I have to disagree with digdirt's posting, no offense but consider the following from an environmental chemist: Tests for the kinds of toxins I described are not $10-$15 like a standard soil test. They cost more like a couple hundred. This would be the EPA method called Semi-Volatile Organic Compounds (SVOC), aka SW-846-8270, using gas chromatography and mass spectrometry analysis after laboriously extracting the soil with solvents and cleaning the extract with various procedures. This is done in an environmental lab rather different from the typical soil analysis lab. Whole different ball game and probably not worth it when you could replace the soil for that kind of money. As to it being safe because of its age, the fact that it was buried, and that it has probably leached away, each of these does not apply in case of asphalt and PAHs. They do not break down in the environment very fast at all. They are not particularly water soluble, so they will tend to stay in the asphalt matrix or bind to soil particles and just sit there. Not much of nature's cleaning action happening here. The earlier posting about building on an asphalt surface is a little different, since prussel has broken up the layer and mixed it into the soil. Increased surface area means much greater potential for both uptake by plants and contaminated particles sticking to root crops. I may be making a mountain out of a molehill but that's how PAHs behave. Gardening amounts to a small but real increased risk over time. Will you get sick and die? Probably not. Does it add to your lifetime cancer risk? Probably. You have to decide for yourself what to do.

Glad I can help, but I don't want to overstep my experience, so I will answer the questions where I have some hands on knowledge. Bottom drains - they will sweep any sand in the immediate vicinity, but have no effect on things a foot or two away as the velocity is negligible. The idea is to get solids to fall to the lowest point and get swept away. If the solids sit in rock crevices two feet away, they stay there. This is the source of the "rock bottm vs smooth bottom" discussion. River rounds - if you have them available, great. If you have to buy them by the bag, you are going to spend a lot to cover a 9000 gal pond. You understand the tradeoffs here- smooth doesn't stack well, but othewise is great. I doubt you can get anything over 30% with rounded stones. There are actually engineering formulae for determining the max stack angle for differnt shapes and density of material, but I don't think pond builders worry about them. Any slope that goes to the edge can be used by raccoons and herons. I find that having a deep pond where the fish can get away from predators helps a lot. I haven't used overhanging rocks. Sand is graded by size, source, and shape. You want a "sharp" builders sand for it's ability to pack. Playbox sand is usually too fine and rounded. Not the most critical issue however. Overhanging deck - a great Japanese design style that works the wonderful contrasts between man made/natural; linear/irregular; water/land; static/changing and many others. See my posts for one example. I use Ipe because it weathers to a beautiful grey, doesn't need any maintenance or finish, and doesn't contain any toxic metals to drip into the water. It has natural toxins of course which make it durable, but I don't let too much in the water. I have dropped a few pieces in by accident (it sinks like a stone) and haven't noticed any effect. I hope the rising water table and tree limbs don't damage the liner. Swimming pool installers (gunite and liner) often use a reverse drain valve meant to allow water in if the pressure is higher than the pool. The big tree limbs probably won't penetrate a rock lined pool but what about the roots? could be an issue digging and in the future. Good luck.

Yo Ken, if your still around your up on this one. Far as Composites go I am with the Larry/whoever We are for the most part. Composites are really no longer using recycled material because there is just not enough of it so most of the raw stuff is virgin,the energy used to make composite is an enviro no no, when its time to remove the project composite is not real big on bio degrade its tricky to burn shreading it would be silly. Bottom line composites are not so enviro freindly. Info like that might suggest its not all that good to clean it either, with anything. I dont agree>> composites will out last Ipe, left to go silver/gray Ipe is as close to no maintance as a person can get. With the softer composites like Choice/MoistureShield even trex= tjunk I have found a coat or two of TWP 116 seals up the decking,locks in the color and keeps mold,mildew,stains from causing major problems. Of course not needing to do this is the reason the Wallet goes for composite in the first place. I my own self dont like composites at all for the reasons stated in several posts here and on other sites. Welcome aboard Larry!!! Sorry I dident understand your intent at the begining . John

"Sorry for the hijack, but for some reason I cannot post a message in the Home Repair forum. I can in all the others, but I don't think asphalt repair has anything to do with woodworking. So, that being said, I guess I'll ask my question here: Hi, absolutely brand new here since I googled "asphalt repair" I found this place. Anyway, I got an asphalt driveway installed 5 days ago. The old driveway was gravel, mostly dirt & grass. The contractor scraped the surface, rolled it, then laid down 2.5" of asphalt. Today (5 days later) I noticed cracks and "buldges" like something is trying to push up from underneath. The area is kind of soft. Is this just an example of shoddy construction, or are moles trying to destroy my new driveway? We do have moles. I live at 9,000' in Colorado if that makes any difference." The contractor did an improper job. Without the proper base,the asphalt will fail. And he didn't even put a base in. Ron