Hi Mohamed, the rotary method ...

Hi Mohamed, the rotary method can drill several diameters and we had several succesful experiencies in drilling in coastal Acuifers here in Central America (right on the sandy beach with all sandy formations), the percussion method has some restrictions wih depth, i recomend reading the book of Driscoll for drilling methods, I think that in this case the contractor doesnt have the machinery for the job and is probably trying to justify that with the drilling methods, for the rotary drilling it all depends on depth, formation, and the expertise of the driller. I talk based on my experience.