Alert C18: Manhole and pipe installation using backhoes

Alert C18: ISSN 1195-5228
Produced by the Construction Health and Safety Program
Issued: January 2000

Hazard Summary:

The investigation of a fatal accident at a water main and sewer installation project revealed that it was caused by a combination of three factors:

1. Unsafe rigging assembly;
2. Unsafe work procedure; and
3. Lack of worker training.

The following explains the unsafe rigging assembly and work procedure.

Unsafe rigging assembly:

The rigging assembly consisted of a series of chains and hooks connected to a ring welded to the bucket of the backhoe. The backhoe had been modified for use as a crane or hoisting device.

Three lines were attached to an "O" ring. Two of the lines were connected to the maintenance manhole section that was being lifted. The third line was looped through the ring welded to the bucket of the backhoe and then attached to the "O" ring by a terminal hook. The hook was not equipped with a safety catch.

Unsafe work procedure:

The company had an unsafe procedure requiring that a worker be inside the manhole section(s) already installed while the backhoe operator moved the additional manhole section above the worker prior to lowering it into proper position. Another worker, in the trench and outside the manhole, would adjust the position of that section as directed by his co-worker inside the structure.

While lifting and lowering the manhole section into position, the chain connecting the ring on the bucket to the O-ring went slack and the hook disengaged because it did not have a safety catch. The worker inside the installed sections was killed when the assembly and the manhole section fell and hit him.

Locations and Sectors:

Excavations/trenches for underground sewer, water main and catch basin installation.

Legal Requirements and Recommendations:

1. Rigging assembly
   • The components of a rigging assembly shall comply with the requirements of the Regulations for Construction Projects (Ontario Regulation 213/91) made under the Occupational Health and Safety Act and shall be connected in accordance with sound rigging practices.
   • Hoisting hooks shall be equipped with a safety catch and shall have their load rating legibly cast or stamped on them in a location where the person using the hook can readily see it–as required by sections 170 to 179 of Ontario Regulation 213/91.
2. Work Procedure
   • Material or equipment that is being moved shall not endanger another worker or pass over another worker. Sections 37 and 103 of Ontario Regulation 213/91 that deal with material handling and worker safety shall be complied with.
3. Modification of Equipment
   • Whenever lifting hooks or rings are added to a backhoe, the modification must be carried out by the manufacturer of the equipment or approved by a professional engineer. Refer to sections 93 and 95 of Ontario Regulation 213/91 and to the ministry's Alert "Modification of Construction Equipment" # C13/05/96.
   • Whenever backhoes are modified for use as cranes or similar hoisting devices, the relevant sections of the regulations for cranes, hoisting and rigging shall be complied with.
4. Training and Supervision
   • Workers should be adequately trained and aware of the hazards associated with rigging, the use of equipment, excavations and trenches.
   • A competent person or the supervisor shall inspect all machinery and equipment at the project to ensure that they do not endanger any worker as set out in sections 14 and 94 of Ontario Regulation 213/91.