Wow nice to have free stuff!! 10 years, must be some really nice stuff. Bet your grass is gonna do so well you're gonna need to mow it nearly everyday!! xD
If I could work in that much compost via bagged stuff it cost me over $300. I already spent $45 for two bales of Happy Frog Soil Conditioner which doesn't even cover 1" in my plot. Probably gonna pick up some Brownie Dairy Cow (1.25 cu ft) manure and Clean Earth Soil Compost Mix (1 cu ft) which are both about $6 per bag at HD... so that I have a mixture of stuff to feed the soil.