Client: Pensar
Asset Owner: Sunwater
As part of the works, a portion of the existing weir requires to be cut to allow the placement of the fishway exit. At the time of Issuing for Construction, the excavation of the existing embankment at the exit was not considered. It is now understood that to complete the fishway exit, excavation and replacement of the existing scour protection is required. To minimise the costs of dewatering and reconfiguration of the fishway exit, it has been proposed to utilise a Fabric Formed Mattress, supplied by Scour Tech International and installed by Commercial Marine Group. This will allow for underwater placement of the scour protection mattress with the use of trained divers and fill ports once the mattress is anchored in place.
The bags will be anchored in place with the use of eyebolts and/or steel pins, anchored into the ground or existing timber members. These anchors are for temporary positioning of the bags and are installed before they are filled with concrete and are not relied upon for long term stability. Commercial Marine Group installed fixings at the interface between the mattress and existing concrete weir with the use of eyebolts, drilled and epoxied into place using Hilti HIT-RE 500 V4. The temporary connections are to hold the bags in place to allow for grouting of the mattress. Once the fabric is fully grouted, the temporary connections no longer provide support for the mattress. Each fabric mattress is lined with webbing straps around the perimeter, where the connection between each individual bag is completed using 10mm polyester rope
