Description of the works
Removal of asbestos (AIB) under fully controlled conditions following the submission of ASB5 notification two weeks prior to commencement.
Demolition and site clearance of the Outpatients B building
Asbestos Removal:
Task 1: Removal of AIB (Amosite & Chrysotile) carried out under fully controlled conditions:
The works took place inside an enclosure held under negative pressure. All asbestos operatives engaged in the work were issued with full face battery powered masks fitted with P3 filter, disposable coveralls and wellington boots. Surfactant was used to effectively suppress fibre release and shadow vacuum techniques were applied. The enclosure, 3-stage bag lock for waste transfer and a 3-stage air lock was constructed in line with DHD & E Ltd. General Procedures & Guidance for the Removal of Asbestos Containing Materials. An independent analysts carried out background monitoring, reassurance monitoring, personal monitoring and the 4-stage clearance on completion.
Task 2: Removal of AIB sandwiched between concrete and reinforced girders:
Due to the AIB being sandwiched between the concrete and reinforced girders and inaccessible, as shown in the picture opposite, all elements of the concrete floor were classed as asbestos and removed in its entirety by mechanical means. The fibre release using this method was <0.01 f/ml and the removal work was completed within 2 hours.
Removing the asbestos by mechanical means minimised exposure to fibre release as opposed to removing under fully controlled conditions utilising enclosure, air and bag lock etc. The roof had been constructed in such a way that the AIB was firmly wedged between the metal girders and concrete above and there was no way of removing the AIB other than to physically break the boards causing fibre release and high exposure levels for the operatives carrying out the removal works working in very close proximity to the AIB.
Prior to mechanical demolition commencing, operatives saturated the AIB product with a surfactant solution applied using handheld sprayers and visqueen was attached girder to girder beneath the AIB to effectively seal the asbestos within the confines of the concrete floor above.
The floor was lifted in a careful and controlled manner in its entirety and all arising lowered gently into the confines of an open topped asbestos waste skip positioned as close to the works as practicably possible.
Demolition
The building was demolished top down by mechanical means using a demolition specification hydraulic excavator protected with full heavy-duty protection cages, ram and track guards and side skirts and equipped with specialist attachments. Demolition was executed in a piecemeal progressive manner; sections of the structure removed using a controlled approach to retain the stability of the remainder and any load bearing walls were identified prior to deconstruction commencing to ensure that they were maintained until structurally redundant.
All ground slab and foundations were grubbed up to a depth of 2 metres and stockpiled on site for further processing / crushing
Dust suppression was in use throughout and dust management points external to the site were established monitored throughout the process.