Concrete Water Jet Cutting on A1260 Bridge Structure
The work on the A1260 was carried out for Osborne and completed by the end of March 2011. The challenge was to remove 245m3 from 12 piers in the shortest time possible. Due to the nature of the project we were competing with different methods of removal at tender stage and we had to ensure that our proposals were both cost effective and able to meet the demands of the programme.
On each pier there was 20.46m3 to be removed and we set ourselves the timeframe of 4 No 24hr periods to complete this. This meant operating with two crews during the day and two crews during the night.
Unfortunately there was no water supply available at any of the piers, which would have been a major problem had we not been able to use our tanker units to both jet with and as static tanks.
We then arranged for a local contractor, IWJS, to collect and deliver water into our tanks throughout the day and night shifts to allow us to jet continuously for 20hrs per day, only stopping to allow clear up of the huge volumes of concrete being removed.
During the first phase of 6 piers we encountered a few teething problems similar to any that occur on a project of this magnitude. We also had to work through freezing conditions with temperatures dropping to minus 14 on site, which is obviously not ideal for water jetting. Despite the difficulties we were able to complete the first phase on programme and leave Osborne extremely satisfied with our performance.
When the second phase began we knew that we would be able to comfortably meet the programme and we therefore reduced the number of jetting crews to three. We also managed to reduce the time taken to complete each pier to 3 No 24hr periods as the freezing weather had subsided and everybody on site knew what was required for the job. The second phase was completed successfully over a 5 week period.