The Quiet Gap in UXO Risk Management: Independent Peer Review
Post 2 of 3 — a series on how the UXO sector can improve, written for clients and commissioners.
The response to the Southway SC250 find on 29 April was, by design, a multi-agency exercise. Royal Navy EOD, Army support, Devon and Cornwall Police, the local authority, the building contractor and the utility companies all sat around the same problem. Decisions were challenged in real time. The decision not to attempt relocation, in particular, was the product of more than one specialist looking at the same X-ray and reaching the same conclusion.
That is how high-consequence decisions ought to be made. More than one trained set of eyes, working from the same evidence, with each able to dissent.
The contrast with the pre-construction phase of UXO risk management is striking. A typical UXO Detailed Risk Assessment (DRA) for a UK construction site is produced by a single consultancy. It is reviewed internally by that consultancy, signed off by a single named ordnance specialist, and delivered to the client. It then drives mitigation decisions that can run into six- or seven-figure sums and shape the safety case for everyone who subsequently works on the site. In most cases, no second consultancy ever looks at it.
This is unusual. In adjacent disciplines, independent peer review is closer to the default. Geotechnical engineering on category 3 structures attracts independent design checks. Contaminated land remediation strategies are frequently reviewed by a separate consultancy at the request of the regulator or the lender. Even ground investigation interpretive reports are commonly cross-checked when stakes are high. The UXO sector — which deals with hazards every bit as consequential — has not yet adopted the same norm.
It is worth being precise about why this matters, because the case for peer review is sometimes overstated.
Peer review does not catch unknown unknowns. If the underlying source data is silent on a particular bombing event, a second reviewer reading the same source data will be silent on it too. What peer review reliably catches is something different: the tacit assumptions inside the first reviewer's head. The decision to weight one census record over another. The judgement call about what counts as "evidence of post-war disturbance". The threshold at which a magnetometer anomaly is escalated. These are all defensible decisions, but they are decisions, and they are easier to see when somebody else is asked to make them too.
For clients, the question is not whether independent peer review is desirable in principle. It usually is. The question is when it is proportionate, and how to commission it without paying twice for the same work.
A reasonable rule of thumb is that peer review pays for itself wherever the cost of the mitigation strategy meaningfully exceeds the cost of a fresh look. On most sizeable construction sites in formerly bombed urban areas — Plymouth, Portsmouth, Southampton, parts of London, Liverpool, Hull, Coventry, Belfast — that threshold is crossed easily. The mitigation budget for a large urban scheme can run to several hundred thousand pounds; an independent technical review of the DRA might cost a fraction of one per cent of that.
Three principles make peer review useful rather than performative.
First, the reviewer must be independent in fact, not just in name. That means a different commercial entity, with no current or recent involvement on the project, and with no expectation of follow-on work that depends on agreeing with the original author. Where consultancies are too closely networked for this to be feasible, an independent senior practitioner — engaged in a personal capacity — can be a credible substitute, provided the engagement is documented.
Second, peer review needs to happen before commitment to mitigation strategy, not after. A review that arrives once the watching brief, intrusive survey programme and contingency plan are already procured can only validate. A review that arrives at the end of stage 2, before the mitigation specification is locked, can change the answer. That is the point of doing it.
Third, the reviewer's brief should be assumption-led, not conclusion-led. The most useful peer review I have seen reads less like a marking exercise and more like a structured interview with the original author's reasoning. Which sources were prioritised, and why? Which were excluded? What would have to be true for the residual risk to be materially higher than stated? What is the lowest-cost piece of additional information that would most narrow the uncertainty? These are the questions that change decisions.
For commissioners who want to embed this as standard practice, the procurement levers are straightforward. Specify in the brief that the DRA will be subject to independent technical review and budget for it explicitly. Include the reviewer's name and credentials in the project audit trail. Where the project is large enough to support a UXO sub-group within the wider safety governance, give the reviewer a standing seat on it.
The Plymouth response showed what happens when high-consequence decisions are made by more than one specialist looking at the same evidence. The pre-construction phase deserves the same discipline.
In the final post in this series, I'll turn to the standards that sit underneath all of this — what CIRIA C785 does well, where it is showing its age, and what commissioners should be asking the sector to push further on.