A recent bridge project had one abutment completed using traditional methods, the other using Gabi® Block. Our alternative represented savings of around 10% in materials and a staggering 80% in labour.

Description of work:
Stepped block wall 24m in length and varying in height from 1.5m to 2.5m
Vertical drainage layer 300mm wide, to be installed behind wall to drain groundwater
Three systems available to fulfil this requirement:

1. Bag drainage rock and stack against wall
2. Place drainage rock against wall and backfill against with a geofabric layer separating the two
3. Aqua Solutions Gabi® Block

Benefits:

1. Installation time took approximately 8hrs, which also included the backfill operation. Traditional methods would take anywhere from 2-5days
2. Installed system was free from contamination from backfilling material (common occurrence with traditional methods) due to the ability to install the system above the backfilling levels
3. Installed system created a straight line that enabled compaction machinery to operate against the drainage system. This is difficult using traditional methods due to the inconsistent lines created from bagging drainage materials or wrapping of gravels in geofabric
4. Drainage system is strong enough to withstand minor hits from construction machinery while maintaining structural integrity to perform its required function
5. Drainage properties seem to be vastly superior to traditional methods from viewing of on-site tests.

Author: Cameron Kretschmann (B.Eng)
Project Engineer - Walton reserve Bridge (western approach)
(Excerpt taken from letter to Blue Whale Industries)

Geofabric is laid under the first layer of Aqua Drainage Block	Aqua Drainage Block is then laid to a safe lifting height.
Once the Aqua Drainage Block has been laid to a safe lifting height it is then covered with geofabric.
Start back filling and compacting. The block will withstand a high level of compaction and still maintain structural integrity.	When fill is up to a work level the geofabric is removed and the Aqua Drainage Block is then re-laid.

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