I have a septic system at my home. I live on a hillside. The leach field is under part of the front garden and some of my front drive, which is concrete. (done by previous owner). I want to take out the concrete and put in pavers, or pavers and gravel, something more appealing than concrete....my husband is worried about the impact on the leach lines, of which I think most of are in the garden border before the drive. Any ideas for how to deal with this issue?