In early 2023 Geotech Limited were awarded a contract to rebuild a failed portion of the Donkey Winch Wall situated high on the Denniston Plateau at the start/loading area of the famous Denniston coal transporting Incline. This site is extremely popular, often cold and bleak, difficult to work on and always rewarding.
The Department of Conservation manage the site under authority from Heritage New Zealand, who administer Class One historic sites such as this. Dominant legislation is the Heritage New Zealand Pouhere Taonga Act (2014). To operate and construct under this regime Geotech had to be cognizant of the following documentation required for the site:-
* Heritage NZ archaeological authority 2019
* Denniston Stonewalls Archaeological Management Plan 05062019 version 3
* Denniston Stonewalls Archaeological Assessment
In addition to the above, reconstruction was to comply with McManus Geotech “Denniston Design Report 2023”
Project Manager: Mark Nelson Senior Works Officer, DOC Hokitika cell: 027 304 3520
Project Engineer: Kevin McManus McManus Geotech Ltd cell: 0272017793
Project Archaeologist : Nick Cable WSP Christchurch cell: 027 705 8330
Stone Mason : GT Stone Gary Swanson cell: 021 024 13052
Reefton's historic hydro-electric power scheme (‘The Scheme’) is fed by water conduit consisting of open races and small tunnels developed in Greenland Group Greywacke. Volunteer work has successfully refurbished much of the water race but minor tunnel related difficulties required specialist equipment and personnel to remediate the problems. Geotech Limited were engaged to sort out those small areas that were beyond the volunteer workforce.
Geotech worked on the interface of the newly installed culvert with the existing tunnel. At the interface a large gap of some 2 metres existed and this was both structurally not acceptable and dangerous. Local mine engineer Nigel Slonker provided steel work design form a steel shotcrete solution. Many materials were donated by Federation Mining and all design effort was centred around providing a robust but least cost solution.
Geotech installed steel sets with a mesh lining that enables the shotcrete to be applied. Wet shotcrete with a high (6 kg / m3) polypropylene fibre (HPP) content was successfully applied closing the gap and enhancing the steel structure. To enable work to progress in the tunnel we installed downstream electric fan providing forcing ventilation. Some intensive scaling of the old tunnel was required.
NZTA took the opportunity presented with equipment and skills on hand during the Kaikoura Earthquake rebuild to increase the width, height, and strength of the state highway 1 road tunnel at Kaikoura. The work was done under NCTIR umbrella and involved milling out the greywacke sandstone tunnel rock, pattern bolting and shotcreting. Geotech employed its Erkat transverse milling head mounted on a 30ton excavator, drill jumbo, Sandvik Torro 307LHD and shotcrete machine. The project was done under the 2016 Mine Operations Quarry Operations regulations.
A good outcome resulted and the Geotech team received plenty of encouragement and messages from the long-haul truck drivers with big rigs that previously had difficulty fitting in the tunnel.
The photo shows Geotech's remote controlled head shotcrete machine, note long extension boom.
Project Engineer Raphael Sierra Ballen 027 499 7912
Using an Ekart 1500X milling head, attached to a 30 T excavator, Geotech are treating a rock face in preparation for installation of a rockfall canopy to protect State Highway 1 at Pekata, south of Kaikoura.
The damage caused by the 7.8 magnitude November 2016 Kaikoura earthquake to the Main North Line (MNL) railway (and SH1 along the east coast of the South Island) was unprecedented in New Zealand. There were 60 major damage sites along the MNL, including tunnels, bridges and embankments. Geotech had two tunnel crews and support staff providing tunnel remediation services.
Geotech were engaged by the North Canterbury Transport Infrastructure Recovery(NCTIR)to assist with restoring road access to Kaikoura after the 7.8 magnitude earthquake in November 2016. Geotech staff have been working on sections of the narrow coastal corridor of SH1 south of Kaikoura, with additional crews working north of Kaikoura. Works have predominantly been made up of clearing landslides. Work is not straightforward due to the fractured cliff faces being unstable. Damaged slopes continue to release rock and material, and weather events and continuing seismic activity have presented ongoing challenges throughout the contract, including additional land and mud slides during bad weather events.
State Highway 6
West Coast 7730
Phone: 03 280 8603