Mining Landfills

[Frickman]

Now this is just me thinking out loud, but I can see a day, a long ways into the future for sure, when it may be feasible to mine landfills/garbage dumps/whatever you call them in your area for raw materials. Most of them in my area already draw off methane gas from the sealed off, capped off sections. Over the years though there has been alot of scrap steel, aluminum, etc. buried in our landfills, especially before recycling became commonplace. Can any of you see this as being feasible, or am I just a nut?

[Furby]

Here's a post I made a couple of years ago:

Actually, I think in a way we already are.
The landfill near me has been expanding rapidly, and from what I can see from the road, they are grinding the older stuff into a mulch like substance. I'm guessing they are separating out the metal as they grind, and the rest of the material is then reused as cover material.
Atleast that's what appears to be going on there.

[farmerdoug]

I know that in Canada the plastic wood decking companies are mining the old industrial plastic dumps for plastic.  I guess the composite wood decking has driven the price of used plastic up.  They use to get it for free but now have to buy it.

[Frickman]

It looks like I'm not that far out in left field after all. There are already folks doing this. I just look at all the resources we have buried just a few feet down and get to thinking they may be more accessible than a raw material halfway around the world.

[Ron Wenrich]

I think a lot depends on when the landfill was started, and how deep you go.  The further down you go, the less disposables you'll find.

How long ago was it that plastic wasn't in vogue?  I remember back in the '50s and '60s everything from milk to beer was in returnable bottles.  Then in the '60s and '70s, they got into cardboard for the milk.  Bottled water wasn't around yet.  Beer and soda just started to be put into cans. 

Plastics come in sometime in the '80s, but recycling hit in the late '90s.  So, I guess your recovery would depend on your strata.

Same would go for aluminum.  It wasn't used much until the '60s.  Shoot, landfills weren't used that much.  Paper and rags were recycled, as were most metals.  When I was in college, we didn't even send much trash to the dump.  We had a hog farmer come in and get our garbage. 

So, the bulk of the stuff to mine would be from the late '70s to the late '90s.  I guess you would call that the disposable era.     I wonder what all those disposable diapers look like after 30 years? 

[stonebroke]

About 15 years ago a local landfill got a grant to try this. It was supposed to extend the life of the landfill. They dug up parts of the landfill and put it though a screen to get rid of the cover dirt and anything that had decomposed. Then they had big tables set up where college students combed though the garbage to see what they could recycle. To start the plastic bags plugged the screen big time and then there was not much you could recycle after being buried so long . I guess if you could get people to work for 50cents a hour it would make economic sense, But with the amount of hand labour involved I doubt if it will ever fly.

Stonebroke

[slowzuki]

I have seen article about mining the artificial tire reefs built in the 70's and also mining landfills for RDF power plants.  The byproducts are scrap metals and glass etc.  The photos of the materials pulled out of capped landfills looked exactly like they had been like when they went in.  Leaves of lettuce, newspaper etc.  The clay cap on the sites preserves stuff really well.

Speaking of wells, the local dump is installing a turbine to generate power from their 5 mW flare that burns full time.  They drilled hundreds of wells to gather the gas for the flare back a few years ago to cut down on stink.

[Furby]

The one by me did that many years back Slowzuki, I belive they are running 6 generators or whatever off the land fill.
The stink is still there and there is also the smell of burning electrical wire pretty offten.
Not sure why and figure they must be doing something wrong.

[Ianab]

Auckland city here in NZ has done a similar thing. The main reason there was that a new indutrial area had been built over an old landfill. The methane kept seeping into the stormwater drains and exploding  Manhole covers where flying all over the place and flames leaping out of the water drains.

So they ended up drilling some bores and laying pipes, then what to do with the gas?

They just have a number of these portable gas turbine gensets built in shipping containers so they can be moved about as the amount of gas on different sites changes with time.

Cheers

Ian

[submarinesailor]

I think at using landfill methane is an outstanding idea.   A lot of government agencies are looking into it.  An example is the US Coast Guard Shipyard at Curtis Bay, located in the Baltimore Harbor.  In my day job, I take care of getting them their natural gas for their boilers.  Well, they are currently working to bring landfill methane from a landfill about 1-2 miles away.  This will reduce the natural gas cost substantially, but they will need some pipeline natural gas because as with most landfill methane the Wobbe Index is too low.  (The Wobbe index relates fuel gas heating characteristics in a manner that is useful for blending fuel gases, or to obtain a constant heat flow from a gas of varying composition. The Wobbe Index does not relate flame temperature, heat transfer coefficients or temperature gradients.)  So, they will be burning a mixture of the two.  NOTE:  Most pipeline gas is about 80% methane and hot landfill gas is about 50-55% methane.  It ranges between 45-55% methane.
Before the BRAC list came out, Fort Monmouth, NJ was working towards a 15.5 MW co-generation (electric and steam) setup that would have reduced their outside electric load by about 80%.  Big saving on my tax dollars.   But Monmouth is closing so the project has been stopped.
If you have any questions about landfill gas/methane, I have several real good contracts over at DOE.

Bruce

[Fla._Deadheader]

 Also, once the landfills have been broken into, the stuff decays VERY quickly from the contact with fresh air, probably Oxygen. Did one where I grew up over 40 years ago. Within 1 year, it was just random lumpy ground.

[Ron Wenrich]

The local dump started producing power from methane back in 1982.  Before, they just vented it into the air.

[Larry]

Well...since I retired from the telephone company I got to thinking.  Why would you want to dig around in some stinky old landfill for pennies.

The phone companies have been burying copper cables for close to a 100 years now.  Due to growth, change in technology, or deterioration they were lucky to make it 20 years.  Some of the long distance cables weighed in around 3 pounds/foot if I remember right.  The only attempt to mine was after the mid-west flood of 1993.  I got the order to do it...but didn’t have enough folks to administer the project so it never got off my desk.

And than the USAF wired up all the satellite Minute Man missile launch control sites to the main control site.  Again very heavy gauge copper cable which ran for miles and  as far as I know was all abandoned.

Of course we can’t leave out the power companies...they buried lots of aluminum in subdivisions.  In some cases it only lasted a few years due to shoddy construction techniques, along with poor quality cable sheaths.

So...I have a 15 ton winch and know how to cinch cable to pull it out of the ground.  Naw...sounds to much like work to me but it is interesting to think about the dollars laying in the ground for the taking.  Who is gonna take the first step?  Who does all that copper and aluminum buried on public right-of-way belong to?

[stonebroke]

The Bell System once owned a smelting company on staten island that was the worlds largest recycler of copper. They used all the old aerial cables  that they took done.

Stonebroke

[Larry]

Yeap, that reminds me.  We had a toll open wire elimination program.  The wrecking crew had put something like 40,000 pounds of wire inside my locked storeroom.  The storeroom was surrounded by an 8' tall chain link fence with barbed wire on top.  The thieves broke in and stole in all because they thought they had hit the mother lode of copper...wrong as it was all copper coated steel which at the time was almost worthless.

At the time I didn't think it a bit funny...I had three days worth of paperwork to fill out on the theft.

[low_48]

I'm pretty sure that the methane is really hard on the equipment that burns it. Really tough on diesel engines unless they have come up with a pretreat. I think it is very high acid. 

[Ianab]

I'm pretty sure that the methane is really hard on the equipment that burns it. Really tough on diesel engines unless they have come up with a pretreat. I think it is very high acid. 

I imagine it would. Like was posted above it's less methane and more CO2, CO etc + who knows what else compared to Natural Gas. I guess thats one reason they use small gas turbines, not so critical what they are burning.

Cheers

Ian

[submarinesailor]

On the cleanliness of landfill gas.  There is a cleaning process that it goes thru before it can be burned.  You can flair off landfill gas directly, but like Ian said, it’s cleaned up a lot.  The water has got to be removed.

Bruce

[New Brunswick]

I work at a landfill, so I hope your a nut, or a looney toone, because it is gross enough putting in the ground when it is fairly fresh, just my thoughts, I'm sure your ok:)

[rowerwet]

UNH Durham just put in a pipeline to carry methane from the Rochester, NH landfill. they will use the methane for power during the sumer and heat during the winter. the methane will replace about 25% of thier current fuel used.