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Adding 15ft of soil above swamp?

Adding 15ft of soil above swamp?

Adding 15ft of soil above swamp?

(OP)
A 10 acre project needs the ground lifted 15ft. The existing site is swampy and directly adjacent to a lagoon. How do I know if (and how deep) the existing swampy soil needs to be cut and filled in order to have a stable surface to add the 15ft? The 10 acre site will hold a small power plant. This is for a very preliminary estimate. From my name you can tell I'm structural and this is way outside my wheelhouse.

RE: Adding 15ft of soil above swamp?

Wow! Has anyone investigated what permits you need to fill a swamp? That would be my first concern, before the technicalities of how to do it.

RE: Adding 15ft of soil above swamp?

[enough "soil borings" to be representative would probably be a good start]

RE: Adding 15ft of soil above swamp?

I mean a swamp is a swamp for a reason. If its 10 acres in size, that drainage area to that must be huge, where is all that water going after you fill this thing?

That is a lot of dirt.

RE: Adding 15ft of soil above swamp?

You have to have a geotechnical investigation or knowledge of the area where the project is located.

If you have information from another project that is located in the same area, that information would be very helpful.

For a power plant, you may be looking at a pile foundation.

RE: Adding 15ft of soil above swamp?

geotechnical reports should also address "consolidation" of substrata.

We recently constructed an interchange on "soft" soils. The geotechnical report estimated consolidation of 12-inches (90-days) which did occur.

RE: Adding 15ft of soil above swamp?

If the 15 feet of fill is for a "stable surface", it would appear that you really need help of that geotech. Are you expecting a flood and that is to stay above it? If not, reconsider that dimension. Putting all that expense where you won't see it later may not add to the value of the property by much.

RE: Adding 15ft of soil above swamp?

What are you going to have to mitigate to fill the swamp? Usually here, for every square foot you fill in, you have to create 2 square feet of wetland (swamp here) in some other location. Sometimes the ratio is worse, depending on the jurisdiction. Sometimes you just can't do it at all.

Mike McCann, PE, SE (WA)


RE: Adding 15ft of soil above swamp?

You need a permit from Army Corps of Engineers, State and at least the county to touch the soil. But you probably need an Environmental study to make sure the slimy 8 toed toad doesn't live there. Not to mention those that don't want a power plant near them.

Richard A. Cornelius, P.E.
WWW.amlinereast.com

RE: Adding 15ft of soil above swamp?

Two issues...environmental and geotechnical....get both resolved before proceeding or you'll regret it!

RE: Adding 15ft of soil above swamp?

Three issues, Ron. There's that pesky floodplain as well.

The geotechnical, environmental, permitting, and flooding issues from this project description are so tremendous it makes me think the OP isn't in the United States. But then he goes and measures his area in acres.

I will be interested to see how this thread develops.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Adding 15ft of soil above swamp?

Looks more like a prank on us.

RE: Adding 15ft of soil above swamp?

Q "How do I know if (and how deep) the existing swampy soil needs to be cut and filled..."

If - It's in the description - "swampy soil" is by definition swampy and therefore not able to support even your foot pressure without sinking so it will need something doing to it

How deep - ~Get a survey. Could be anything from 3 ft to 15 ft. Anything more and you would probably pile it or raft it as the cost is too high. The Victorians knew how to do it - http://www.engineering-timelines.com/scripts/engin...

As said the real issue is not the technical one - its environmental and planning (it was a bit easier in 1820's...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Adding 15ft of soil above swamp?

4 issues Ron - #4 structural engineer in charge of the site grading plan...

why isn't there a qualified civil or geotechnical engineer in charge of the site grading and foundation design?

RE: Adding 15ft of soil above swamp?

Five issues: Is the proposed structure within the wetland buffer?

Mike McCann, PE, SE (WA)


RE: Adding 15ft of soil above swamp?

Agree guys....the plot sickens!

That's almost 250,000 cubic yards of fill material, placed as engineered fill...that will take months. Assuming you can compact 1000 sf of soil per hour per lift, you have about 7,000 hours of compaction. That would be almost 4 compactors working full time for a year. Must be a government project.

RE: Adding 15ft of soil above swamp?

too bad your handle isn't (Nuclear) bigsmile that would get people up

wetlands i've mucked out have all been the 3 to 4 feet variety. if i had to pick something on a very prelim level, i would go with 4'. for that size an area, you should discuss with the future Geotech about surcharging and settlement monitoring because there will likely be time and materials to do it.

RE: Adding 15ft of soil above swamp?

Just build the thing and turn it onto a brothel. The compaction should be achieved rather quickly and at less cost.

Mike McCann, PE, SE (WA)


RE: Adding 15ft of soil above swamp?

Hey Darth Soils: How about 40 to 80 feet of peat?? Yup, we build structures on it. No piles.

RE: Adding 15ft of soil above swamp?

easy OG. he said it was 'very preliminary'. i'm reading this being the stuff the owner (or interested buyer) does to decide if the property is worth spending money on a feasibility study.

RE: Adding 15ft of soil above swamp?

“The plot sickens!” and thickens. This is just one of a number of fairly random and wildly varying problems which StructureMan44 has brought to the forums, with scant evidence of any engineering judgement or experience to really address them. Then he seems to fade away without providing sufficient meaningful engineering info., or additional info., needed for a meaningful discussion. One can only wonder who is feeding him these crazy problems without any supervision, guidance or mentoring. What do these managers or clients think engineering is all about, can just about anyone do good engineering, if they just call themselves an engineer? What do they think of the need to grow and mature into being a real engineer, assuming some engineering education to start with, and some intelligent guidance along the way? What do they think of the need for engineering experience and judgement as relates to meaningful engineering advice or an intelligent solution to a problem. It seems that with a computer, some software and E-Tips (the internet) for real world (non-vetted) answers and direction, anyone can engineer anything, with little regard for practicality or real world considerations.

RE: Adding 15ft of soil above swamp?

Sounds like this project is getting bogged down

Mike McCann, PE, SE (WA)


RE: Adding 15ft of soil above swamp?

Mike:
Yah..., get back to work. The next thing we know, you’ll be changing your name to Peat Boggs, so that this looks like legit work when the boss walks up behind you. smile

RE: Adding 15ft of soil above swamp?

bow

Mike McCann, PE, SE (WA)


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