This old disused quarry is home to a small retail park, Woodside retail park. Following a fire to one of the units whilst undertaking the restoration of the unit a large block fell from the face above into the site compound below.
As a local contractor CAN was approached to quickly produce a design and build solution to protect the site and units below.
The most cost effective solution was to use a drape (or passive) netting solution. The design comprised covering the slope with 2574m2 of Geobrugg DELTAX rock fall netting, held in place with 85 rock bolts.
Access along the crest of the face allowed the crest bolts to be installed from a small excavator with the drill boom mounted on it. Additional face bolts were then installed by hand to better contour the netting to the face.
Installation of the netting took place by pre-stitching the rolls together on the floor and then lifting them into place using a 50t crane with a 40m jib incorporating a 16m fly jib with a specially designed boom attachment.
With such a large crane blocking access to the rear of the units for delivery trucks CAN decided to undertake this section of work over the weekend meaning that normal service for the retail units could continue undisturbed during the week.
A potentially high risk area was identified during the initial design phase. An additional lower drape of netting was installed, which incorporated slip rings. This effectively acted as an energy absorption mechanism, allowing the mesh to pull out from the face, containing the debris but stopping the mesh failing.
A catch ditch was created at the toe of the slope, comprising separation geotextile and pea gravel. Being situated behind the existing gabion structure this gave an additional measure of protection.
This total solution means that use of this popular retail park can now continue risk free for many years to come.
Duration: 4 weeks
Client: Angus Ponsford/Triton Construction