I have a client that has a lawn that was installed Fall 2002. The base is mainly sand, topped with about 1/2" topsoil and then turf laid on top. The grass grows very poorly. During the Summer the soil dries out within a few hours. We are restricted to watering twice a week. Over the next 2 years the grass kept thinning out. About 2/3 of the lawn is in shade. Moss started to grow almost immediately. Last spring I applied moss control then power raked. I topdressed with more topsoil and reseeded. The seed germinated but by late summer the lawn started thinning out. This spring the moss returned with a vengence and most of the reseeded areas have thinned out. Is this lawn doable or am I wasting my time due to the sand base?