Case Study - Harbour School, Bovington
Project: Harbour School, Bovington
Client: Galiford Try
Program: 16 Weeks
Location & Overview
Harbour School was situated within its own grounds shared with a temporary school and associated car park that needed constant access and egress for staff, pupils and school vehicles.
A main arterial road into the centre of Bovington ran adjacent to the project and was heavily used by the military. The perimeter of the site was secured with a combination of open mesh fencing and hoarding. Tree protection was also provided to ensure no damage occurred to the trees and their roots throughout the project.
Separate entrances were formed to segregate the project deliveries, visitors, and parking. And access to the site was controlled by a gateman and banksman at all times.
The various buildings on the site compromised of two multiply storey structures, consisting of traditional masonry with concrete floors, pitched steel frame roof with corrugated asbestos roofing & other various forms of non-licensed asbestos-containing materials were distributed throughout the buildings.
Pre-contract
Portsmouth Demolition & Salvage Ltd were sub-contracted to Galiford Try, who were the principal contractor for the project and were responsible for all notifications to the local authorities.
Our management team attended a pre-contract meeting on site with Galiford Try’s team. The Harbour School had a number of requirements that needed to be met at all times. These requirements were discussed at the meeting and methods of compliance were agreed and developed into the demolition phase plan.
Typical requirements included:
Management of asbestos;
Control of noise;
Control of dust:
Traffic management;
Restricted working due to exam schedules; and
Site security.
Bespoke Works & Challenges
Some of the buildings and a chimney were located in close proximity to the site boundary and adjacent to the temporary school and its access and egress routes. With the consent of the school and Galiford Try, the works to demolish these sensitive areas were undertaken out of school operation hours and returned to service prior to the school becoming active on a daily basis. This required careful planning and coordination with the school and Galiford Try’s management team.
Prior to the works commencing on each wing of the school building, the non-licensed asbestos was removed by Portsmouth Demolition & Salvage Ltd trained operatives under the close supervision of the site supervisor. The works were carried out in accordance with the HSE guidelines and the 2012 CAR regulations. A detailed method statement and risk assessment were developed for this operation, and the materials were removed from site and disposed of at a licensed facility in closed and sheeted bins.
Background and personal monitoring for the asbestos operatives was periodically undertaken to ensure the workplace exposure limits were not exceeded, and to provide reassurance to the school that the works were being suitably controlled. Following the successful removal of the asbestos, and being issued clearance/reoccupation certificates, the building was stripped of all furniture, carpets, ceiling tiles, doors and frames and services etc.
Prior to the mechanical demolition works commencing, a survey of the structure was undertaken to ascertain the location of the load-bearing elements, therefore enabling a safe sequence of demolition to be determined.
The excavators commenced demolition of the buildings at the furthest distance from the temporary school, removing a section of the steel framed roof trusses so the stability of the building remained uncompromised. Following this the excavators using selector grab attachment dismantled the second floor level masonry walls down to the top of the first floor block and beam flooring ensuring the masonry from the walls were periodically cleared from the flooring to reduce the risk of over loading.
The excavators then carefully removed sections of the flooring followed by dismantling the lower level masonry walls working with the integral strength of the building to ensure that a premature collapse did not occur. During the above methodology, the supervisor and banksman carried out close and continuous observation on the stability of the building. And dust suppression units were used to control the dust.
Due to the method of construction, the building was demolished in a piecemeal top down method that allowed each element to be cleared on a daily basis, leaving the remainder of the structure stable and without the need for temporary support works.
The slab and foundations were broken up and excavated. The concrete/hardcore materials were crushed on site to 6F2 ready for reuse by Galiford Try. Water cannon was used at all times to control dust, and noise levels were reduced by the selection of the most appropriate plant and accessories which fully maintained and operated at low engine revolutions. Long drops of demolition elements were avoided by skilled operators exercising care when dismantling the structure, further reducing the likelihood of noise and dust nuisance.
The works were carried out to budget & without an adverse incident.
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