compaction issue on new turf

I have a new sodded lawn that went in last part of November. Came though the winter in great shape and no real issues with not taking. I have noticed that I do have a few areas that seem to yellow or have a lighter green color than the rest of the yard. Yesterday I planted a small tree and in one of those areas and I hid a hard pan 4 inches below sod. Basically the way they do the yards here in my part of Omaha NE is lay sod over clay with no top soil. The one side of the house was used for all of the construction traffic when building the house and that is where I have the compaction issue. We have been getting plenty of rain and I water as well. I have read a couple options: 1 would be to plug it with a aerator and the other is to use a drill bit and basically drill holes in those areas. My question how deep should I go and what kind of bit? I am thinking 6 or 8 inch deep with a 1/2 inch dia bit. Looking for some suggestions, thank you,