Bailey: Deficient drainage may have contributed to failure

The deficient drainage system that formed part of the construction of Jack’s wall at Ratho Mill was just one factor that may have contributed to its failure.{{more}}

Chief Engineer with the Ministry of Transport and Works, Brent Bailey, told a coroner’s inquest looking into the September 19, 2008, collapse that killed Patsy Bowman he visited that scene after the incident and concluded that a “significantly large landslide” had occurred.

He added that the structure of the wall was examined immediately after the collapse when their main concern was clearing the debris to determine if anyone had been crushed beneath.

During cross-examination by Counsel Samuel Commissiong, Bailey said the drainage system had been compromised by the sandy clay soil behind the wall.

Additionally, while being cross-examined by Nicole Sylvester, Bailey noted the soil contained more clay than sand. Clay, he said, has the tendency to retain water. It binds and the permeability of the soil is reduced.

“The more water, [the worse the situation becomes],” he added.

Because of this, the engineer explained, the properties of the soil must be considered when designing the structure of a wall.

Bailey also said in his report that weep holes in the wall [used to allow water through the structure] were not working properly since a number of them were blocked with soil. He pointed out that the section of the wall opposite the entrance to the SunSail Restaurant and Hotel at Ratho Mill was taken down by machine and an electrical stay wire that extended across the road was removed as a safety precaution.

The public works official revealed, however, that the strength of that section of the wall appeared greater as it proved difficult to remove.