I'm sure you mean 6 inch thick wall? provide drainage at the top of the slope to drain water away from the wall. provide adequate weep holes to relieve pressure behind the wall. ask your geotech for help with this
If the shotcrete (and soil nail?) wall is temporary, either no drainage is necessary or just some drilled-in weep holes spaced regularly over the wall face.
If it's a permanent wall, you can install some vertical geocomposite chimney drains, at about 10 to 12 feet horizontally on center, against the excavated face before you shotcrete. Fabric side faces the dirt. The drains should be about 2 feet wide and extend from near the top of the wall down to either weep holes at the base of the wall or to a collection pipe or to a horizontal geocomposite drain running along the base of the wall behind the shotcrete.
As cvg said, include a paved drainage swale along the top of the wall