Rock Netting

The Installation of Rock Netting

Following the cleaning of the Green Moor Quarry RIGS, all parties directly involved in this project agreed that the decision by the geotechnical engineer to apply netting to the rock face was good practical common sense. Although the conditions for the planning permission, to conserve the RIGS, were strictly adhered to by the developer, the elimination of potential Health and Safety hazards for the occupants of Stoneway Manor was considered to take priority.

The Green Moor Quarry RIGS after cleaning

After the scaffold had been dismantled and all remaining loose material had been cleared from the base of the quarry face, I arrived very early on site to take photographs of the cleaned RIGS - before the rock netting contractor commenced work.

Tools and materials

Even though I wasn’t paid for my time to take these photographs, having been involved with the Green Moor Quarry RIGS for 17 years, I was not only curious to see how this was done, but I also thought that it was needed to record this project - from start to finish.

In the time that I was on site, I was only able to observe the setting out of safety lines and drilling and netting to the south of the RIGS - the highest point on the old quarry face - but it was enough time to provide me with a good introduction to the techniques, tools and materials used to undertake this kind of work.

Looking at the materials – the 80 mm mesh rock netting, rock anchors, cables, various other nuts, bolts and epoxy resin – these were obviously of a grade that would be used when unstable geological conditions make the rock susceptible to rock falls and landslides. 

A detail of rock netting

As a geologist, with an appreciation of structural defects and structural loading - acquired in the general construction and specialist restoration industries - I agreed with the opinion of the engineer.

Conservation projects like this are so rare but, ideally, I think that there might be scope for the rock netting industry to make a “conservation grade” product which allows unwanted plants to be removed and still let the geological features be seen.

Drilling

That said, with Stoneway Manor essentially complete, except to finish off some road surfaces and gardens, I was very impressed by the way that the whole team worked in the tight spaces available; I was also quite surprised by the speed at which they progressed.

I particularly liked the way that the mobile access platform was used. The operative skillfully manoeuvred it into position - lifting rock netting to the top of the rock face, where other site operatives had previously sunk ribbed stainless steel dowels, ready to receive it.

When the cleaning work took place at the beginning of May, after a long winter that had extended well into April, the vegetation along the quarry face had largely died back but, 6 weeks later, the root balls that had been left on the RIGS had sprouted into plants. To the south of the RIGS, where vegetation covering the overburden had been left untouched, large ferns formed obstacles to the placing of the rock netting and, in some instances, they were very difficult to remove.

The removal of a deeply entrenched fern