Two joiners were shoring up the arch after it become unstable due to the removal of some masonry on one of the support pillars. One fractured a foot and the other injured his back in the incident at a former toffee factory in Ouseburn, Newcastle in February 2011.
The Health & Safety Executive (HSE) last week prosecuted Brims Construction Ltd, the principal contractor for the project, and designers Cundall Johnston & Partners LLP after an investigation into the collapse identified safety failings.
Newcastle Magistrates' Court heard that brick pillars adjoining the archway had been weakened after 'pockets' were created in the masonry to hold steel beams, which were being installed as part of a refurbishment.
The court was told the removal of the masonry caused the arch to become unstable, as the pillar had acted as a buttress. The condition of the arch was brought to the attention of Brims' site foreman who instructed the two joiners to shore it up.
They devised a plan of work, but it was not reviewed by Brims to check that it was a safe method of working. While work was underway, the archway collapsed onto the two workers.
HSE inspectors found that Cundall Johnston had not provided information in its designs to ensure those carrying out the work would have known removing the masonry would cause the archway to become unstable.
Brims also failed to plan and manage the work to deal with the unstable archway safely.
Brims Construction Ltd, of Austin Boulevard, Quay West Business Park, Sunderland, was fined £1,000 and ordered to pay £5,000 in costs after pleading guilty to breaching Regulation 22(1)(a) of the Construction Design and Management Regulations 2007.
Cundall Johnston & Partners LLP, of Horsley House, Regent Centre, Gosforth, Newcastle, also pleaded guilty to a breach of Regulation 11(6)(c) of the same legislation. The company was fined £1,000 with costs of £7,000.
Speaking after the case, HSE inspector Keith Partington said: "Fortunately the injuries suffered by the workers were not serious. However, if could have been a lot worse as around two tonnes of brickwork fell down when the arch collapsed.
"This incident could have easily been avoided. Firstly, if the designers had ensured sufficient information was available in the drawings it would have alerted those carrying out the work to the potential dangers to start with. Brims should also have properly planned and managed the work."