St Catherines Court
The whole site was steeply sloping and enclosed on all sides with the Pro Cathedral to the high side, and Berkeley Place and the Triangle to the lower part. Some large and very old masonry retaining walls formed one edge of the site, and an existing steep footpath known as Pro-Cathedral lane formed the other.
The logistics of placing plant and materials onto the site were tricky from the start. The only access at the start of the piling works was between the old Pro-Cathedral and the existing Upper School Buildings, then by a smart left turn into a temporary access formed through the old school building, and onto a narrow platform at the top of site.
In order to develop the site, Sisk’s plan involved working generally down the site from the high access mentioned above, at an elevation of 60m, towards the lower boundary on Berkeley Place some 15m below. This meant progressive piling and anchoring works from the top level to form a new platform, then second tier anchored pile retaining walls from this level down to the road level 15m below.
Ground conditions consisted of made ground above Dolmitic Congolmetre over Upper Cromhall sandstone. As the piles needed to penetrate significantly into these rock formations a combination of specialist rock drilling techniques were used including DTH rock drilling and rotary rock auger/coring.