Innovation Exchange challenge: Understanding Corrosion and Geometry of Sheet Pile Walls

The Environment Agency and their delivery partners, including VolkerStevin and AtkinsRéalis, are currently undertaking a major innovation programme to significantly reduce the carbon impact of their flood protection operations and assets.  Understanding the geometry and condition of sheet pile walls will enable improved management of these assets, reduce carbon intensive replacement and enable reuse or repurposing.

The Environment Agency currently has extensive sheet pile wall assets in excess of 20 years old with mixed construction records and inspection history.  These are typically used as cantilever walls for earth retaining structures such as sea defences, harbour walls, wharfs, river banks, drainage channel banks, and occasionally wet wells.

Access to the walls can be problematic.  In some instances, access to the dry retained ground side may not be possible and the wall side may be water: river, tidal river or the sea.  Generally, access is not restricted on this wall side other than by safe-working and practical considerations.

The piles are predominantly made from interlocking profiles in carbon steel that are vulnerable to corrosion, these create a corrugated wall of roughly 400-500mm trough x 200-500mm deep with a wall thickness between 8-20mm and on occasion 28mm.  Walls can be as much as 8m, or more, high out of the ground with rough proportions of twice the out of ground height wholly embedded into the ground to the cut-off level.

Sheet pile walls are used in many ground conditions, with driveability into very hard ground the limiting factor.  They are frequently used in softer soils, silts, clays, marls, sands, gravels, shales and mixed types.

Corrosion defect management and resulting analyses are currently based upon specialist experience based visual inspection and occasionally discrete intrusive inspection that can be costly (drilling and excavation).  This is supported by as-built records, albeit of mixed quality and availability and previous inspection reports and observations.

These methods do not give a full picture of the geometry of the pile wall, particularly the cut-off-depth (the level of the pile toe), how the cut-off-depth varies along the wall or any information of corrosion of the submerged or underground extent of the wall.  The Environment Agency have used magnetometer technology in the past but found the results inconsistent and the practicalities of the equipment limiting.

This absence of data creates uncertainty that often drives carbon intensive solutions.  It can underestimate the residual capacity of the wall leading to an unnecessary renewal or replacing rather than adapting the wall to a new loading condition.  It can also overestimate the residual wall capacity exposing the Environment Agency to a hidden risk, potentially requiring unplanned costly emergency works.

The Challenge

The Environment Agency are seeking non-destructive solutions that can significantly improve their understanding of their older sheet pile wall assets to enable better modelling and analysis for better management and planning.

Of particular interest are identifying:

• The cut-off-level of the pile toes along the length of a wall
• The remaining wall thickness of the piles below mean-low-water and below the ground
• Installation defects including bends, buckles and clutch damage

To acquire information on the underwater and underground aspects of the wall, technologies that sense through the media in way of the wall (water, silt, mud, soil) are sought, as are technologies that physically couple to the piles visible, accessible face to detect along its length using time of flight type methods or by inducing a detectable signal for example. They may be equipment or a contracted service; for the former please consider how the source output data is interpreted and the ease of use.

It is recognised that an ideal solution may be out of reach with current technologies, so partial solutions or compromises are accepted; please identify what your proposed technology both can and cannot do in your submission.

Solutions should be ready for prototype testing within a 6-month period, for field trials within 12-18 months, leading to field use within around 24 months on real assets.  Trials can be made available on new walls of known condition and old walls that are scheduled for removal and can then be fully inspected after removal.  Where lab or bench testing is intended, please outline the testing methods proposed.

It is likely that once confidence is gained in the technology that there will be widespread inspection of the older assets to establish a baseline with subsequent re-inspection on a risk-based frequency and discrete inspection for specific flood alleviation projects.

Solutions are not sought through this challenge for the measurement, or interpretation, of visible corrosion, or modelling of structures.

For full functional and technical requirements, operating conditions, and scope, visit the Innovation Exchange site at the link below.

Who can apply?

Entrants to this competition must be:

• Established businesses, academic institutions, start-ups, SMEs, or individual entrepreneurs
• UK based or have the intention to set up a UK base
• Committed to adhering fully with the SHEW Code of Practice

Consortia of potential solution providers with complimentary technologies are welcomed.

Rewards and market opportunity

Successful applicants will be given an opportunity to pitch to the Environment Agency and their partners, VolkerStevin and AtkinsRéalis.

Selected solutions will benefit from collaboration with the Environment Agency, VolkerStevin and AtkinsRéalis technical teams in developing the solution to meet the particular needs, including access to sites, followed by funded trials with potential for further adoption if trials are successful.

The solution has the potential to be deployed across many kilometres of older sheet pile walls on a Risk based rolling programme with periodic assessment thereafter.

The benefits package for a successful applicant may also include:

• Support from Innovate UK Business Connect
• Support in the development of a prototype or pilot
• Technical support
• Invitation to attend or present at Innovate UK Business Connect events
• A potential business collaboration
• Investor introductions (if investment is required)
• Support if any Innovate or similar competitions are relevant