Sid, The current statement that there is a layer of silt in between the salt layers is actually pretty consistent with both what you observed and the measurements save the salt have done over the last 10 years. The average for their measurements has been about 1.8" across the courses. We have been racing on thin salt for years. Some thing definitely needs to be done but I don't think this is the end. At least not this year.
JL222 when you are doing your calcs there are a few things you need to consider. First a cubic yard is 27 cubic feet. Second, the salt will not stay on the track. You have to figure that 4 inches across the entire basin, 36,000 is acres. That's 19,360,000 cubic yards. The average belly dump holds about 18 cubic yards. 1,075,556 truck loads. Say an average of 20 mile round trip with average consumption of 10ish miles per gallon that's 2,151,111 gallons. Diesel is what about $4/gallon, that's $8,604,444 just in fuel. Plus you have to pay for people, trucks, etc. Dry salt laydown is a good concept but tough to make that feasible.