Jackson’s engineering acumen came to the fore on this unusual project to remove, demolish and replace a 54 metre-high reinforced concrete tower at Boulby Potash Mine in North Yorkshire. The mine supplies over 60% of the UK’s potash and extends almost 6km out under the North Sea.
Weighing in at 2,700 tonnes, the tower, which houses the crane headgear used to lift potash out of the mine, had to be replaced within a two-week outage window to minimise downtime of the mine.
Jackson Civil Engineering became involved almost two years before the demolition to provide early contractor involvement and come up with a method for this very complicated scheme.
In a nutshell, their plan was to construct a slide path to literally slide the existing tower away to be demolished, and then slide the pre-constructed new tower into position. Sounds simple, but a staggering amount of enabling work was required to ensure the project was finished within the two week window.
Timing work so not to disturb the mining shifts, a concrete collar was constructed at the base of the existing tower in order to strengthen it, and then a cruciform beam was installed underneath to allow it to be moved safely.
The slide path was constructed just above ground level on cast insitu bored piles, between 35 and 38m deep. Due to space constraints, the slide path travelled south 14 metres, and then took a 90 degree turn east to ensure the old tower was a safe distance away for it to be demolished.
Once the enabling works were completed, the existing tower was cut at the base, jacked up 60mm and moved along the slide path using hydraulic jacks. The slide went off without a hitch, and the old tower was successfully demolished in a spectacular explosion involving 25kgs of C4 explosive.
The new tower was then moved into position over the top of the mine shaft and a concrete shroud constructed around it.