known Member
I don't have access to 1" steel plates which IMO would be somewhat unwieldy however I think Im going to mill some 6' 4x12" white oak timbers , 3 per outrigger.. We currently use 3" thick 3'x4' oak pads but as you saw they didn't hold up. I really think if we had some cribbing on it to spread load we might have been OK..

Life is a crap shoot
I haven't used them, but my occasional 22t crane company has rentable steel plates for things, and presumably uses them for his crane when in need.
 

Stephen Moore

Well-Known Member
I’d imagine a tank or pit could be bridged using 6x8” wooden ties with a plate on top to spread the load.
I know around here that if the owner has a dry well, septic tank, septic field or oil tank below ground, must be registered with the provincial health authority. The location is referenced from the property lines and also measured from the structure. Your jurisdiction may not have that regulatory control. If my septic field goes bad, I have hire a certified installer to remove the saturated material of the field, replace with new parts and back fill with perkable soil. Then they need to inspect the tank for leaks. The process requires documentation that needs to be submitted to the ministry of health.
Seriously not trolling here, most of us are not in the septic business and may not be aware that a record of it may exist with your county. If the client is unsure about the location or history of a system and you plan to load up the ground, it may be worth your time to check! Kinda like “ call before you dig “.
 

SRTsteve860

Active Member
one good form of personal assurance and insurance, is to perform the necessary math specific to the crane and determine the maximum force that would be exerted on one outrigger, and once that load is determined, you can determine the necessary pad area to be within standardized load ratings for typical subterranean systems such as tanks, detention/retention systems as well as duct banks and utility tunnels. The general go to standard in the USA is aashto H20 load rating which is what your typical manhole cover and frame/catch basin and grate are required to withstand. the H20 load rating is with respect to a 32,000lb axle load, or 16,000lb load per tire/set of duals. The latest standardized testing/certification method for these structures is loading a 9x9 pad in the center of the structure to 40k lbs deriving a 2.5x safety factor. that 16,000lb load over 9x9 surface area (81 in-sq) would give you a ground pressure of 197.53PSI. Work your loads on your crane backwards to determine what pad area you will need to fall at that or below (for an even greater safety factor). from there you have a leg to stand on when it comes to recognizing the pertinent loads expressed by an outrigger pad onto the ground and anything beyond that would be from defective, non disclosed, or improperly installed structures.

On another note, for the construction company I am an engineer for, I have handled the construction of many crane pads, where it typically involves the excavation of any organic and fill materials down to virgin structural bearing soils and then filled with structural fill in uniform (typically 1' or less) lifts compacted and depending on the spec written for the project compaction tests are performed on each lift to assure everything is done properly.

-Steve

BTW-feels good to be back on the buzz, been away for too long guys!
 

ATH

Well-Known Member
.....

On another note, for the construction company I am an engineer for, I have handled the construction of many crane pads, where it typically involves the excavation of any organic and fill materials down to virgin structural bearing soils and then filled with structural fill in uniform (typically 1' or less) lifts compacted and depending on the spec written for the project compaction tests are performed on each lift to assure everything is done properly.

-Steve

BTW-feels good to be back on the buzz, been away for too long guys!
Great info there. However, in an environment where people still want to grow stuff, we don't appreciate the removal of the best soil and compaction of what is left. I think that should be part of the conversation. If it were my yard, I'd want larger pads long before soil destruction... but this is a common problem on any construction site.
 

SRTsteve860

Active Member
Great info there. However, in an environment where people still want to grow stuff, we don't appreciate the removal of the best soil and compaction of what is left. I think that should be part of the conversation. If it were my yard, I'd want larger pads long before soil destruction... but this is a common problem on any construction site.
that's why it was on "another note" in reference to a previous buzzer who mentioned pads on construction sites. I wouldn't advocate that type of process to be performed in a clients front yard, after all we usually use cranes to avoid damaging the landscape to begin with. Just wanted to discuss what goes into the preparation for big lifts, I've done some large warehouses where some real big iron was brought in to hang huge precast freestanding concrete panels and a lot goes into the preparation of those sites, luckily we can set the crane within the building pad which has already been excavated, filled and compacted in lifts, and ready to receive the slab as soon as the walls go in.
 

Stephen Moore

Well-Known Member
that's why it was on "another note" in reference to a previous buzzer who mentioned pads on construction sites. I wouldn't advocate that type of process to be performed in a clients front yard, after all we usually use cranes to avoid damaging the landscape to begin with. Just wanted to discuss what goes into the preparation for big lifts, I've done some large warehouses where some real big iron was brought in to hang huge precast freestanding concrete panels and a lot goes into the preparation of those sites, luckily we can set the crane within the building pad which has already been excavated, filled and compacted in lifts, and ready to receive the slab as soon as the walls go in.
The reason y’all do that- is the same reason we make sure a load limit is never exceeded in rope work! You can always dig out good ground to either prove the sub strata safe or make it so and replace with good when done work. You wouldn’t build a building on a foundation that wouldn’t take the highest loading sit will likely see, I wouldn’t pad up a crane on ground that wouldn’t take my cranes capacity, that’s just guessing on safety!
 
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