High chromium soil

Hey y'all

Just got a soil test back with concerning levels of chromium (1290ppm in one broad area, 2460ppm in another, 1010ppm in another). Should I pull the plug on this piece of land? It's really cool for so many reasons, but it's got serious soil and subsoil issues from the mafic bedrock (soapstone). In any case, I'm waiting on results on the hexavalent chromium determination, but does anyone have any advice?

Thanks!

Drew

Ah bummer! I'm sorry, that sounded such a nice place!

It seems like there is several times the recommended levels of chromium. US EPA recommend clean up above 230mg/kg (which although it looks different I work out to be the same as ppm). source.

There are ways of mitigating the levels, and it matters what form of chromium you have too.

Hexavalent chromium increases the risk of some cancers, can cause skin ulcers, and has potentially harmful impacts on kidney and liver. The trivalent form of chromium is an essential nutrient and is much more benign than its hexavalent counterpart, although some studies suggest that high exposure to Cr(III) might interfere with essential iron uptake.

source
from same source:

a major strategy in chromium remediation "is to make the conversion to trivalent chromium before the metal" enters biological tissues

Plants as diverse as tumbleweed and alfalfa are being assessed for their ability to stockpile Cr(III) so that harvesters can incinerate the toxic crop.

I thought this one might be a possibility if a) you had damp soil and b) could set up a solar pv system :clean up Chromium contamination using electrolysis

The only other point I picked up was that there may be other contaminants, as most Chromium comes from industrial pollution.

What are your goals for the land?  If it is primarily gardening, I would go with raised beds.

I know Nancy, this piece of land has an extraordinary set up: covered in native edibles and wildflowers, it's a fire-loving prairie with sections of pine/post oak/blackjack oak savanna. It's got 3 sources of water, south facing slope, covered in serviceberry, hazelnut, dogwood, willow, hackberry, plums, apples, cherries, viburnum trees, and redbud, just to name a few.

If it's Cr(VI) we're out, nobody should live on this piece of land. We're probably out anyways. Here's my reasoning as to why it might be Cr(III), though without the actual results this is speculation. However, I asked the geologist to look for many other heavy metals and pollutants and he noted none other than the chromium, which--in addition to the fact that mafic and ultramafic rock weathers Cr(III), leads me to believe it's more a by-product of the bedrock than of industrial pollution. Additionally, since Cr(VI) is water soluble and Cr(III) less so, both the geologist and ecologist I went out there with suggested that Cr(VI) would be leached out after 80 years of no soapstone mining. Idk, this is in part coping and in part hoping. It's such a cool piece of land, but I am not a geologist or a chemist or an expert on these things.

Most of the research I'm seeing focuses on reducing Cr(VI) to Cr(III) before its ingested or absorbed by humans. Let's just say, for the sake of dreaming while waiting on real results, that it's all Cr(III). I understand Cr(III) is not readily absorbed and not easily available, but can be in certain leafy greens (esp. brassicas) and in roots. What effect would raised beds have? Does anyone have an idea as to whether or not this will effect tree crops? I imagine this soil will extend the amount of time it takes for a tree to begin fruiting.

In any case, this plot might not work. Lots of rocks, lots of marl clay subsoil. Which sucks cuz it's almost already a food forest (or food savannah/prairie). Not so, I suppose, if that food is poisoned.

Ugh, that sucks! But if I've got it right, it might not be hopeless. I believe plants have two systems blocking uptake of toxins, including metals: one between the roots and aerial parts, and one between the vegetative parts and the reproductive structures. So while root crops might be a bad idea (depending on whether a given species of plant has a high level of chromium uptake) leafy vegetables, and especially fruits/nuts/seeds/flowers, will probably be a lot safer. Also, if Cr(III) is less soluble, the plants might be less inclined to take up excessive amounts.

Would it be feasible to run a test on some of the foods already growing there, to see if they contain large amounts of chromium? Doesn't really matter what the soil contains if the food is ok. Except... the water might be a bigger issue. But I suppose you could go for rainwater harvesting for drinking purposes and use the water from the sources for watering the plants, cleaning, etc.

Also, maybe you could reduce the availability and mobility of chromium in the soil somehow. Here is a study that seems to say biochar is a viable way to do that. It also seems like biochar can reduce Cr(VI) to Cr(III).

I hope you can find a way to live there. It sounds like an awesome place.

There's a lot in what you have to say that reveals that there is a lot that is not said, yet to be said, or yet to be learned.

When i first saw this yesterday, my initial reaction was that you do not want to become in any way responsible for any part of this.  Not of your creation, so no way do you want to put yourself in that position now.

Now my curiosity is once more aroused.  yep.  word choice matters.

Let's put it this way...if you decide to pass on this, I may ask for contact info to at least look at it, if that's ok by you.  I know the worst case.  From where I sit, the worst is I get a bit of a trip and see some countryside and arrive at the same decision you did.  If you do decide to bite on this, drop me a line.  same applies.

So i'm pretty much where you are right now...there's more data to be acquired.  Then you try to make sense of it.

I believe you are in a position where you need to find divergent points of view.

My question is, what do people do with old soapstone quarries?  I'm not asking how (permaculture principles would be an example of how)...I'm asking what.

Or maybe I should ask what your goals are.  Then we get to some of the other parts of this piece of land and if you can accomplish your goals.

My other question, that has always been bouncing around my brain but I haven't asked...results of water tests?

Hey Eino,

Thanks for all this---it's super exciting to hear about the biochar, because most if not all of the property will be under a prescribed burn regime. This might do the exact thing you're talking about across the land every time we burn.

If we buy the property, we can definitely test the plant materials for chromium, but unfortunately our study period is starting to wrap up. We might be able to extend it again, but we've got some time constraints.

I agree, the well water is another big issue. It doesn't seem like chromium accumulation happens through ingestion, really, but water is the real problem. Thankfully, we can definitely do rainwater collection. It's also got two quarries on it filled with water, and the heavy metals in that water will be wayyyyyyy down on the bottom. But the clay subsoil is also limited our septic options. I'm planning on compost toilets anyways, but at least for the present moment this is all prodding the part of me that wants to be safe and at least care a little about resale value. I dk! It's got so many other great things we won't find elsewhere, and I hope we can find a way to resolve these challenges.

Hey Dane,

I'll shoot you a line if we bail on the purchase. In all honesty, it's worth just the look. It's got an old growth prairie root/seed bed on it, and from what I understand these are poorly understood but potentially immortal. It's truly such a sick piece of land.

The 'what' question is really a great one. There's a lot of soapstone quarries here in this county. Some of them are on private land, used for swimming. People'll build houses around them and gardens around them, but obviously the geography of each spot is gonna be radically different. There's also a 40 acre quarry garden nearby, with a whole suite of rare and endemic flora on ultramafic soil/rock.

My goals for this property would be a house, food forest and garden, hopefully enough to survive off of, and then to continue to cultivate the land through burning. I've grown pretty attached to east coast grasslands restoration and conservation, and would love to be a part of an ecosystem that welcomes a clear niche for humans.

Good Q about the water! There's no well, so I dk how we'd test that water. But the quarry water is fine, all the heavy metal contamination is sunk to the bottom. As for real water tests, we'll have to wait until after the study period.

Drew,

I almost don't want to tell you this, but it's worth the knowing and I'd feel like a colossal prick if this is all that kept you from this:

There's this guy I know...nothing ever good came from a tale that started with a buddy, right?  at any rate, there's this guy who lives a couple miles from me, he's a blooming genius when it comes to bacteria and remediation.  heavy metals, pollution of all kinds, stuff that normal people quake at the sound of, he goes, no problem.  Not only that, but he also goes, i can remediate it for a price that everyone at every level can skim off the top and it'll still a tenth the cost of what most similar projects cost.

most of what he does is wetlands/aquatic based.  but there's always a way to adapt a process to various conditions.

I can tell the process and the equipment. the jump start for the bacteria, that's why i know people who know much more than me.

just thought you might be interested, should it ever get to that point.

Sounds interesting, Dane---I went down the remediation research hole but ran into a big problem, which is that it isn't pollution that's the reason for the chromium, or not primarily. Any harmful and available heavy metals would have mostly leached away in the 80 years since the quarry shut down. So at least part of the chromium is going to be because of the actual bedrock that formed the soil, which seems unfixable. We'll do some more thinking about it, but it might be really hard to pull off. I'm interested tho, if remediation seems necessary. But I think I'm more interested in whether or not organic matter can support trees in soil that varies from hardpan to about 16-18 inches of Cr(III)-high soil on top of the world's finest, most impermeable clay lol

Let me also give some more information, cuz I could probably use some humbling on my plan anyways. The plot is 58 acres, around half of it is an old-growth prairie remnant that's never been plowed. I'm not gonna touch that, but we are going to start burning it again. This is filled with tons of medicinals and edibles that'll love the fire, and a few invasives that can't dominate the mafic soil anyways that'll hate getting burnt to a crisp. And, of course, the great grassland/savanna enemy: trees. There's some post oak, blackjack oak, and short leaf pine that'll create a savanna once the burn regime is established, but the sycamore and tulip tree will die. A ton of edible and useful shrubs will also benefit from the fire. It was all pine when it was timbered eleven years ago, and wasn't replanted for timber. I dk if there's like, a landscaping tree planting or something or if they just let it start to return to forest.

After the prairie, there's more level-ish flat areas with various things beyond what seems to be the disturbance line. Right now, the plan is to burn this too and see if anything pops up from the seed bed, and then start experimenting with either burns and periodic grazing or with permaculture and controlled burns. This soil is deeper, in general, but there are hardpan vernal pools too.

Then, there's a two terraced cliff thing, constructed out of mine boulders and finished at least 80 years ago. This has thin soil on top of it, then it's made of rocks. I've wondered if anything's possible here, but it's likely not.

The soil might be too challenging---gotta have the whole system to work. But it's got so many other cool things, so I haven't given up quite yet.

Hey all,

Tests came back with 5 to 10 times the EPA recommended residential level of Chromium(VI) in the soil, so we've terminated the contract. Thanks everyone! Be back with more soon.

Drew

Sometimes that is how it is. Good on you doing your due diligence and following through! You will find the right spot.

Drew Newitt wrote:Just got a soil test back with concerning levels of chromium (1290ppm in one broad area, 2460ppm in another, 1010ppm in another). Should I pull the plug on this piece of land?

If you buy it, will you ever be able to sell it? You would pretty much have to discloses these levels to a buyer to avoid liability.