Castlerock Excavating’s evolution from a tiny excavation company developing water sources on local ranches into a large firm repairing and replacing municipal water and sewer lines has been gradual.Duffy Duffield and his wife, Sheri, were living on a ranch 40 miles outside Billings, Montana, when they started developing water sources for cattle in 1996. When their two sons were ready for high school in 2001, they realized it was time to move and find other ways to grow the business. In Billings, the company moved into new construction.“We did all the excavation for houses — digging foundations, backfill, water and sewer
