Construction on top of wastes

[killswitchengage]

Hello, and here i come with a very weird question
So the project we studied focused on geotechnical study of a soil composed of wastes , the maximum depth according to the client is a whooping 40 m !!
Mind you, those wastes were absolutely not treated , we found later on everything you can imagine : raging from organic matter , to clothes , bags , concrete, bricks , even bras ....etc!!
No i am not stupid enough to offer any solution in this case ,i thought of anything but the basic fact is : this is no natural soil so there is no soil mechanics . For the record the region is highly seismic . The only mistake we did was that the soil sampling were limited at 10 meters.
Now my boss had this brilliant idea of modifying my report , he wrote : light construction on woods can be made ,other then that the metallic construction underlain by massive foundation can be used .
I was furious that he gave himself this stupid idiotic idea of modifying my report for the sake of money . Anyway, the planned constructions are mostly one floor level but some of them are composed of 2 floors ,there is also water tank built on the floor....

 

[oldestguy]

First factor to consider is methane. Not only does it have no odor, but it is poisonous. Of course it burns also.

Two steps may be considered, First overload it so as to compress what might compress. Then your building might be flexible (perhaps that is your wood recommendation). Another method is to reinforce the foundation so as to allow it to settle and also not break apart the structure.

Overload can be an earth pile that is moved along the building site, with top of pile at or beyond building limits. We call it a rolling surcharge.

Typically waffle concrete slabs are built for these sites in my area Wisconsin. Two story apartments are built, but venting of the area under the slab is needed to help keep methane from the interior. However,if the fill is all garbage and little earth or rock, only very light structures are considered, such as a picnic shelter, on a concrete slab.

Buried utilities also must be built to allow much differential settlement.

 

[cvg]

[ul]
[li]roads will settle and pavement will degrade quickly[/li]
[li]drainage is a problem due to differential settlement[/li]
[li]if the landfill is capped, then the capping material is essentially impermeable, this nearly eliminates infiltration and greatly increases runoff[/li]
[li]leachate is generated by water which infiltrates the waste material and is generally collected near the toe. if not collected it will go into the groundwater[/li]
[li]settlement will continue for years and even a light weight structure will not eliminate the settlement. deep foundations are recommended for structures with periodic adjustments in the grading as necessary. gravity utilities need to be constructed at very steep slopes to provide positive drainage and should be flexible material. expect clogging.[/li]
[/ul]

I really do not see much opportunity for building structures on a landfill.

 

[killswitchengage]

@oldguy but the major problem is how in the world can you assess mechanical properties of the waste ?!
@cvg you are my herooooo , could you please provide any document about what you said just so i can prove my words

 

[cvg]

https://www.epa.ie/pubs/advice/waste/waste/EPA_landfill_site_design_guide.pdf

http://www.epa.ohio.gov/portals/34/document/guidance/gd_1003.pdf

 

[killswitchengage]

thanks cvg

 

[oldestguy]

In my experience, building on fills that include waste we do not need to know any mechanical properties of the waste. We know it will (may) settle and allow for that in the design of the structure. One rule that seems to work quite well on many soft, compressible supports (such as peat) that any one area of the building 10 x 10 ft. has zero support and suggest not exceeding 500 to 1000 psf adjacent thereto. All I can say is that I know of no building situation in these cases that has later come back complaining about the recommendations.

This situation may be something like building a boat. You know the stuff you sit on is lousy and so you keep the building as stiff as you can, considering economics and that some "bending" will occur. Even ships at sea in a big storm will flex. In my military Navy days on an LST the flexing was seen to be quite obvious, one foot in 300 feet, yet the ship did not break in half. The mechanical properties of that old garbage and fill stuff may vary, but you don't depend on it as having any strength.

Drive piles through it works, but then if the ground settles away, that is not such a nice situation either. You hang the service utilities from the building and allow for them to bend as they leave.

 

[BigH]

Hey Oldest Guy - my dad was LST 212 at Normandy!

 

[killswitchengage]

Thanks again Oldestguy , but it seems to me highly expensive to drive piles on a 40 m fill.
the major problem is seismic response of the fill and aggressiveness toward concrete or metal !

 

[oldestguy]

BigH:

Mine was LST845 during Korean thing. I was the Exec. Officer. One is still operating as a museum maintained by retired vets. LST825 in the Mississippi River and at Mobile, Al.

 

[Mccoy]

OG, where are you in the Group?

By the way, LST 825 Hickman County in the Wikipedia voice is indicated as 'fate unknown', maybe the voice needs an update.

http://www.mccoy.it

 

[oldestguy]

Hey McCoy:

Now you see why my handle is Oldest Guy. Bad memory The memorial ship is the 325. Sorry.

The 845 photo was probably before I was on board, but the docking to pontoons was common for us. We carried them on a channel a foot or so above the water line on each side.

http://www.lstmemorial.org/-

Anyhow my tour on LST 845 was 1952-1954. Required service since they sent me through CE education at Cornell U. NROTC.

I was not "lucky" enough to be there when transporting North Korean prisoners off to a prison island. Imagine that tank deck full of prisoners. Quite a clean up later I was told.

 

[hokie66]

killswitchengage,
Yes, it is highly expensive to build over a landfill. Landfill sites are best used for parks, soccer fields, etc.

 

[IRstuff]

Landfills have been used for construction, ala San Francisco downtown, but I'm not sure how long they waited, and most of the fill was no worse than wood and dirt and stone. Things that decompose are going to drop in density.

TTFN
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