I seem to always battle the same ongoing problems. I thought maybe some input from others may help. Let me try and explain. I tend to get long winded, so my apologies in advance. I build grain storage tanks and grain handling equipment, both commercial and on the larger farms. Some of the smallest storage tanks I build are 30,000 bushels or so. The largest I've built holds 600,000. I'm bidding on some that hold over a million bushels. Grain weighs 56-60 pounds per bushel. Figure it up..There's a lot of weight on the ground..60 million pounds. Needless to say, the foundation has to be right. Manufacturers of grain storage tanks offer different foundation designs based on different soil conditions. But, all of their designs state the normal ..They're not responsible, these are just guidelines. Depending on the size of the tanks, their designs are based on soil bearing capacities of 3,000# per square foot, up to 5,000# per square foot. The small 30,000 bushel tanks haven't been a concern, but, the larger tanks are. Typically the basic foundation design is an Inverted T. A footing around the perimeter, 5-12' wide reinforced with rebar, then a wall on top of the footing 15" wide and 2-8' tall. This part of the country where I live and work doesn't have rock. Clay dirt is typical. We're loacted between the Mississippi, Ohio, and Tennessee Rivers. There's a lot of low lying bottom type ground that has filled in for millions of years. I know from experience 3,500# soil bearing capacities is hard to achieve. There's several locations I've uilt on that were at 1,000# or less. The right way to do a project is to start with soil borngs. Soil boring reports come back and to me it's mostly jibberish. I'm a contractor, not an engineer. I like the borings to be overseen by a reputable engineering firm,who reads and interprets the reports, then tells me how to build the foundation based on the actual soil consitions of the site. Some of these larger tanks cost well over a million dollars. Engineering and soil borings cost $5,000-10,000 depending on the scope of work. I'm a simpleton, but, it's a no brainer. DO the soil borings. But, time after time after time, the people want to proceed without the soil borings. WHY would they balk at this? I just don't get it. (cont)
Here's a description of the latest fiasco I'm involved in. The storage tank is 78' in diameter. Overall height is right at 100'. Holds 320,000 bushels of grain, roughly 20 million pounds. The site is suspect from the beginning. The site has a small creek running through it. The site is bottom ground. Water stands on the site. I've worked for this guy before. Started off with 50,000 bushels tank. They keep growing, and the tanks keep getting bigger. At 100,000 bushel tanks, I pleaded my case on the soil borings. Owner refused. I've got statements in my contract that should hold me harmless in the event of a failure, but, you guys know how our court systems are...Get the attornies and insurance companies involved...EVERYONE will be in court. Anyhow, Again, I push for soil borings. Again he refuses, assuring me, THIS is GREAT ground to build on. We excavate the footings, and 1/2 of the site turns to a loblolly. The other half stays firm. Drive a piece of equipment across the ground, and the ground pushes up and pumps, 10' away. We probe the bad side with rods, and in places one man can push a 1/2" rod 4' deep into the ground by hand. I recommend we excavate it out until we hit hard ground, since we had NO soil borings, and don't truly know what's under ground. We dug test holes first. Some of the holes we went 12-14' deep before hitting anything somewhat substantial. Others places it was solid on top. We recommend excavating the entire site out the full 12' deep. Then haul in crushed stone 3-6". Come back with 12" or so of DGA as a fill to choke off the water. Then a layer of filter cloth, then a cheaper sandy red gravel that's used under state highways. I'd rather have crushed stone all the way up, but, there's a cost factor involved. (cont)
The guy cut the big rock tonnage in half. He doesn't use ANY DGA or filter cloth, and he uses a cheaper bank gravel as fill. He gets the first layer in, turns the vibrating drum on, and it almost turns over. In case you can't tell, I'm frustrated. I HATE seeing people waste money. I HATE everyone thinking they're an expert. How do I head this off before a job gets to this point?
Personaly I wouldn't do it with out soil bores and an engineer signing off. The liability of someone getting killed from a failure are to great. Your customer will probably find out no one else will build them either with out an engineer getting involved. My local CooP has had several 105s put up and would not think of not doing it right. good luck pointrow
I would not do it without the proper soil tests and site engineering. You are setting yourself up for a major disaster. they will have a hard time finding anyone else to do it without the proper procedures being done before any ground is broke. Remind your customer that everyone will loose if legal issues come up and he as the owner will be the first in line.
I would of thought the local building dept would have to sign off on the foundation subgrade, around here they inspect yard barns
blademan, usually agricultural is exempt from code restrictions / enforcement. Impact, you just learned why building codes came into being. Aforementioned farmers silo tips over and kills someone, then come lawyers... Try this with him show him the cost drilling the soil per bushel stored. Pay a soil tech to explain to said farmer what he is doing is about to capsize his silo. Bring over another farmer, maybe a friend or someone else that can talk reason, do you have ag resource people from the state university to help in matters such as this. Last but not least explain it to his banker. If that doesn't work you need to do one of two things, walk away from the sale, or do it the right way at less profit or possible loss to save the customer relationship. Imagine the phone call after 320k bushels of corn + the silo are ruined... No business was ever ruined by doing right by the customer, even if they didn't know it at first.
I'm confused or not comprehending your post. Are you building the silo and someone else is doing the site work or are you the GC from the site work to completed silo? I understand your frustration, however the projects that I have done over my career involve multiple layers of inspection and review and an engineer -civil, geotechnical, structural, etc are foregone members of the project. I couldn't imagine building a structure like that without soil borings and geotechnical engineering. So in your area are there no plans review, inspections, local building department approval etc for a structure like this? To me it sounds like the engineering liability is being somewhat placed on you, which is a very scary situation. As you stated your a contractor and not an engineer, I also share that sentiment. Engineers are paid to design a project and compile a set of plans for the contractor to go by. Everyone shares in the risk. Engineers are paid well for their design and knowledge and contractors are paid for their ability and knowledge to take paper to reality. You shouldn't be taking on the risk of "engineering on the go" when you are not being paid for it. The best advice I could give you without knowing more of the specifics is an old saying - "I never lost money on a job I didn't get". :cool2
Stumpjumper What you said about explaining it to his banker is a very effective tool........ it may seem a bit underhanded at the time, but in the long run he may be glad he did......if for no other reason than to be able to sleep at night.
Some times its hard to tell when you think solid ground is, one time i saw a well driler lower a casing into the hole, he took the chain off and turned to secure it, i was standing a few feet away watching, all of a sudden the pipe took off out like a bullit down the hole, the well driller turned around and looked astonished that the 8" pipe was gone. Some times you just have have to stand your ground, its a hard spot somestime. Good luck, stall as long as you can untill it gets worked out.
Typically these jobs are negotiated. Not the typical Design/Bidding process/Build/Inspact like you'd see on commercial and governmental building projects. I consider myself the GC, although in reality the Owner acts as his own GC. Typically the Owner contracts the site work and electrical. I've done several building projects Design/Build with great success. Whenever the project is finished, the Owner, myself, and the sub-contractors are all more than 100% happy. I've tried to break into grain storage projects as Design/Build, and the market seems to balk at the idea. Everyone would be better off if it was a Design/Build project. I typically will contract the project based on certain geotechnical minimums. If the site is suspect, I've insisted on geotechnical work. If it's not, I strongly recommend it anyway. That's worked for me, for the most part. Most people understand, and don't balk at the few thousand dollars it takes to do that. There's always a few that balk though. I met with an engineer, and an excavation contractor yesterday. Starting now, my proposal will include the geotechnical exploration, and the engineering required to do it right. It won't be optional, it's just part of the package.
Agricultural projects are exempt from plan review and inspection processes. The only difference is larger projects within the boundaries of city limits. Even then all that they want is the building permt fees. Never saw an inspector on one of these type of jobs. The only problem I've seen in permitting those jobs was hight restrictions based on dimensions to property lines etc.
Agricultural projects can have major failures as well. One such case in my area ended up killing a truck driver, structural failure was the cause in that particular incident, that was a grain leg as well. I'm glad to hear you are making the borings mandatory and part of the package.
OK I understand it now. I'm sure you have a detailed contract with the owner that protects you and defines each party's responsibilities and liabilities? Good idea. Having it included is going in the direction of design build too. You may have to slowly introduce the design build process a component at a time to your customers, until they see the value firsthand.
I do...BUT, being the devil's advocate here...I'll paint a picture of reality.. Let's say there's a catostrophic failure. The tank bursts wide open spilling 20 million pounds of grain and twisted steel. Buries a truck driver who has three kids, one handiapped, and a wife with a bum leg, and a bad eye. The owner is facing a loss upward of 2 million. HE may understand our contract, that outlines liabilities and responsibilities, but..Bottom line, he turns it in to his insurance company. They don't want to pay the damages neither. They're looking for the responsible party. They have attornies on retainage ready to argue a case. Before it's over...The owner, myself, my subs, and suppliers ALL end up in a legal entanglement lasting 5 years or more. If it goes to court, no matter how my contract is worded...I forecast the courts would rule that since I have my business sign up stating I'm a professional business specializing in these types of structures, I should have known better. I say it doesn't matter what the contract says.
My thoughts exactly. Remember, a lady sued McDonalds because coffee was hot [gee...ya think?], and won the case. Even if you have all the perfect wording in your contract that defines your legal liabilities...you still have to go through the court process to exonerate yourself. It's still a hassle.
Well yes and no. Unfortunately I have first hand experience with the scenario you have described. The issue was implied warranty of fitness not a catastrophic failure. As the insurance companies duke it out with one another, your contract with the owner and how it is written is very important. Arbitration clauses can be enforced by a Judge even if the other party skips straight to court. Indemnity clauses and detailed responsibilities of each party are other important aspects of a construction contract. The lawyers will use these items in your contract to compel the other side to abide by the conditions of the contract and from my experience a Judge will rule in favor of the contract conditions. My point is, a well written contract that jives with your insurance policy and carriers guidelines will go a long way in the defense department should something happen, although when the :shf every person involved in the project will get some on them. A good contract is just another layer of protection coupled with a good insurance policy. It won't keep you out of trouble but give you something to fight with.
Very well spoken CM. A lawsuit is what it is, so having every Ace in your hand from the begining will enhance your chances of coming out on top or at least from loosing everything that one has worked so hard for to accumulate in life. Another reason to periodically review insurance needs to insure that a your are covered to the best of your ability and current needs.
Is there not a court tested contract that you can use? may be a government type design and build, or a design novation type. As a specialist contractor you will be deemed to be the competent party and in that role you may be held liable. Now here is a little question .............would you or any one put up a 20 story building on the site without a geo survey?? By advising on the type of foundation without all the info you are ass out to the wind. Having a properly designed substructure will be cheaper in the long run and from what you have said thus far I would be looking at a piled raft.................. Do a google on this transcona grain elevator failure
It seems like overkill, but I would have an attorney draft a standard form contract to provide you with the best protection possible. Also, it has already been said but I would present the geotech investigation and report as a standard procedure (which it should be) the geotech should work for the owner, NOT you. If the geotech finds that the native soil types/conditions are suitable for the load of the structure, I would proceed but would require that the owner continue to retain their services for construction and material inspection throughout the project to insure that their recommendations are followed. Should the geotech find that the site conditions will not be suitable in their natural state, I would require that the owner retain their services in determining what measures can be taken to improve the site conditions to bear the load. If the native materials cannot be worked into a suitable state, I would require that the owner retain the services of a structural engineer to coordinate with the geotech to design an alternative foundation that will bear the load in the native conditions/materials. I just went through this exact process on a foundation project and ultimately it all worked out for the best. I would also try to estimate the potential cost of a catastrophic failure of one of these structures and make sure your general liability claim limit is high enough to bear it.
Stock, I looked up the elevator failure and have some questions, first if I understand correctly they righted the silo, as in put it back upright and used it again? If so how did they do that, next, since the report only had the requirements needed to hold it up, what was the recommendations of how it should have been done to avoid the problem in the fist place? set down pilings, put in 50 feet of rock first, what? I'll admit I got lost in the lingo they used, but also was the study done in the 1950's to the existing silo site with the silo still on it or after the silo was down and gone? Impact, I understand fully what your dealing with, farmers are excempt from the laws that govern most out there, it sounds like you have a good plan, even if its not required by law to be done, require it for your business to be done, no exceptions, if it were me, depending on how things are going, I'd hire the engineer out of pocket on the project and follow his advice, if he says its not safe to build on, then don't, give the owner the ultimatium of either doing it right or hire another contractor to finsih the project, its never too late to have stipulations on any job while your onsite and working there yet, get an attorney involved and right now, follow his recommendations and do as he says. I've refused to do work that cut corners, and I've also left jobs where corners were cut, those are not jobs worth having or doing, if the owner has alrready cut corners, I'd toss up a red flag and start to put stipulations on things, before they get ugly or tied up in court later on, today you have a choice, tomorrow in the legal system you have none, but are dictated as to what happens, if things are looking bad, stop or correct it today, before its too late, any way you have to and if that means to leave the job uncompleted, so be it. Just my two cents worth.
Update on the current project. The foundation is in place. As stated in my first posts, the site was excavated 10-12' deep. Instead of the 18" of big stone, he used about 8-12". He used a bank gravel that was sopping wet until he firured out it wasn't working. He dug it all back out again, and started over. He started off right this time, but halfway up he let money dictate and he used a cheaper fill material. It seemed satisfactory, but barely. I feel the structure will be OK, but, barely. What's under the 12' of fill material? :beatsme Hopefull if it settles, there wouldn't be much differiantal settlement. I'm on the verge of signing another contract on a larger tank for a commercial customer. The soil boring costs are in my contract. The proper fill materials (with allowances) are in my contract. If soil borings dictate special foundations be engineered, the procedures are in my contract. I suppose he could balk at the procedures, but, he'd be in breech of contract. (provided he does sign LOL) Dang it's hard to change my ways as I get older. :Banghead
Stock, The transona elevator read was interesting. I did a project couple years ago that seemed to have no bottom. We used auger casts. It's been in operation 2 years and we can't see any settlement issues. But, man, that is a sloppy procedure.
Yes if the structure is of sufficient strength to take the stresses involved it can be possible to inject grout to raise the CBR of the ground. I hear that, on smaller structures it is possible to inject a two part chemical structural foam that expands and returns the building to a corrected position. The most famous righting of a building was the leaning tower of Pisa where the removed the better clay ie the side that was capable of holding the dead load of the building and letting it settle as the tower was not of sufficient structure to take the stresses involved be the injection process.............. Ultimately a good foundation or substructure will distribute the dead load of the building through to the ground. http://www.wbdg.org/ccb/DOD/UFC/ufc_3_220_01n.pdf go to chapter 11 for some reading..........
Stock thanks for the articles to read and replying. Do you have any articles of recent failures of bin setups, these size bins going up today, with none or little engineering scares me and I'm thinking its only a matter of time before something major happens, we've been taking down a lot of silo's in recent years and most have that leaning tendency, the base prep is about the same for new bins going up and it makes me wonder, just how right or adequate these sites are, with the major amount of weight difference there is to the old outdated small silo's of the past. Impact sounds like you've got the system figured out, have it in writing to give you room to do what needs to be done so it is safe, as for getting set in your ways, I'd like to think of it as getting too told to be jerked around by someone wanting to save a buck. I've always been under the idea of do it right the first time, saving a buck only ends up costing way more in the long run. While we're on the subject and since I'm not an engineer, can anyone tell me how sand can be an acceptable base material for a large bin? There was guy near me that built one last year, a big one, and he dug down till he hit sand and started building his bin from there, my question is what happens if someone were to do some excavating beside the bin and the sand is in a pocket and the collapsing or oozing of sand would literally erode it from under the bin, Now I understand that rock would make a solid base material or compacted clean rock even better but whats to stop the sand from shifting, expecially when saturated with water. We had to install some drain tile around the bin and the ground was so sandy we had to use socked tile to keep the tile from filling up with sand, and this is an acceptable base material for a bin, I"d think bedrock would be better, can anyone educate me on this.
You're right in one regard, sand is OK as long as it's contained. I've been on projects they've used rock around the perimet to contain the sand, with sand in the middle. I've also built a few tanks on the edgeof the Mississippi river where the ground has a tendancy to be sandy, and shift. Engineer speced it out expecting 12" of settlement. Again, 12" was OK if properly planned for, and it's not differential settlement. We shot grades on the structure before it ws filled, and after. It settled 12" in spots and as little as 9" in spots.
Impact. I would say a soil bearing study is a must, and nobody in thier right mind would go without it on a bin of that size. Especially on the soil you describe. You can do the math easily enough. Take the total weight of the bin and divide by the total area of the foundation circle. That gives you the pounds/sqr ft you need to support. Bin structures normally support the internal weight uniformly over the floor area. If your calculated load exceeds the load bearing capacity of soil, she'll settle. Of course, it won't just go down nice an even like. It'll start to drop on the edge somewhere, cracks will open in the concrete. It will take several years likely to get to the point of sidewall rupture. But by then you're (the owner) screwed because it takes 10 times as much to fix it as it takes to do it right in the first place. You only get once chance to do a foundation right. If you could find some pics of bin wall failures on the web, you should be able to convince the man of your point of view. Keep in mind though that an engineer is going to design a foundation structure so overblown you won't believe it. That has been my experience.
I took a quick look at the gsi website, that bin you're talking about is a 27 ring monster. Before i go any further, i want pics of her when she's done! Your 20,000,000 pound estimate is likely right including the weight of the bin and foundation. Divided over 5280 sqr ft of foundation, and you have just under 3800#/sqr ft. That is higher than some of the best soils. I simply can not believe even the bin provider will allow the bin to be erected without and engineers stamp on the foundation. That is just insane. What i have seen done in this situation is the engineer will widen the bearing area by building a concrete apron around the the bin. I know of a 30' silo with a 60' diameter foundation. This was done because the bearing tests came up short. The foundation cost the same as the rest of the silo because it was thick with concrete and rebar. If i was you, i would swallow the engineering costs on it and have your tests done, knowing full well that the soil is going to fail, and your "farmer" is going to balk at the solution. What happens after that won't be your fault. You can walk away with a solid reason, or you can convince him to do the right thing. Either way you don't come out looking bad, or liable. Good luck, and post pics!!!
Here's some photos of a project a couple years ago. Soil borings came back at 1,000# or so. We did 18" auger casts 58' deep. There were about 210 as I recall on a 105' diameter tank. Capped the top of the auger casts with a 2' thick slab 120' in diameter. Placed 8' ringwall type foundations on top of that. Oops...going to have to work on the photos.
Ok, didn't want to start a new thread with this one, so just posing it here. I get a call yesterday, (while I was running a crane on a job, but was idle at the time) from a guy wanting me to offload a locomotive from a flat bed trailer. Evidently it's going into a local new park/museum under construction. I have a 100T and a 60 ton hydro. My first question of course is...what's it weigh? 70 tons. My first comment was, there's NO WAY my 100 T will do that, you need a 200T. He starts argueing with me saying, you can get right next to it, and we only have to lift it high enough to clear the trailer, then right down to the ground. What makes people want to argue? I got back to the office and checked my load charts using both cranes. It takes 12' just to celar the outriggers. I'd guess 18' radius..My 100T is good for 105,000 pounds. The 60 is good for 60,000-65,000. 105,000 + 65,000 = 170,000 or 85 tons. Still, the guy needs to rent a 200 ton crane. Here's my take on it. A 200 T will be as cheap or cheaper than me sending both cranes. One foot makes a HUGE difference. The reality of actually getting an 18' radius? I'd allow 20-22'. How can I be assured that the 100T will get the 105,000 and not 120,000 or 75,000. If the 100T has 75,000 , the 60T is overloaded. I don't even have rigging for that sort of load. I don't know where to attached to a locomotive. I think this guy is a broker somewhere trying to make a deal. I hate those guys. How would you handle this situation? I just told him I can't do it, and refuse to argue with him.
Impact don't forget the spreader bar /frame & rigging.............................
Can you go rent a 200T and do the lift for him, and bill enough to cover the cost and add some money for your trouble?
Exactly. My spreader bar isshop built and I pick 10,000-20,000 pounds with it. Not designed for that kind of weight
As far as I'm concerned you handled it right, just refused to do it and hang up, as for argueing with anyone on the phone over what your machines are capable of, I wouldn't waste my time, I tell them to just find someone else, I'm busy and that usually ends it there, remember your probably not the only one who's maybe wondering what kind of idiot they are, the ones with a crane capable of doing the job probably told them off aready and now they are desperate to get it done any way imaginable, and if something goes wrong, they are not responsible, you are.