Sinkhole’s sucking sands a real risk to bathers

Outdoor Living

GROWING PROBLEM When this photograph was taken, from the warning sign to the far end of the sinkhole was about 20 metres. The entire area within the stakes is sinking sand. The condition of the bathing beach continues to deteriorate. Pic: Aerial Photography Mayo

Country Sights and Sounds
John Shelley

The popular bathing beach at Moore Hall has become increasingly perilous as the sinkhole, which is surrounded by only a few inches of water, continues to grow. Now many times its original size it is an object of curiosity that draws people to its unsteady side.
Castlebar resident Artur Caplac, a Polish man, recounts how he fell into the original sinkhole two years ago. “It was only small then,” he says, “but I plunged in and sank to a depth of two feet. It felt like someone had hold of my legs and was pulling me down.”
Another regular visitor who swam in the area as a child says her father often warned her of dangerous sinking sands, both on Lough Carra and parts of nearby Lough Mask.
Owen Regan from Claremorris has been making regular trips to Moorehall for many years. He recalls the late James Reilly, who operated a successful boat hire business nearby, warning that the shallow corner of the bay where the sinkhole has appeared was always dangerous, and that the only safe place for bathing nearby was close to the Lough Carra Anglers boat enclosure.
Generations of children have enjoyed the shallow water here, their parents unaware that the sand they dig into with their plastic bucket and spade is in fact no more than a crust, beneath which lies a thin white porridge several feet deep. When I conducted my own highly scientific experiment of poking with a stick I found a quagmire at least eight feet deep. I feel compelled to record my observations.
Friday, June 6. I had known of a soft area, circular in shape and perhaps three meters wide, for a few years, and also of a permanent small sinkhole about a hundred metres out into the lake. Today the soft area has increased considerably, with minor subsidence to the south and east. It looks as though something interesting is taking place.
Saturday, June 7. Moore Hall Bay is thronged with people. They use the woods across the road as a latrine and when they leave the place is filled with litter. I think dark thoughts, that sinkholes might have a purpose after all.
Monday, June 8. Considerable changes have occurred over the weekend. The depressed area has fallen away to create a pool 18 inches deep, the center of which is now extremely soft. People bring children to play in the area. I try to alert them to possible danger. Men from the Council arrive to erect signs warning of deep water and erect a temporary barrier.
Thursday, June 11. The lake bed has continued to sink overnight – not by much, but the depth of water has increased by two inches or so.
The amount of extremely fine material on the lake bed has also increased considerably, particularly to the east of the sinkhole where a layer of marl dust swirls into a cloud beneath my feet.
Bubbles of gas rise to the top when pressure is exerted on the lake bed adjacent to the sinkhole, again on the eastern side. This is a new development. The gas is likely to be carbon dioxide, methane, or according to Taly Hunter Williams, senior geologist with Geological Survey Ireland, it might be oxygen being released from oxygenated water trapped in a subterranean cavern.
The lake bed to the south of the sinkhole is beginning to feel decidedly unstable, with further areas becoming depressed and very soft; 24 hours ago I could walk around the entire depression in my wellington boots, but this is no longer possible.
Friday, June 12. This is the last time I intend to wade around the sinkhole. The lake bed feels very unstable, as if it is ready to collapse under my weight. The main depression has expanded far beyond the area cordoned off yet, strangely, I was able to circumnavigate the area without shipping water into my boots, so I can only surmise that pressure from beneath must have forced the flexible marl crust upward once more. Gas continues to bubble from beneath my feet. Tonight I used a boat to explore and found numerous further softening patches nearby.
Sunday, June 14. There is no question that the lake bed is becoming progressively unstable as it continues to sink over an increased area. There is talk of remedial action. It is hard to see what can be done, apart from close the area to the public and allow nature free rein.
Tuesday, June 16. Heavy rain has brought the lake level up a little. Multiple eruptions of fine silt are appearing on the marl crust and more gas bubbles from new areas. This is Water Safety Awareness Week. The weather is expected to warm up over the coming days. Visitors will come flocking.
Over the last ten days I have seen the condition of the lake bed at Moore Hall pass from relatively safe to dangerous. That is my own inexpert, unscientific opinion. Unless something is done I fear another tragedy. Water Safety Awareness Officer for Mayo County Council Patricia Flynn is aware of the issue, and I understand a number of potential remedies are being considered.