If runoff, grading is first choice, then tiling or drywell. If you are trying to improve percolation through soil, you must determine the soil profile. A good place to start is with your county soil survey. Soil types will be indicated and defined. You can determine roughly from the survey if the problem is shallow or deep.
Also must be aware that any interface between two soil types will cause percolation problems: everyone knows that a sandy surface layer will not percolate well into a lower clay layer, but a surface clay layer will often not drain well into a lower sand layer. I have even seen two different sand types layered, and water would not move well through the interface. Have found lawns that require some work 6-8 feet deep in order to accomplish percolation, and have gone to 10' on one without any success - that one is a hill of clay: great runoff, no percolation.
[Edited by GroundKprs on 09-14-2000 at 03:51 AM]