asbestos

Hi, quick question I've been pondering. We live in my husband's grandfather's old place, where he used to have a photo studio. Back in the day they used these lovely asbestos discs, which I now keep finding all over the garden. There's one site that's clearly been used as a dumping site, but I keep finding the odd one where ever I dig. So my question is, should I be concerned about this if I want to grow food? I know burning or inhaling is pretty bad, but what about plants, perennials in particular, will they break it down, can they absorb it over time?
The obvious dump site was on this seemingly random placed foundation built for a tiny shed (yet never finished). They put it on there and either left it and dirt accumulated by itself over time or it just got covered by a little dirt. I dug most of it out (unaware of what it was at the time) and now covered the rest with some plastic cover material, which has now filled up with rainwater. So I'm thinking to go along with this idea of covering it up with a lot more dirt, heightening, possibly hugelkulturing the sides and creating a larger pond. Possibly pond liner plus rocks in the bottom. Thing is this is in the area where we wanted the chickens and/or ducks to go, but we don't want them to be dust bathing in asbestos or scratching the stuff up. Any thoughts, suggestions?

Asbestos is really only hazardous when it's airborne. I think the safest thing you could do is to cover it to a sufficient depth that it won't be accidentally exposed in the future by you or the chickens, and them avoid unnecessary digging (i.e. no root crops) that might stir it up. The fibres are too large to be taken up by plants.

Elementally, asbestos is silica, magnesuim, and oxygen, all common elements in the soil, and it won't form any chemically harmful breakdown products.

If the disks were treated with other chemicals, that might pose other problems.

I have done quite a bit of asbestos work. It poses no danger to plants. Every disk that is found, should be bagged. They will break down with tillage and they can have a negative impact on property value. If there's an area where many disks are found, get rid of the surrounding soil.

Okay, so I've been digging a bit about in the garden and pretty much located a trash dump site. Besides the leaking battery, which of these would you consider harmful and which harmless aka re-usable: old red bricks (some whole, others crumbling), red roof tiles, old grey roof tiles, clear glass (like lots of it), little glass bottles (cute, but probably had some yucky stuff in them), tin cans, old plastic and the few remains of an almost fully rusted away barrel. I'm thinking only the red bricks and red roof tiles are okay to be re-used (and please don't tell me I'm wrong on the bricks, because I've already used a bunch for bordering a garden bed and made my herb spiral with it). I want to use the broken bricks, tiles and other rocks I come across to create a nice large rock pile as habitat for garter snakes and beneficial bugs, as we have lots of slugs during the summer. That would be on top of the place where I found huge amounts of glass I simply couldn't dig through, let alone get out and the battery was there too. Instead of building a hugelbed there, it got covered back up.
Another question regarding the grey roof tiles, which I guess probably contain asbestos. My neighbor's barn is tiled with similar tiles and being on the property border all run-off water comes into the garden. Downhill from there I plan on having trees, bushes, veggies and chickens. I have started digging a swale to catch this water and guessing I should stick to trees, bushes and green mulch (chop and drop) for the berm and grow the veggies and keep the chickens further "down hill" (though really this is no hill, only a slight slope, ground is awesome in this part of the garden and absorbs all rainfall, no run off here). Any thoughts?
Another idea I had was to use the less degraded red bricks as a bottom for boxed-in, raised beds to place on the dump sites (there's two right on the most obvious spot for a veggie garden). I was thinking bricks on the bottom as a barrier, then logs and branches and topped off with healthy soil. Yes, I'm aiming for tall raised beds. I really want to use this space, because even though our true backyard has far better soil, it does not have any shade (once I have some trees established that problem should be solved). Any other ideas? Would hugelbeds work if I got the topsoil from somewhere else?

If you suspect anything contains asbestos, I would either get it professionally removed (bagged and disposed of appropriately) or if its not bothering you where it is, then leave it. Asbestos in water pipes has been an issue where I live, until the council replaced them all, so any asbestos fibres that are capable of entering the air or your potable water source should be dealt with. Anything thats in your garden, if your not encountering it every day, and its nots something you're going to dig up regularly, then I wouldn't worry about it. It wont creep up on you one day and surprise you. As for the other stuff in the garden, I'd use it where you can, but just be aware of things that might contain harmful aspects, like perhaps asbestos in the grey roof tiles, (I think your red bricks are AOK) PCB's, Arsenic, etc. Simple things like bricks, old glass, etc are safe, but I'd be aware of anything that can corrode, or leak into the soil. If it was me, I'd be sending that stuff off site.