Risks of Building Home on Reclaimed Strip Mine Land?

[LoneRanger]

There is a developer selling acreage and lots for both recreational use and also permanent home construction. The land used to be a surface mine for coal, i.e. strip mined. The mine ceased operation in the 90's but unknown when the reclamation was finished. Safe to say 15 - 20 yrs ago. On first glance this seems to me like a bad place to put footers down for a new home. How would one know if the home site had been compacted enough? And the compaction necessary, it would seem would need to be extreme since we're not talking a few feet of fill brought in to bring an area up out of FEMA flood plain risks as some developers commonly do. Rather, we're talking God knows how deep the reclamation fill is in spots. It would seem that such areas would be settling for a century or so, or maybe I don't know squat about the subject and should stop flapping my lips (or keyboard as the case may be...) ?

I would think some very thorough soil testing would be in order.

 

[Onetor]

Do you have mineral rights? Prob too late anyway, but technology changing rapidly. Have a friend that owns a couple gold mines. Waiting to mine it for economical reasons.

 

[Silverado12]

I worked for a concrete company about 20 years ago and they would take a core and for deep footers would use "flowable fill", which basically is grout. It's certainly doable.

 

[LoneRanger]

Found this paper on the exact topic, authored by geological engineer.

https://pdfs.semanticscholar.org/18a2/2093f74925a3f9cd3571b2800e1a2c6042b5.pdf

 

[AZjeff]

I worked in strip mines in the east many years ago. How it works is, the dirt is all moved, the coal seam is removed, the dirt is put back. No special attempt at compaction was made. The company office was built on reclaimed land and was basically a 30 x 60 1 story ranch with a full finished basement and I knew of no settling issues. Midwest strip mines are different as far as the large areas involved, do you know if there are compaction laws? Are there developments built on reclaimed land nearby that have been there for a while? Has to be some info you can find locally.

 

[Shannow]

The coal usually has a solid substrate, and a sedimentary rock overburden.

In this region where there are underground workings, and it's a shallow seam, they come back and "open cut" it. They take the topsoil off with the vegetation and seeds, and push that to one side, then take the overburden off the coal then mine the coal.

They mine it down to the bedrock, push the overburden back over (heavily fractured sedimentary rock), then push the soil back over it.

There's a development here in town for a retirement village where the developer is currently doing exactly that to extract 100KT of coal that was remaining from early mine workings...he's stripping that and selling that before compacting for the retirement village...done right there's no problems.

Here in Oz, when a mine is closed, the "mine closure plan" and rehabilitation, and ongoing care and maintenance need to be publically available...for example

https://data.centennialcoal.com.au/domino/centennialcoal/cc205.nsf/0/E41E5BB5239BA4F0CA257EDF0081E4D5/$file/Rp_CCC18-004_Lamberts%20Gully%202010%20AEMR_Final.pdf

(which I turned into this)
http://www.flyash.info/2013/153-Whiteside-2013.pdf

For interest, my whole town is undermined, my house included. All bored and pillar works, and reasonably deep. In Oz, we don't own the mineral rights of a property, so if "Australian Coal Mining 1910" come knocking, they have rights to remove my house and mine under it.

 

[MolaKule]

Originally Posted by LoneRanger
There is a developer selling acreage and lots for both recreational use and also permanent home construction. The land used to be a surface mine for coal, i.e. strip mined. The mine ceased operation in the 90's but unknown when the reclamation was finished. Safe to say 15 - 20 yrs ago. On first glance this seems to me like a bad place to put footers down for a new home. How would one know if the home site had been compacted enough? And the compaction necessary, it would seem would need to be extreme since we're not talking a few feet of fill brought in to bring an area up out of FEMA flood plain risks as some developers commonly do. Rather, we're talking God knows how deep the reclamation fill is in spots. It would seem that such areas would be settling for a century or so, or maybe I don't know squat about the subject and should stop flapping my lips (or keyboard as the case may be...) ?

I would think some very thorough soil testing would be in order.


If it's that eastern Kansas land near "Big Brutus" it has settled and compacted itself many years ago.

The state's geological department should have borehole readings and reports for public viewing.

Just for peace of mind, I would specifically ask the developer for borehole reports, but I would not hesitate to build on it.

 

[Vern_in_IL]

Nope. I would not "build" on it. I would go as far as a Manufactured home, with pillars in crawlspace, the whole house actually sits on I-beams. Should there be settling, you can adjust easily.

 

[Andrew1972]

Do you have municipal water? I would not drink any water from a drilled well there.

I would not worry much about foundation.

 

[dishdude]

Originally Posted by Vern_in_IL
Nope. I would not "build" on it. I would go as far as a Manufactured home, with pillars in crawlspace, the whole house actually sits on I-beams. Should there be settling, you can adjust easily.


Agreed. There has to be a lot of other land in the Midwest that wasn't used for mining that you can build on.

 

[Shannow]

As a species, globally, we have concreted over all of the most productive and fertile land where we built and expanded our early cities.

What on earth is wrong with building over an old open cut coal mine (assuming due diligence done) ?

It's not like a toxic gold mine or lithium mine.

 

[Silk]

Like Shannow, the town where I live is completely undermined...under the river, both sides of town. Not enough strip mines to be a problem, but they will remove a town to do it. More of a worry are reclamations....most of downtown Auckland is reclaimed land, and holds up tall buildings. Reclaimed land from rubbish dumps is more of a worry, not just settling, but gassing as well. A town to the south of us had a large landfill in town, it's been open land for decades, with vents dotted around. Some have recently been removed, presumably now deemed safe. Having been a rubbish dump scavenger as a kid I know what is down there...I wouldn't want to build on them.

 

[LoneRanger]

Wait, what? You're tarnishing the image in my head of New Zealand being a mysterious paradise at the bottom of the world, land of exotic green spaces, mountains, and idyllic scenery everywhere you look.

 

[Silk]

Just a myth we are happy to let run, we are just like any place on earth on a smaller scale. Our mines are small compared to the rest of the world.

 

[cjcride]

Originally Posted by Silk
Just a myth we are happy to let run, we are just like any place on earth on a smaller scale. Our mines are small compared to the rest of the world.

You're a good man Silk