Too bad it is such a large area. I xeriscaped my front and back yard when I was in Denver. I got tired of the husband complaining about mowing the lawn. I can mow the lawn, but I'm petite and he bought a lawn mower I had to have my hands at the level of my head and couldn't get leverage. Our dirt was mostly clay, so like rock and it had hills. I couldn't barely get the lawn mower to move. It wasn't worth injuring my arms and back to mow. He was 6'1" and the handles of the mower were right at chest height for him. (I think the handles were adjustable, they would have to be, as there aren't a lot of huge gorillas pushing lawn mowers that I've seen.) So he wasstuck with the mowing because of the two high handles. But the wailing that came out of him was unbearable.
I put large stock pots on all the burners of my stove, filled with water. Took the stock pots out and started to systematically dump the boiling water on the grass to kill it. Covered it with thick layers of newspapers and pavers. A week later, when I needed the pavers for a different spot, I moved them. Since I worked full time, it took about two months to kill all the grass with the boiling hot water.
Of course, there is a risk for injury using this method, but it was as fast as I could work to kill off the grass. I was able to plant the area where I dumped boiling water on the grass a week later, after lifting the pavers. I don't know about your area, but we had a lot of clay in the soil. Very hot water will penetrate enough to kill the grass roots, but I had to punch at least a few holes to make sure the hot water could seep down to the roots. The grass and all roots and anything living will be very dead.
Another thing I've done at a farm I worked at over one spring and summer when I was younger, is to burn the grass. Only if it is safe to do so! They have those flame thrower things. It was a large area, but we soaked down the perimeter we were to burn out next. Don't burn grass on a windy day and always have a few buckets of water if flames get out of hand. Of course, it isn't much of a problem if the grass is short. The flames don't get high enough to get out of control. The area we torched was for a huge terraced strawberry bed that had a few garden benches and a statue at the top. That was actually my first taste of doing any landscaping. I'm not a big fan of grass, but I am a huge fan of strawberries and seeing that many strawberries at once was really great. I ate a lot of homemade strawberry jam that summer and fall.
