Demolition Of Harraby College, Carlisle
CUMBRIA COUNCILFollowing a stringent pre-qualification process and a successful tender submission Connell Brothers Ltd (CBL) were appointed to carry out the asbestos removal and demolition of the former Harraby College, Carlisle. The site comprised a number of buildings, two of which were to be retained.
These comprised of the New Sports Hall and the New Theatre (highlighted in purple above). The theatre was to be mothballed for later incorporation into the new build. The sports hall was in use and was to be temporarily closed during demolition. This was necessary as heating, hot water and lighting was supplied from the college and a new plant room required constructing to enable the Sports Hall to become a stand-alone building.
In addition to these constraints the caretakers house to the front of the college was to remain, as well as the sub-station also located at the front of the college.
Prior to commencing any demolition works the electrical gas and water supplies to the building required disconnecting, and in some cases diverting to location of the new plant room.
Once the building services were disconnected the removal of asbestos containing materials from various locations around the site and soft stripping in readiness for demolition could be undertaken. Asbestos removal was carried out by Connell Brothers in-house asbestos removal specialists and was closely co-ordinated by the Site Supervisor and the Asbestos Site Supervisor to enable works to be carried out safely in a number of locations.
In addition to these works the formation of a new plant room was commenced. The initial location was within the existing Sports Hall plant room but further investigation proved this location to be impractical therefore the new plant room was relocated to the front of the Sports Hall
During these initial works it was discovered that there was a significant amount of asbestos within the service ducts running below the ground floor slab throughout the building. The asbestos was in the form of Asbestos Insulation Board packers placed beneath the duct covers. Removal of these required the erection of numerous enclosures to enable the asbestos removal operatives to lift the concrete duct covers safely using a mobile hoist and remove all the asbestos materials under fully controlled conditions. In addition further asbestos insulation board was found beneath various windows which also required the construction of enclosures and removal under fully controlled conditions.
Whilst the asbestos removal and soft stripping works were being undertaken the separation of the building from the retained sections and the construction of the new plant room was commenced.
Asbestos located under duct covers and within ducts
Enclosure to enable asbestos to be removed from beneath windows
Services located within the ceilings to the corridors were cut back and terminated to allow for re-connection and a block wall was constructed to seal the retained buildings. Careful hand separation was then carried out to allow the roof of the retained buildings to be extended and made waterproof. New boilers, electrical installations and gas installations supplies were then installed to the new plant room and connected to the existing system, which was upgraded to comply with current regulations. Finally new services, water, gas, electricity, were brought through the car parking areas to the new plant room.
The entrance to the Sports Hall was also redecorated and a new door fitted. The perimeter hoarding was extended around the sports Hall and fitted with bulkhead lights to enable the Sports Hall to be reopened before the completion of the demolition project.
Prior to the commencement of structural demolition the location of the existing foul and surface water mains running under the site was identified and protected by the use of timber navi mats. Additional steel plates were used in areas identified for use by heavy plant that was required to cross over the sewers.
Structural demolition was phased to follow the removal of the soft strip and asbestos materials and was carried out by excavators equipped with a number of specialist demolition attachments.
An area to the back of the site had been identified by the client for crushing and storage of materials. The topsoil to this area was removed and stockpiled on site and a hardcore haul road to the crusher constructed.
An additional complication that arose during the demolition was a number of nesting gulls that decided to make their home on the roof of one of the buildings. In co-oporation with the council environmental officer works were re-programmed to avoid disturbance to the gulls and only re-commenced following a site visit by the enviromental officer to confirm the gulls had left the buildings.
Following the removal of the superstructure the ground floor slabs and foundations were removed to the buildings. Piles had been used in close proximity to the sewers and these were identified and the pile caps carefully removed as part of the demolition works. In some locations existing foundations were left in place due to their proximity to the sewers and the potential for damage. The location of these areas, together with all the service positions, were identified in the final Health & Safety File to enable the new construction to be designed to avoid them.
Finally the site was finished with a layer of crushed material to provide a safe hazard free site for future development.
This challenging project was undertaken in close proximity to a community centre, housing, and a primary school. Another consideration was the requirement to minimise the amount of time the sports Hall was out of use, all of which required careful planning and co-ordination.
In addition to undertaking the demolition works Connell Brothers also engaged the local primary school who were invited to view the site and were given a presentation by our Site Supervisor as part of a school project.