As the litigious nature of society grows and employees appear to be encouraged more than ever to pursue claims with their employers, the likelihood of claims for manual handling injuries is also likely to increase. Manual handling injuries are part of a wider group of musculoskeletal disorders (MSDs). The term ‘musculoskeletal disorders’ covers any injury, damage or disorder of the joints or other tissues in the upper/lower limbs or the back. HSE states that statistics from the Labour Force Survey (LFS) indicate that MSD cases, including those caused by manual handling, account for more than a third of all work-related illnesses reported each year to the enforcing authorities. So, what aspects of geotechnical site work may be exposing the workforce to risks of manual handling injury which could lead to an unexpected claim.

Legislative Background

The Manual Handling Operations Regulations, 1992¹ is the main part of legislation which employers should be familiar with but additionally they should also be aware of other related HSE guidance such as the Manual Handling Assessment Charts (the MAC tool), INDG383 (rev 3)². This sister guidance to the Regulations provides a detailed insight into how an employer should assess the risk through three types of assessment: lifting operations, carrying operations and team handling operations.

Most employers and hopefully their employees will be aware that the law does not identify a maximum weight limit. It places duties on employers to manage or control risk; measures to take to meet this duty will vary depending on the circumstances of the task. Things to be considered will include the individual carrying out the handling operation (e g strength, fitness, underlying medical conditions), the weight to be lifted and distance to be carried, the nature of the load or the postures to be adopted or the availability of equipment to facilitate the lift.

The HSE MAC Tool

The MAC tool provides a colour coded and numerical approach to risk assessment which takes into account all of the above factors but in a pragmatic and user-friendly approach and defines the following levels of risk:

G = GREEN – Low level of risk   Although the risk is low, consider the exposure levels for vulnerable groups such as pregnant women,  disabled, recently injured, young or inexperienced workers.

A = AMBER – Medium level of risk   Examine tasks closely.

R = RED – High level of risk   Prompt action needed. This may expose a significant proportion of the working population to risk of injury.

P = PURPLE – Unacceptable level of risk   Such operations may represent a serious risk of injury and must be improved.

The first part of the assessment is to assess the load weight and for lifting and carrying for individuals this requires the employer to assess the weight of the load but also the frequency/repetition of the task. Although most single person lifting operations have ‘manageable’ load weights i.e. bags of sand/gravel/bentonite are limited to 25kg and bulk samples are around 25kg, if there is a repetitive nature to the task then the operation may go into the RED or even PURPLE. Therefore, tasks such as manually loading a lorry with bulk bags or unloading a couple of pallets of bentonite/gravel may push the task into the RED which would be deemed a high-risk task requiring prompt action. This is not surprising and why the employer must ensure collections and deliveries are assessed and where required are made with hi-ab lorries or tail lifts and have pallet trucks or a forklift available.

Team Lifting

Team lifting operations in our industry are generally a two-person lift. In this instance the MAC tool requires the employer to simply assess the load weight and does not take into account the frequency. The tool indicates that for two person lifts a weight in excess of 65kg is a high-risk activity and lift weights in excess of 85kg is an unacceptable risk. Employers can obtain equipment weights from the manufacturers and suppliers and a list of standard cable percussion tooling weights is provided in the current BDA Cable Percussion Guidance³.  Therefore, as examples: a sinker bar of 80kg or a 6” casing lead length of 77kg would mean a high-risk lifting operation whilst a U100 slide hammer at 93kg and a standard SPT drop hammer at 115kg would be an unacceptable risk. The choice of core boxes is another area of concern. A 3m two channel core box containing S size core of Chalk (a relatively low density rock) can still weigh in excess of 77kg which takes the lift into a high level of risk whereas higher density rock may become an unacceptable level of risk. As the frequency of the lift is not a factor then for each and every lift where there is a potential for a manual handling injury there is a potential claim.

Other factors

The MAC Tool does not simply use weight and frequency alone to assess the risk and also requires the employer to assess:

B – Hand distance from the lower back

C – Vertical lift zone

D – Torso twisting and sideways bending

E – Postural constraints

F – Grip on the load

G – Floor surface

H – Carry distance

I – Obstacles on route

J – Communication, co-ordination and control

K – Environmental factors

Therefore as an example, the assessment for using wooden core boxes has to start factoring in: having to bend down to pick the load up (B), leaning to one side as the box is picked up and carried (C & D), the use of looped rope handles which cut into the fingers (F), potential lifting on slippery or uneven ground (G) and potential obstacles (I),  then the overall risk of the task becomes high risk as a minimum and therefore prompt action is required.

Risk Control Measures

The first step required to comply with the Regulations is that the employer should, so far as is reasonably practicable, avoid the need for their employees to carry out manual handling operations that involve a risk of injury. If this is not reasonably practicable then the risks to employees of the manual handling operations carried out in the normal course of their work should be assessed and reduced.

On geotechnical sites that means using hi-ab lorries, winches or other mechanical lifting devices where possible, reducing the length of casings and other equipment, working on hard standing or creating more solid work areas with bog matting, using mounted hydraulic SPT hammers and using support vehicles and trailers to move equipment and materials around the site.

So what about the wooden core boxes? The employer may be able to improve the ground surface conditions and use mechanical lifting devices when in the core store or once on pallets but the weights are still going to mean a high to unacceptable level of risk in the field and in many core stores. Improvements to the handles will also help but the overriding problem will still be the weight and therefore the only solution left open to the employer is to reduce the size of the core box.

Any claim for a Manual Handling injury will result in the court looking at the current Regulations and Guidance and the measures the Employer has taken to reduce the level of risk of the task so far as reasonably practicable. Have you?

References

¹ HSE, Manual Handling Operations Regulations, 1992

² HSE, Manual handling assessment charts (the MAC Tool), INDG 383 rev3, 2019

³ BDA, Guidance for the operation of cable percussion rigs and equipment.

Article contributed by Julian Lovell, Managing Director of Equipe Group

Trial pitting and trial trenching have long been a popular investigation tool within the geotechnical and geo-environmental industry. Trial pits and trial trenches are commonly specified in both geotechnical and geo-environmental investigations and are often a preferred investigative method to enable a rapid check of the condition of the ground. They permit examination of both horizontal and vertical faces exposed as the pit is advanced and also enable the collection of a wide variety of sample sizes and types. Trial pitting and trenching is commonly undertaken using a machine excavator, whether this be a backhoe excavator or a tracked 360 machine. For shallower excavations, or where trenches are required to provide more detailed interpretation of the stratigraphy or underground service identification and mapping, these are often undertaken by hand with or without machine assistance. Vac-Ex technology has also been used by the industry to excavate trial pits and trenches.

Trial pitting is seen as an economically advantageous investigation tool which enables a fair spread of exploratory points to be undertaken within a typical working day. In addition, trial pitting facilitates a wide variety of in-situ tests, for example Hand Shear Vanes, California Bearing Ratio (CBR) tests, Plate Load tests and Infiltration tests in accordance with Building Research Establishment (BRE) Digest 365 Publication (2016).

With a better awareness of health and safety risk within our industry over the past decade or so should we not, however, ask the question whether trial pitting is still fit for purpose and therefore should we strive for an alternative method?

Health & Safety law often uses the term, “so far as is reasonably practicable (SFARP)” forming the basis of any risk-based activity and as such must be used as a decision tool on the risk against the cost and availability of technology to control it.  The HSE, in investigation and prosecution, make a computation in which the quantum of risk is placed on one scale and compared with the sacrifice involved in the measures necessary for averting the risk (whether in money, time or trouble) on the other scale.  The legal test would be that measures which are disproportionate (or grossly disproportionate) would not be SFARP.

All trial pitting activities including site preparation, excavation, sampling, logging and backfilling must be planned and a suitable and sufficient site-specific risk assessment made, contributing then to a method statement. However, consider this: with the Work at Height Regulations (2005), any excavation which has the potential for a person to fall is classed as working from height and, therefore, requires measures to be put in place in accordance with a specified hierarchy (while considering “SFARP”) to comply. Whilst injury can be caused from a fall from any height, a trial pit which is excavated to depths often in excess of 3m can pose a significant risk of injury should an operative fall into the excavation.

Additionally, the Construction Design and Management (CDM) Regulations (2015) were amended and now identify ground investigation as an integral part of the construction activities. Trial pitting as an activity is covered under Regulation 22 (Part 2) which states that “Suitable and sufficient steps must be taken to prevent any person, work equipment, or any accumulation of material from falling into any excavation”.

Furthermore, Regulation 22 (Part 1) of the CDM Regulation states that “All practicable steps must be taken to prevent danger to any person, including, where necessary, the provision of supports or battering, to ensure that; no excavation or part of an excavation collapses; no material forming the walls or roof of, or adjacent to, any excavation is dislodged or falls; and no person is buried or trapped in an excavation by material which is dislodged or falls”.

Therefore, all excavations require an assessment to be made of the stability of the excavation prior to commencing the dig and during the dig. These risk assessments should consider factors such as influence of the excavation method, ground conditions, buried services, obstructions, groundwater level, water strikes, contamination etc. An initial risk assessment can be produced to reflect the general approach but inevitably the trial pitting supervisor/logger will need to carry out dynamic, sometimes called “point of work”, risk assessments and where these necessitate or identify significant changes to the risk or methodology it should be documented.

However, as trial pitting work is often undertaken by graduates or technicians, can employers be sure that these individuals possess the required knowledge, training and experience to meet sufficient competency requirements or have the ability to make these assessments and informed decisions?

When detailed logging (i.e. service identification, detailed fabric logging, scan lines or assessment of slip planes) is required, due consideration should be taken to the necessity of entering the trial pit/trench. Where the designer determines that entry is essential, the Contractor must ensure that the excavations are sufficiently shored or the excavation sides battered back or benched to reduce the height of exposed material and potential collapse. Due consideration should also be taken by the Client to allow sufficient time and resources (money) to develop this safe system of work, to carry out any additional training requirements and for the actual work. In addition, these type of trial pits should be located to provide sufficient working room for the plant which will be required for the installation and maintenance of the support system and spoil. As these types of works may be of a longer duration than typical trial pits, physical barriers such as fencing may be required which adds additional costs and time.

When trial pits are part of a more typical ground investigation and require standard logging, in-situ testing and sampling the designer and contractor should consider carefully whether any entry is required whatever the depth. The AGS promotes an approach which does not require entry and therefore, the risk of injury through collapse and subsequent burial is reduced. However, this does not eliminate totally the risk of working at height.

With trial pitting seen as a relatively quick and cost-effective method of ground investigation, the use of edge protection and trench support can be viewed as unrealistically costly and time consuming to install. Compliance with the hierarchy of controls within the Work at Height regulations might suggest to some employers that installation of edge protection or a suitable fall arrest system or other safe system of work, should be mandatory for all excavations. However, the main advantage of trial pitting is to provide a quick and easy way to view the stratigraphy and close up inspection of the pit is necessary to obtain the desired results. Judgements on the required controls under the Work at Height regulations are however to be determined “SFARP”.

The current AGS Guidance on safe excavation of trial pits suggests a number of control measures such as the supervisor/logger should approach and stand at the opposite narrow end of the open pit to the machine, , arisings should be placed a minimum of one metre from the pit edge, and other controls. However, the industry, and associated industries who undertake not dissimilar construction activities, can still not agree on the approach to controlling the risk of working at height when trial pitting or even whether it is a significant risk in the first place.

The principal arguments for the requirement to approach open pits is to observe the formation of the ground and groundwater in situ, accurately measure stratum boundaries, water strikes, final depth and to take photographs. The industry could for example re-evaluate the necessity for photographs and the way they are taken, and whether they are used as anything else but proof the pit was dug. The question could also be asked as to ‘how accurate is accurate’ with respect to depths and is there a safer way to obtain this information. Some excavators can now determine depth of dig whilst excavating and perhaps providing depth markers on the excavator arm may be another alternative.

Figure 1 – Typical example of a machine excavated trial pit where the pit is logged from samples only

Employers must also consider the risk of injury from contact with plant and machinery. It is essential that the supervisor maintains good communication (both verbally and using agreed hand signals) with the machine operator at all times. Supervisors should be aware of the danger areas (red and amber zones) around the excavation and always stand in the yellow zone to maintain a clear line of sight.

Figure 2 – An example of a safe working zone for mechanical excavation using a 3CX or 360 machine

It is not uncommon that the supervisor (often a graduate and in some cases with limited years of experience) will take on responsibilities for both the H&S and the technical goals of the trial pit investigation. In effect, they take on a role of supervisor, logger and banksman. In the construction industry, banksmen are operatives specifically trained to direct vehicle movement on or around site. How common is it that graduates or even experienced engineers are specifically trained in the role of a Banksman (or vehicle marshal), but are expected to fulfil such a role when directing plant and machinery around site. Therefore, the employer should provide training to allow the individual to carry out this role. This could be delivered through a formal Banksman course or might be better delivered as task specific in-house training which should include all aspects of safe trial pitting to help create competent people who can dynamically risk assess excavations.

But is trial pitting really or inherently a high-risk activity? Excavations are typically left open for only a very limited length of time and are backfilled as soon as the pit is completed in comparison to most construction industry excavations. In addition, there are no clear statistics from the HSE on injuries or fatalities from falls associated with trial pitting. These do occur in the wider construction industry, generally as a consequence of a collapse of the excavation which has been open for some length of time. As an industry we are all aware of the fatality to a Geologist in September 2008, however, statistics of injuries, accidents or near misses are not widely known and are often only communicated internally with site staff and not shared to the wider ground investigation community.

As an industry we must strive to continually improve the safety culture within ground investigation and trial pitting offers us all a chance to either look at current and future innovations to reduce the risk or find safer alternatives. There is a concern that if the industry does not obtain consensus that others may develop approaches which the industry may not find palatable both practically and commercially.

The current AGS document looks to provide practical guidance on trial pitting considering the current H&S guidance available, however, the Designer always has the choice to replace trial pits with boreholes or dynamic sampling holes which would, in many cases, provide similar design data.

The question remains, is trial pitting fit for purpose and the AGS would welcome views from the industry and will be sending out a short questionnaire to determine current industry practice and thoughts.

Article contributed by AGS Safety Working Group

Principal Authors – Adam Latimer, Ian Farmer Associates; Steve Everton, Jacobs and Julian Lovell, Equipe Group