Thursday, December 6, 2012

popsicle time

It's starting to feel like winter around here - it's been below freezing at night for a while now, and the other night, I drove home from work in snow flurries. The snow started sticking, so the ground is starting to freeze.

And when it gets really cold out and I'm collecting soil samples, I need to worry about popsicles.

If it's super cold and I'm overseeing extremely fast drilling, such as direct push technology (DPT), which produces a large number of samples in plastic acetate liners, my samples may freeze if they stack up too fast.

Frozen water can be difficult to break into sample-able pieces. Dense soil can be difficult to mix up properly. But frozen soil with chunks of gravel, wood, and other extremely hard bits is nearly impossible to sample. Sure, you could stick it on the dashboard of your truck to warm up, but often you're trying to sample volatile organic compounds (VOCs) which need to be preserved or sealed in an airtight container right away. Warm up the soil, and all your VOCs will just... leave.

One memorable winter, we were trying to collect a large number of shallow samples. The drillers were in a hurry to get the samples and get the hell out of there, so the samples started to pile up. The samples were frozen solid, and we had to sample for everything under the sun - VOCs plus large volumes of everything else. The soil cores were so hard and consolidated, we had no hope of beating them against hard objects to dislodge anything. So what we ended up doing was breaking tiny chips off the ends with whatever we could (mostly screwdrivers and icepicks) and sending off those for VOC analysis, hacking the cores into whatever would fit into mixing bowls, and piling the bowls in the corner for later.

Hacking at slippery, literally rock-hard chunks of contaminated soil with frozen hands is perhaps not the safest way to spend an afternoon.

 ...I have millions of photos of acetate liners with soil samples, but they're sort of privileged. It was harder than I thought to find a photo online. This is from a drilling company:

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