Ok I'm not geologist but I am a Civil Engineer which covers the topic of soils. I'd build raised beds. Me personally I'd build off grade. Which is easier than you would imagine if you use the square foot gardening methods. If I build raised beds on grade then I would line them with some type of barrier so that the roots don't sink into the soil. Square foot gardening theory is most crops only need 6" of soil and even carrots only need 12". You just have to make sure to give it good soil. Rent or buy the book Square foot gardening for mel's mix. I use it and my veggies grow great even in only partial sun. It is expensive at first to make the mix but after seeing the results it is worth it and you don't redo the mix each season you just add some compost to renew the nutrients. A row of cinder blocks would be 6" high. Also Lowe's has a mixing tray that is a nice size and about 7 to 8" deep for $13 it is used for mixing concrete but is a perfect heavy duty plastic planting tray with several square feet. I drill holes in the bottom for drainage. Raise this up alittle to discourage roots growing through the holes. bricks would work or you could spring for some 4x4's 2x4's and build a waist high tray holder lining them up making garden less back breaking work. Allowing you to level everything as well. You'd want to irrigate with not contaminated water. I'm assuming whatever you drink isn't contaminated (cause if it is protecting the plants is of minimal concern in that case). Roof collection is great or if you are on city water and it isn't contaminated then you'd also be fine. The ground water would not seep up into your soil in a raised bed unless you have an artesean well which you'd know cause your ground would be soggy all the time. But you have to take care from your plant roots growing down into the water table. If you know your water table/contamination plume is deep then you wouldn't need to worry about that. Around here it isn't uncommon for us to have a contamination plume from old gas station leaks but the contamination doesn't reach near the surface so for veggies it wouldn't matter.

This year I successfully remediated 2 cubic meters of aminopyralid-contaminated 9 year old manure that was delivered spring of 2011. Aminopyralid and chlopyralid is similar to picloram. In the fall of 2011, I spread the manure over the 15' x 20' area of lawn/quack grass. Spring 2012, I pulled the quack grass which was easy as roots had entered the loose manure. This exposed the underlying soil and incorporated some of it with the manure. I build a sheet mulch bed around the perimeter. Next I drenched the contaminated soil with active aerated compost tea made with high nutrient compost and well spiked with activated effective microorganisms (EM - brand used ProBio Balance Plus, manufactured by SCD). I did this twice, deeply raking the surface to oxygenate the soil micro-organisms without destroying them. Then I planted the manure area with corn and the sheet mulch area with various squashes, both of which produce much biomass and are the least susceptible to pyralids. I also did a weed survey, finding less than 10 misshapen and malformed weeds of three species along the margins. Three weeks after planting, I did another soil drench with AACT and EM. I also ensured adequate watering (mostly rainfall with a bit of irrigation By mid July the corn was waist high and the squash were rampant enough that drivers heading up the street would brake suddenly for a better look. I harvested 40 ears of mid-quality corn and more than 120 pounds of high-quality squashes. The best was the weed survey completed at the end of August. Fourteen different species in robust health. The biomass will stand over winter, collecting snow and moisture, then in the spring, I'll chop it and add it back to the soil and do another AACT and EM soil drench. I'm wondering if perhaps AACT and EM along with biomass accumulators and ensuring soil moisture might help remediate your contaminated soil?

oh dear it must be awful! i wouldnt know what to do in such circumstances - but can you remove the top layer of potting mix to reduce the chemicals in the soil and replace with fresh? i dont know whether or not flushing would make it better or worse - i would think if you flushed it for the usual 30 minutes with the slow hose it would flush everything out, but dont quote me on that! it flushes all of the others salts and stuff out of the mix, it may do the same with the wasp stuff. it hopefully wouldnt be around long enough to cause problems. but i would wait for an experts opinion on this. until they respond, i would use warm water with a few drops of dish soap (not dawn, many say, but ive no idea what that is in the uk lol) to wipe down any leaves and fruit on both plants. then i would do it again just to be safe - top and bottom of leaves. again, this is just what i would do, it might not be the best solution! i really hope everything turns out ok. it must be an awful predicament to be in :(

Susan, I was afraid maybe Horn's was your source, but Gene has listed some other local retailers who carry it, so hopefully y'all can still find it at a reasonable price even after the loss of Horn's. Patty, I am sorry you went through that. Legionaire's Disease. Yikes! I think your hunch that it might have come from the potting soil is a good one. You're a true survivor in more ways than one. Thankfully, our bodies can recover from such things with the help of medical science. Carol, I'm lucky, too, to have an endless source of leaves in the fall. If I am diligent and rake and collect them, that is....lol Some years I do a better job of collecting them from the woodland than others, but I do take care not to repeatedly take them all from the woodland and not to take them from the same area every year since they are important to the health of the woodland soil too. I do rake up and use all the ones that fall in the actual yard, and since the woodland creeps closer to my garden every year, some of the taller trees now drop their leaves into the garden, but I still have to rake them and chop them up. If I could get Pro-Mix without driving 100 or 120 miles to find it, I'd use it. This year I bought MG Moisture Control in February, March and April to add to all my containers because I feared a summer drought, and I am glad I did. As I fill up more containers for the greenhouse for this winter, I think I'm just going to make a version of Al's 5-1-1 mix. Gene, I agree that with any form of soil-less mix or other soil amendments, you get what you pay for and I absolutely will not cut corners in this area. I'd rather cut corners some other way. In gardening, I think the quality of the soil is the overall determining factor in a person's success. Everything starts with the soil. My dad used to say you shouldn't plant a $10 tree in a $5 hole, and that sums up how I feel about using cheap soil-less mixes too. Bon, Bio-solids have been sold as fertilizer or as a soil amendment since at least the 1960s as far as I know, and I've always gone out of my way to avoid the stuff to the extent that we can. One of my favorite garden supply sources in Fort Worth always carried Sul-po-Mag and I always cringed when I walked by that product, knowing where it came from. Some commercial vermicomposting facilities use bio-solids and others feed their worms pig manure (and probably other manures as well) so I won't purchase bagged worm castings unless I am sure of how a given company produces theirs. I just try to feed the earthworms in the ground here really well so they'll strew their castings everywhere as they tunnel through the soil. Our earthworm population has increased a huge amount since we moved here and began improving the soil, and I am so glad it has. My preference is always going to be for amendments from something right here on our property as much as possible because at least then I know the source and I know what is in it. We had rabbits in our early years here. Not because we purchased rabbits, but because after we moved "to the country", everyone we knew in the city who had a cat, dog or rabbit they didn't want any more and thought we should take it off their hands, and we did, because we didn't think any animal should live where it wasn't wanted. I'll qualify that by saying one family had a dog they truly loved, but had a small yard and thought she'd be happier here with us. We agreed and they sent her here to live with us, which I thought was a true act of love on their part. It was not that they didn't want her, but rather they loved her enough to put her happiness ahead of their own. She lived to be 18 years old and was a happy country dog who took great delight in roaming our pasture and woodlands. As long as she lived, she kept the squirrels away from the garden and yard. I found rabbits difficult to keep alive in the extreme heat that often plagues us here. Also, our rabbits really watched the wild rabbits roam free and resented being keep in a coop. We built them a fenced run that they loved because it was a more natural setting for them, but they occasionally escaped from it. After they eventually died, we did not get more rabbits. I've spent two consecutive very long very hot summers with cats and dogs cooped up indoors trying to stay cool and I'm just not ever going to bring chickens or rabbits inside in extreme heat. There's a limit to how many animals I can bring indoors before the house becomes more of a barn than a house! It is nice to be able to send them outdoors on a day like today and know they'll be happy outside all day and won't be roasting in the heat. I hope the heat doesn't return and that our animals can get used to being outside all day again. Dawn