A senior engineer from Dublin City Council has communicated to councillors that, thus far, no definitive cause has been determined in the investigation of the Sandymount sinkhole. This substantial sinkhole, which formed over a week ago and measures over 1 metre in depth, spread across an area of 5 square metres on Sandymount Green’s roadway, directly opposite the Mace shop.
Following the emergence of this cavity in the core of the south Dublin village last week Wednesday, Gardaí arrived promptly at the scene. Council workers were then mobilised to conduct immediate safety operations. Roy O’Connor, a senior engineer from the Protection of Water Bodies Office, informed that his team has been engaged since then to fill the Sandymount pit and completely repair the damaged roadway.
On initial analysis, it appears the cavity developed gradually over an extended period, as the sandy soil, a characteristic feature of the Sandymount area, steadily drained into the drainage network. This eventually led to the formation of the void, compromising the structural soundness of the layer of carriageway above. He communicated this to councillors on Friday.
The seepage source is currently being determined by the council’s CCTV inspectors stationed at the site, he disclosed. He said, “We are certain that the water main did not exacerbate the situation and while the sewer may have aided the removal of sands, it is not necessarily the root cause of the issue. Additionally, a privately owned sewer that appears to have been damaged for quite some time is also present there. We are attempting to confirm the precise cause of the sinkhole now that the CCTV team has arrived at the scene.”
However, he emphasised, “There is no clear evidence pointing to a single cause for this situation.” Dermot Lacey, a councillor from the Labour Party, praised the timely reaction of the council staff and associated services and also expressed concern over the likelihood of a similar sinkhole appearing in the future.
The scale of the Sandymount sinkhole is highly unusual. “Over a period of two decades since I joined the drainage department in 2002, according to various engineers who have been involved throughout this duration, only three or four sinkholes of this size have formed, none of which were in Sandymount,” stated O’Connor.
He mentioned that the city possesses tens of thousands of kilometres of drainage infrastructure, excluding the multiplicity of private connections to every individual private property as well as more than 55,000 gullies feeding into our drainage network. It would equate to looking for a needle in a haystack, he said, to predict the next occurrence of a sinkhole. However, he assured that the probability of witnessing a chasm as large as the one in Sandymount was considerably low. He confirmed that the restoration of the ravaged road is slated for completion by Sunday. It is noteworthy that in recent times, sinkholes had emerged in locations such as Dalkey, Clontarf, Dame Street, and Dublin 7.