Run-off tank was built by hand and was very porous
The farmyard in Fawnagown, Co Tipperary, is in the Golden Vale, the heartland of Irish dairying, and a 'run-off' tank was a common feature on Irish dairy farms.
Built to collect water that was used to wash milking parlours, these run-off tanks were typically built with concrete blocks or mass concrete and covered with concrete slabs or slats.
Mary Lowry's brother Jimmy told the trial he was 12 or 13 at the time of construction of the tank where Bobby Ryan's body was ultimately found.
He recalled his father 'inside in the tank' building it out of nine-inch cavity blocks, he said.
The tank on Ms Lowry's farm was built in the 1970s with cavity blocks and was 1.6 metres deep, was 3.6 metres long, and 1.8 metres wide. It was finished with a light 3mm skim of plaster coating the interior of the tank, and it had a concrete base.
Farmyard building experts say that over time the walls of these tanks may have cracked and become porous and, if disused, they may have been allowed to overflow. In many cases, grass and weed growth would have covered them over.
Engineer Michael Reilly told the trial that access to the tank was via two removal covers on one side of the tank, while the rest was covered with an in-situ cover not designed to be moved, and which had been cast on site, by pouring wet concrete on top of a piece of corrugated iron.
The trial heard that in February 2014, Mr Reilly tested the tank, where over two days the entire water supply of the farm at Fawnagown was pumped in. He pumped in more than 21,000 litres to a tank that held at its maximum 4,212 litres.
Over the two days it lost more than 17,000 litres because, he said, the tank was too porous to hold it. Days later, he found the water level in the tank had dropped back to the same level as it had been before the tests began, at 250mm.
"Once it reached a certain position, it was going out of the tank as quickly as it was coming in," he said.
How long Mr Ryan was in the tank was looked at in the trial and forensic entomologist Dr John Manlove said it was his opinion that Mr Ryan's body had remained in the tank 'for most if not all of the time' since he went missing in June 2011. He determined this by the level of insect infestation on the body.
He quoted an engineer's report that said once muck and cow waste were placed on the slabs, the tank would be perfectly sealed, making it impossible for flies to get in or out.