Whether to use the wet or dry process depends primarily on your production schedule. With wet you will get much higher production; it will be easier to entrain air; and rebound and dust will be less. It is suggested that you use a wet-mix, steel fiber reinforced, air entrained, silica fume shotcrete, mechanically connected with L-bar anchors and small diameter bars (not mesh) spanning between the anchors. For precedence with this type of retrofit of the face of a dam, see the publication on “Seismic Retrofit of Littlerock Dam, by Forrest, Morgan in ACI, Concrete International, November, 1995, pp. 30-36, or an abbreviated version of the paper in the ASA Shotcrete Magazine, May,1999, pp. 46-55. If you must specify the shotcrete you can use ASTM C 1436, “Specification for Materials for Shotcrete”, which will cover all the materials mentioned, including fibers. For a general shotcrete specification you should review ACI 506.2. You should not use welded wire fabric and fibers together. Fibers will hang up on the mesh causing voids behind the mesh. I recommend a steel fiber meeting ASTM C 1436, Type I, Deformed at approximately 85 lbs/c.y. (50 kgs/c.m.). The steel fibers will tend to lie in the plain of the shotcrete surface; however, you should be aware that some fibers may protrude from the surface, and over time will corrode. Thirty years of experience shows corrosion is only to carbonation depth (2-3 mm), and corrosion of one fiber does not effect other fibers nor disrupt the shotcrete. Staining of the shotcrete surface is a possibility. Some spray a thin ( ½ in.) layer of non-fibrous shotcrete as a final finish to cover fibers.