Myra Falls, Canada

• Client: Undisclosed
• Contractor: Nuna Innovations Inc.
• Gripple Terra-Lock™ System: TL-100 & TL-A3
• No. of systems: 10,000 Systems (TL-100 & TL-A3)
• Application: Reinforcing Concrete Canvas® for channel lining

In August 2016, over 10,000 Terra-Lock™ anchoring systems were used to reinforce over 11,000m2 of Concrete Canvas^® at an underground zinc and copper mine on Central Vancouver Island, Canada, for a large diversion channel.

The diversion channel, which conveys clean water from the hillside above to a lower creek, was originally lined with shotcrete and reinforced with steel rods but the material and structural integrity had begun to degrade over time. It was recommended that the diversion channel should be enlarged and realigned to effectively handle the high-water volume and velocities. The Terra-Lock™ system was chosen as a durable long term solution due to its ability to withstand the high flow velocities (20m/s) and to stabilise the side slopes of the channel (2:1).

Since the water was diverted away from the channel during installation, the speed of installation was key as the diversion pipes wouldn’t be able to handle the high-water volume expected to begin in early October. The use of Terra-Lock™ system meant measures could be in place much faster with a lightweight and greener product.

Adjacent layers of CC were overlapped by 100 mm in the direction of water flow and secured using 1.5 m corrosion resistant Terra-Lock™ anchors with 3 mm stainless steel cables every meter along the overlaps. This was further reinforced by the TL-100, helping to maintain intimate contact between the CC and subgrade surface. The Concrete Canvas^® was also pinned into 300 mm deep anchor trenches on either side of the channel. The trenches were then backfilled with material to provide a neat termination and prevent water ingress.

The installation took 6 weeks to complete with an average crew size of 6 men and daily temperatures up to 34°C.

The client was satisfied with the product and the minimal amount of specialist training or equipment required. In addition to this, the speed of installation meant the project was completed before the heavier precipitation arrived at the mine in early October which may have caused significant project delays.