Bassman:
As an aside, if you get the OK from your state folks, you ought to consider removing the contaminated soil to someplace else on your own property.
The oil will naturally degrade to the point it is of no risk, over time. Exposure to air and food for the microbes will speed the process. If you can find an area where stormwater flow will not cause you problems in your pond or any neighboring streams suggest this to them.
Haul it someplace, spread it rather thinly (maybe 24" deep or so) and add some really cheap fertilizer (the mix is not critical) or, even better, some manure. Till it up some, and leave it alone. Seed it if you wish, or let native plants cover it.
Over a couple years time, the TPH levels will gradually decline to zero.
This is how we've handled several spills over the years (diesel fuel, motor oil, hydraulic oil, etc.) and it does work. Heat, moisture and air are the critical ingredients. Fertilizer just makes things happen faster.
Obviously, having someone else handle it or pay you to do so would be great. However, in the end, the goal is to get your property to the point you can use it as you see fit. This is just one way of doing so relatively cheaply...get hold of me, if you want more specific info. This is what I do and I'd be glad to help you if possible.
Matt Clark
