The water company wanted to send down an exploratory submarine into the tank to investigate the water, but it was vital that nothing dropped in during the concrete cutting. “It had been suggested that a stitch-drilling operation would be the best way to cut an opening into the tank,” said Emberson.
“But once I assessed the job, I could see that there was too much of a risk that it could flake concrete from the underside of the slab and that would end up in the water. I decided that we could use a hydraulic handsaw to cut down within 50mm of the full thickness and collect the slurry as we went along. Then the final cut would be made using a hydraulic ring saw because we could minimise any slurry due to the speed of cut.
“The main contractor put in place all water hygiene and cleanliness measures as well as the lifting equipment as the concrete slab was to be secured by an A-frame above the opening with chains and lifting eyes fixed to the slab before any cutting took place.”
D-Drill carried out a trial run of the job on a different site witnessed by water authority inspectors who were satisfied with the result. The main contractor then employed D-Drill to carry out the cutting of three openings at the treatment works.
“We were delighted with the end result and was a testament to the expertise and professionalism of the team that we carried it through and the main contractor and the water company were happy with the result,” said Emberson. “It is always satisfying when you have to come up with a solution to a unique problem and it then works so well.”