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MJ starts with ... Hi everyone I have a contaminated site, due to having bulldozed an old house and rebuilding. I am planning to grow a lot of fruit and veg on this site, so I am going to have to work out ways around that. :) I'm planning a couple of raised vegie beds, and with a bit of weed mat or something underneath I think that will be okay. I might do wicking beds here, depending on energy and motivation. :) Elsewhere I have planter boxes, which I can fill with clean soil, but I'm wondering about the bottom. I will put some dwarf fruit trees and grape vines in these, but roots can go a long way down. It would be too deep for wicking beds, I think, as I've read that the "wicking" bit is only good for about 30cm. Another area I have a bed about a metre deep and I am planning to line the edges with 1.2m root barrier, and then fill with clean fill again. This is where I'm hoping to put apples. Another spot, similar, is about 2m x 2m, and I've got herbs and a lemon planned there. Ditto the root barrier and clean fill. So that leaves another area which I'm thinking I will get bobcatted out and filled, again, clean fill. Again if I use the root barrier to prevent the roots going into the contaminated area, I'm hoping that this area will fit several fruit trees and various vegetables and support plants. (Oh, at the same time I'll bring in a truckload of mulch and clay and hopefully create a good soil, very different from my native sand.) I am planning to leave the front garden contaminated, as it will be native ornamental only. The back area will have a lawn too, and again I'll just improve what is there and leave it contaminated. I'd like to think of a way to prevent the roots going too deep though. I can provide, say, a metre of clean fill, and have the top 30-40 cm of good topsoil, but roots go a long way, especially the grape vines I'd like to include. Does anyone have any good ideas? I'd already accepted the need to bring in clay and compost and mulch due to the atrocious soils (sand, picture a big yellowish sand dune...) we have here, so bringing in soil isn't too bad in that context. It would at least only have to be done once. Thanks! | About the Author 4 Perth 25th April 2012 7:24pm #UserID: 6823 Posts: 132 View All 4's Edible Fruit Trees |
| About the Author Cairns 25th April 2012 7:35pm #UserID: 5418 Posts: 1438 View All 's Edible Fruit Trees |
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MJ says... Mike, it is termite traeatments, mostly, dating back over about 60 years. I'm assuming we had industrial strength treatments as we didn't treat at all in the last 14 years, and nothing in the house at all, but they were elsewhere in the block. In fact, a nearby house just got condemned due to termites in the roof timbers. :( | About the Author 4 Perth 25th April 2012 7:52pm #UserID: 6823 Posts: 132 View All 4's Edible Fruit Trees |
| About the Author 4 Perth 25th April 2012 7:53pm #UserID: 6823 Posts: 132 View All 4's Edible Fruit Trees |
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Mike says... Ok so it is a cocktail of insecticides like lindane a bit of arsenic and maybe a few other household wastes.Termiticides break down especially with heat,sunlight and water.Clay and humus can bind and neutralise them also.The ground may be less contaminated than you think.I don't know if the trees will suffer much or it is possible for plants to take them up and present a risk.I might sus it and get back to you. | About the Author Cairns 25th April 2012 8:24pm #UserID: 5418 Posts: 1438 View All 's Edible Fruit Trees |
MJ says... I spoke to a chemist who can test the site for me, for about $180 to set up the tests, and then $180 per sample. I think I'd need about 10! V. expensive. He said that the modern stuff is less problematic as it has a much much shorter half life, so probably it is really only the old stuff - which was really long lasting in the environment -is what I'm worried about. He said the class of insecticides included DDT. But yes, also other household stuff. Certainly there'd also have been lead based paint at some point. Would love to have a new site out in the bush somewhere! Then I'd have other issues... I've been told that fruits take it up much less than things like leafy greens, but I haven't found a reference for that, so at this point I'm keeping it in the back of my mind but not counting on it. | About the Author 4 Perth 25th April 2012 9:05pm #UserID: 6823 Posts: 132 View All 4's Edible Fruit Trees |
| About the Author 4 Perth 25th April 2012 9:14pm #UserID: 6823 Posts: 132 View All 4's Edible Fruit Trees |
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Mike says... MJ I can't give too much advice before I check it out.It could be the that the levels of harmful chemicals have dropped over time.Risks associated with old termiticides could highest for animals through dust and soil ingestion.If you can do some detective work and find out the likely termiticides used and look them up with US EPA or the NRA for vet and ag. chems you'll know more. | About the Author Cairns 25th April 2012 9:28pm #UserID: 5418 Posts: 1438 View All 's Edible Fruit Trees |
| About the Author john53 sydney 26th April 2012 7:28am #UserID: 6822 Posts: 23 View All john53's Edible Fruit Trees |
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amanda says... Also...worms are fantastic for cleaning up contaminated sites! Start getting them up and breeding :) The geotextile root barriers should work for you...I have it here on my subsurface retic and have had no problems with it MJ. Almost all of your trees/vines feeder roots are in the topsoil so you should be fine with a geotextile membrane - in a big! planting hole. It's the tap roots that go deeper - and they are to anchor the plant and generally have little to do with nutrition. Once you get the all clear then you could always dig down to the membrane and cut as much away as u can - thereby allowing the feeder roots to spread out. I would be tempted to ring one of the soil testing labs and get some prices MJ...I had my soil fully tested for $500 all up (but not including chemicals tho) And - you can also have the actual fruit itself tested down the track - peace of mind :) Heptachlor was the termiticide used awhile back? - (we lived in an old house in Cott' that stunk of it under the floorboards...it never needed follow up sprays either... :-( | About the Author amanda19 Geraldton. 400km north of Perth. 26th April 2012 9:27am #UserID: 2309 Posts: 4607 View All amanda19's Edible Fruit Trees |
MJ says... I will call the chemist again - he did some investigating for me - and ask for the names of the chemicals. Amanda, the cost is due to the several runs and analysis he has to do. Originally he thought $150 set up and then each run, but after investigating the chemicals he'd need to be looking for he said $180. That's fair, as now he knows there are multiple runs needed due to the various chemicals. (3, I think.) I'm thinking 10 spot tests would cover the yard reasonably well. What geotextile did you use? I'm assuming that the tap root (if it has one, I've just found out that a lot of them don't have one at all!) will just pierce the geotextile as it is larger and hopefully contain the feeder roots which will be smaller and more fibrous? My daughter wants me to put a smiley face here. :) :) | About the Author 4 Perth 26th April 2012 10:01am #UserID: 6823 Posts: 132 View All 4's Edible Fruit Trees |
amanda says... Not sure MJ - the geotextile membrane came with/wrapped around my sub surface retic pipe. It kept out Acacia roots tho - so I was impressed! (they are highly invasive and damn hard to kill too) Try asking at a reticulation specialist shop maybe..? Otherwise google geotextile root barriers perhaps. I had my tests done at CSBP and had 6 spot tests/sites analysed - with 25 individual tests each (so 6 x 25 tests) costing just under $500. But yea - I have no idea if they do chemicals or not (possibly - as they do a huge amount of testing for farmers..) :0) back to your daughter too! | About the Author amanda19 Geraldton. 400km north of Perth. 26th April 2012 2:55pm #UserID: 2309 Posts: 4607 View All amanda19's Edible Fruit Trees |