Insights Archive - Hawkins Forensic Investigation

Maintenance Insights: From Coal To Solar

Chloe Duggan — Tue, 01 Sep 2026 15:22:30 +0000

‘Modern power station practice’, to those in the industry, refers to a set of printed textbooks found in power station libraries, design offices and control rooms across the country and anywhere else where British engineers were responsible for equipment. First published in 1963 by the Central Electricity Generating Board, it became the engineer’s bible for design, construction, operation and, pertinent to this discussion, maintenance of power stations.

Less has changed in the power industry since that time than outsiders might guess. During my decade working for a large power company, I frequently referenced documents from the 1960s and 1970s, as well as rules of thumb passed down from senior engineers. However, one notable exception can be found in the development and growth of the renewables sector, firstly with wind and more recently solar generation becoming an important contributor to the power system.

‘Conventional’ coal, gas and nuclear power stations are large and extremely expensive assets, usually designed (at least in part) by the eventual owner and operator. These companies are, if not still owned by the state, successors of nationalised industry with a large engineering support staff either supervising or conducting comprehensive maintenance regimes on their assets. Periods of maintenance lasting weeks or months are common, with hundreds of contractors on site during these activities. Detailed records are produced and reviewed by teams of expert engineers, allowing trends, predictions and comparative analysis to identify the best possible technical responses, with a recognition from the owner operators that keeping a complicated and expensive station running smoothly requires substantial investments and interruptions have serious consequences. The legacy and structure of the industry also allows engineering functions to hold significant sway in some of the decision-making processes. This does not always go as planned, with the loss of power to Heathrow Airport being a recent example of a critical asset falling through a maintenance record gap, but generally the conventional stations can be held up as examples of good practice

Maintenance in the Renewable Sector

Renewable generators do not always follow this format. Whilst the initial design and construction of installations is still done by large engineering companies with substantial expertise, the eventual owner is frequently a financial vehicle of some sort. These owners do not have large engineering departments, or sometimes no engineering function at all, and must, therefore, rely on others for technical services. This has led to a growth in independent Operations & Maintenance (O&M) providers who bid to provide the technical support required to keep the assets running.

In my experience, the usual bidding process involves the O&M company providing both the technical scope and the price for review by the owner. Perhaps due to the limited engineering expertise within the owners, there is a risk that the technical scope is not given sufficient weight, and that more limited maintenance scopes are selected because of their lower costs. This can also lead to the subcontracting of testing or inspection tasks to third parties. The relatively lower asset values of renewable generation sites when compared to conventional power stations tends to steer discussions away from what may be perceived as ‘overkill’ comprehensive approaches.

Example

Those who have heard me speak on this topic may recall the example I frequently use to illustrate this difference, contrasting a cheaper, ‘designed for the non-expert’ inspection regime with the legacy engineering-led approach.

A common method for the collection and presentation of inspection results is the traffic light approach, identifying results as satisfactory or unsatisfactory. The tools used in inspections are sometimes designed specifically for this approach, illuminating a coloured light rather than recording detailed data.

This can result in data such as that presented in the chart below:

I would expect that anyone presented with this information would infer that the installation was fine until 2024, at which point it failed. There were no signs that anything was going wrong, and there would have been no need to change the maintenance approach, prepare for any repair action, or take pre-emptive measures against failure. Had the O&M contractor asked in 2021 or 2022 for a substantial investment to replace a component, or to take the installation offline and lose income while inspections were undertaken, in my experience the owner would likely have declined. Cases such as these often arrive on my desk described as “sudden and unexpected failures”, often leading to long periods of business interruption for the owner (and their insurers) as spares are ordered and investigations take place.

Contrast this with the actual values recorded by the measurement equipment behind these traffic light reports, presented in this second chart:

With this data, an engineer would be much more justified proposing actions in 2021 or 2022. The sudden and unexpected failure of equipment in 2024 now appears predictable and can be prepared for, either by intervention to slow the progression of whatever is causing the clear trend in the data, or by having plans and spares ready to minimise the impact of the failure and restore full operation in a much shorter timeframe.

Summary

There will always be a trade-off between gold-standard O&M, with comprehensive and expensive inspections and analysis by highly trained engineering staff, and the legitimate desire to not overspend on assets of lesser value. Running every small solar farm or three-turbine wind farm as if it were a nuclear power station is not a desirable (or feasible) solution.

However, my experience of investigations suggests that at the moment the trade-off is being made on the basis of sub-optimal set of data and assuming unrecognised risks. Closing this gap and making sure that the implications of decisions are better understood will bring value to all parties.

About the Author

Ben Lister is a member of the Institute of Engineering and Technology and, prior to joining Hawkins in 2019, spent 10 years working in the power generation, transmission and distribution sectors in both the UK and Europe, specialising in the design and analysis of electrical network equipment such as switchgear and transformers. More recently, he has investigated failures of electrical equipment in industrial and commercial applications ranging from large power stations to factory plant rooms, and has spoken at several conferences and industry meetings on the topic of common failures in renewable energy installations.

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PFAS: The Persistent Problem of ‘Forever Chemicals’

Chloe Duggan — Mon, 27 Jul 2026 11:25:18 +0000

The environmental burden of per- and polyfluoroalkyl substances (PFAS) is huge: Recent estimates suggest the cost to remediate PFAS pollution across the UK and Europe could exceed £1.6 trillion over the next 20 years.¹ These so-called ‘forever chemicals’ degrade extremely slowly and are increasingly associated with adverse health effects. As a result, businesses should take notice of their potential exposure to PFAS-related liabilities.

What Are PFAS?

Everyday products contain thousands of chemicals, each selected for a particular function because of its unique characteristics. There are dyes that impart colour to clothes, medicines with specific biological activity for curing disease, and materials with the electrical and physical properties required in the batteries that power our mobile phones. The chemical industry has, without doubt, greatly enriched our lives.

PFAS are a large class of chemicals with a number of useful properties, such as oil and water repellence and resistance to chemicals and high temperatures. This is a consequence of their chemical structure: PFAS are characterised by the presence of multiple carbon–fluorine bonds, which are amongst the strongest bonds carbon can form with any other atom. Given these attractive attributes, it is easy to understand why PFAS have found a broad range of applications, including the following:

What is The Problem?

The widespread use of PFAS has had an unfortunate consequence: it has led to the substantial release of PFAS into the environment, particularly the hydrosphere. A peer-reviewed study assessed over 45,000 samples of surface and groundwater from around the world and found that many were contaminated with PFAS at levels exceeding those recommended for drinking water.²

The chemical and heat stability that make PFAS useful also make them highly resistant to degradation in the environment, rendering them persistent contaminants of water and soil – hence the label ‘forever chemicals’. These contaminants are taken up by, and can accumulate within, plants, animals and humans. As humans are at the top of the food chain, this poses a significant risk to human health. There is a growing body of evidence linking certain PFAS to a range of potential adverse health effects, including several types of cancers, infertility, hormonal changes and developmental defects in unborn children.

How Do PFAS Get Into The Environment?

Environmental contamination with PFAS originates at locations where there is potential for significant discharge into the surroundings, for example:

Industrial facilities that produce, process or use PFAS may release them into the environment; examples include textile, paper and plastic manufacturing.
Airports, firefighter training areas and sites of major fires where PFAS-containing aqueous film-forming foam (AFFF) is used for firefighting, and ultimately ends up in soil and local water bodies.
Wastewater treatment plants where outflowing water and sludge contaminated with elevated levels of PFAS may be discharged into rivers and spread over fields.
Landfill sites are commonly the disposal route for PFAS-containing products, forming leachates that release PFAS into the surrounding earth and watercourses.
Incinerators often do not operate at temperatures sufficient for the complete combustion of PFAS in waste, and can therefore produce ash that contaminates the air, soil and water.

Even after the activity that releases PFAS at a site has stopped, emissions often continue, with PFAS leaching out of contaminated materials, like waste, concrete and soil. Furthermore, on account of their chemical stability, and high mobility when bound to airborne particles or dissolved in water, many PFAS can be transported over long distances.³ As a result, they have been detected at significant concentrations far from any known source of their release, such as in the polar regions.

How Are PFAS Regulated?

The global regulatory landscape surrounding PFAS is constantly evolving as we learn more about their risks. This makes it likely that manufacturers will face increasingly stringent standards restricting the PFAS content of their products. For instance, the PFAS compound perfluorooctanesulfonic acid (PFOS), which was commonly found in AFFF used for firefighting, has been subject to a worldwide ban since 2011. From last year, perfluorooctanoic acid (PFOA), which was also found in AFFF, has been prohibited in the UK and EU.

Regulation relating to the use and release of PFAS in the USA has progressed in some areas. In 2024, the US Environmental Protection Agency stipulated limits under the Safe Drinking Water Act for six different PFAS, including PFOS and PFOA. The limits for PFOS and PFOA are four parts per trillion (ppt, or one part in 1,000,000,000,000). Other PFAS are limited to no more than 10 ppt. Some US states have also set their own limits on individual or combined PFAS concentrations.

UK and European legislation have not yet set limits as stringent as those in the USA. The UK Drinking Water Inspectorate has set an action level when the sum of PFAS exceeds 10 ppt, and an emergency level of 100 ppt. New EU drinking water regulations introduced in January 2026 set a limit of 500 ppt for total PFAS and a combined maximum of 100 ppt for 20 selected PFAS of concern.

Critics of existing regulatory frameworks argue that such measures do not go far enough and continue to push for a blanket ban. Decision-makers need to consider:

One approach is to regulate only those compounds with a proven risk to the environment or human health. However, all PFAS contain multiple carbon–fluorine bonds that render them persistent environmental contaminants.

There may be important uses of PFAS that can be tolerated if there are suitable controls in place that can mitigate the potential harm to the environment.

As the situation stands today, there are not many alternative solutions that are viable, readily available and cost-effective for many use cases. The development of such replacements is costly and bringing them to market can take time to ensure that ‘regrettable substitution’ [4] does not occur.

What Does This Mean for Businesses?

The types of PFAS-related claims faced by businesses may involve environmental or pollution claims (including remediation costs), property damage, personal injury (from employees, customers or members of the public), and even allegations of deceptive marketing.

Some noteworthy examples include:

In 2023, 3M Company reached an agreement with various public water systems in the US to pay a $10.3 billion settlement to resolve thousands of lawsuits.
DuPont and its spin-offs, Chemours and Corteva, made a deal with the State of New Jersey in 2025 that included an $875 million settlement payment and the creation of a fund of up to $1.2 billion to remediate four industrial sites in the state.
In a groundbreaking ruling in 2023, the Swedish Supreme Court ruled that a municipal water company was liable for compensating more than 150 residents who had suffered personal injury as a result of drinking water with PFAS levels that far exceeded approved limits.
As of 2026, a large multidistrict litigation in the United States District of South Carolina focused on AFFF is underway, aggregating more than 10,000 individual claims.

Therefore, it is important for companies to take steps to manage their exposure to risk. The starting point is to conduct a thorough assessment of internal operations and supply chains.

Elements of this assessment may include:

Work with suppliers to obtain detailed information about the composition of all purchased materials.

PFAS may be used indirectly (e.g. in lubricants), creating hidden sources of supply chain contamination.

Assess the feasibility and impact of transitioning to PFAS-free alternatives while avoiding regrettable substitution.

Companies operating across multiple jurisdictions must monitor rapidly-evolving and inconsistent regulations.

How Can Hawkins Help?

Hawkins has a team of experts with the technical knowledge and experience to advise, investigate and assist individuals, businesses, insurers and legal representatives at every stage of a contamination case.

We can provide:

About The Author

Dr Mehul Jesani is a forensic chemistry expert with a PhD in organic chemistry. He has worked in pharmaceutical research and has authored publications relating to both his academic and industrial work. Mehul joined Hawkins in April 2025 as an expert in fire investigation, chemistry and contamination.

Get in touch to discuss your needs with one of our contamination experts.

https://www.theguardian.com/environment/2025/jan/14/cost-clean-up-toxic-pfas-pollution-forever-chemicals?CMP=share_btn_url
https://www.nature.com/articles/s41561-024-01402-8
https://www.nature.com/articles/s41561-024-01402-
This term describes the replacement of a chemical identified as problematic with another that has an unknown or unforeseen hazard.

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Stormwater Management on Bridges

Chloe Duggan — Sun, 19 Jul 2026 18:36:51 +0000

Bridges play a vital role in our daily lives by connecting areas separated by natural or man-made barriers, enabling efficient transportation and access. China has over 1 million bridges (CEIC, 2023), and Hong Kong alone currently has 1475 flyovers and road bridges (Highways Department, 2025). Each bridge contributes to ensuring smooth traffic flow and supporting daily commutes.

Bridges are typically designed to last more than 100 years; therefore, ensuring long-term performance is critical. Every year, billions of dollars are allocated to maintaining bridges worldwide and this figure is expected to rise as new bridges are constructed and existing ones age. A well-designed and properly maintained bridge will contribute to both its durability and reduced maintenance costs.

Among the many aspects of a bridge structure, stormwater management is particularly crucial. Poorly designed, installed, or maintained drainage systems can lead to water accumulation in undesirable areas, accelerating the deterioration of structural components and creating safety hazards for users and the surrounding environment, as shown in Figure 1. Effective drainage design and maintenance not only extend a bridge’s lifespan, but also reduce overall operational costs and improve safety.

This article provides an overview of stormwater management in bridge structures, with a particular focus on surface runoff control in concrete bridges and its role in ensuring structural safety and long-term durability. References to established design standards, including the UK’s Design Manual for Roads and Bridges (DMRB) and the Hong Kong Structures Design Manual 2013 (HKSDM2013), are included where applicable to illustrate best practices and regulatory guidance.

Discussion

Stormwater on a bridge is generally managed through four key methods: Structural Elements, Deck Drainage, Waterproofing Membranes, and Watertight Joints.

1. Structural Design

During the design stage, structural engineers and architects have the opportunity to incorporate strategies into the bridge geometry, surface shaping, and reinforcement detailing to minimise stormwater accumulation, often at little or no additional cost.

> Bridge geometry should ideally prevent standing water or ponding by incorporated appropriate longitudinal and transverse deck gradients. The UK’s DMRB-CD358 recommends a minimum longitudinal gradient of 1:100. Unfavourable geometries, such as vertical sags (Figure 2), can lead to water accumulation and should be avoided whenever possible. Where they are unavoidable, special attention to drainage and detailing is required.

> Structural shape plays a key role in stormwater management. Sloping the surface finish, such as on the bridge deck and bearing seat areas, helps prevent standing water by allowing it to flow naturally out of the horizontal surface towards designated drainage points. Drip edges and grooves are also important, as they help direct water away from structural surfaces. HKSDM2013 provides visual examples of both effective and poor practices for designing drip edges and grooves (see Figure 3). Any gaps exposed to stormwater should be avoided or properly sealed.

> Reinforcement detailing: Design codes and standards typically require crack width calculation to ensure that the size, number, and spacing of reinforcement bars are appropriate. This helps prevent excessive cracking from forming during the service, which could otherwise allow water to penetrate the concrete more rapidly and accelerate deterioration.

2. Deck Drainage

The deck drainage system consists of the intake, the drainpipes, and the outlet. Stormwater enters through the intake and is delivered through the drainpipes all the way to the outlet, where it connects to a local drainage system or natural water body. Poor design and maintenance can lead to several problems:

> Inadequate drainage design: Insufficient drainage capacity can lead to water build-up during heavy rainfall, leading to overflow into unwanted areas. This creates hazards for users and the surrounding environment. Incorporating drainage design from the early stages of bridge design is essential to achieve effective drainage.

> Blockages: Debris carried by stormwater can cause blockages, so drainage systems should be designed for ease of maintenance. Regular inspection routines are also crucial to ensure issues are identified and resolved promptly.

> Unsuitable materials: The material chosen should be durable and require minimal maintenance. Design codes often specify suitable material types. For example, HKSDM2013 requires the use of Unplasticized Polyvinyl Chloride (uPVC) for drainpipes in Hong Kong.

3. Waterproofing Membrane

A waterproofing membrane is an additional impervious layer, typically made of bitumen, polymer, or cementitious materials, applied over the bridge deck to prevent direct water ingress. Selecting the appropriate material for each specific project is crucial to ensure effective waterproofing.

These membranes can be applied in different forms, such as liquid, sheet, or spray. It is essential to adhere to relevant design codes when applying waterproofing to ensure long term effectiveness. Improper application can lead to issues such as insufficient bond strength, leakage due to poor detailing, and damage due to construction activities.

4. Watertight Joint

In modern bridge design, continuous bridges are increasingly favoured over simply supported designs. This shift is largely due to the risks associated with bridge joints, which are prone to leakage, deterioration, and high maintenance demands. Modern design codes such as HKSDM2013 and DMRB CD350 include clauses encouraging designers to minimise joints wherever feasible.

In certain circumstances, joints might be unavoidable, for example monolithic connection at abutments or when connecting new structures to existing ones. Such cases present their own challenges, and using a movement joint can be a safer and more economical design choice. In these cases, joints must be fully watertight, and access for maintenance must be considered in the joint design.
Joint watertightness can be achieved through, proprietary watertight movement joints or integrating drainage systems within the joint. If joints are not watertight, accumulated water can lead to:

Role of Technology in Bridge Drainage Maintenance

Maintaining drainage systems on bridges can be labour and cost intensive, especially for long bridges spanning challenging terrains such as seas or valleys. The use of modern technologies can improve safety, enhance maintenance quality, and reduce operational costs. For example, CCTV cameras installed on bridges allow personnel to inspect drainage inlets and identify surface blockages or flooding without the need of road closures or traffic diversions. Drones and drain inspection cameras (Figure 7) can inspect hard-to-reach locations, such as drainpipes running at the underside of the bridge. Various sensors (flow, pressure, moisture, etc.) combined with artificial intelligence have the potential to support real-time monitoring, early detection of anomalies, and predictive maintenance planning. These approaches reduce the likelihood of sudden failures and help maintenance teams respond proactively.

Final Remarks

Stormwater management on bridges is a well-established aspect of bridge design, addressed by various design standards such as HKSDM2013 and DMRB. Adhering to these guidelines when designing both the structure and the drainage system results in more durable, reliable and cost effective bridges. In summary, stormwater management on bridge is achieved through:

Structural design: bridge geometry, element shape, and reinforcement detailing.
Good deck drainage system design and maintenance.
Application of appropriate waterproofing membranes.
Provision of watertight joints and minimisation of joints where possible.

Technologies such as CCTVs, drones, inspection cameras, and smart sensors powered by AI are increasingly important for improving the safety, quality, and cost-effectiveness of bridge drainage maintenance. These tools enable remote inspections, real-time monitoring, and predictive analysis making them particularly valuable for long bridges spanning challenging terrains.

About the Author

Eng Phin is a structural engineer with over 10 years of experience in bridge and building design. He began his career in Indonesia, contributing to major bridge projects such as the Semanggi Interchange Upgrade and Kualanamu Light Rail Transit system. His expertise spans modern bridge construction methods, temporary works, and post-tensioning.

He has since worked on international projects in Hong Kong and beyond, applying local and global design standards while promoting digital engineering in structural design.

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Acoustic Design In School Buildings

Chloe Duggan — Mon, 22 Jun 2026 08:02:35 +0000

Acoustics is an important factor to consider when designing school buildings, because it affects the quality of communication and learning in classrooms and other spaces. Poor acoustics can make it difficult for students and teachers to hear and understand each other, leading to frustration, fatigue, stress, and reduced academic performance. Good acoustics can enhance speech clarity and create a comfortable and productive learning environment.

The UK Department of Education published the Acoustic Design of Schools: Performance Standards, Building Bulletin 93, in 2014. This set out the requirements for indoor ambient noise levels, reverberation times, and sound insulation for new and refurbished school buildings. These requirements are also linked to the Building Regulations, the School Premises Regulations, and the Independent School Standards.

One of the main factors affecting classroom acoustics is the indoor ambient noise level, which is the sound level in the room when no one is speaking. This noise can originate from external sources, such as traffic, construction, or playgrounds, as well as internal sources, such as ventilation, heating and cooling systems, or other equipment. High indoor ambient noise levels can mask or interfere with the speech signal, making it harder for listeners to hear and comprehend what is being said. Low indoor ambient noise levels can allow quiet, yet audible, disturbances to be far more distracting than they usually would be. This can affect the ability of students to follow instructions, participate in discussions, and concentrate on their work.

Another factor that affects the acoustics of a classroom is the reverberation time of the space. In layman’s terms, it is the ‘echo’ in a room, but technically, it is defined as the time it takes for an impulsive sound (such as a hand clap or a balloon burst) to decay by 60 decibels. Reverberation is caused by sound reflecting off the room’s surfaces, such as walls, ceilings, floors, or furniture. Reverberation targets vary depending on the type of room and activity planned for the room. For instance, a piano rehearsal music room will not have the same requirements as a classroom, and a dining hall will not have the same requirements as an assembly hall. This is because reverberation can be detrimental to speech, especially in large or crowded rooms, but is not necessarily detrimental to music in the same way. Long reverberation times can make speech sound muffled, distorted, or ‘echoey’, reducing its intelligibility and increasing the listening effort. It can also affect the vocal health of teachers, who may have to strain their voices to speak louder or more clearly. This can affect students’ learning outcomes, especially those with hearing impairments, language difficulties, or special educational needs (SEND).

Acoustics is especially important for the design of SEND schools because many students have hearing or communication challenges, or other conditions that affect their listening and learning abilities. According to the 2010 Equality Act, all schools have a responsibility to improve their accessibility plans for pupils and staff, and this includes providing optimal acoustic conditions.

Some of the strategies that acoustic engineers can use to improve the acoustics of schools include:

Choosing a suitable location and orientation for the school building, away from noisy sources or facing away from them to minimise the impact of external noise on the school environment
DevelopmentUsing sound-absorbing materials and finishes, such as acoustic tiles, panels, or carpets, to reduce reverberation s that could be affected by sources of flooding other than rivers and the sea (for example surface water, sewers, groundwater and infrastructure failure)
Installing sound-insulating materials and structures, such as double-glazed windows, doors, or walls, to block or reduce external or internal noise
Making use of acoustic barriers or screens, such as fences, hedges, or walls, to deflect or attenuate noise from outside or inside the school
Using acoustic baffles or diffusers, such as suspended ceilings, shelves, or furniture, to scatter or redirect sound waves and improve sound distribution
Ensuring mechanical ventilation, heating, and cooling systems are quiet, well-maintained, and are acoustically treated
Using sound amplification or enhancement systems, such as microphones, speakers, or hearing loops, to improve the speech-to-noise ratio and the audibility of speech. These systems can amplify the speaker’s voice and deliver it directly to the listener, or to a hearing aid or cochlear implant.

Given the propensity to affect the quality of communication and learning in classrooms and other spaces, acoustic consideration is an essential aspect of the design of schools.

By applying the principles and practices of acoustics, acoustic engineers play an instrumental role in creating school buildings that provide optimal teaching and learning conditions for teachers and students.

If you have an acoustical related issue and need the services of our Acoustics Consultancy team, please contact us.

References

Equality Act 2010 – https://www.legislation.gov.uk/ukpga/2010/15/part/6

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Secant Pile Walls & Basement Excavations: What Could Possibly Go Wrong?

Chloe Duggan — Mon, 08 Jun 2026 08:05:43 +0000

Basements are now routine in urban developments – from plant rooms and car parks to premium residential space. Yet “routine” should not be confused with “simple”. Underground works introduce a unique set of construction risks, which, if not properly managed, can lead to significant issues, increased costs and programme delays. When properly executed, these works enable the construction of challenging basements, even on constrained sites and in areas with high groundwater tables.

Many properties now require basement construction. In most cases, this is achieved using embedded retaining walls, especially in places with limited space with each option. Where groundwater is present, an embedded retaining wall type must be chosen that can retain the groundwater. Sheet pile, secant pile or diaphragm walls are feasible options. CIRIA C760 ‘Guidance on embedded retaining wall design’ provides selection guidance across wall types.

Secant pile walls, in particular, are widely used because they provide support in both temporary and permanent conditions and can be adapted to suit challenging sites. They retain ground and groundwater, minimise ground movement and can carry substantial vertical loads.

Basements may be routine, but they are not simple. Poor planning and/or execution can lead to significant technical issues, cost overruns, and programme delays. Due to their frequent use, this article focuses on secant pile walls – their role, what can be expected of them and the common issues associated with their design and construction.

What is a Secant Pile Wall?

A secant pile wall is a continuous wall formed by interlocking bored piles, as shown in Figure 1.

Primary piles, often referred to as female piles, are installed first, and secondary piles, also known as male piles, are drilled so that each one cuts into the adjacent primaries, creating an interlocking line of concrete. Primary piles are typically unreinforced (see Figure 2).

This system of interlocking primary and secondary piles creates a hard/soft or hard/firm secant wall. The difference between the two wall types is the concrete strength in the primary piles. If the secant wall is used as temporary works only, there is no need for durability or strength requirements for the unreinforced pile, and non-structural concrete may be used. Due to advances in rig power and the cost of using secant walls as temporary works only, hard/soft secant walls have become less common compared with hard/firm secant walls where the primary pile often consists of a low-grade structural concrete, such as a C8/10.

However, in very deep excavations and in response to additional structural requirements, it may be necessary to also reinforce the female piles (see Figure 3). This combination then becomes a hard/hard secant wall which uses high grade structural concrete in both primary and secondary piles.

Secant walls can be constructed using various techniques:

The choice of technique depends on the project requirements, especially permissible tolerances, retained height, depth of interlock required and prevailing ground conditions, see Figure 4. Interlock is the length of wall over which the secondary piles cut into the primary piles. This distance is of particular importance for groundwater exclusion.

Achievable tolerances and typical depth of interlock are defined in the ICE Specification for Embedded Retaining Walls (ICE SPERW) in Table B1.4 and partially reproduced below in Table 1. Whilst the verticality of wall and depth of achievable interlock increase from CFA towards RBP, so does the cost, complexity and the timeframe to install the secant wall.

Advantages of Secant Pile Walls

There are numerous reasons why secant pile walls are often the preferred solution for basement construction:

1. Space Efficiency in Constrained Sites

Urban basements are frequently built tight against property boundaries or adjacent structures. This makes secant walls ideal for city-centre projects where every metre counts.

2. Groundwater Management

Secant walls provide an effective horizontal water barrier when installed correctly. This is particularly valuable where high water tables or sensitive neighbouring assets are present. However, they do not necessarily mitigate vertical groundwater flow into the excavation and should be used in conjunction with a groundwater management strategy (CIRIA C750 ‘Groundwater control: design and practice’).

3. Structural Versatility

Secant walls can serve both as temporary excavation support and as part of the permanent basement structure, reducing duplication of work. They can be designed to carry substantial loads, making them suitable for deep basements and complex load cases.

4. Adaptability

Secant pile walls can be constructed using a variety of piling techniques to address a range of retained heights, tolerance requirements and ground conditions. Secant walls can also adapt to accommodate many footprint shapes. This flexibility makes secant walls a practical choice for many UK ground profiles.

Where Things go Wrong

On paper, secant pile walls look like the perfect solution: strong, versatile, and great for tight sites. But in the real world, things do not always go to plan. Here are the most common issues we see and why they matter.

Misalignement

Secant walls depend on the interlock between primary and secondary piles. However, piles (typically secondary piles) can become misaligned for a variety of reasons, see Figure 5.

Some common root causes for misalignment are given below:

> Primary concrete too hard, causing the secondary pile to deviate into ‘softer’ soil. This is often caused by inadequate or untested concrete mix design and is most commonly seen in CFA walls.

> Incorrect sequencing. Sequencing is of particular importance in CFA secant walls. If the sequence is not planned properly, or disrupted due to site changes or plant breakdowns, the concrete in the primary piles may become too hard, resulting in the defect described above.

> Incorrect technique chosen for interlock requirements. Due to the significant increase in costs from CFA to CCFA and RBP, the interlock limits of CFA are frequently pushed. Joints, especially in standard CFA augers, create a degree of flexibility and make it easier for piles to deviate from the vertical. To minimise this risk, having fewer joints in the auger is better.

> Obstructions in the ground, either natural (such as boulders) or man-made (in the form of old foundations or walls etc.), can cause piles to deviate from their intended position and verticality. RBP techniques are best placed to deal with obstructions in the secant wall alignment and should be chosen if obstructions cannot be removed prior to secant wall construction.

Misaligned piles can affect projects in multiple ways. If the interlock between primary and secondary piles is broken, unwanted soil and water can ingress into the excavation, which will require immediate remedial works (typically through resin injection).

Having sufficient interlock is not only important where it can be seen, i.e. above excavation level, but also below this level to guarantee sufficient water cut-off to make the excavation safe and free of running water. Groundwater entering the excavation from the bottom can destabilise the soil and, in extreme cases, cause uplift failures which should be considered in the geotechnical design of the basement (BS EN 1997-3:2025 – Eurocode 7 – Geotechnical design. Geotechnical structures). To avoid these, the design of the basement should be accompanied by a groundwater management strategy (CIRIA C750 ‘Groundwater control: design and practice’).

In severe cases, a misaligned pile (shown in Figure 5) can impact the spatial requirements of the basement, e.g. the position of liner walls. In these cases, either the out-of-position pile or the secondary element will require structural modification, potentially impacting layouts, available space or structural capacity of the secant wall itself.

Water Ingress

For the avoidance of doubt, secant walls are rarely found to be perfectly watertight. Due to the number of joints between primary and secondary piles, secant walls are vulnerable to water ingress. Damp patches and beads of water (individual droplets of water) are to be expected and do not constitute a defect. The size of damp patches, however, should be less than 4m² per patch, or less than 10% of the visible face of the wall (refer to ICE SPERW 3^rd Edition, Clause B1.9.1 for further details). Weeping water, i.e. where the water runs down the face of the wall, is not acceptable.

Water ingress may occur even if there is no visible sign of misaligned piles. An allowance should be made in the construction programme to permit the piling contractor to deal with leaks through resin injection or other sealing methods.

It is also important to understand that secant walls are classified as Type B protection against water ingress (see BS8102:2022, Table 1) and alone cannot provide a performance level better than Grade 1b (no seepage, damp areas from internal and external sources are tolerable) in accordance with BS8102:2022, Table 2.

Protrusions

Protrusions refer to irregularities on the exposed face of a secant wall after excavation, see Figure 8. Instead of a vertical surface, the wall may have protrusions extending beyond the face of the wall into the excavation. Whilst this is not a structural defect, it can have consequences for follow-on trades and potentially the construction programme.

Protrusions frequently occur in

> Loose natural granular soils or soft clay deposits

> Poorly compacted or poorly graded backfill after obstruction removal (often associated with the removal of an old basement).

> Certain ground conditions where over flighting is a risk associated with CFA techniques (refer to FPS Guidance paper ‘CFA Piling: Preventing ground & rig instability through over-flighting’).

Protrusions in soft/loose/insufficiently compacted ground cannot easily be controlled by the piling contractor. The piling contractor is only responsible for the removal of protrusions in excess of 100mm thickness (ICE SPERW 3^rd Edition, Clause B11.4.2). It is therefore important to allow sufficient time in the construction programme to deal with protrusions, although it is structurally permissible to leave protrusions in place unless they interfere with waterproofing or finishing works.

Concrete Defects

Concrete quality is critical for durability and long-term performance of secant pile walls. Defects can occur during placement and often remain unnoticed until later stages. Using a trialled and tested concrete mix design from established concrete suppliers and undertaking concrete performance testing, are effective ways to minimise the risks of defects. How the concrete is handled on site, for example, avoiding changes to concrete properties through the addition of water, and ensuring the timely and appropriate placing of concrete in accordance with the relevant standards, such as BS EN 1536, ICE SPERW, EFFC Tremie Guide is also of vital importance. Inadequate base cleaning or support fluid exchange, poor tremie practice (RBP only) or concrete supply interruptions can also affect the final product.

Some common concrete defects in secant walls include:

> Shadowing/mattressing, refers to situations where concrete does not flow adequately around the reinforcement bars and leaves ‘shadows’. This defect only occurs in rotary piles.

> Inclusions in piles, which are a common problem and are often the result of inadequate concrete workability. They consist of entrapped materials that differ from the specified concrete and can originate from the surrounding ground (soil or groundwater), poorly cemented material from the original segregated concrete, and may also contain drilling fluids (if used during construction). Inclusions occur more frequently in rotary bored piles as the concrete is placed after the installation of the reinforcement cage and must flow around the bars, but can also occur in CFA or CCFA piles when the concrete has lost its workability.

As a result of inclusions, concrete cover becomes inadequate requiring remedial work. If the inclusions are extensive, they may also provide additional pathways for water ingress (though the reduction of interlock) and may require the down-rating of pile/wall capacity.

What to Expect

Many disagreements occur when expectations between parties are not aligned. The points below summarise what can reasonably be expected:

Secant pile walls are not fully watertight

Secant pile walls manage groundwater inflow, but they do not provide completely dry basements. Damp patches or minor seepage are common and should be anticipated. Flowing water or concentrated leaks, however, are unacceptable and usually indicate defects requiring remedial works. Waterproofing should always follow BS 8102:2022 guidance, with allowances for remedial sealing such as resin injection.

Damp spots do not mean defects

Clients often expect a completely dry basement. In reality, even with a well-built secant wall, some moisture may appear. This is normal and should be addressed through the waterproofing strategy, not treated as a defect.

Overbreak is common

Expect some irregularity on the exposed wall face after excavation. Overbreak often occurs in loose granular deposits, soft clays, or poorly compacted backfill from obstruction removal. Whilst it does not present a structural problem, it complicates waterproofing and finishing works. Extra trimming or patching may be needed, which can affect programme and cost.

Straightness varies by technique

Walls formed using rotary bored piling (RBP) tend to achieve better verticality, greater interlock and straighter faces than those installed with CFA methods. However, while these advanced systems deliver superior alignment, they come at a higher cost.

Consequences for Projects & Claims

When secant pile walls do not perform as expected, the impact is rarely minor. Even small defects can significantly affect the programme and budget. The following outcomes are typical:

Remedial Waterproofing

If water ingress occurs, the leaks are usually treated by polyurethane or acrylate gel injection. This treatment generally stops the leak but can be very disruptive. Injection requires specialist contractors, access to the affected areas, and often multiple visits. Blocking one leak often causes others to appear, meaning costs can increase quickly, and programmes become delayed.

Additional Surface Preparation

Whilst overbreak may be more of a cosmetic problem, it can mean that the wall face is not ready for waterproofing straight away. Trimming, patching, or applying thicker coatings adds time and labour. These tasks are rarely in the original programme, so delays are common.

Structural Downgrades

In rare cases, if tolerances or concrete quality fall short, the wall’s structural capacity may need to be reassessed. This can lead to redesigns, additional props, or strengthening measures, all of which add cost and complexity.

Programme Delays and Cost Overruns

Every remedial step, whether sealing leaks or smoothing surfaces, pushes the schedule out. Waterproofing trades cannot start until the wall is prepared, and follow-on activities like slab casting or fit-out are held up. Claims for delay and disruption are common in these scenarios.

Bottom line: Defects, even cosmetic ones, can have significant commercial consequences. Early planning, engagement with relevant specialists, realistic tolerances, robust quality control, and allowances in programmes are the best approach to avoid subsequent issues.

From our experience, it is essential to follow these steps to minimise issues on site or disputes:

> Define the waterproofing performance grade early (BS 8102:2022) and appoint the waterproofing specialist at the concept stage.

> Select the right wall type for depth, deflection limits and groundwater context (CIRIA C760).

> Make allowances for realistic tolerances (ICE SPERW).

>Plan groundwater management: combine secant cut‑off with dewatering where required; design for uplift; protect adjacent assets (CIRIA C750).

Conclusion: Why Early Attention Matters

Secant walls make complex basements possible, but they are not an “install and forget” solution. Misalignment, protrusions, water ingress, and concrete defects are all common issues that can lead to extra work, cost, and programme delays. Most “problem basements” are not the result of a single catastrophic error – they often stem from a series of small, foreseeable mismatches between design assumptions, construction tolerances, and waterproofing expectations. Addressing those early is far cheaper than dealing with issues later. Standards and guidance exist; the key is to use them proactively.

If you are facing secant wall performance questions, planning a deep basement, or navigating a claim, Hawkins can help – from early risk reviews and design due‑diligence to independent failure analysis and expert evidence. We translate complex geotechnical issues into clear advice and defensible conclusions for clients, contractors and insurers.

About the Author

Yvonne Ainsworth is a Chartered Civil Engineer and Principal Associate at Hawkins, with over 25 years’ experience in geotechnical and structural engineering. Her career includes senior roles delivering complex foundation and retaining wall projects, including secant and diaphragm wall construction on major UK infrastructure schemes. Yvonne is widely recognised for her expertise in piling, ground engineering and resolving high-risk technical challenges, with experience directly relevant to the behaviours, risks and performance of secant pile walls discussed in this article. She brings specialist insight into design, construction methodologies, and failure investigation in complex ground conditions.

References

BS 8102:2022 – Protection of below ground structures against water ingress — Code of practice

BS EN 1536:2010 (+A1:2015)- Execution of special geotechnical works – bored piles

BS EN 1997-3:2025 – Eurocode 7 – Geotechnical design. Geotechnical structures

CIRIA C750 – Groundwater control: design and practice, second edition, 2016

CIRIA C760 – Guidance on embedded retaining wall design, 2017

EFFC Guide to Tremie Concrete for Deep Foundations, 3^rd Edition,2024

FPS Guidance Paper ‘CFA Piling: Preventing ground & rig instability through over-flighting’, 2014

ICE Specification for Piling and Embedded Retaining Walls, 3^rd Edition, 2016

The post Secant Pile Walls & Basement Excavations: What Could Possibly Go Wrong? appeared first on Hawkins Forensic Investigation.

Keeping the Lights On

Chloe Duggan — Mon, 27 Apr 2026 13:10:45 +0000

The Importance of Fuel Systems in Marine Operations

When combining diesel combustion engines with aeroderivative gas turbines in power generation assets and mechanical drive systems, the fuel specification and adherence to the specification are critical. Compliance ensures the optimal operation, and longevity of the asset and minimises down time.

In marine installations, large vessels can have a mix of propulsion drive systems. Typically, these consist solely of large diesel units, however, in some large vessels, the addition of gas turbines can be found – for that extra bit of thrust/speed.

Both can be susceptible to damage and loss of power if issues exist within the fuel supply system, problems can be caused by using the wrong fuel, or if contaminants are present in the fuel system. If contamination occurs, this can lead to a sudden loss of power which can affect the safety of the vessel. Contamination can compromise the integrity of not only the engine, but also the fuel system, which will require draining and cleaning; both of which will be costly and time consuming to execute. A typical propulsion system schematic is shown in Figure 1. This shows two diesel units and one gas turbine in a two-propeller propulsion system.

If fuel issues arise, both power unit types can be affected. In the example below, I look at how fuel contamination can lead to a buildup of deposits in the fuel system, especially in the final fuel delivery section, which in a gas turbine is the fuel nozzles. The fuel nozzles are complex components that premixes fuel with compressed air and inject the fuel mixture into the combustion can. Combustors see the hottest temperatures.

A schematic diagram of a typical fuel nozzle in a single annular combustor (SAC) is shown in Figure 2. The fuel nozzle is the final link prior to the fuel being atomised into the compressed air flow and ignited.

Issues in the fuel system can be detected by the gas turbine monitoring systems which include temperature and pressure sensors. In SAC gas turbines, there are around 30 fuel nozzles. If issues are developing, the temperature spread around the combustor is likely to change and exceed the permitted temperature spread which is typically limited to approximately 100 to 150°C across eight thermocouples dispersed around the turbine. The fuel pressures in the delivery pipework will also increase as blockages develop. These are both indicators of problems in the fuel supply system, and monitoring of the system’s sensors is of critical importance.

In the case study that follows, excessive temperature spreads and reduced power output were detected over a 72-hour period, indicating an issue with the combustion that required further investigation. This shows how rapid the degradation can be once coking occurs.

Once an issue has been identified, there are limited options for a vessel at sea. The first is to inspect the fuel nozzles to see if there are any visible signs of distress. If deposits are found as in the example below, then all the fuel nozzles will likely need to be replaced. On a gas turbine, each fuel nozzle can cost in excess of 5,000 USD, and a vessel will not carry a spare set on board.

To determine the source of deposits, a laboratory examination of the affected nozzles will be required.

A typical suite of tests includes:

Case Study

Visual examination of the nozzles from the gas turbine that had exhibited excessive T-48 temperature spreads (Figure 3), revealed remnants of liquid fuel, with both the primary and the secondary fuel line blocked by deposits. The primary flow line had been cleared prior to receipt into the laboratory but was reported to be blocked on removal from the gas turbine.

Within the residual fuel, solid deposits were found that were collected and examined. The solid deposits revealed a layered structure (Figure 4) consistent with deposits forming over several operating cycles (stops). This appearance is consistent with coking of the fuel during shut down and thermal soak back. Soak back is the cooling off period after shutdown and can be challenging as it can lead to very high temperatures in the engine damaging equipment back equipment¹. The appearance would also indicate that a purge cycle was not undertaken to remove residual fuel from the fuel line in the area.

The samples collected were analysed using an EDS analyser attached to an SEM. This revealed the deposits to be predominately carbon, however significant traces of sodium (Na) and chlorine (Cl) were detected in areas exhibiting a cubic crystal form (Figure 5). The cubic crystals were observed in all samples examined.

The coking found in the fuel nozzles would indicate that issues were present in the purge sequence of the fuel lines on shut down. In most industrial gas turbine applications, on shut down, the fuel manifold is purged with compressed air to clear the line of residual fuel to minimise the possibility of coking. This did not appear to have occurred. The presence of cubic crystals of sodium chloride indicated contamination of the fuel by ingress of sodium chloride rich solute, such as seawater into the fuel system at some stage.

Besides the issues generated by the coking on the fuel combustion, the gas turbine had been exposed to elevated levels of sodium, which had passed through the high-pressure turbine section. At the temperatures in the hot section of the turbine (high-pressure turbine) this can lead to Type 2 hot corrosion of the turbine blades (which are more expensive than the fuel nozzles). This can lead to a catastrophic failure of the unit if not rectified.

Normally, sodium levels in fuels are specified/restricted to levels down to parts per billion to avoid this degradation mechanism. On the completion of the analysis, it was clear that further investigation was required, into the operating procedures and fuel monitoring during the operation of the vessel.

About the Author

Stephen is a forensic metallurgist with extensive global experience providing independent materials and corrosion advice to multi-national companies within the built environment and engineering industries.

He has over 25 years of experience undertaking failure and root cause analysis for clients in the power, process, and pipeline sectors and has acted as an expert witness across the globe.

¹Predicting engine soak-back with SALAMANDER | Clean (clean-aviation.eu)

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Do I Have a Cladding Dispute?

Chloe Duggan — Mon, 13 Apr 2026 09:45:05 +0000

Over recent years, the safety of a building’s cladding has become a major concern in the UK and the UAE. This is primarily due to the use of combustible cladding materials and ill-fitted or absent fire stopping.

The typical cost of recladding an 18-metre tall building is in the region of £4-5m in both the UK and the UAE. This has led building owners and occupants to consider whether these costs can be recovered from other parties.

Before being able to answer the question, a prospective claimant must first ask ‘do I have unsafe cladding?’. Safety concerns regarding cladding includes structural and fire issues, but this article will focus on non-load bearing facades and therefore fire safety concerns only.

Many of the headlines covering combustible cladding materials initially focused on aluminium composite panels (ACP). However, a building clad in ACP is not the only type of material which could present a risk. There are other cladding types, such as high pressure laminates and external insulated render systems known as EIFS, ETICS or EWI, which may appear to be acceptable but could give rise to a claim.

How do I Know if a Building’s Cladding is Defective?

Defective cladding could be due to the design, construction (installation and workmanship related defects) or both. Design and construction are governed by local building codes, and it is necessary to review a building based upon the codes relevant at the time of design and construction.

In England and Wales, the current relevant codes include the Building Regulations 2010. In the UAE, the current relevant codes include the Fire and Life Safety Code of Practice 2017.

Was the Design Defective?

In England and Wales, there is more than one route to demonstrating compliance with the fire safety requirements of the Building Regulations that the designer/s could have followed:

Linear route: Following the guidance in the Approved Documents, although this does not guarantee compliance with the Regulations.
Performance route: Demonstrating that the performance criteria for external walls in BR 135 have been met by using fire test data from a large-scale BS 8414 test to determine how the proposed façade build-up performs in a fire.
Fire safety engineering route: This would generally follow the recommendations in BS 7974 ‘Application of fire safety engineering principles to the design of buildings – Code of practice’ and take the form of a desktop study that states whether the performance criteria in BR 135 would be met, and as set out later in this article.

Whilst the UAE did not develop its own Fire Life Safety Code until 2011, with the National Fire Protection Association (NFPA) standards being adopted previously, it has been quicker than many other countries to update and introduce more stringent requirements following significant fires.

The review of a design’s compliance with the Code is undertaken by the Civil Defence Authority, although compliance with the code is still the responsibility of the consultant. Any façade system must have been tested and approved by the Civil Defence Authority and the relevant and current approval certificate must be submitted as part of the application for Civil Defence Approval. This, in theory, means that, a design post2011 should not be defective.

However, a building gaining building control or code approval does not necessarily mean that the cladding as designed and installed meets the functional requirements and is not defective.

The most common design defects we have come across at Hawkins include the lack of fire barriers and/or cavity closers. Both of these defects can lead to extensive areas of the external envelope of a building where the spread of fire could be hidden from view. The restricted nature of these cavities can lead to flames that extend up to 10 times the height they would otherwise reach if they were not within a cavity.

The Consultant Told me the System had Been Tested

In the UAE cladding systems must be tested to NFPA 285, which replicates a fire breaking out in the building, spreading through the glazing and igniting the external façade. The test determines the fire performance of an exterior, non-loading bearing wall assembly.

BS 8414, first published in 2002 and some 30 years after the origins of NFPA 285, also provides a test method for determining the fire performance of non-load bearing external cladding systems. The standard is split into two parts; part one tests systems applied to the masonry face of a building, whilst part two tests systems applied to a structural steel frame.

There are a number of issues with statements that a system has been tested to a standard:

Firstly, what was the result? Results for BS 8414 tests are generally not made publicly available, and the BS 8414 test results are not given as a pass or fail (this must be determined by using BR 135). In the UAE, NFPA 285 are available as part of a supplier’s marketing material and without it their products are unlikely to be specified.

Secondly, is the system tested going to be applied in the same way as the test? A masonry applied system will behave differently than a steel frame applied system.

Thirdly, does the system tested match exactly what was proposed for your cladding system? For example: where fire barriers are installed around openings in the test is the insulation the same; and, if it is, is it the same thickness? In one of our cases, it was stated that the EIFS system was tested to BS 8414. The test was relevant for insulation thickness up to 200mm yet the designed system was 320mm in places

The Fire Engineer Said the Design was OK

By following BS 7974, fire engineers can use an analytical process based upon a qualitative design review, in which the possible ways a fire hazard may arise are considered and a range of strategies adopted to ensure that the risk is kept to an acceptable level. This process has a number of stages, including:

A review of the architectural design of the building
Establishment of the fire safety objectives
Identification of fire hazards and the possible consequences
Establishment of trial fire safety designs
Identification of acceptance criteria and methods of analysis
Identification of fire scenarios for analysis
Assessment against criteria.

As you may be able to tell, this is not a quick exercise, and a fire engineer should provide a substantiative reason as to why the guidance in Approved Document B has not been followed, together with supporting evidence to show how the Buildings Regulations are being complied with through another route.

Was the Installation Defective?

What the consultant draws is not always what gets built. Defects we have encountered include lack of fire barriers, intumescent strips to fire barriers impeded so they cannot act as designed during a fire, and incorrectly installed EIFS resulting in cavities between the back of the insulation and the supporting structure.

It is likely that only an intrusive survey will be able to determine if there are defects in the installation. However, an intrusive survey needs to be carried out correctly and those carrying out the survey must understand what they are looking at. In one instance, I have seen a surveyor incorrectly label solid aluminium cladding as ACP, which will have had an effect on the building owner’s insurance premium. In another instance, a surveyor had considered that a lack of cavity barriers in an external wall, indicated that there had been a breach of the Building Regulations, despite the layout of the building meaning there was no other compartment to which a fire could spread.

The above points provide some insight as to whether building owners have a potential route to bring a claim for the costs of remedial works either against consultants, contractors, or possibly both, before a building fire highlights any defects and when it may be too late to ascertain defects in construction.

About the Author

Austen Smith is a Forensic Architect in Hawkins’ Dubai office who specialises in construction defects and defects in architectural design. He has twenty years’ experience in construction projects spanning Europe, the Middle East, the CIS, East Asia and Australia.

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Avoiding a Case of the Blues

Chloe Duggan — Mon, 23 Mar 2026 09:04:41 +0000

Blueberries are a popular ‘superfruit’ with global consumption continuing to increase. In 2023, over 45% of world production was exported. Blueberries can have a shelf-life of up to three months and can be stored below 5°C for up to seven weeks, making them suitable for long-distance transport. However, when a container of blueberries reaches its destination, there could be a ‘case of the blues’ if they have spoilt in transit. In these cases, a forensic investigator can determine where in the supply chain things have gone pear-shaped.

Here Comes The Sun

Optimising a long shelf life starts with good crop husbandry to control pests and diseases. In hot climates, the crop is grown under shade netting, protecting the fruit from sunscald, with polytunnels used to prevent damage by heavy rain or hail in wetter climates. Blueberries should be picked at the 85–90% blue stage in dry conditions in the morning, before heat builds up in the fruit. High humidity at harvest promotes rots and moulds, and berries picked at more than 90% blue stage have a shorter shelf life. Once picked, blueberries should be cooled within five hours as, high temperatures accelerate fruit degradation.

Blueberries are sometimes harvested into crates in the field, but frequent handling removes wax from the skin. This reduces the nutritional quality, accelerates water loss, and speeds decay. To minimise handling, growers are increasingly picking berries directly into branded clamshell retail punnets.

Time to Chill

After harvest, blueberries remain metabolically active, so respiration, ripening and cell aging continue. Upon arrival at the packing facility, the temperature of the berries should be lowered to near 0°C by forced cooling immediately. Temperatures below 2°C for 96 hours kill fruit fly eggs and render mould spores inactive. Care is needed though – while insufficient cooling reduces shelf life, temperatures below 0°C increase chilling injury risk to the berries.

Like many fruits, some blueberry varieties ripen when exposed to the ripening hormone, ethylene. Knowing which variety is being shipped is important, as removing ethylene from storage air can delay their ripening. Ethylene absorbing sachets can help, but add cost.

Happy Atmosphere

Controlled atmosphere transport involves increasing carbon dioxide (CO2) and decreasing oxygen concentrations in an airtight container. Some ‘reefer’ (refrigeration) systems offer a CO2 injection option, allowing containers to be pre-charged to 15% CO2 for blueberries. The auxiliary supply automatically tops up CO2 during transit. However, CO2 supply failure can lead to increased metabolic activity and subsequent fruit breakdown.

Modified atmosphere packaging initially alters the atmosphere inside the pack, but it changes over time. A range of perforated bags are available from manufacturers to wrap entire pallets or individual crates. It is important to use the correct wrapping to avoid losses.

Active packaging changes the condition of the atmosphere to extend shelf-life. Sodium metabisulphite pads release sulphur dioxide (SO2) gas, which kills fungal spores, sanitises small wounds on the fruit surface and maintains the relative humidity within the package at around 89%.

The pads must be placed on top of pallets before wrapping, as SO2 is heavier than air. In addition, the pad must not be allowed to come into direct contact with the blueberries because it is toxic to plant material. Incorrect positioning of these pads can cause mould spoilage or skin bleaching.

Breaking The Mould

More than a dozen moulds can affect blueberries, and an increase in temperature above 2°C stimulates spore germination, initiating irreversible fungal growth, spoiling the shipment. Some moulds, such as Anthracnose (Colletotrichum species) and Grey Mould (Botrytis species) originate in the field due to poor hygiene. Others, such as Blue Mould (Penicillium species), colonise berries during transit due to poor conditions. SO2 primarily controls the mould Botrytis cinerea, a major cause of blueberry spoilage.

Over 300 pests can affect blueberries. One major field pest is the Spotted Wing Fruit Fly (Drosophila suzukii), whilst other fruit fly species colonise the fruit post-harvest. Correct mould or pest identification helps establish liability in the event of a claim.

When The Ship Comes in

Reefer containers maintain the temperature of pre-cooled produce but cannot reduce it further. Pallets should be positioned inside the container to allow for the uniform circulation of cold air. Humidity levels inside the container must also be carefully controlled as too much can promote mould, whereas too little can lead to fruit dehydration and shrivelling.

Take Out Some Insurance On Me

Failing to take the critical steps highlighted above could lead to a ‘case of the blues’ on arrival and an expensive insurance claim.

When faced with a container of spoilt blueberries, it can be daunting for the owner to ascertain how best to understand the root cause and whether the damage is a result of issues during growing, storage or transportation of the crop. A detailed forensic investigation using industry knowledge and expertise in plant diseases can help establish where and why things went wrong and where liability should be attributed.

About The Author

With over 25 years of experience, Plant Pathologist James Townsend has expertise in berries, fresh produce, horticulture and agriculture and is experienced in investigating the causes of plant diseases, crop failures and spoilage of fresh produce. James regularly investigates crop germination failures, crop storage problems, fallen trees, mould contamination, pesticide damage, wildfires and plant disease outbreaks in domestic commercial settings.

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A Structure is Only as Strong as its Weakest Link

Matthew Carrington — Mon, 09 Mar 2026 15:41:10 +0000

Construction projects of all kinds, over a wide range of scale, require structural engineering design input to direct the way they are built. The structural engineering design is almost always implemented in conjunction with architectural design, other specialisms, and the knowledge and skills of the contractor and specialist sub-contractors.

Civil and structural engineering design is a complex field where many engineers are highly qualified, with professional accreditations from engineering institutions after several years of industry experience, following a university degree. However, there is no safeguard against less qualified or less experienced people also trading as civil or structural engineers.

This article discusses the typical aspects of structural engineering design that are required in most construction projects. It includes case studies investigated by Hawkins, where the action of the structural engineering designer could be at fault.

“The strength of a structure depends on the strength of its elements and the way they are joined together.” – Gustave Eiffel

Weak Links

Some building faults might be related to issues with the structural engineering design, or omissions in it. Others may be due to the actions of other parties in the design or construction team, or faulty materials. The design process for each project must consider all the potential modes of failure of the structure. Any one thing could be missed in the design process and cause an issue with the performance of a building. Sometimes, a combination of circumstances needs to coincide to cause a failure. Almost every construction project is a prototype due to the varying combinations of building shape, location and formation of the team performing the work. The following sections describe five links in the structural engineering design chain.

1. Design Issues

It is possible for a structural engineer to completely design the strength and stiffness of the individual elements for the structure but miss a wider issue that can lead to damage or failure.

For example:

The lateral sway stability of part of a building can be reduced by replacing the vertical support from a solid masonry wall with a steel beam;
Loads on a gravity retaining wall at a change of level of external ground that were not allowed for in the design can occur if drainage is not detailed (Figure 2);
Overall structural capacity can be exceeded if a whole category of loading is omitted, such as wind or snow load.

2. Site Issues

There are cases where the design might have considered the typical scenario for the type of structure they designed, but there was something different on site that they did not allow for.

For instance:

If a designer assumed that a wall was a cavity brick/block wall, when it was in fact a solid stone wall, then the wall would be heavier than assumed. A beam installed to create an opening and support the wall could then be overloaded;
A wall that was retaining higher ground could collapse if the rest of the building that was providing lateral support to the wall was removed without considering the interaction (Figure 3);
The effect of a row of small trees on building foundations movement can be greater than the individual trees;
Different ground conditions can have more or less aggressive reactions to the concrete they are in contact with. The wrong mix of concrete might look suitable initially, but in aggressive ground conditions, it can degrade over time.

3. Calculations

Sometimes, the structural designer can miscalculate their designs.

Examples might include:

An assumed length of a beam was not updated in the design calculation when the length of the opening was longer than first planned;
In a structural assessment, the engineer might have used the material properties for normal density concrete when the element was lightweight or aerated concrete, which can only provide lower strengths;
In computer aided design, using finite-element modelling or calculation sheets prepared by a software company, the wrong input for the situation being built can lead to an understrength member. This might arise from one wrong tick in a box within the software options.

4. Stages of Design

There have been cases where the structural engineer provided sufficient design information for a preliminary stage of the design, such as submission to building control, to gain approval for the project to proceed. Then, the client or contractor did not go back to the engineer to ask for detailed design and construction details, or did not correctly apply the submitted preliminary design.

These cases have included:

Where relative positioning between structural members and their supports was critical to the building performance, but the individual member capacity design was sufficient to pass the building control plans check;
Where the order of construction would be critical to the capacity of the structural members. During construction, an unrestrained steel beam would have considerably less capacity to carry vertical loads until it was restrained by the floors to both sides (Figure 4);
Often, changes that appear to make the building simpler to construct can introduce complications to the way they would perform. The changes would need further structural design and could cause a problem if the designer had not been notified.

5. Missing Design

We have investigated cases where an item was overlooked as needing civil or structural engineering design. This can occur at interfaces between specialist contractors’ responsibilities:

i. Roof vents (Figure 5);
ii. Cladding boards (Figure 6).

These will likely perform satisfactorily in normal conditions but might not be sufficient for high winds or rain. This would likely present in the failure of several of the same items. Identifying the fault early might allow the rest of the items to be remediated.

Failures can exhibit a range of states of distress and at different times in the life cycle of a building.

The questions which must be considered when investigating the root cause of the failure will vary with the scenario, including:

Was the designer provided all the necessary and correct information?
Should the designer have found out the correct information by looking into the situation more than relying on drawing or reports they were provided?
Was there information that the designer needed to show in more detail to a competent contractor?
Was there a coordination responsibility to make sure the correct information was provided?
Should a competent contractor have given feedback to the designer that the situation was not as allowed for in the design?
Did the client appointment limit how much the designer could do in any of these aspects?

In some cases, we have been able to advise that urgent action needed to be taken to avoid further damage occurring. This can save people spending time in a position of danger looking for material damage or conducting intrusive investigations that might tip the situation further towards collapse.

“The best design is the simplest one that works”. – Albert Einstein

Conclusions

Sufficient structural engineering design relies on considering all the relevant design issues and all the particular conditions on the site. The structural engineer must complete the design calculations correctly and present the construction information clearly to the contractor. Greater levels of detail are required for the construction issue of the structural drawings than for the building control submission. That is a situation where misunderstandings can arise. Also, there are proprietary and peripheral items related to construction that might not be part of the scope of a structural engineering appointment but would have benefitted from a review by a structural engineer.

How can Hawkins Help?

Hawkins’ Built Environment team can review when something has gone wrong and assess the relevant specialism or party that might have contributed to the issue. Professional experience is important in engineering, including experience of investigation.

About the Author

Jolyon Antill is a Chartered Civil Engineer based in our Reigate office. Graduating with a first-class Master’s Degree in Civil and Structural Engineering, Jolyon has 27 years of design consultancy experience.

His range of industrial and commercial project design work includes new builds, renovations, and structural surveys, both in the UK and overseas. Jolyon also has extensive experience in regional civil and structural engineering consultancies working on educational, residential, leisure and commercial projects. If you have a civil or structural issue and need Jolyon or one of the team to investigate, please contact us.

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Is it Enough to Rely on What The Manufacturer Has Told You?

Matthew Carrington — Mon, 23 Feb 2026 09:51:24 +0000

Construction product manufacturers (‘manufacturers’) frequently provide free continuing professional development (CPD) content. The information is often the first that building designers and other specifiers (‘designers’) receive about a particular product. Designers may then seek further information and advice from manufacturers, including literature, standard details, and specification sections for the selected products, so that they can be incorporated into a project’s technical drawings and specification.

The information received can significantly influence design development and decisions made throughout the procurement process. If a problem arises from a specification incorporating information received from the manufacturer that causes a loss to the designer’s client, the client will most likely hold the designer accountable – not the manufacturer. This is particularly true where a clear contractual relationship exists between the client and the designer, but not between the client and the manufacturer.

Since the Grenfell Tower Fire

Following the Grenfell Tower fire on 14 June 2017, many of the long-standing norms in the construction industry have been scrutinised and found wanting.

In ‘Building a Safer Future‘ published in May 2018, Dame Judith Hackitt highlighted the complexity of construction product testing, labelling, and marketing that designers must navigate, stating that:

“The system that covers product testing, labelling and marketing is at least as complicated as the entire regulatory system […]. It is apparent that the current system makes it difficult to know whether the right products are being used.”

Since 28 June 2022, legal claims can be brought against manufacturers under sections 148^[1] and 149^[2] of Building Safety Act 2022 (‘the Act’). Under section 148, claims may be made where a product has been “installed in, or applied or attached to, a relevant building.”^[3] and it can be demonstrated that the manufacturer took specific actions (including making misleading statements) that resulted in a relevant building being “unfit for habitation”.

Section 146 and Schedule 11^[4] of the Act also states that the “Secretary of State may by regulations make provision in relation to the marketing and supply of construction products in the United Kingdom” called the “construction products regulations”. These may “prohibit the marketing or supply of construction products which are not safe products”.

Following this, in April 2023, the Department of Levelling Up, Housing and Communities published ‘Testing for a Safer Future An Independent Review of the Construction Products Testing Regime’^[5] (‘the Morrell-Day Review’) which made recommendations about how to improve the regulation of construction products.

Since the Grenfell Tower Fire

Statutory duties for designers were introduced in October 2023 when Part 2A of the Building Regulations came into effect. Designers are now required to take “all reasonable steps to ensure the design work carried out by them (and by any workers under their control) is planned, managed and monitored” so that, if built in accordance with that design, the building would comply with all relevant requirements of the Building Regulations.

Phase 2 of the Grenfell Tower Inquiry (‘Phase 2’) further examined construction product testing and marketing and the Phase 2 report, issued on 4 September 2024, recommended that:

“Steps be taken in conjunction with the professional and academic community to develop new test methods that will provide the information needed for such assessments to be carried out reliably”.
“Copies of all test results supporting any certificate issued by the construction regulator be included in the certificate;
“Manufacturers be required to provide the construction regulator with the full testing history of the product or material to which the certificate relates and inform the regulator of any material circumstances that may affect its performance; and
“Manufacturers be required by law to provide on request copies of all test results that support claims about fire performance made for their products.”

The government responded to the Morrell-Day Review and the Phase 2 report by launching a consultation on the “Construction Products Reform Green Paper”^[6] stating:

“Despite the significant reforms initiated in response to the Grenfell Tower tragedy, the government is clear that critical gaps persist in the construction products regulatory framework.”

At the time of writing, the government has signalled its intention to enact further construction product regulations. In the meantime, new testing methods are being developed.

Has a New Relationship Between Designers and Product Manufacturers Emerged?

Some manufacturers will no longer provide technical information without recording project details and caveating the reliance that can be placed on that information. This may include drawing the designer’s attention to the limitations of any tests that the product has undergone, and whether it will be used in an untested configuration.

Yet the designer must still rely on manufacturers’ information to develop designs and select the “right” product for the specific circumstances of each project.

So, What Practical Steps Can be Taken?

Understand What is Required:

Before taking any action, each designer must understand the scope of their design responsibilities relative to others and consider how they will demonstrate compliance with both the standard of care required by their contract with the client^[7] and that required under Part 2A of the Building Regulations. Designers should not assume these responsibilities are the same across all projects, therefore reading and understanding the contract is imperative.

Provide Good Information:

No two projects are the same, and manufacturers can only give advice based on the information they receive. Clearly setting out project-specific criteria helps focus the designer on the principal considerations and enables them to assess which products might be suitable. This information can also serve as a benchmark against which manufacturers’ replies can be compared.

If it Isn’t Clear, Ask:

It is not what the designer believes the information says, but what the information actually says that matters.

If a clear answer is not received, further questions should be raised until the designer is satisfied that a reliable conclusion can be drawn.

Seek Advice From Multiple Sources:

Tempting as it may be to consult only the market-leader, designers should, whenever possible, approach several manufacturers and evaluate each product in context.

Designers must also review the industry guidance and advice that is available at the time of specification and where necessary, seek project-specific advice from independent bodies. The designer should inform the client in writing when further specialist advice is required.

Taking these steps ensures that designers receive a broader range of perspectives and advice upon which to form an opinion.

If a solution limits the choice of material, or if insufficient information is available, the designer should inform the client of the potential implications so that the client understands the risks associated with proceeding, and work collaboratively with the client to explore alternative options.

Certifications, Test Data, and ‘Desktop’ Studies:

In Martlet Homes Limited v Mulalley & Co Limited [2022] EWHC 1813 (TCC), His Honour Judge Stephen Davies reminded designers that a British Board of Agrément (BBA) “certificate is simply one of a number of … specified aids” that “may be used to establish the suitability of use of a material for a specific purpose”, and that the “BBA Certificates cannot be said to amount to a form of “guarantee” or “passport” to compliance with the Building Regulations.”

Designers must establish whether third-party product certification (BBA or equivalent) and product test data are current and applicable to the proposed build-up, and whether additional information is required, such as classification reports from full-scale tests in accordance with BS 8414.

It is often impractical or commercially unviable for manufacturers to undertake full-scale tests for every configuration for external walls; for example, the certification might not exist for the specified build-up. In such cases, an assessment in lieu of tests (AILOTs, ‘desktop assessments’) may be used “to establish by extrapolation how the system being assessed would perform if subjected to the same or a similar test”^[8].

Both Building a Safer Future and the Phase 2 report criticised the use of AILOTs prior to Grenfell. Concerns centred on “the quality of the data available for that purpose and the competence of the person carrying it out”^[9] such that some AILOTs were used to justify materials and components substitutions without sufficient evidence.

The Phase 2 report concluded that AILOTs “should be treated as only part of what is a complex exercise that requires information from various sources.”^[10] Where AILOTs are necessary, they must be “properly evidenced” and based on relevant, existing test data, and undertaken by appropriate accredited bodies e.g. UKAS.

Designers may need to be persistent to be able to demonstrate that they have exercised the standard of care required in obtaining the information needed to make informed decisions. Where information is unavailable, they must carefully assess whether the product is appropriate for use and whether an alternative specification is necessary. Reliance should not be placed on the assumption that a product will pass future testing.

Passing Swiftly From Manufacturer to Designer to Client, Without Passing go:

It can be difficult for designers to verify the accuracy of technical information, and they may lack the competence to scrutinise certain test data. If operating outside their expertise, designers should advise the client and seek support from qualified professionals, such as fire engineers.

Nonetheless, designers should still consider carefully whether the information received passes a ‘fair reading’ and is not ‘an affront to common sense’. They should be able to demonstrate that they reviewed the advice before passing it to others who may reasonably rely on it.

For example, if incorporating a manufacturer’s standard details and specifications into project documentation, designers should review them as if they are its own, since, they may assume legal responsibility for that information. Even if the client instructs the designer to include it, this may not absolve the designer of liability. Limits of responsibility should be clarified in writing at the time of instruction.

Manufacturers’ responses often contain wide-ranging caveats intending to limit their liability. Designers should consider the caveats carefully alongside the technical information received.

Designers should also be cautious of relying solely on their own caveats in their drawings and specifications to limit their liability. Caveats that attempt to unilaterally amend the terms of the designer’s contract with the client may prove ineffective if challenged in court.

Finally – Records, Records, Records:

Records are essential for tracking decision-making and changes throughout the life of a building. Thankfully, most building projects do not end in dispute but when they do, the records kept play a significant role in resolving matters.

The client must only make arrangements for a digital record of ‘golden thread information’^[11] to be retained on higher-risk buildings^[12], not all buildings. Irrespective of literature, notes from meetings with manufacturers, current standards, certification, and other contemporaneous documentation relied upon.

Records are not kept solely for the designer’s benefit, but for those who may need to review them in the future, and understand the detail and reasoning behind the decisions made. Designers should be mindful that product literature changes and manufacturers’ websites are frequently updated, often without clear revision histories. The information they relied upon might not be readily available in the future.

Conclusion

In conclusion, manufacturer information remains a valuable resource, but designers must adopt sound strategies and draw on a range of resources to make informed decisions so that they may demonstrate that they have exercised the standard of care required.

Hawkins can support clients and designers by providing pre-loss risk management advice, and conducting investigations when failures occur. If you think that you may need the services of a forensic architect, please get in touch with us for a free consultation.

References & Footnotes

References:

[1] Section 148 relates to liability relating to construction products.
[2] Section 149 relates to liability for defaults relating to cladding products “attached to, or included in, the external wall of a relevant building”, and applies retrospectively as well as prospectively.
[3] A relevant building is a building that consists of a dwelling or contains two or more dwellings.
[4] Schedule 11 sets out the statutory framework for all construction products.
[5] Authored by Paul Morrell OBE and Anneliese Day KC.
[6] The consultation opened on 26 February 2025 and closed on 21 May 2025.
[7] Foreseeably ‘reasonable skill and care’.
[8] Paragraph 111.50 of the Grenfell Tower Inquiry Phase 2 report.
[9] Paragraph 111.51 of the Grenfell Tower Inquiry Phase 2 report.
[10] Paragraph 111.52 of the Grenfell Tower Inquiry Phase 2 report.
[11] Information about the building required under Regulation 31 of The Building (Higher-Risk Buildings Procedures) (England) Regulations 2023, and which will include the specifications.
[12] Higher-risk buildings are defined in the Higher-Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023.

Footnotes:
> Building a Safer Future: https://assets.publishing.service.gov.uk/media/5afc50c840f0b622e4844ab4/Building_a_Safer_Future_-_web.pdf
> Building Safety Act 2022: https://www.legislation.gov.uk/ukpga/2022/30/section/148
> Testing for a Safer Future An Independent Review of the Construction Products Testing Regime: https://assets.publishing.service.gov.uk/media/6440f2596dda69000d11e15e/Independent_Review_of_the_Construction_Product_Testing_Regime.pdf
> Construction Products Reform Green Paper: https://www.gov.uk/government/consultations/construction-products-reform-green-paper

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