IN Brief:
- Investigation work is due to begin during the week commencing 14 September and continue through the autumn.
- The programme combines boreholes, foreshore trial pits, drainage inspections, and offshore habitat surveys.
- Results will inform future coastal-defence options rather than construction of an already selected scheme.
A second phase of ground and marine investigations is starting along Ventnor seafront as engineers gather the geological, drainage, and ecological evidence needed to develop future coastal-defence options for the Isle of Wight town.
Equipment is being mobilised ahead of work beginning during the week commencing 14 September. Most active investigation work is expected to last between three and six weeks, with the full programme scheduled to finish by the end of November.
The Environment Agency is developing the Ventnor Coastal Defence Scheme with Isle of Wight Council, which owns the existing coastal-defence assets. The current programme is an evidence-gathering stage rather than construction of an approved defence design.
Ground investigation will include boreholes along the seafront to recover samples and identify possible voids beneath the surface. Trial pits will also be excavated on the foreshore, providing further information on ground conditions that will influence the feasibility, foundations, access requirements, and buildability of later engineering options.
Drainage is another part of the investigation. Surveys undertaken earlier in the summer identified substantial accumulations of sediment and debris in sections of the existing drainage network, preventing complete inspection in some locations. The second phase is intended to close those information gaps before design choices are narrowed.
Offshore ecological work will run alongside the ground investigation. Teams are using drop-down video equipment to inspect underwater habitats, allowing the project to identify potential access and construction locations that minimise effects on protected features within the Maritime Special Area of Conservation.
The combination of geotechnical, drainage, and ecological work reflects the constraints on any future defence scheme at Ventnor. A solution has to respond to coastal change and ground conditions while working around an occupied seafront, existing drainage assets, constrained access, and environmentally protected marine areas.
The borehole programme may also establish whether hidden voids or other subsurface conditions could affect existing assets or constrain new structures. That information has a direct bearing on foundation design, temporary works, construction risk, and the level of contingency required when future options are costed.
Ground uncertainty is particularly significant on coastal schemes because the preferred engineering concept can change once the actual geology and condition of existing structures are understood. A wall, revetment, stabilisation measure, or other intervention that appears viable at concept stage may require different foundations, plant access, or sequencing once intrusive investigation data is available.
Construction access will be another design constraint. The current investigations require temporary restrictions along parts of the seafront and Bonchurch Cliffs Promenade, with localised fencing around borehole positions and pedestrian diversions where necessary. Businesses and seafront facilities are expected to remain open during the work.
The principal daytime restrictions are expected on part of Bonchurch Cliffs Promenade between late September and November. Where practical, the route will reopen during evenings and weekends, providing an early indication of how even comparatively small investigation works have to be fitted around public access.
A main construction phase would increase those pressures significantly. Plant movements, materials storage, temporary compounds, marine access, pedestrian management, and protection of neighbouring properties would all have to be planned around a narrow coastal corridor while maintaining access to businesses and public areas.
The offshore habitat survey reduces another source of later programme risk. Establishing ecological conditions before a preferred option is fixed allows working areas and construction methods to be assessed against protected features early, rather than discovering at detailed-design or consent stage that a chosen access route creates an avoidable environmental conflict.
The Environment Agency has not selected a preferred defence option, and the current work should not be read as a commitment to a particular form of construction. The investigation data will feed into the comparison of future approaches, alongside cost, performance, environmental effects, access, and the condition of existing infrastructure.
That sequence also affects procurement. Reliable ground and asset information gives designers and future contractors a firmer basis for quantities, construction methodology, risk pricing, and programme assumptions, reducing the amount of uncertainty that would otherwise be transferred into tenders.
For Isle of Wight Council, the surveys will also improve the record of existing coastal and drainage assets. Where defects, blockage, or hidden ground conditions are identified, they can be incorporated into option development before the project reaches detailed design.
Investigation work is expected to continue through the autumn, with public engagement running alongside the technical programme. Once the field data has been analysed, the project team will be able to narrow the engineering choices and establish which options can meet coastal, environmental, access, and construction requirements.
The end-of-November target is therefore a survey milestone rather than the start of the main works. The value of the current programme will be in replacing assumptions about the seafront with measured ground, drainage, and habitat data before a more expensive defence solution is selected and designed.
