Application. A domestic copper mine with a tailings dam that overflowed onto adjacent forest service land had constructed a new dam to hold additional tailings. The customer needed an immediate solution to the overflow problem to avoid fines. Because the encroachment area was odd shaped with an uneven bottom and some very shallow points, we recommended Crisafulli’s aluminum hull, self-propelled, shallow draft dredge, the Rotomite SD-110.
Composition of dredged material. The tailing material was comprised of 31% sand, 59% silt and clay, and 10% gravel, with a PH level of 8.5-11 due to lime treatment to enhance the copper floatation process.
Functioning of Rotomite-SD110. The Rotomite SD-110 was placed in the tailings encroachment area to dredge and pump tailings over the new dam’s 15’ wall. The dredged slurry was then pumped 900’ to disposal sites. Tailing material ranged in depth from a foot to more than 30 feet. The self-propelled, shallow draft dredge’s ability to maneuver throughout the encroachment area was key due to the area’s terrain and varying water depths, since it was necessary to keep water levels from rising to avoid further encroachment of the slurry onto adjacent forest service land. Dredge operators were able to move the dredge around with minimum effort and continue dredging as water levels varied.
Results. The customer was very happy with the performance of the Crisafulli Rotomite-SD110 dredge. The customer removed 100,000 cubic yards of dredged solids from the encroachment area in a little over 3 months, achieving the customer’s goal in less time than was budgeted.