Geotechnical engineering specialist, CAN Geotechnical Ltd, has been awarded the contract to undertake the stabilisation of the 25m high cliff of the former Berry Hill Quarry in Mansfield.
In November 2019, an extreme climactic event – unusually heavy rainfall – caused a complex failure of the Chester formation Sandstones which make up the cliff, causing a mudslide to fall into the gardens of properties in Stone Bank and Bank End Close.
Homes were evacuated, with some able to return immediately while others remained out of their homes for two weeks. Emergency work cleared the gardens of mud and trees and temporary safety measures were then installed, consisting of an exclusion zone along the base of the cliff, with a temporary stone access maintenance path at the rear of the properties, along with the construction of concrete blocks and bunds to form temporary protection.
Mansfield District Council engaged geotechnical specialist Fairhurst to carry out detailed surveys and identify optimum solutions to stabilise the cliff surface, in the long term. The resulting scheme of stabilisation work was put out to tender in April 2020, with CAN being appointed as the Main Contractor. The council had hoped to start the work last year, but it was delayed by lengthy legal discussions with landowners. The complicated access arrangements were recently finalised, which enabled work to start on site in March 2021.
The importance and urgency of the work had become apparent, with further small slippages happening in the past few months, fortunately contained within the exclusion zone and behind the barriers that were installed by the council in November 2019.
Following the removal of vegetation on site, CAN is ready to progress the project and stabilise the cliff face itself by the installation of over 3800 soil nails drilled up to 8m deep, as well as laying 9000m2 of high tensile steel rock netting and erosion matting over the cliff face, which will be secured by the soil nails.
The final stage of the stabilisation process is the installation of a high capacity catch fence barrier that will then be installed along the base of the cliff face, providing additional security against any future cliff instability.
Once the cliff has been safely stabilised, residents’ gardens and fencing will be able to be reinstated, along with the existing pathways.
Work on the Berry Hill Quarry stabilisation project is due to last for 22 weeks on site, with works planned to be complete by mid-summer.
For details about this, any of CAN’s other recent projects, or any of the company’s products and services, visit the company’s website at www.can.ltd.uk or call 01474 538100.