2.1 million square foot distribution center investigation
2.1 million square foot distribution center investigation
(OP)
I would like to know what you would do for an investigation for a large distribution center warehouse about 2.1 million square feet in size.
How many borings would you do, what type of equipment would you use, how would you structure your investigation? And how much could you charge for it? How much would your clients be willing to pay? What sampling would you collect, and what lab testing would you do? How long would it take you to do, and what would you put in a report? How much effort would it take you to write such a report?
I would like to get a feel for how much difference there is amoung all of you on something like this.
A little background to help.
You know the geology quite well. The land is flat, and the building will likely be constructed very close to the grades of the existing ground. The groundwater is shallow, the earthquake shaking is very high. Bedrock is 20,000 feet down, your geology is probably lake deposits, blow sand, and alluvial deposits. You have conducted investigations on land in the immediate vicinity, or have some data from the land close by to help with your overall understanding and comfort level of the geology etc.
What type of foundations would you consider?
How many borings would you do, what type of equipment would you use, how would you structure your investigation? And how much could you charge for it? How much would your clients be willing to pay? What sampling would you collect, and what lab testing would you do? How long would it take you to do, and what would you put in a report? How much effort would it take you to write such a report?
I would like to get a feel for how much difference there is amoung all of you on something like this.
A little background to help.
You know the geology quite well. The land is flat, and the building will likely be constructed very close to the grades of the existing ground. The groundwater is shallow, the earthquake shaking is very high. Bedrock is 20,000 feet down, your geology is probably lake deposits, blow sand, and alluvial deposits. You have conducted investigations on land in the immediate vicinity, or have some data from the land close by to help with your overall understanding and comfort level of the geology etc.
What type of foundations would you consider?





RE: 2.1 million square foot distribution center investigation
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as far as subsurface conditions, if something goes wrong in one single bay of the building, the client could lose massive amounts of money since problems typically extend out several bays from a single problem bay. it may boil down to shutting down the building or having a problem renting out the space or selling the building. but if they've got the money to build a 2mil sf warehouse, they've got the money to do the exploration. besides, on top of saving them money through good engineering recommendations, it is added insurance for them. they could go get cheap recommendations that may cost them big time by the time the building is constructed.
hope this helps.
RE: 2.1 million square foot distribution center investigation
I'd do a CBR or two in the building area for correlation to subgrade modulus. I'd also drill in the heavy-duty pavement areas and also get a CBR or two. Each CBR will have a Proctor, so it can help during construction as well.
No clue what local issues may change my generic approach, but for many jobs I've been o.k.
f-d
¡papá gordo ain't no madre flaca!
RE: 2.1 million square foot distribution center investigation
shouldn't you be doing this ?
RE: 2.1 million square foot distribution center investigation
You haven't said what the floor loads are going to be. If they are large and they're laterally extensive, you may have settlement issues. If your geology is Holocene, you probably do have settlement issues. If the geology is older, then you probably don't as all that earthquake shaking will have densified the sand.
I think you should propose a phased approach - depending on floor loads and your expected vertical zone of influence, you should do some deep borings to see if you have compressible strata at depth. If you don't, I think I would do one CPT per acre scattered across the footprint and see how variable the subsurface is. I would also do a couple of geophysical lines across the footprint to see if there's some buried feature that you might have missed with the borings.
RE: 2.1 million square foot distribution center investigation
My problem is a real one that I realized would be a good one to use for discussion. My other problem is that in my particular neck of the woods I am up agains not one but three other geotechs who will do it for quite cheap. And they have been long established so that is what most people expect. Makes it hard to get work. Something like this is where I might be able to work my way in and get a job. Things are very very slow for everybody in my area right now.
As I first said we have data in the imeadiate area to start with so that helps. We most likely will start out slow with only a very minimal amount of work to get our foot in the door, then see if we can do a real amount of investigation after that. I would like to do CPT, some hollow stem, and then some test pits.
Msucog, I have read the open file report and in most of our area it will help out in reducing the shaking we design for, but it will not make to much difference in this area. The ground will liquefy, there is no doubt about that, the only question is how much settlement, and how badly I will loose bearing capacity. I would like to think I could make a mat slab or raft foundation system work, I don't know how it would do over so large an area with the liquefaction. I don't know what the floor loads will be, or anyting really beyond the fact that it is some kind of distribution wearhouse, of which there are many all over around here. So probobly heavy forklift traffic and large stacks unloaded from the containers as they come in from asia, then redistributed to the rest of the country. I might have to put it on piles or do some ground improvements, but that gets expensive fast. The problem I have with piles is the downdrag from the liquefaction adds up so fast. Any body have any thoughts on that? I will probobly try to push a seismic CPT to 100 feet at least very near the beginning to see what we have down there. The sediments are fairly young fairly deep. They were laid down as part of a lake bed many time over the years. The lake would fill, then dry out, then fill again etc. It has created many layers of interbedded sands, silts, and clays. Even if the liquefaction settlement is not that much because the water i lower in any area, then the dry sand settlements will do me in as well.
Fattdad, Even though I am in California, we don't do CBR's around here, how well do they work? How deep of an influence do they provide you info. As I understand it you are using about a 1 foot square plate to test the subgrade in the field? Is that correct. Around here practicaly all pavement design is done by the R-Value test, so we kind of miss out on the actual field testing of the subgrade, usually have to infer that from the drilling data. Do you have good correlations between SPT and CBR? or is that not very practical. Mostly I have just been looking at NAVFAC to get subgrade modulus, but for more critical work sometimes I would like to do something more. How much does it cost to do a CBR test?
RE: 2.1 million square foot distribution center investigation
this sounds like a very challenging project to say the least. i leave the discussion to those of you more familiar with these conditions.
one thing you might consider is using ReMi in conjunction with your exploration to assess the shear wave velocities. since it can evaluate conditions very deep from the surface, you might realize some cost savings while obtaining information about the deeper conditions across the building pad. also, for seismic assessment the 100' depth should really extend deeper for such conditions. i see folks argue this both ways but my interpretation of the language is that it should extend deeper for these type conditions.
RE: 2.1 million square foot distribution center investigation
I am not familiar with the term ReMi, can you please explain more? Thanks
RE: 2.1 million square foot distribution center investigation
www.optimsoftware.com is probably the best place to send you.
RE: 2.1 million square foot distribution center investigation
Set up a systematic grid pattern. If the borings or subsurface profile remains pretty consistent, then begin to widen your pattern.
On jobs where competition is tight, I have given at-cost pricing for the geotechnical work provided a guarantee is given for the materials testing (where most of the money is made for my firm). This requires good conversation and rapport with the owner and their team. Also, do you know any of the other players (structural, civil, architect) who could get your foot in the door?
RE: 2.1 million square foot distribution center investigation
Don't really think I'd like to make a correlation between SPT and CBR.
Don't really like to do this sort of design without a site-specific CBR test (they're just not that hard to do).
Don't like making a wider grid if things look consistent - here's where the body is buried: During construction the contractor turns the site to mud, the geotechnical testing firm looks to the data and sees that the "soft" ground is in an area where the borings are spaced at 400 ft rather then the other area where the borings are at 200 ft. The contractor claims the borings missed it and you're off to a pi$$ing contest. I think there's value to setting a program and being consistent. If anything looked to be really that consistent, I'd maybe make alternating borings 10 footers and keeping the others are the more conventional 15 to 20 ft (depending on the overall grading plan).
I would widen the boring spacing if there was dilatometer or cone data also in the field program. I would not do just in-situ testing (i.e., were samples are not recovered).
f-d
¡papá gordo ain't no madre flaca!
RE: 2.1 million square foot distribution center investigation
RE: 2.1 million square foot distribution center investigation
RE: 2.1 million square foot distribution center investigation