What lies beneath: A deep dive into geotechnical claims

The most expensive problems are often the ones you can’t see. In this episode of Fortune Favours the Brave, we uncover the unseen world beneath construction projects with guests Giles Tagg and Alessandro Morgan-Gianni from DAC Beachcroft, and Thomas Jones from Howden.

We explore:

• How hidden ground conditions lead to seven‑figure claims
• Why sinkholes signal deeper geotechnical risks
• Practical ways engineers and developers can protect projects through better scope, evidence, and documentation

You’ll also hear about a real case involving chalk ground—where negligence was proven but caused no recoverable loss due to causation.

Key topics include:

• What geotechnical engineers do and why uncertainty persists
• How sinkholes form and why images can mislead
• Sampling limits, borehole density, and value engineering trade‑offs
• Common claims: settlement, heave, contamination, drainage failures
• Defence strategies using early expert evidence and causation analysis
• Direct and indirect losses - from remediation to finance costs
• The Tilehurst case and its causation outcome
• Practical risk controls: scope, reliance, records, liability limits
• How climate change and planning reform increase claims exposure
• Predictions for more sinkholes, landslips, and multi‑party disputes

Transcript

Welcome And Guest Intros

SPEAKER_00 0:04

Welcome to Halden's podcast, Fortune Favours the Brave. We all take risk in our everyday life, and business is no different. In this podcast, we're speaking to the experts about a topical challenge or issue and what business leaders can do to overcome it.

SPEAKER_03 0:19

Hello, and welcome to Halden's Fortune Favours the Brave podcast. My name is Thomas Jones, and I'm a claims and technical executive here at Howden. Today's podcast is called What Lies Beneath. And joining me today are the excellent and erudite Giles Tagg and Alessandro Morgan Gianni of DAC Beechcroft Solicitors. Now, today we're going to be diving into the deep and discussing claims against geotechnical engineers as well as the emerging risks posed by sinkholes. And I just wanted to ask you both to sort of give yourselves an introduction, I suppose, beyond Erudite and Excellent, obviously. And as is the sort of spirit of this podcast, an example of a risk, please, that may or may not have paid off.

SPEAKER_01 1:09

Sure, great. Nice to be here, Tom. So I'm Giles Tagg, and I'm here mainly because I love sinkholes. Indeed, some would say I have a minor obsession with sinkholes. I'll explain a bit more about that later. In terms of a risk I've taken, well, I'm a lawyer, and this morning I only tied my shoelaces with one knot. That's a risk to me. I'm quite risk averse. However, I did recently do a cycling race where the head protection involved was a small cotton cap. So that was a real risk, and it paid off because I suffered no injuries, but I did feel the breeze through my hair for the entire event, which was lovely. Well, there we go.

SPEAKER_02 1:55

Now hi, yes, Alessandro Morgan Jani from DHC Beechcraft. I'm a senior associate in a team based in Bristol dealing with uh construction professional indemnity matters. In terms of a risk I've taken recently that's paid off, uh sticking with the bike theme, I stepped back onto a mountain bike for the first time in 20 years, a couple of weekends ago, over in Bike Park Wales and came out relatively unscathed. A couple of uh cuts to my shin, but that was a risk that paid off.

SPEAKER_03 2:27

Brilliant.

SPEAKER_02 2:27

20 years out of the mountain bike, so that's my risk.

Why Sinkholes Captivate And Matter

SPEAKER_03 2:30

Brilliant. Thanks, Al. Yeah, well, Giles, just before we get stuck in, you've already touched on your well, I've sort of seen it as an apocalyptic obsession almost with sinkholes. Yes, fair description. Every time the word is mentioned, I'd say a glint in your eye sort of is evident, and very much the same with Al as well. So I suppose the first question to ask is why are you both so interested in the topic? You know, not just sinkholes, geotechnical engineering as well. Um and why should the listener be interested?

SPEAKER_01 3:03

So sinkholes are spectacular. When you see a picture of a sinkhole, it can be quite striking because they are kind of catastrophic sudden events where the earth simply opens up in a circular fashion and swallows things whole. So obviously, this is a podcast, so we can't show pictures of sinkholes, but they are a spectacular phenomena. And I tend to sort of follow news articles about sinkholes, and either the AI algorithm has got my name associated with sinkholes, or they are becoming relatively more common. And Al and I have also dealt with a couple of legal cases revolving around actual sinkholes and more claims uh in relation to geotechnical claims generally. So for me, the sinkhole is a kind of portal into the world of geotechnical claims generally.

What Geotechnical Engineers Actually Do

SPEAKER_03 4:04

Well, there we go, diving into the deep indeed. So I suppose it's worth taking a step back at this point. And uh, by the way, before I forget to mention for anyone listening, I very much recommend not only reading Giles and Al's articles on the topic, but also having a little look at uh Giles' LinkedIn, and it's quite amusing how obsessed he is with this topic. But anyhow, take a step back one moment and let's just talk about geotechnical engineering as a whole, you know, as a profession. What is geotechnical engineering?

SPEAKER_02 4:38

So, geotechnical engineering, from a sort of broad summary of the professional role, is uh something which uh is a subset of civil engineering. These engineering professionals are investigating below ground material, seeking to establish its um engineering properties, its characteristics, so that detailed designs for buildings and infrastructure can be considered. So it's a fundamental engineering discipline which is central to almost all projects. And it's a specialist discipline, as I've mentioned, that that really is at the heart of a lot of projects. And if something goes wrong from a geotechnical engineering point of view on a construction project, there can be very severe consequences in terms of claims.

SPEAKER_01 5:24

Can I add um uh a comment to that? Yes, please. So that's a perfect description of what it is, and one thing I would emphasize about it is that a geotechnical engineer interprets and assesses risk so no engineer can be exactly sure about what lies beneath the ground and how it will operate when a load is put on it. It can never be precisely sure, so they have to essentially assess risk. And one illustration of this could be as follows, and this is from a real life example. So imagine a developer wants to develop um a housing estate, they need to investigate the land on which they intend to build, so they sink, let's say, 50 boreholes throughout that site to try and establish the nature of the ground. It is possible that each of those 50 boreholes will miss a void in the ground just because they can't sink a borehole over the whole the whole place. So you could sink 50 but miss a void or voids. Equally, you could sink three boreholes and strike lucky and hit the void with one of those three. Yeah, and I think that's a useful illustration of how you can't be sure and it's a risk assessment. Um, and I think it's important to understand that when we go on to discuss the types of claims you get and the different types of geotechnical problems that arise.

Uncertainty, Boreholes, And Risk

SPEAKER_03 6:57

And I suppose you can see how those problems would arise if it is, as you say, I mean, I suppose an inherently uncertain area, isn't it? I mean, even, you know, I suppose to to go to the sinkhole example, they happen without warning, much as other problems within the profession occur, I suppose, you know, it's uh what's happening beneath the ground you can't see. And and yeah, a whole host of problems can come at the uh the engineer, and you know, no warning at all. But um, yeah, perhaps it's worth you sort of discussing the common kinds of claims you see in this area.

SPEAKER_01 7:33

Yeah, I think perhaps I'll let uh Al deal with that. I'll just maybe describe because I just love sinkholes. Let me describe how a sinkhole uh happens, yeah, because I think it's quite interesting. So I referred to uh voids in the ground. So a void will occur where the geological material under the ground is soluble, so that's rocks like chalk or gypsum. Um they're soluble, so they can dissolve and be washed away by water, and as that happens, voids form. And a void is basically a pocket of air under the ground that that can get bigger and bigger as more material gets washed away. Eventually, the load of the natural ground above that void will become so much that the ceiling of the void can't take it anymore, and then all of a sudden it will drop down, and that's why you end up with a circular hole at the you know, the sinkhole void. It's just a column of earth shooting down, closing the void that's opened up. So that's that's a sinkhole claim. Yeah, but um Al, I think you've got um uh some examples of wider types of geotechnical that's right.

SPEAKER_02 8:50

So just sort of sketching out a few different types of geotechnical engineering and issue that can come up. So you've got classic uh ground movement uh issues, you've got differential settlement, as Giles has mentioned, which can be to do with sinkholes, but you've also got um heave, which is the upward movement of uh ground material, so the opposite of settlement, which can affect buildings and infrastructure and can create differential movement. You've also uh got issues of land contamination, so geotechnical engineers can be involved in investigating um contaminated land, particularly where you're looking at a development site that's had a previous use, perhaps an industrial or commercial site that's um got some history with perhaps pollution and contaminants in the soil. So geotechnical engineers can get involved in looking at uh at those sites and where things are missed, there can be claims. You've also got uh an area of uh development where uh engineers are looking at uh drainage infrastructure and designs for drainage for residential sites, for example, where they're looking to work out how rainwater will um infiltrate the ground and therefore what the parameters of the drainage design can be in terms of how um how naturally the the water can can disum can dissipate. And of course, if mistakes are made or problem or things are missed during that stage of the investigation, the wrong drainage strategies can be employed and the things like storm water can't be accommodated. So there really is a range of issues to do with how the earth interacts with with water in a lot of cases, um, which which end up if if mistakes are made or or things are missed during the interpretation of um data, uh the claims can arise.

Types Of Geotechnical Claims

SPEAKER_03 10:34

And if a uh geotechnical engineer is faced with on a you know a claim from that sort of example, uh from that list of examples, how do they, or indeed how do their lawyers go about defending such a claim?

SPEAKER_01 10:47

I'll take this one if you like. So I think the key thing from my perspective in this sort of claim, because these claims, generally speaking, aren't cheap. Normally, if a problem happens of a geotechnical nature, it's going to be quite expensive to sort out because you're likely to have suffered damage to a building and it will need remediating, and in order to do that, it you know, it's likely to be quite expensive, and we'll talk a bit more about that sort of thing later in the discussion. But the key thing for me on these claims is you need to instruct an independent expert engineer, generally speaking, quite early, and you need to find a good one. Um, and for certain areas of geotechnical expertise, there aren't too many individuals who have a good level of expertise in that area allied with experience of litigation and claims. So, as a sort of key top tip, I would try and identify your expert in these claims pretty early. And then that expert, in this case, let's say the claim is in fact against a geotechnical engineer, yeah. And let's say the claim is for failure to advise properly on the risk involved in developing a certain piece of land because they haven't either surveyed it properly or interpreted uh desktop data properly. Um, then the claim will be against the geotechnical engineer for negligence or breach of contract, and your expert to your point, uh, you retain them to advise you on two things really. Normally the risk on liability, and that will be whether or not the geotechnical engineer in question has breached their duties, what those duties are, have they attained the standard of reasonable skill and care or not? And if not, has that failure caused the problem in question? So you need your expert to advise you on those things so you can assess the risk of liability, and then very importantly, often you also need the expert to advise you on what is a suitable and proportionate remedial scheme for the problem in question, because very often there'll be a range of potential remedial schemes, and you need to be sure that the one that you're identifying is cost-effective and proportionate. Sinkhole example commonly the the remedy for sinkholes is to for the um the party in question to pump liquid concrete into the ground until they can pump no more, and the the all the voids are filled with liquid concrete, which then solidifies and creates uh a hard piece of land which you can develop, that can be extraordinarily expensive because you don't really know how much liquid concrete you need until you keep pumps, pumped it all in and it fills it up. Um, so it may be that in circumstances there are more cost-effective uh remedial solutions such as designing raft foundations that will span a gap rather than filling the whole ground up. So um experts uh are very important for those two particular reasons, I think.

SPEAKER_03 14:08

Absolutely. So not only expensive litigation, but very complex litigation too.

SPEAKER_01 14:15

For sure. Al, do you want to say something about that?

Defence Strategy And Expert Evidence

SPEAKER_02 14:18

Yeah, so the the complexities arise all across the areas of a case, really. Just looking at the sort of losses that can arise in a geotechnical engineering dispute, they can be very varied. You've on the one hand, you've got your direct losses, so the cost of putting right a site if things like dissolution features um voids have been been missed, and you have to remediate the ground by by by pumping concrete in, like Jars says, or indeed coming up with an alternative design or foundations for buildings, um, and the costs of those remediation programs can be your direct losses. But you've also got your indirect losses which are case-dependent, but it is possible that in the right sort of claim, a developer might be able to say uh the site has has uh suffered a loss in value, the diminution in value is ahead of loss, and I need to be compensated for that financial consequence of having purchased a site that is not worth what I thought it was because of the underlying um ground stability issues. You could also, in the right sort of cases, have claims for uh prolongation and delay in a building contract. So if you've got a building contractor who's uh faced with a geotechnical engineering issue for which they are responsible to their employer client, they may be then looking to pass on the costs that are associated with the extension of the program in addressing and remediating these difficulties, overheads and preliminaries, etc., from their professional consultants. Um in addition to that, we've been involved with cases, haven't we, Giles, where there has been finance provided to a developer to construct uh uh a residential development, and the fact that they are delayed from selling the units on that site uh and can't pay back their lender more quickly increases their borrowing costs, um, and that that can that can inform um an indirect head of loss as well. So the losses are really quite varied in these cases.

SPEAKER_01 16:17

And that's yeah, and that's why taken in the aggregate, these claims can be very expensive. Yes. One final one on the consequential losses is things like rehousing people if they have to be moved out of their houses, for example, uh, andor business interruption. If a business has to stop production in order to remediate, then that's another consequential head of loss. So we tend to see quite big numbers on these claims um in as a generalization.

SPEAKER_03 16:49

Yeah, well, absolutely, that's really interesting. Thank you both for that. Uh moving to sinkholes in particular, excellent. In terms of case law, sure it strikes me that this may be um a brewing storm as opposed to something that has really arrived at full force.

SPEAKER_01 17:08

Yeah, it's interesting.

SPEAKER_03 17:09

Yeah, so is there much case law in this area, or is it is it a sort of a developing body?

Losses, Remediation, And Costs

SPEAKER_01 17:14

Do you know what there is a bit of case law actually? Yeah. So um we'll come on to talk about why we think that these events might become more common. Yeah. But Al and I have I have personally worked on two cases involving sinkholes. Al and I worked on one of them. Uh, and I I thought it might be quite helpful to just to talk through that as a working example. Absolutely. And I will do this on a no-names basis, but interestingly, there was a judgment. This was originally a three-party dispute, which became a two-party dispute. The two parties went to trial, and there was a judgment, and it is in relation to a sinkhole. So I'll I'll I'll give you a sort of narrative account of this case. So there was a housing development on the edge of Tilehurst near Reading, and that is chalk-based land, uh, so soluble, vulnerable to things like voids and sinkholes. The developer retained two geotechnical engineers. Geotechnical engineer A were retained to do a desktop study into the feasibility of building houses on this land. And what that desktop study does is it collates all the available geological data and maps and things like that, and based on the available information in paper, it then gives you a sort of risk assessment in relation to the land. Now, that desktop study found that there was a low risk of dissolution features, and a dissolution feature is essentially a void that can turn into a sinkhole. And so they said low risk. The developer then went to a second geotechnical engineer, geotechnical engineer B, and they said, We've got this desktop study, it says there's a low risk. Can you please go and do some physical investigations on site, sink some boreholes, and tell us what you think about the site. That geotechnical engineer did some boreholes, not that many. And there is an issue there about value engineering. The more boreholes you sink, the more expensive it is. Developers don't want to pay for lots of boreholes, but they will need some, so there's a balancing exercise there. Anyway, Geotechnical Engineer B did some boreholes, got the results, and they said, yes, this is a low-risk site. The developer then started to build houses with piled foundations, and during the piling of those foundations, it was discovered that there were voids in the ground, at which point everyone went, Oh dear, there's voids in the ground. Piling might not be suitable, work had to be stopped, more investigations happened, and it was determined that this land had dissolution features, which are voids, which could turn into sinkholes andor cause differential movement. Okay, so it was a kind of oh dear, we better stop. Then the developer went to a team of professionals and said, What are we going to do? They said, pump away that liquid concrete, pump it in, and keep pumping until you fill this lot up. So that's what they did. They pumped in liquid concrete at millions of pounds worth of expense, huge amounts of the stuff, to remediate the ground. Once they had done that, they could then develop the site and build the houses. The developer then commenced litigation against both of the geotechnical engineers. The first geotechnical engineer they said, your desktop study was negligent, it was an incorrect interpretation of the data. You should have warned us that there was at least a medium, if not high, risk of dissolution features, bearing in mind all the information available on the site. And they said against the second geotechnical engineer, you placed an over-reliance on the desktop study, you didn't sink enough boreholes, you should have done more and more intrusive investigations. You were, in a sense, led into feeling too comfortable about this site because of the desktop, you didn't interrogate it enough, and all in all, you were also negligent and were suing you as well. And this claim then went through phases of litigation. Eventually, Geotechnical Engineer B assessed the risk, thought, okay, we are at some risk here, we're going to try and settle with the claimant for our portion of the recoverable losses. Cut a long story short, that settlement occurred. The claimant entered into a deal with geotechnical engineer B, and then they were out. But Geotechnical Engineer A fought the case through trial, and very interestingly, it was found in the judgment that that geotechnical engineer was negligent. There had been a breach of duty. The desktop study was not competent, but then by some sort of miraculous twist of fate during the trial, it was found, as a matter of fact, that even if the desktop study had said medium or high risk, what would have happened would have been the developer would have gone to the second geotechnical engineer and said, do a physical study, tell us what you think, having done more investigations. And therefore the negligence of the first geotechnical engineer didn't cause the loss. So amazingly, that geotechnical engineer was found liable, but didn't have to pay any damages because the negligence was found not to have caused any loss. So really interesting case. In some sense, quite a strange outcome, but that was a sinkhole claim in real-life action.

SPEAKER_03 23:18

Yes, fascinating. Thanks so much for that really brilliant summary. And I suppose for geotechnical engineers, then this is a sort of, you know, quite literally a perilous and uncertain landscape. But this podcast is about risk taking and you know embarking upon those projects that might pose risks to the relevant professional. So with that in mind, maybe it's worth, you know, summarising, discussing how a geotechnical engineer can mitigate the risks of these kinds of sinkhole claims materializing.

SPEAKER_02 23:56

Yeah, sure, Tom. So I think one key area is establishing at the outset what you're doing and not doing for a client. And that sounds quite basic, but it's very important, particularly when looking at a phase two investigation where you're actually on site doing some intrusive investigations. And I think it's important to have a documentary trail of your instructions and also what those entail from the engineer's perspective. And if there are any concerns about the sufficiency or scope of those investigations and what they may or may not reveal, it's important for the engineer to make that clear to the client. Particularly where clients may be wanting to reduce the costs of a phase of investigations or design work, they may be keen to reduce the scope of those investigations, but it's important that an engineer flags the risks associated with that. When producing reports for clients, it's important to include reliance sections stating who is able to rely on the report. Now there could be some dispute as to the circumstances in which someone might rely on a report who's not the client, and that that is a whole other topic. But I think it's important for engineers to make that clear in their reports that uh specifically who is to who who they are producing the report for and who who can rely on it. And then finally, my my my suggestion would be to have clear scope of services and terms of conditions and within that limitation of liability clauses, but to make sure that those are appropriate for the financial value of the services being provided, i.e. the the exposure of the professional in terms of the advice that they're providing. Because there can be some arguments around limitation of liability clauses, particularly in insurance limits and things. So um those are the three three three tips that I'd have.

Real Sinkhole Case: Tilehurst

SPEAKER_01 25:46

Yeah, limitation of liability clauses. I don't have too much to add to that. The only other thing I would say is sometimes a geotechnical engineer may need to push back and say this scope of works that you're wanting me to do isn't good enough. So in an example, sort of referring back to my previous story, if the developer is saying we'll only pay for three boreholes across a huge site for development, in some circumstances a geotechnical engineer should say that will not be good enough, it won't be adequate, and they will need to push back and say, No, we need to do X number of boreholes. So a bit of sometimes a bit of pushback against extreme value engineering might be required. Yeah, absolutely. Thank you both.

SPEAKER_03 26:35

That was really helpful. So looking to the future, what do you think the sort of realm of sinkhole claims, what's that going to look like as you know, more sure climate change, that type of thing?

SPEAKER_01 26:47

Yeah, absolutely. So going back to the algorithm I've got, it seems like sinkholes are happening every week, but that could be that could be a strange phenomena with my internet feed. I don't know. But we do genuinely think that um we're going to see more geotechnical claims generally, actually, more sinkhole claims. We haven't mentioned landslips and landslides, but I think there's going to be more of those as well because of extreme weather. So, and in particular, extreme inundation events. You know how rain is just getting harder, faster, stronger. You're getting more of it in a short space of time. That is a real catalyst of sinkholes because of the washing away phenomena in the voids. It's a real catalyst for landslips, and it also is a catalyst just for general difficult ground conditions. So that will enhance and increase the prospect of all sorts of different geotechnical claims, I think. So I think climate change is intrinsically linked to this, and we're going to see more of it. And then I think Al's got something about the way developments are happening and where they're happening, which will ally with climate change to make this an active area.

SPEAKER_02 28:01

That's right. So there is uh developments on the horizon in terms of planning law and planning policy. The government is putting some legislation through Parliament at the moment to reform the planning system effectively to streamline and free up decision making and create presumptions in favour of development, particularly in relation to brownfield sites, which are previously developed sites in towns and cities and other areas, but also in appropriate cases, um, some development of uh greenbelt land. Typically, we think of the greenbelt as being an area that can't be developed, and there's a presumption against development in those areas to preserve the countryside, etc. But what we are suggesting is that if there is going to be more development in these areas following uh the planning restrictions being relaxed, there is going to be uh development in areas that haven't been looked at before, particularly if it's a green belt. But in relation to brownfield, just a greater level of risk associated with building on former industrial and commercial sites. And where there's more construction activity, there will be more engineers called upon to provide their advice, and so naturally the scope for claims uh increases. But it but as as Giles says, and I don't want to talk um over your your climate change a bit, Charles, but I was gonna mention that the the impact of of high greater levels of rainfall, we're having more wet, you know, wetter weather, uh, and that's impacting on below ground material, isn't it, Charles?

SPEAKER_01 29:28

Absolutely, yeah. I mean, it's uh there's always been claims to do with what lies beneath what calling it. So that those claims have always been there since I started my career, and they've always been quite expensive to resolve. They're often multi party as well, because not only it's not normally just the geotechnical engineer who gets sued, it's also the structural engineer, the piling contractor. So they're often multi party, and that makes them a bit harder to resolve. Um, so they've always been there, it's always been an active area for construction claims. Lawyers, but I think we're going to see more of it and potentially bigger claims as well. So that is at least our prediction.

SPEAKER_03 30:09

Yeah, absolutely. Well, thank you very much. It's very helpful. Any final thoughts before we finish?

SPEAKER_01 30:18

I think I will be looking out over the next six months, it being the winter season, I'll be looking out for more sinkhole news in the UK and further beyond. And I will bet£10 that there'll be a sinkhole headline in the UK over the next six months for absolute sure. Yeah. Wow. Al?

SPEAKER_02 30:40

From me, I would just say keep an eye on the planning and infrastructure bill going through Parliament, and it's obviously subject to amendments and will potentially be different than how it started, but it'd be interesting to see how that changes the planning landscape and what impact that might have on development in different areas that haven't been developed before.

SPEAKER_03 31:00

Well, Giles, Al, thank you so much for your time today. I really appreciate you coming in to discuss this topic and thank you very much for listening.

SPEAKER_00 31:08

Thank you for listening to this episode of Fortune Favours the Brave from Howden. To hear more episodes and subscribe to our channel, search Fortune Favours the Brave on your favourite podcast app.