Royal Sussex County Hospital, Brighton

Hughes and Salvidge were appointed the role of subcontractor for demolition works at Royal Sussex County Hospital, Eastern Road, Brighton.

Outline Scope of Works

• Soft Stripping of all Buildings
• Asbestos Removal
• Mechanical Demolition of Superstructures
• Mechanical Demolition of Substructures
• Crushing of inert arisings

Asbestos Removal

The asbestos enclosures were formed using the existing matrix of the building, and additional timber supports were installed where required. They were sealed using 1000gauge polythene, adhesive tape, spray adhesive and expanding foam as required. Following the erection of the enclosures, a 3-stage air lock and separate bag locks were attached.

Where possible, the non-asbestos ceiling tiles and supporting grid were lowered and cleaned for disposal as general waste. All cables and services within the work areas were cut out, cleaned, and again disposed of as general waste. The exposed pipe sections had a dilute solution of wetting agent applied to the localised area using a low-pressure hand pump spray bottle. Sufficient time was allowed for the surfactant to absorb until the dry material, former pipework, etc was wet as reasonably practicable before removal commenced.

The areas to be removed were needle-injected to ensure they were thoroughly wetted prior to removal with hand tools. The accessible loose material and debris were carefully removed via gloved hands and immediately bagged for disposal. The contaminated sections of pipework were double-wrapped in 1000-gauge polythene and sealed with adhesive tape, ready for cutting out into 2.5m lengths. All pipe work was cold cut with a reciprocating saw and removed to enable a complete clean of the ceiling voids and provide better access to the walls and ceiling debris. All residue to the walls and ceilings was removed with the use of scrubbing pads with the hotspots of residue sprayed with a fibre suppressant via hand-held units. The works continued as described above until all the specific pipe and associated residue sections were cleaned/removed and all debris bagged.

Upon successful completion of the four-stage clearance procedure, the analyst issued a "Certificate of Re-occupation" to the client and our Site Manager for follow-on trades and inclusion in the Health and Safety File.

Soft-strip

Soft-stripping of the Barry Building was completed to two sections ahead of mechanical demolition. A third section was completed during the structural demolition of the initial sections. All soft-stripping debris was initially segregated into appropriate waste streams stored internally and scheduled for removal during the mechanical demolition stage. This was due to the limited external space.

Several areas within the structure were designated for storage, with structural calculations performed to ensure the waste point loadings would not compromise the building's structural integrity.

Scaffold handrail and Heras fence panels were installed at any point that would become a leading edge to ensure safety. These handrails were then demolished with the structure to prevent labour from working adjacent to a created opening.

The additional buildings followed the same process of soft-stripping.

During demolition, skips were moved, delivered to the workface, and positioned adjacent to the work area. Locations were agreed between all parties and recorded on the temporary works register.

Mechanical Demolition

Following the completion of asbestos removal and soft stripping, structural demolition commenced. Initially, a single-storey structure was removed to create a larger working area. Our ZX300 supported our high-reach equipment in reducing the four-storey sections. The Komatsu PC490 Excavator was set up in a high-reach configuration with a 28m reach, and it handled the Barry building, which was approximately 16.5m in height. Demolition started on the southern elevation, progressing north and then west.

The excavator, equipped with a selector attachment, first removed the timber-pitched roof, lifting and lowering it to the ground floor. It then progressively removed the window units on the southern elevation within the machine's reach, lowering them to the ground floor. The excavator reduced the height of the external masonry walls on the third floor, allowing the material to fall to grade after scraping it from the floors. The brickwork was reduced top-down in sections and progressively cleared from the floors to prevent overloading.

With the perimeter masonry removed to the third floor, the internal walls and intermediate floors were exposed. The excavator progressively reduced and removed the internal walls, lifting and lowering any remaining timber or stud partitions to the ground floor. The next intermediate floor was removed, followed by the external wall below. This process was repeated top-down, with the three identified basements backfilled with inert arisings as work progressed.

A second machine was present throughout the demolition to process the arising materials. Inert materials such as brick and concrete were stockpiled for crushing as works neared completion, while other materials, like general waste and metals, were removed to keep the site clear and maximise working space.

Throughout the works, one structure remained operational and required mechanical separation from the other structures. A fire exit route had to be maintained, and scaffold screen protection had to be installed to safeguard the live hospital's air intake system.

Once a significant portion of the ground-bearing slab was exposed, machines equipped with impact hammers and buckets began removing the slab and foundations. They punctured the slab and foundations to break them into movable sections. Machines with buckets then lifted and stockpiled sections for further processing. Machines with pulverisers processed arisings further to separate concrete from reinforcing bars and load away respective materials.

All excavations and basements were progressively backfilled after foundation removal. The area was graded to match the surrounding site contours, and the footprint was tracked in by machine, leaving a flat site.

Concrete Crushing

Site-won hard inert arisings were crushed on site to produce aggregate for re-use. Concrete/hardcore was loaded into the hopper by an Excavator, which is hydraulically fed into the Crusher. The crushed material falls onto the conveyor where any reinforcement bar or other ferrous metal is removed by a hydraulic belt magnet fitted above the main conveyor. The crusher then discharges crushed aggregate and metal into two separate stockpiles. Metal was periodically loaded away into metal bins, and aggregate was regularly cleared and stockpiled in the client's desired locations. Aggregate stockpiles were formed with a suitable angle of repose to ensure they remained stable and to mitigate any "land-sliding" of aggregate. The Crusher is fitted with a dust suppression system, whereby water is sprayed onto the discharge conveyor to minimise dust. Arising stockpiles were dampened down at regular intervals to mitigate dust release. The area was left clean and tidy on completion.