Friday, October 28, 2016

solid waste storage

So how do we actually handle and store the investigation-derived waste (IDW) that I mentioned in my previous post? I got a little carried away when I started writing, so for this one, I'll just focus on soil.

For big excavations, soil gets stockpiled (hopefully on plastic sheeting, and then covered) prior to disposal. But as a geologist, I don't usually have to personally manage stockpiles. My stock in trade is usually drums and roll-off containers.

55-gallon drums are the easiest to handle - I can hoist around empty drums myself, and my contractor (usually the drilling crew or a separate disposal/waste handling crew) should have equipment to safely move filled drums. This does not mean hanging a mostly full drum off the mast and letting it swing freely as the drill rig moves to the next location, by the way. However, once you get beyond a couple hundred gallons of soil or water,  managing drum storage can get complicated fast. Also, the aesthetics of a drum farm are terrible. This is the classic:

Ah, so many fond memories of cranking the bolts open and closed again and again to add more stuff, sample, figure out what was in there after the label rubbed off... And then, after they've been banged around a while and start to rust, the ring and lid get harder and harder to open and close, and you end up beating on them with a hammer to get them to cooperate.

So we often use open roll-off containers. These are good for big jobs, especially if we're drilling large boreholes and are expecting large volumes of soil and/or water. However, the roll-offs need lots of space to maneuver for drop off and pickup, and each lid is its own special snowflake (protip: never let the transporter leave without having him demonstrate how to operate the lid, and if it looks sketchy, refuse delivery. You don't want to fill the thing halfway and realize you can't open the other side), and if these suckers get too wet or too full, you've got to figure out how to either solidify them so they don't slop out the back when lifted, or scoop enough stuff back out of them again. Example in mid-drop off below (from wikipedia). Note the lifting angle.

How does one solidify an overly sloppy roll-off? Well, you can wait for the solids to settle and try draining the free liquid. If you have some extra well screen, you can poke that in there before you get any real accumulation and fill around it. Stick a pump in the screen and remove as much water as you can. It probably won't be much. You can borrow extra materials the drillers left - bentonite clay, sand, and road-building gravel - to try and give the slop enough structure that the roll-off can be lifted. Or, find a local farm supply place and buy a couple bags of wood shavings.

The main thing, though, is to keep your solids dry and secure, regardless of whether you're keeping them in a 5-gallon bucket or a 40-yard roll-off.

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