Dead Lawn in Denver

[Matt M.]

Kinda at a loss on what to do with this dead lawn. The weather has been great in Denver, but our weather can change in an instant. With that being said, I'm hesitant to put in a sprinkler system since I'd have to be careful about having water in the lines and it freezing. 

My wife keeps saying lay sod, but I guess I'd need a timed above ground sprinkler to keep it moist. We are mulching the majority of the back yard, and you can't see that area in the pictures. 

On top of it, the soil is almost pure sand, so with sod, I'd have to bring in some topsoil etc. Any tips, etc would be appreciated! These pics are a week old. The yard has been cleaned, and that tree is gone.