Closing the survey specification gap
Huibert-Jan Lekkerkerk speaking at Dredging Days. Credit: CEDA
Dredging projects are assessed against survey data from the earliest design stages through to final acceptance. Yet where specifications leave room for interpretation, the gap between what a project requires and what a survey can reliably demonstrate can become a source of uncertainty, delay and potential claims.
Project documents may set out target depths, tolerances, survey intervals, equipment requirements and acceptance criteria. However, unless those requirements are clearly defined and understood by all parties, different interpretations can emerge once the work is underway. For example, a specification may describe the desired end result, without fully addressing how it should be measured, which survey method should be used, what level of uncertainty is acceptable or how the resulting data will be assessed.
In dredging, these details matter. Survey data is used to demonstrate progress, establish whether design depths have been achieved and support decisions around handover, payment and further works. Where expectations are not aligned from the outset, a technically sound survey may still fail to answer the precise question a client, contractor or project team believes it should answer.
The perceived gap is therefore not always a matter of poor survey practice. It can begin much earlier, in the wording of the specification itself which must take on the challenge of providing all relevant details. Clearer requirements create a stronger shared basis for verification, helping all parties understand not only what must be achieved, but also how compliance will be evidenced.
Practical approach to the problem
At CEDA’s Dredging Days 2026, this challenge was explored through a practical, discussion-led format by Huibert-Jan Lekkerkerk, to identify why ambiguities arise, why verification is rarely straightforward in dredging environments, and how clearer requirements and earlier alignment between project stakeholders can support more transparent, claim-resistant project delivery.
Rather than treating the issue as a purely technical matter, the workshop invited delegates to share their own project experiences, challenge assumptions around survey requirements and work together towards a clearer, more claim-resistant approach to specifying and verifying hydrographic survey parameters. This highlighted - in real time - how different people can interpret the same written information in different ways and confusion can occur.
He, along with Gert Brouns of DEME and Giulia Sforzi of HR Wallingford, created space for different perspectives to be tested against real project experience. Delegates were encouraged to consider where assumptions can enter the process, how wording can affect expectations and what steps can be taken to make verification more transparent.
Verification in dredging
Lekkerkerk pointed out that verification in dredging is rarely a simple comparison between a target level and a survey result. The seabed is dynamic, sediment behaviour can vary across a project area, and conditions may change between dredging, surveying and final acceptance. These factors can affect both the data collected and the way it is interpreted.
Questions can arise around the timing and frequency of surveys, the coverage achieved, the type of equipment used, the treatment of isolated high spots or low spots, and the level of confidence that can reasonably be placed in the data. Even where all parties are working from the same written specification, these practical considerations can influence whether results are seen as demonstrating compliance.
This is particularly important where dredging tolerances are tight or where the works form part of wider infrastructure activity, such as port developments, offshore energy projects or navigation channel maintenance. In these settings, survey outcomes may influence the next stage of construction, vessel access, operational safety or contractual decisions.
Lekkerkerk believes that recognising survey verification as part of the wider dredging process, rather than a final check completed once the works are finished would be the most effective way of tackling this issue. He pointed out that when verification requirements are considered early and discussed openly, project teams would be better placed to anticipate limitations, avoid misunderstandings and agree what constitutes sufficient evidence before issues arise. Additionally this would have a positive impact on structuring contract deliverables.
Moving towards clearer practices
The final part of the discussion focused on what better practice could look like. The answer was not simply more detailed specifications, but better alignment between the people responsible for defining, delivering and verifying the work.
For clients, this should mean setting requirements that are clear, realistic and linked to the decisions the survey data will ultimately support. For contractors and hydrographic teams, it would mean raising potential issues early, rather than waiting until surveys are reviewed at the end of a project. It also requires a shared understanding of how tolerances, uncertainty, survey coverage and data interpretation will be handled in practice.
A more claim-resistant approach does not mean removing every possible uncertainty from a dredging project. Seabed conditions, operational constraints and changing project requirements will always introduce complexity. However, clearer specifications and earlier dialogue can help ensure that uncertainty is recognised, managed and communicated before it becomes a source of disagreement.
A clearer path forward
Attendees of this CEDA Dredging Days session left the room with first hand insight into how the gap between specification and verification can heavily impact a project and is not limited to technical matters. By bringing clients, contractors, hydrographers and technical specialists into the same conversation, the workshop highlighted the value of clearer requirements, realistic verification methods and earlier dialogue.
Survey requirements influence how work is measured, accepted and, ultimately, trusted by those involved in the project. These steps cannot remove every uncertainty from dredging delivery, but they can reduce avoidable ambiguity and support more transparent, reliable project outcomes.
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