I’m only going to do this very roughly, only for the transport and using US prices (as they’re easier to find), because the total cost of mining, transporting and dumping that much material is astronomical compared to the $70m budget. Even the transport cost alone are an order of magnitude higher.

Soil has a density of between 1,200 and 1,700 kilograms or 2,645 and 3,747 pounds per cubic metre.

I couldn’t easily find bulk rates for trunking soil, but bulk trucking rates for grain seem to be in the right area from what I can see. A truckload of up to 80,000lb costs somewhat over $6 per mile.

Given the weight limit per truck, and taking a middling estimate of soil density of 3000lb/m^3 (rock would be heavier and so increase the cost), we can transport around 80000/3000=26m^3 per truck, at a cost of at least 615=$90, or $3.46 per m^3. Our budget for the whole operation was 75,000,000/(3,500,000100)=$0.20 per m^3.

From those figures we can see that simply trucking the spoil fron the operation would be more than 15 times the cost of paying the landowners. That ignores all of the other costs. Local rates may be sonewhat cheaper, but probably not enough to make a serious difference, and you’d need to ship over 10 million truckloads of dirt, which would put massive strain on local infrastructure too.