Prosecution Details

Being a Principal who in the course of trade or business engaged contractors to carry out work for it, and failed to provide and maintain, so far as practicable, a working environment in which persons employed or engaged by those contractors to carry out or assist in carrying out the work concerned were not exposed to hazards, being matters over which the Principal had the capacity to exercise control; contrary to sections 19(1), 23D(2) and 19A(3) of the Occupational Safety and Health Act 1984.

At all relevant times the material facts were as follows.

The accused operated a building business and was engaged by John Orr Independent Constructions Pty Ltd as a subcontractor for a development by Finbar International, constructing a multi-storey apartment complex in West Perth.

The accused engaged one employee to carry out the plumbing work and another employee as an excavator driver to dig a trench of about 20 metres alongside a brick retaining wall so that the plumber could lay the sewer pipes. The accused employed a site supervisor and a labourer.

The site plan showed the level to which it was necessary to dig the trench to accommodate the sewer pipes. It was not below the depth of the footing of the brick retaining wall. If the trench had only been excavated to this depth it would have been unnecessary to take any further measures to remove the risk of the brick retaining wall collapsing.

On 4 April 2006 while the excavator driver used the excavator to dig the trench the plumber and the labourer intermittently worked inside the trench.

The trench was dug to a depth below the base of the concrete footing of the brick retaining wall, and the sides of the trench were unnecessarily steep. As a result it was very likely that the brick retaining wall would collapse and/or the sides of the trench would cave in.

The stability of the brick retaining wall was not protected by sheet piling, shoring, bracing, guying or any other means. The steep sides of the trench were not supported by trench boxes.

When the trench had been excavated to about 2 or 3 metres from the end of the boundary wall and was about 10 metres long the excavator driver thought that the retaining wall was in danger of collapsing, and the labourer told the excavator driver that he could see daylight coming through the concrete footing of the retaining wall because the trench had been dug to below the base of the footings of the brick retaining wall. The plumber then walked to that part of the trench where the labourer was standing. The brick retaining wall then collapsed narrowly missing the labourer but crushing the plumber and pinning him against the side of the trench.

An ambulance was called and the plumber was taken to Royal Perth Hospital where he was diagnosed as having suffered a broken collarbone, broken ribs, a punctured lung and ruptured spleen.

The accused subsequently pulled down the brick retaining wall to remove the risk of further collapse.

The risk of a retaining wall collapsing due to excavation of the sand which supports it is a well known and obvious hazard that could have been prevented by inexpensive and very practical means such as:

(a) compliance with the site plan, which showed that it was not necessary to dig below the footings, to ensure that the trench was not over excavated; or

(b) the use of readily available materials such as sheet piling, or shoring, bracing or guying to support the brick retaining wall and trench boxes to support the sides of the trench from collapse. This would not have been necessary if the trench was only excavated as far as necessary and was not unnecessarily steep.

The WorkSafe Western Australia Code of Practice: Excavation 2005 states that a continuous length of trench with depths of greater than 1.5 metres and side slopes steeper than 1V:1.5H requires trench support. The depth of the trench was about 2.5 metres and the side slopes significantly steeper than 1V:1.5H, and the trench was not supported.

Plead Guilty