A lack of geological and integrity studies were among the reasons that led to the collapse of a road at Chadwick Lakes, leading geologist Peter Gatt said on Friday.
A large section of road that runs parallel to the watercourse collapsed on 1 November after heavy rainfall. Works had been carried out in the area in 2019.
In a Facebook post, Gatt said he ha predicted back then that the retaining wall on which the road is located would fail.
The excavation and removal of sediment from Chadwick Lakes in the summer of 2019 was intended to significantly increase the capacity of water storage retained by the dams, but the project went awry for several reasons, he said.
“The commissioned project Perit (acting in the capacity of a Civil Engineer) tried to do the work of a Geologist when he is not qualified to do so. The applications of Engineering Geology are essential in such projects, but were absent.”
Gatt said the Perit had also failed to do his work as a Civil Engineer, which include the assessment of the integrity of existing built structures, namely the dam and the retaining wall over which the road along the 'lake' is located.
Furthermore, the excavation works produced exposed vertical walls along the channel which are unstable and failed during the recent heavy rainfall. These excavation works may have damaged the retaining wall, as can be seen by the large scratch marks seen in 2019 photos, and which were caused by hydraulic back-hoe excavators.
Gatt also said the photos suggest that the bedrock of the channel, made of Globigerina Limestone, was excavated.
“If this is confirmed, it proves gross incompetence and bad planning from a lack of understanding of Engineering Geology.”
“The question that now arises: since no one assessed the integrity of the built structures which are more than half a century old, and bearing in mind that the water pressure on some of the dams may have doubled as a result of this Project, are the dams still safe?”
“We might learn from this incident not to repeat it, but I doubt that will happen,” Gatt wrote.