Working with Dandara Jersey Ltd & Park Heights Ltd over 14 months in Jersey
CAN delivered a major stabilisation project to make an unstable quarry and cliff safe above occupied homes. Acting as Principal Contractor, the team combined earthworks and specialist ground engineering to prepare the site for future redevelopment.
CAN delivered this multi-million pound design and build project to stabilise an old quarry and the unstable cliff above inhabited multi-storey residential properties on adjacent land, acting as Principal Contractor. The requirement was to excavate a historic landslip from a disused quarry, stabilise the rock faces above the quarry and adjacent buildings, and prepare the quarry site for redevelopment.
The design solution provided by CAN included the installation of 69 4-stage 8-strand 2400kN ultimate capacity DCP anchors installed to depths ranging from 25m to 30m within the quarry back wall. Holes for the anchors were drilled with a 191mm dia. DTH drill system utilised a high-pressure (25 bar) air supply fed from an on-site air receiver. Drill arisings were controlled using a mist flush with Hydrocyclone technology to maintain efficiency whilst controlling dust pollution within a town-centre environment.
The anchors were installed from temporary benches formed during the progressive excavation of the failing rock face, using both standard and long-reach excavator-mounted drill rigs. In several areas it was necessary to use sacrificial steel casing to support the collapsing drill hole within broken ground. The substantial earthworks were also managed by CAN, carefully sequenced with the stabilisation work.
To enhance material properties, the anchor grout used a super-plasticiser additive and post-grouting was undertaken to further enhance anchor capacity. In order to sufficiently distribute the high anchor loads across the poor ground, substantial reinforced sprayed concrete wailing beams were constructed.
