Leeson Road information.
Update November 28
Leeson Road, between Shanklin and Ventnor, will re-open on Sunday morning (1 December).
The road will be fully opened to all two-way traffic and pedestrians from that date.
This planned re-opening follows the completion of three boreholes and the installation of monitoring equipment. The deepest of the boreholes reaches 130 metres.
The monitoring equipment in the boreholes and on the surface of Leeson Road will measure ground movement and water pressure to inform Island Roads and the council of changes that may indicate land movement.
The equipment will continuously monitor the area and in addition there will be weekly site inspections and regular reviews of automated data.
Using the data, Island Roads and the council have agreed on an emergency response plan that will use triggers to indicate low, medium, or high-risk scenarios.
Depending on the risk level, appropriate actions will be taken to ensure public safety. If the road needs to be closed information on the closure will be published on the council’s social media channels and sent to local press as quickly as possible.
Councillor Phil Jordan, council leader and Cabinet member for highways and infrastructure, said: “We are extremely pleased that the road will be reopened ahead of the Christmas period, and I would like to thank residents and the business community for their support and patience during this work.
“I know how difficult this has been for the community generally and work has not been without problems to overcome but I am extremely pleased with the outcome.
“The monitoring equipment installed, plus the information we have taken from the boreholes themselves, have confirmed our understanding of the underlying geology and also allowed systems to be put in place that will allow us to monitor the area in detail to provide early warning of any increase in the risks of a future landslip.”
Further information
What equipment has been installed:
Automated Monitoring Systems:
Manual Monitoring Systems include:
Rainfall Monitoring: Ventnor Park Weather Station: This station continuously records rainfall data, which is vital for assessing the impact of precipitation on landslide activity.
Drone Surveys: Photogrammetry and LiDAR surveys produce high-resolution digital terrain models and orthophotographs, allowing for detailed monitoring of ground changes over time.
Monitoring Workflow and Action Plan:
Data from the equipment, added to that already being retrieved from existing equipment will provide the information needed to manage an early warning process that will allow the road to be re-opened and operated safely in parallel to the landslip risk.
Update November 18
Work to sink three boreholes, the deepest of which reaches a depth of 130 metres, is expected to be completed this week (w/c 18 Nov).
Two of the boreholes are already completed. The first of these is 115 metres deep and houses an array of inclinometers which records ground movement.
The second is to a depth of 130 metres and also houses an inclinometer. Boring to this depth allows for gathering data about groundwater conditions across the wider area – over and above what is needed for the safe re-opening of Leeson Road.
The third borehole has proved more challenging. After casing became stuck in the greensand layer (approximately 125 metres underground) and numerous attempts to retrieve it failed, it was necessary to drill an alternative borehole nearby to house the agreed monitoring equipment — several piezometer tips which record underground water pressure. Underground water is a major factor in ground movement.
The aim is to sink this borehole to 100 metres. We anticipate this depth will be reached this week after which the monitoring equipment can be installed. The original borehole will be backfilled because the casing stuck within it prevents any meaningful monitoring.
Data recovered from the equipment installed in these boreholes – added to that already being retrieved from new and existing equipment – will give us all the information needed to manage an early warning process that will allow the road to be re-opened and operated safely in parallel to the landslip risk.
We anticipate that the third borehole will be completed and all instrumentation installed by the end of the 10 to 12 week timeframe previously communicated.
Island Roads and the Isle of Wight Council can assure residents that our intention remains to re-open the road as soon as we are satisfied it is safe to do so and we have agreement in place to ensure effective ongoing management. We will continue to keep the community informed.
Update 12 – October 11
Work to sink the third and final borehole at Leeson Road has begun. The borehole will reach a depth of 130 metres and – in common with the two completed boreholes – will house monitoring equipment.
Ground samples from each of the boreholes is also being retrieved and these will also add to our understanding of the area’s geology.
All this additional knowledge will be crucial to agreeing an early warning system that will enable the road to be re-opened safely.
The core samples from the first borehole have established the depths of the various ground layers which were more or less in line with expectations: chalk and sandstone to a depth of 43 metres, then gault clay to 95 metres and sandstone below that.
Despite some very wet weather, we remain on target to complete the borehole work within the stated schedule of ten-12 weeks.
Lastly, we would like to remind residents that businesses at both ends of the closure – in Shanklin Old Village as well as in Ventnor – are open and accessible via the diversion. Please continue to support our local businesses.
Update 11 – October 1 2024
Work to drill three boreholes at Leeson Road, Ventnor, is progressing very well.
The boreholes are being sunk to depths of up to 130-metres to help the IW Council and Island Roads further understand the ground conditions at this location and to allow additional monitoring equipment to be installed.
Data retrieved from the enhanced monitoring will help partners agree an early-warning scheme so the road can be re-opened safely.
Drilling on the first borehole is now complete and the second borehole has reached a depth of 100 metres.
Progress was interrupted on Sunday when a casing – used to house the core samples taken from the ground – temporarily became stuck deep underground.
The casing has already been retrieved and we expect drilling to recommence today (Tuesday) once the rig has been re-set.
This type of issue is not unexpected in such complex work, and we remain on course to complete the project within the published timeline.
Update 10 – September 9 2024
Specialist ground engineering work that it is hoped will lead to the full re-opening of Leeson Road at Ventnor will begin on 9 September.
Work will start on that date in sinking the first of three boreholes to help build a picture of the area’s geology following the catastrophic landslip in December last year.
The boreholes will be sunk to a depth of around 110-metres, though the actual depth will be determined when they reach the lower sandstone beneath the Gault Clay, known locally as blue slipper.
The ground investigation will take core samples of the rock layers which can then be assessed and recorded by geological engineers to confirm changes following the landslide.
The process will also allow various monitoring equipment to be installed which will be able to record any ground movement and also water levels which are a key driver of ground movement.
The boreholes are thought to be the deepest ever sunk on the Island. Data from the new equipment within them will complement that already being taken from other apparatus already installed across the site to give the best possible picture of ongoing movement and the risk of further landslips.
All this information will help work by the Isle of Wight Council and Island Roads to develop and maintain an early warning system that will allow the road to re-open but shut immediately if significant movement is detected.
The information will also be used to help geo-scientists and engineers understand the unique ground formation across the wider 12 kilometres of the Undercliff area which is North Western Europe’s largest urban landslide system.
The council, Island Roads, Ventnor Town Council and geological experts, Jacobs, met with representatives from local residents’ groups last month to discuss the proposed works.
Natasha Dix, service director for waste, environment and planning, said: “While all this information will help our long-term understanding of both Leeson Road and the wider area, it will also give us the short-term information necessary to install the early warning system that will allow us to re-open Leeson Road without ongoing traffic management.”
Michelle Love, service director for highways and community protection, added: “We know how important it is to keep Leeson Road open and that has always been the aim.
“What we have needed is the accurate real-time data for us to be able to do that safely. These boreholes – and the equipment that will be installed within them – will give us the information we need.
“Naturally we cannot give any guarantees until the latest data can be analysed but we are hopeful this work will prove a crucial step in the safe re-opening of Leeson Road.”
In order for work to start on Monday September 9, the road will be closed from 10pm on Sunday, 8 September. The aim is to reopen the road by Christmas.
Island Roads and the Council will work proactively with Southern Gas Networks and Southern Water to ensure the level of roadworks around the Ventnor area are kept to a minimum while Leeson Road is closed.
This will exclude emergency works which need to take place in the interests of public safety.
To read answers to Frequently asked questions about the borehole work visit this link
Further Information about the Undercliff landslide complex can be accessed on the council’s website.
For archived updates on Leeson Road and Ventnor accessibility visit this link here.
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