Thursday, October 31, 2013

alone in the hotel

I have an overactive imagination and I can scare myself easily. So if I'm in the right mood, I can definitely freak myself out when I'm by myself late at night in a hotel room. I don't fret about actual potential intruders, perhaps because a stranger once barricaded himself in my hotel room (long story) and I know I can handle myself well in that sort of situation.

When I get into a certain mood in the hotel room, there are particular features I'm especially aware of. So for Halloween, I figured I'd list them, as well as the reasons I keep an eye on them:

1. Drains: It (I made the mistake of sort-of watching this because it was in the background at a Halloween party)
2. Mirrors: there's a million iterations of "freaky thing in the mirror", but I grew up with Bloody Mary - say her name in the dark in front of a mirror three times, and she's come out and... do something terrible. This completely freaked me out when I was a kid at sleepovers. I wouldn't participate, but I also figured if Bloody Mary was going to come out, she wasn't just going to stop at the bathroom door.
3. Closets: I heard a third- or fourth- hand account of a family that moved to a new house and the young daughter didn't like her bedroom because she didn't like "the lady who lived in the closet".
4. Under the bed: there could be anything under there. It's just dust bunnies and errant tissues, but you don't check under the bed when you first get into the room because who does that? And looking under the bed would be ridiculous... when it's not 2AM and you've just woken up from a nightmare.
5. Windows: again, a million iterations of "freaky thing looking in/coming through the window" but mine is Spring-Heeled Jack. Or Buffy (the movie) where vampires come and scratch at your third-story window.

So what this means is that when I wake up freaked out and need to pee (of course), after I do my business, I do a final check behind the shower curtain and wait for the last second to turn off the bathroom light. Then I race across the room, leap into the bed to avoid ankle-grabbers, lie on my back, and my eyes go window-closet-bathroom until I eventually fall asleep.

Monday, October 28, 2013

fun stuff to drill through (2)

Karst is my least-favorite material to drill through, because you never know what you may find. You can drill through hundreds of feet of essentially solid rock, then move over 20 feet and drill into a cavern. I was at one site where a drill rig set up about 100 feet from a major highway, began drilling, got down about 2 feet, and then the drill rods dropped the full length of the rods (20 feet). They scrambled off that location and ended up dumping a truck's worth of gravel in the hole to stabilize it and fill the boring.

Another problem is the necessity of drilling beyond a big void without letting that giant pool of (possibly) contaminated water flow downward to mess up (possibly) clean material below. In that scenario, we usually telescope casing. That is, start drilling with a larger diameter bit, say 10- or 12-inch. Drill down to the big void and set casing through it and seated into the rock below. Make sure you are well seated (at least a couple feet) so that you can pump cement down there. You'll likely need a special plug so that you can pump cement down the inside of the casing and force it out to the outside. Once everything is sealed, re-start drilling and repeat the process with the drill bit that's a size smaller. Repeat process for each big void and hope you don't need to telescope too often to get where you need to go. If you guess wrong and don't start with a large enough borehole in the first place, you'll need to drill another, wider hole and start the process all over again.

Water control is another big problem. The fastest and cheapest way to drill through relatively hard material like limestone is to use air-rotary drilling, where you blast compressed air down the borehole while a drill bit chews away at the rock. Air, rock chips, and water get sprayed back out the top of the borehole, where it is contained by a big contraption that allows everything to fall out and not cause a complete mess. The material collects in a mud tub, which is regularly shoveled (solids) and pumped (water) to drums or holding tanks. However, if you hit a big water-filled void of contaminated water, you can get 200 gpm or more that you need to be able to contain and pump, and somewhere to pump it to. So  air-rotary drilling may not be the best application. An alternative is cable-tool drilling, where a heavy bit free-falls and then the little broken-up rock pieces are bailed out of the borehole. Cable-tool drilling is painfully slow, and hardly anyone does it anymore in the areas I work in, so the pool of (antique) drill rigs available and drillers familiar with them is small.

I always err on the side of caution when I'm in an area known to have big voids. But if everything goes well and we don't hit much of anything, then I get an earful about why we spent so much time and money on giant boreholes or slow drilling methods. And why, exactly, we have a bunch of 20,000-gallon tanks for a couple of piddling boreholes. This is the part where having a manager or client with a basic understanding of geology really helps.

Thursday, October 24, 2013

fun stuff to drill through (1)

I got a comment on my last post about drilling in karst vs. in other places. Most of the environmental drilling done on the east coast is within the top 20 feet of the surface, because that's where the water is. And within that upper zone, you are more likely to encounter soil (overburden) than bedrock.

Bedrock adds all sorts of complications to drilling, but even staying above the bedrock can be troublesome. For example, the heaving sand I alluded to in my last post.

If you're drilling in a valley or another area with a significant thickness of overburden, it's not uncommon to drill through layers of saturated soil which may act as barriers to vertical flow. If you go through those layers, you may encounter material which is slightly pressurized (confined), and when you punch a hole through, you open a space that has significantly less pressure. That water (and the soil) wants to go up. That's fine if you're drilling through material that has a decent amount of silt or clay, or perhaps has lots of gravel. But if you're drilling through nice, relatively clean sand (of pretty much any size), that sand will flow with the water. Especially because the drill rods have been vibrating as they've been chewing their way down. And you end up with flowing/running/heaving sand. That is, when you pause to take a sample or to add another rod, sand flows/runs/heaves upward into the drill stem and binds everything up. Or, you stop for the day and come back the next morning to find that your drill rods been pushed way up out of the hole and you've got 80 feet of steel waving around in the breeze.

There are ways to minimize this. One way is to make sure you always keep the inside of the drill stem full of water, so there's some pressure acting to keep that sand back. You can also add "drilling mud" - a clay or polymer - to your drilling water to hold things back, although often in environmental applications you're not allowed to add anything fancy that may interfere with later samples or well installation. Or you can close your eyes and try and get through those layers as fast as possible, and then seal your casing/drill stem into something that won't flow, like a clay bed or bedrock.

In certain environments, such as coastal areas, heaving sand just comes with the territory. I've had big sites with scores of boreholes drilled, and one particular 15-20 foot zone is just blank with "heaving sand" for every single boring log because every time you stop to get a sample, you just get loose, undifferentiated slop from who-knows-where. Nothing's wrong with the driller or the rig geologist - it's just the way the stratigraphy is.

Monday, October 14, 2013

dry wells

I've made quite a few dumb mistakes over the years, but one type of mistake is particularly hard to minimize/live down: installing a dry monitoring well.

When you start an environmental investigation, you don't have all the information you need to site a monitoring well. That's why you're installing it in the first place. So the initial approach is to find the regional water levels (USGS, currently offline, is a good resource for this) and guesstimate the target zone. If you're in a relatively wet climate, which I usually am, the water level in nearby ponds and streams can give a good approximation of the minimum depth you need to get to.

Most of the time, we want to install wells that intercept the water table (for contaminants that may be lighter than water) or that sit on top of a confining unit (for contaminants that may be denser than water). The standard length for monitoring well screens is 10 feet. You need to get enough water in the well to sample, so ideally, our shallow well(s) would cross the water table 7-8 feet in, so you'd have 2 feet of play in case the water level rises.

Determining the exact depth of the water table while drilling isn't easy. The capillary zone above the water table is saturated, so you need to ensure that you've drilled deep enough that a well installed will actually yield water. The safest thing to do would be to keep drilling until you have free water in the borehole, and send the drillers out on a coffee break and wait until the water level stabilizes and then install the well accordingly. But in slow-producing formations, you run the risk of installing the well too deep. You usually don't have the luxury of waiting for hours or overnight to confirm the depth in a boring, so you guess and move on.

A decent shortcut is to check water levels in nearby wells (if you have them) and plan accordingly. The two wells that I installed that were utterly useless (entirely above the water table) used that reasoning. In one case, I was sighting off a well that was a couple hundred feet away, and although the water table was essentially flat in the area, I didn't realize that I was on a very gentle incline. In another case, I had another monitoring well about 30 feet away, but didn't appreciate that the water table had taken a nosedive because of wonky hydraulics around a nearby dam.

Of course, all this assumes that the well didn't get accidentally pulled up as you were removing the tooling or that you didn't run into heaving sand and have the borehole fill in 10 feet as the driller added the well material...

ETA: this is about overburden drilling, obviously. Bedrock is a whole 'nother ballgame...

Friday, October 11, 2013

pre-bid meetings

If I've got a site that has some funky access issues, or some complicated logistics (need to get a bunch of contractors to work together on a tight schedule?), I always call for a pre-bid site meeting for the major contractors, and then require a detailed explanation of how, exactly, they plan on doing the work as part of the bid response. That way, there are no surprises on either end. And no surprises = no additional costs/contract wiggle room.

I occasionally got some push-back from other managers who didn't appreciate all this time spent on the front end. That's pretty easy to combat - one site visit can eliminate a huge waste of time and effort if you find out that the original plan is untenable. Better to find that out before you have a drill rig and a big crew idling in a vacant lot.

However, I also ran into some issues with managers who didn't believe in pre-bid meetings on principle. They were convinced that all the subcontractors would exchange cards after leaving the meeting and conspire to submit uniformly high bids. Here's the problem with that: in my area, the identity of the other contractors expecting to bid on a particular project isn't much of a surprise. It's a small industry. When I try to get work, I have a pretty good sense of who my competitors are and our relative strengths and weaknesses. Same thing with contractors. Maybe someone's a little thin on work one month, and so they'll have an unexpectedly low bid to keep the equipment running. Maybe another contractor thinks that he's got an in because I've sent a bunch of work his way, and he jacks up the prices. So having everyone meet at the site doesn't change any of the underlying dynamics between contractors.

I probably only decide that I need a pre-bid meeting for 10% of the projects I start up. But I'll fight to keep the meeting for that 10%.

Thursday, October 3, 2013

shutdown blues

The US government shutdown has impacted the environmental biz in a bunch of ways, some obvious and some not. Those of us who work closely with the EPA may have been issued a stop work order directly. But other federal agencies and facilities, such as the Department of Defense (DoD) and Department of Energy (DOE), have major environmental obligations that may be put on hold.

In the last few days, I've run into a few more snags during the course of my work. Want to download GIS layers or other basic hydrogeological info from USGS? Sorry, can't do. Looking for some details on environmental technologies or trying to find some training now that your schedule has opened up? is closed.

We have a "start-up" pool in my office. I have a mid-October date. But I'd much rather be wrong and be back to full capacity.