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Controlled Explosives

Every detail is methodically scrutinised...

John F Hunt Demolition has extensive experience in the use of explosives for the controlled demolition of Industrial, Commercial and Residential structures from reinforced concrete to heavy structural steelwork. The following provides a brief insight into the preparation of a structure for demolition by explosives.

  • Firstly a desktop study of the information provided by the client is undertaken by the Demolition Management Team, Explosives and Structural Engineers. The risks associated with the proposed method of collapse are assessed, together with anticipated air overpressure, local infrastructure and historic weather pattern.
  • Those likely to be affected by the event and implementation of the required exclusion zone is also determined. Procedures necessary to ensure third party safety during the demolition are identified.
  • Confirmation that the proposal can be carried out in accordance with current legislation, guidance and British Standards is required before moving to the next stage.
  • After the desktop study, meticulous planning and physical preparation of the structure in question can commence.
  • Ensure a synchronised approach and efficient communication between all parties affected by the works. e.g. Local authority, service utilities, police and fire service. Regular coordination meetings are held and chaired by the John F Hunt Project Manager, with the attendance of the Explosives and Structural Engineers.  These meetings also determine the provision of local community liaison and regular information flow via newsletters.
  • Detection and isolation of all M&E services supplying and contained within the structure.
  • Identification and implementation of all noise and vibration monitoring requirements.
  • Structural engineers carry out a survey of the building and establish the pre-weakening locations.
  • Other surveys include pre and post demolition condition surveys of all adjacent buildings and infrastructure.
  • Preparation of the structure: ie soft strip, removal of all fixtures, fittings and glazing.
  • Structural and Explosive Engineers jointly establish the category/strength of explosives, confirmed by on site test blast. This will determine the explosive charging patterns, detonation sequence, timings and blast shielding requirements.
  • Careful drilling/cutting to comply with pre-determined detonation pattern. Charging/placing/stemming explosives.
  • On the day of the Blow Down prior to detonation a coordinated management of the exclusion zone initiated.
  • Finally the controlled demolition of the structure is carried out by the Explosive Engineer firing the explosives from a pre-established location demonstrating good lines of sight and communication.
  • Following the Blow Down and after all necessary safety checks, the exclusion zone lifted and a local community cleaning programme is commenced.
  • Debris is later cleared and recycled.

Note: The activities detailed above are undertaken by those who have the Skills, Knowledge and Experience, in accordance with safe systems of work which include detailed risk assessments and method statements. These notes are indicative and not exhaustive.

 

 



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