Last week’s Testing Day took 10 years to get to. It was the spring of 2015 when we moved onto the neighboring lot for our affordable Tiny House experiment and I begun shoveling soil samples into sandwich bags to mail out to University of Massachusetts to get a base level testing of the soil conditions. Those tests are designed for backyard gardeners and didn't tell us much we didn't already know, there were high levels of heavy metals and lead in the soil. But nearly 10 years later, thanks to the Equitable Community Revitalization Grant we were able to get comprehensive testing of not only the soil, but groundwater, and soil vapor.
I’m very excited to review and share the lab results that should be coming in a few weeks, but the testing process itself was quite interesting:
VTS Drilling was the company hired by our Consultants Ninyo and Moore to do the digging. Since they’ve done other digs in the neighborhood, including the property just next door on the corner of Pine and 10th, they knew that the soil in the area is very soft and sandy. They didn't need their typical drilling machine, they were able to do all the digging manually with hand augers. These were the size of a shovel that could be extended once the hole got deep enough.
They dug 2 holes next to each other at 3 locations spread across the lot, 6 holes total. The first 3 holes were to get groundwater samples and soil samples. The second round of holes, next to the first three, were to install a soil vapor capturing system.
The first two locations, toward the front of the lot and in the center of the lot, brought up nearly perfect-looking soil, there was even a wiggling worm in the first pull! There were a few bits of broken glass in the first foot, but after each foot of depth they would make a pile on a tarp near the hole, so you could see the progression of the soil by depth. At around 4 feet it looks like beach sand. By foot 6 you could start to see that the sand was wet. By 7 feet they hit groundwater.
Once groundwater was hit, they put a PVC pipe into the hole that has little slits at the bottom to let the water into the tube. They then run a plastic tube down the pipe and connect that to a special pump that doesn't interact with the water, so they don't have to worry about decontaminating it between uses, and then after letting the pipe fill with water, they flip the switch on the pump and fill brown tinted mason jars with the groundwater that looked as if they were pouring beer from a keg. Soil was captured at depths of 1’, 2.5’, and 5’ and put in small jars, along with a few other small vials, some with liquid inside for specific tests. Many of the tests we were taking, the crew had never done before because they are specific to the information about the soil quality and DNA of organisms present that the Bioremediation Consultant will use to design our Bioremediation Pilot experiment.
The third hole, located at the back of the lot, closest to what we know was likely the main car-crushing activities of the former junkyard, based on reports from neighbors who used to work on the site, was less clean looking. The first foot or two was full of plastic and metal shards, including sparkplugs, a battery terminal, and a chunk of a seatbelt.
The third hole at the back of the lot, gave the crew using the hand auger the hardest time as they struggled through chunks of metal to dig down. At one point they had to do whats called “fishing” to clear the hole to dig further. With a magnet attached to a string, they had to fish out shards of metal so their tool could dig deeper. But by 3 or 4 feet the soil was basically sand and easy to dig again. Groundwater was located again around foot 7-8 as in the other holes.
The second round of holes were for Vapor capturing. They do a second hole because they need a dry environment to best capture the vapor and the first set of holes were now full of ground water at the bottom. They dug the second set of Vapor holes only 4’ deep to avoid hitting groundwater. Then they used a combination of sand and a substance called crumble (uniform chunks of clay) to line the bottom of the hole to prevent moisture from getting in and create a filtered environment. The bagged sand they had was a bit wet from the distributor because it came in plastic bags that sat in the rain, so they had to improvise by drying the sand first in the sun on tarps before using it in the vapor wells.
Once the holes were dug, they applied specific amounts of sand and crumble at the bottom of the hole and then inserted a PVC pipe. Then they attached a little device the size of a bullet on the end of a plastic tube and slid it down inside the PVC pipe. The bullet device is a series of screens and filters that is designed so that just pure vapor can go through. After that, they install a metal cylinder at the top of the hole and cement it in. The cylinder has a manhole cap that can be bolted down. When the time comes, someone will come back with a canister that creates a sucking vacuum and will catch the vapor through the tube. They can come back multiple times and test vapor in case there are seasonal changes.
The first set of holes they filled with grout, to prevent future contaminants to the groundwater through the holes they made. And that's it. Bob’s your uncle!
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