Beginner Gardening: White film on soil keeps grass from growing, 1 by kpnewton

kpnewton wrote:
Last year we planted our lawn. There are a several areas where there is a white film on the soil and grass will not grow. My dad thinks that it is from where the builders washed out their paint brushes. I can not imagine that the paint would still be in the soil after a year, but I don't want to rule anything out. My uncle thinks that it is from the water discharged out of our sump pump - the discharge from our water softener gets dumped in the the sump dump, so there is some salt being discharged onto the lawn. However some of the spots with the white film are not very close to where the water from the sump pump comes out.

Any suggestions regarding what this film could be? And more importantly, how can we get grass to grow in these areas?