My expertise is in mowing, edging, trimming, etc but not renovating a lawn. I have a customer with 3300 sq ft that needs grass. She insists on centipede. The area is in total sun. The problem is she had 2 huge oaks cut down and the stumps ground up before she hired me and now she wants grass where the trees were. I moved almost all of the mulch from the stump grinding out of the area and put a thin layer of top soil down. Then I rented a seeder from Home Depot (she could not afford to sod the area, I tried) and layed down 3 lbs of seed. Some of it came up, some didnt and alot of it washed down the yard due to heavy downpours of rain. She wants me to "fix it". That seed is $28 per lb so this time I need to do it right. Should I just till the area and install more topsoil and peat moss or what. Any advice would be appreciated. TIA.