McMahon Services Demolishes Adelaide’s Tower
January 31, 2023
This article was originally published in the March/April 2008 issue of DEMOLITION magazine.
The demolition of the Advertiser Building in Adelaide, South Australia, involved the removal of over 800 cubic meters of friable asbestos; demolition of 15,385 tons of structure and removal of debris from the site; excavation of 1,500 cubic meters of spoil in the lower basement level and removal of spoil right through the city’s adjacent City Central Tower 1 basement; and installing 250 cubic meters of building layer to the basement excavation.
In order to meet the complex project’s completion date, McMahon Services established a 24-hour multi-shift operation, as well managing demolition on upper floors while asbestos decontamination was undertaken concurrently on the floors below. The requirement to deliver the project in 22 weeks presented significant challenges. McMahon Services had to develop a deconstruction procedure whereby the tasks of asbestos removal, upper level structural demolition and basement civil works occurred concurrently.
The Advertiser Building was located on one of Adelaide’s busiest intersections, the corner of Waymouth and King William Street, and to the south abutting a historic building, the Electra House. On the western side of the building, Adelaide’s new 20-story CCT 1 building was under construction.
The demolition project involved complete asbestos decontamination of the 14-story building, including a two level basement, before demolition of the structure down to top of ground level slab. Concurrently, alterations were made to the existing column, beam and slab structures in both basement levels. In addition, the lower basement was excavated a further 2 meters and a reinforced mass concrete raft slab was poured to provide a stable platform to support the new structure.
Located in the basement were two major ETSA transformers, which serviced a significant portion of the western Central Business District of Adelaide. The transformers had to remain operational at all times throughout the project.
Maintaining crane support to the various work fronts and failsafe protection systems for low-level personnel was a critical factor in the demolition process. It was determined that a combination of fixed tower crane and mobile crane would present the most effective and safest solution.
The tower crane was erected in such a way to be supported by the structure being demolished but also to avoid interference with the full height demolition scaffolding. A retention base was engineered and constructed for the tower crane, rather than a piled support base, due to the myriad of in-ground services below the adjacent King William Street roadway and sidewalk. A complex system of full height demolition scaffolding based both on the ground and cantilevered from the superstructure was also utilized.
To achieve the tight completion date, demolition work was undertaken concurrently on multiple upper story levels, while basement works proceeded. At any one time during peak production, demolition of upper level structure was occurring while multiple levels of asbestos removal were being carried our at lower levels and, below ground level, basement excavation and raft slab construction works were underway.
To manage this complex and multifaceted methodology safely and efficiently, the McMahon Services site team leaders and subcontractors met each morning with the on-site workforce at a startup toolbox meeting prior to works commencing. At these meetings, the day’s activities and objectives were planned and reviewed in detail to ensure the works would proceed safely. A series of target milestones were identified and the project was broken down into clearly defined areas of responsibility.
The site manager, Russell Cummings, oversaw the day-to-day running of the site. Work teams were then split into five areas of responsibility, with a supervisor controlling each of the structured demolition: upper levels, asbestos removal, safety, basement works and night shift operations.
Advance notice of planned activities was given to adjoining stakeholders and neighbors and feedback was evaluated for avoidable impact on their interests. In particular, nighttime activities were designed so that there would be minimal noise impact on the surrounding environment. The McMahon Services project manager was designated as the 24/7 contact point for the surrounding stakeholders.
Minimum laydown space was available within the site area and ongoing planning was required to achieve safe and efficient truck movement to and from the site, as well as efficient temporary storage of demolition materials. Detailed planning was carried out with Adelaide City Council personnel to develop traffic management systems for both vehicles and pedestrians.
The continuous removal of demolition materials in a systematic and orderly manner was crucial to maintaining project momentum. Excess material could not be left to overload floors and compromise the integrity of the remaining structure. A waste chute was constructed to enable rubble to be dropped from the upper levels into a contained environment before being loaded into semi-tippers for removal and disposal. Water was used for dust suppression on a continuous basis, and roads were regularly swept clean and silt traps regularly inspected and emptied as required.
During all phases of demolition, vibration and noise monitoring was carried out in the adjoining occupied heritage listed building. An independent engineer’s assessment of vibration and noise impact was carried out on a regular basis and outcome reports prepared, measuring data against industry standard benchmarks.
McMahon Services was involved with the design team throughout the development of the CCT2 project. Initially, a refurbishment of the building including modification and installation as a new column and beam superstructure. This concept was developed to a point where it became apparent that this option would not meet the clients building finish, environment and budget requirements.
Safer, faster and more efficient removal of material from the upper floors was achieved through construction of a waste chute, enabling rubble to be dropped from the upper levels into a contained environment.
Protection of the basement workforce required early construction of slab infills at the ground floor level to ensure that all voids from lift shafts, stairwells and riser shafts were sealed. Complex shoring systems were installed, providing temporary support while structural beam and column modifications were carried out. The historic building adjoining the south boundary was protected at all times.
Adelaide’s City Central Precinct is a high profile development with a clear client commitment to upholding 5 Star Green Star standards. On this project, compliant requirements were defined and documented in a comprehensive Environmental Management Plan. This plan provided the framework and defined all standards and procedures to ensure we competently managed all the environmental issues arising from asbestos removal and demolition work. It met all Adelaide City Council and relevant statutory authority requirements, as well as the general amenity of the surrounding area.
Priorities included a minimum of 80% for recycled demolition materials, use of recycled materials in new construction and mitigation of on-site environmental impacts from asbestos removal and demolition.
Actions taken to mitigate any adverse environmental impacts from the demolition and construction works included:
Dust: To ensure dust release was kept to an absolute minimum, work practices were introduced and diligently followed, such as continual wetting down at the workface, application of mists sprays for waste chutes, and wetting down trucks. No dust complaints from neighbors or authorities were received during the entire project.
Noise: The EMP also paid particular attention to noise emissions and all works were carried out in accordance with the OHS and Welfare Act of 1986 and Regulations 1995, National Code of Practice for Noise Management & Protection of Hearing at Work; and EPA and ACC requirements. All plant and associated attachments selected for the project were fitted with the latest available silencing and noise suppression systems. All personnel were issued with appropriate hearing protection.
McMahon Services was particularly sensitive to the operations of adjacent businesses and ongoing liaison with surrounding stakeholders led to occasional changes in work practices. For example, the accelerated works schedule required a 24 hour shift operation, but the work scheduled for nighttime was those generating the least impact.
McMahon Services is third-party certified to AS/ISO 14001, the international environmental management system standard. This accreditation reflects our corporate commitment to best practice in ecologically sustainable development. In 1992, McMahon Services founded Resourceco in South Australia to better manage the recycling of materials produced from its own and other contractors’ projects. The company has since introduced a corporate policy to achieve 0% waste materials for all of their projects, and we are continuously refining their methods of demolition and waste processing to achieve this goal.
As a management and assessment protocol, McMahon Services has adopted the Green Building Council of Australia (GBCA) Green Star system as a measurement system to monitor our performance. Against this background, we are delighted to be associated with the City Central Redevelopment as the client has adopted best practices 5 Star Green Star standards for all its projects. To achieve at least this standard, we implemented the following environmental management procedures that were all fully documented in our Environmental Management Plan.
Even though the site was extremely restricted, sorting procedures were implemented to facilitate increased recycling opportunities. Specifically, materials were separated and sorted into ferrous and nonferrous metals, combustible materials, concrete and masonry before being removed from the site. A project specific and comprehensive tracking system was developed and followed. This system tracked all material removed from the site as part of the demolition process. It identified the destination of the waste and recycling processing procedures.
This system also detailed the form and quantities that the waste was to be recycled into and nominated the end users of the recycled product. These details were compiled and provided to the client on a monthly basis.
To assist with the achievement of 5 Star Green Star Rating for the project, McMahon Services committed to a minimum 80% recycled materials. However, an outstanding result of 98% recycling of waste materials was subsequently achieved through detailed project planning, responsible on-site work practices and effective use of Resourceco’s waste handling facilities.
The South Australia government, together with the Adelaide City Council, has identified reduction in greenhouse gas emissions as a priority for South Australian industry and wider community.
For the construction industry, an essential ingredient in achieving this objective starts with waste management and recycling initiatives. McMahon Services is at the forefront across the industry with its zero waste policy in conjunction with sister company Resourceco.
McMahon Services believes the essence of quality public and community relations is a combination of defining the right thing to be done and then performing and communicating the substance of that performance, basically a “no-surprises” approach.
Consultation was initiated and communication maintained on a number of fronts to ensure minimal disruption to the on-site work. This approach proved to be telling in the successful delivery of a complex demolition project in a lively business district environment of downtown Adelaide.
Before work commenced, members of our project team visited all premises within 100 meters of the site along Waymouth Street to explain the scope of the upcoming project and provide contact details should the need arise.
Similarly, vehicle and people movement management was a particularly difficult assignment on this extremely tight site. Extensive consultation was undertaken with ACC personnel to devise the most efficient and safe arrangements for managing site traffic access and egress while maintaining safe avenues for vehicle and ambulatory movement past the site.
All required notices and approvals were obtained from the various statutory authorities such as the EPA and WorkSafe SA. Arranging termination of existing services, while maintaining essential electrical and water services, proved to be a difficult but necessary outcome. Relationships were built with key representatives from each utility in order to obtain a degree of priority attention in arranging timely responses.
In a letter from the site’s principal owner, Caversham Properties, their manager of major projects Bob Boorman to David McMahon summed up the owner’s feelings about the work performed by McMahon Services on the Advertiser Tower:
“Working in combination with the ever present professional crew, the team approach taken by everyone was a major factor in achieving such an outstanding result.”