This section of sandstone masonry was reported to have ‘significant’ leaks with water passing down and under the sandstone masonry and exiting down stream at the next section.
Drawings and investigations determined that the sandstone blocks upstream and downstream of this section, were bedded in most locations on a 300mm thick concrete slab, whilst this section had been bedded directly on to the puddle clay core.
It was decided that this section of sandstone blocks be lifted and that 300mm depth of puddle clay be removed, to include a 500mm deep central ‘toe’, and replaced with a new re-inforced concrete slab.
After completion of this work, the sandstone blocks were bedded back in their original positions, to include some new replacements, and re-pointed.
This work was undertaken during August when the reservoir was at a natural low level.