Stafford College Demolition

Connell Brothers were appointed as demolition contractors for the demolition of various buildings at Stafford College as part of a redevelopment project.
The buildings were located within the main campus, which was occupied for part of the works, and adjacent to a busy main road in the centre of Stafford.

The buildings comprised a single storey steel framed structure, two three storey reinforced concrete teaching blocks, a single storey plant room, two link bridges between the main buildings and the retained buildings and an access ramp. Furthermore there was an access opening between the two main buildings to be demolished with classrooms overhead. At one end of the works there was an interface with the listed section of the college that was to remain.

The close proximity of the adjacent building along one side necessitated the erection of a protection scaffold to ensure the newly replaced windows and existing façade remained undamaged. A full perimeter timber hoarding was also erected to ensure total segregation between the works and the students and teachers on campus.

Initial works comprised the removal of various items of equipment to be retained by the college. During this time, asbestos containing materials were removed from the building by a specialist sub-contractor. In order to protect the listed building a solid block wall was constructed just beyond the cut line for the demolition. These works were carried out following a site investigation in conjunction with the architect to determine the cut line for the demolition. These works also required a new door access to be formed within the existing building to enable access to the adjacent rooftop plant for maintenance. Fire escape routes also required diverting within the building prior to blocking up works taking place.

Service disconnections formed a large part of the initial works. During investigation activities in the early stages of the project it was discovered that a large gas supply existed to the buildings. In order to cap this supply a specialist contractor was employed and the works programmed to take place during a bank holiday period to minimise the disruption to the rest of the college due to the need to turn off the main gas supply to allow for disconnection of the required branches.

Following the disconnection of all the services, the construction of the block dividing wall and the erection of the scaffold, demolition could commence in earnest.

Mini- excavators were placed on the roof of the building and operatives using hand tools began to remove the section adjacent to the listed building. The two structures were separated and the mini-excavator used to remove the first two bays of the roof. Operatives working from the access scaffold then removed sections of the outside walls adjacent to the listed building. The inner walls were then cut back before the excavator was lowered to the floor below to complete the wall removal. These works continued down the building until a physical separation was achieved to allow for demolition by high reach excavators.

In order for the high reach excavator to gain access to this section of the building the first connecting bridge required demolishing. The access to the bridge from the retained building was secured and the finished stripped back to reveal the structure.

An inspection of the structure revealed a soft joint connection between the bridge and the retained structure that allowed for the demolition of the bridge by a high reach excavator. The concrete elements were pulverised in-situ, working down and along the bridge until only the bottom beams remained. Therese were then pulverised along their length before the reinforcement was sheared through and access achieved to the building behind for the high reach excavator.

Demolition could then continue along the length of the buildings working away from the listed building. The access between the two main buildings was formed by the use of numerous precast concrete beams, forming a tunnel under the teaching blocks. The bay to each side of this tunnel was retained and the buildings demolished down to first floor level. The beams were then systematically demolished by pulverising them in-situ before the bays supporting them to either side were removed.

The last remaining link bridge was demolished in a similar manner to the first link bridge to provide a physical separation between the retained structures and those to be demolished. This also enabled demolition of the other end of the main buildings to be carried out and thus reduce the overall programme duration by working on two faces at once.

The next area of separation involved the removal of the top section of the access ramp. The lower section was retained as it containing a plant room. The top section of the ramp was constructed using a series of steel beams with infill reinforced concrete and was removed by pulverising along the length of the section before shearing through each beam in turn.

Once the top of the ramp had been removed the remaining section of the main building could be demolished. This provided access to the steel framed building adjacent to the boundary. This building was clad in composite cladding which was removed by the excavator as the demolition proceeded. The steel structural elements were removed by shearing through the roof beams and columns in sequence, working along the length of the building.

Following the demolition works Connell brothers were instructed to remove the ground floor slabs under the watching brief of an archaeologist. This was carried out by breaking the slab into sections using an excavator equipped with a hydraulic breaker and then removing the sections using a toothless bucket to minimise disturbance of the ground beneath.

The footprint of the new building was then plotted on the ground and the ground level reduced to the level required for the new construction. As part of these works the existing footings that fell within the footprint of the new building also required removal. This additional work was also carried out under the watching brief of the archaeologist. The concrete from these works was crushed so the required specification and remained on site for use by the following building contractor.

Key Facts

This project presented a number of different challenges. • The requirement for demolition against a listed structure that required investigation to determine the exact line of the demolition. • Removal of a number of bridges in congested locations against retained structures. • Extensive ground works under the watching brief of an archaeologist. • Carrying out works within a live college environment and the requirement to minimise disruption to students and teachers alike. Close liaison with the project team ensured that this challenging project was completed within the required timescale, with no incidents or injuries and with minimal disruption to college activities. CLIENT: Stafford College Earl Street Stafford ST16 2QD PROJECT MANAGER: GVA Grimley ARCHITECTS: CPMG Architects Ltd COST CONSULTANTS: AA Projects CDM CO-ORDINATOR: AA Projects STRUCTURAL: BWB Consulting
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