We just moved into a house with a yard that's about 45'x80' with some pretty bad drainage issues. After large rain the whole yard is water logged for days, with a few square yards where it actually pools. I think we'll need to level the yard to get rid of the low spots but before doing that I want to resolve the drainage issue. I've been reading about french drains and dry wells, but I'm not sure what the best and most cost effective solution would be.
On a somewhat dryer day I tried digging a bit to see what the soil was like and it looks like the top 10" or so are very heavy clay. Would perhaps using a post hole auger or similar to make multiple paths through the clay be helpful? What are the steps I need to take to assess the situation?