I have a "potential" customer that has an existing fescue (3 variety mix) that they are unhappy with due to having to treat it 6x's a year for disease. What type of disease I don't know. If I get the job, I will be re-grading an adjoining lot, removing the existing grass, (that they don't like) and re-planting so it is all the same type, etc. The existing area is pretty much shady areas, which may be why they have problems with disease. My question is this: Would you recommend removing 4" -6" of soil along with the existing grass, and bringing in fresh dirt before replanting? I am afraid that if I just kill off the existing grass, or till it under, rework the area, and re-plant that I may be asking for trouble with disease in the soil?? Hope this makes some sort of sense!! Thanks in advance for your input!