1) A gamma emission is a gamma emission regardless of whether it comes from Radon, or Cesium (albeit with variations in emission energy, though that's captured in the dose conversion factors of any impact assessment methodology).  Background radiation in Canada, averages around 3mSv per year.  If the doses rates from the NSDF are orders of magnitude below that, (and they are, according to the EIS) then they ARE comparable with natural background radiation.  
2) My understanding is that the NSDF will have a 50 year operational life (accept wastes over a 50 year period) and then be closed, and become the permanent final disposal for that 50 years of waste.  Please provide a quote from the EIS if you believe I am mistaken.