Tag Archives: site clearance

River Clyde Homes

 The controlled use of explosives

  Case Study - River Clyde Homes (329.5 KiB)

A redundant 17-storey tower block in Scotland has been successfully brought down by the controlled use of explosives, under the watchful eye of specialist consulting engineers RVA Group.

It was evident that demolition of the 6,500 tonne concrete and brick structure required meticulous planning and robust scientific methodology, but the close proximity of an electric Network Rail commuter line – the boundary of which sat just 3 metres from Octavia Court – posed an added challenge. It was essential to protect the rail infrastructure during the demolition, whilst ensuring disruption to rail services was kept to an absolute minimum.

 

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The value of the explosives engineering discipline

The controlled use of explosives is, on occasions, selected as the preferred demolition methodology for projects, as it can provide a safer and faster alternative to bringing large structures down mechanically over a period of several months.

Therefore, despite the seemingly ever-increasing size of long-reach excavators, explosives still have a crucial role to play in the safe and efficient execution of complex demolition projects. But do people realise the important and exciting nature of the discipline? And are enough young adults considering a career within the explosives industry?

These are topics the RVA team was asked to cover in a detailed article for Explosives Engineering, the official journal for The Institute of Explosives Engineering (IExpE). The full piece, which describes what a career in explosives engineering involves and what value explosives brings to the modern-day demolition environment, is shown here in its entirety….

“The world of demolition is becoming increasingly varied. Assets across the globe are reaching their end of life and there is an unprecedented need to demolish these safely, cost-effectively, in an environmentally sound manner, and often within strict programme constraints. But as the nature of demolition projects continues to evolve, so too do the possible methodologies used to carry these projects out.

Whilst there has been limited radical advance in demolition technology over the last few years, plant manufacturers are managing to build larger machines capable of dealing with taller structures. In 2009 for example RVA Group oversaw the mechanical demolition of a 50m chimney stack that was brought down using an excavator with a 60m telescopic boom and even this machine is dwarfed by more recent models.

However, it isn’t all about size and in certain instances the controlled use of explosives is still selected as the preferred demolition method. Often this is because it provides a safer and faster alternative to demolishing structures of all types, whether they be high-rise residential dwellings or steel framed industrial building or process plants. A structure may be too tall or complex for conventional machinery for instance, but the alterative of manually dismantling it piece by piece would necessitate operatives working at height for extended periods of time. Not only may this have implications for the project programme, but the risks posed to the operatives is also unnecessarily heightened.

There are also many other potential influencers. The structure may have become unstable due to working life stresses, concrete decay or even poor build quality, so mechanical demolition could simply be too dangerous; the structure might be positioned in close proximity to assets that require absolute protection; environmental and/or community disruption may need to be kept to an absolute minimum; and cost can even play a deciding factor too.

Ultimately though increasingly sophisticated explosives systems tend to ensure greater predictability of the outcome. Last year for instance, RVA Group project managed and coordinated the safe demolition of a 17-storey tower block in Greenock, Scotland. Meticulous planning and robust scientific methodology was needed to protect a nearby Network Rail infrastructure, the boundary of which sat just 3m from the building. Disruption to the electric rail commuter services also had to be kept to an absolute minimum.

The controlled use of explosives posed the most suitable methodology by far for bringing down the tower – not only would the alternatives of mechanical demolition or floor-by-floor dismantling have increased the possibility of debris falling onto the railway line, but a longer demolition period would have heightened the potential risk for project workers and the community. Furthermore, this demolition plan meant that only one railway line possession was needed and as the blowdown took place at night, commuter service disruption was minimal. At the time of the project the client – social landlord River Clyde Homes – praised the fact that site operations were carried out safely, the integrity of Network Rail’s assets was not compromised and ultimately the demolition programme was a great success.

Having assessed a structure and considered the suitability of explosives methodology, the explosives engineer then has a series of justifications to make with regard to a suite of factors including project safety, cost and programming.

Before proceeding with any demolition exercise, the engineer must therefore be able to conclude that the level of risk presented by the controlled use of explosives is manageable and acceptable. Of course every single job presents specific challenges, so extensive preparatory work is always crucial. Numerous precautionary measures can be employed:

  •  Construction materials and even process residue samples can be taken to assess the degree of contamination – if any – within a given structure. Decontamination strategies can then be devised and executed accordingly;
  • Test blasts can be carried out prior to the blowdown to validate the design of the charge weight, drilling pattern and primary protection;
  • Vibration specialists can determine that the demolition will not cause disruption or damage to the surrounding environment.
  • Before a blast is carried out the project team should also liaise closely with all relevant external stakeholders, including the community, local authority and emergency services. Because the explosives engineer takes ownership of the project when the explosives phase is underway, responsibility for risk assessments, exclusion zones and contingency and misfire arrangements must also be assumed. Once a structure has been demolished, the rubble should be inspected to ensure inherent stability and to certify that no undetonated explosives remain. Debris and dust should also be cleared from the surrounding area – not only does this protect the environment but it allows any site neighbours to return to normality as soon as possible.

Demolition is only one very small sector within the explosives industry, but there is still great scope for the discipline to excel within this engineering arena. The number of large-scale production facilities being closed worldwide remains staggering, and there is a need to clear these sites safely, cost-efficiently and with minimum environmental impact. Even regeneration projects that have been temporarily shelved as a result of economic difficulties will need to be addressed in the near future.

There is no reason why the role of explosives engineering within demolition cannot therefore have longevity. Yet unfortunately there are very few experts within this compelling field and the evidence of new blood wanting to make a career in this sector is also sparse.

There are two main elements to the explosives engineering discipline. Of course there is the need to truly understand pure explosives technology – how to handle them safely, the different types, how they should be stored, how they work and how they can best be used.

But engineers are simply utilising the explosive product as a tool to effectively achieve an objective. To be of value, pure explosives knowledge must therefore be aligned with a practical understanding of the defined profession, whether this is demolition, mining, tunnelling, quarrying or special effects for example.

So in demolition the engineer should also have an understanding of structures and a comprehension – perhaps with the input of other specialists such as structural engineers – of what the project needs to achieve in terms of collapse. The engineer must analyse and design where to place the detonator, how much charge to use, where to place the charge, what delay sequence to employ, what detonation methods to implement in order to reduce the quantities of explosives required, and what the suitable exclusion zone should be.

The considerations are numerous, and the competencies of a skilled explosives engineer multi-layered. An appreciation of the product science should be complemented with a level of articulacy and comprehension with the discipline to follow creative yet meticulous procedures and methodology. A respect for the power of explosives, within any field, is also essential.

But knowledge grows with experience, and the importance of continuous professional development cannot be underestimated. Where possible engineers should attend educational seminars and events not only to learn more about advances in explosives, but to remain abreast with safety systems and standards, environmental issues and ever-changing legislative control measures too. A true explosives engineer will have empathy for all related project factors.

Professional bodies such as the IExpE ensure that explosives engineers, scientists, logisticians, academics and legislators alike are recognised in terms of occupational competence, as membership to the Institute is earned by achievement not subscription. All industry specialists should equally acknowledge their duty to help shape industry developments and nurture the explosives engineering talent of the future.

To what extent people beyond the industry understand the exact science and extensive preparation involved in an activity which appears to last less than 10 seconds, is difficult to say. However the truth is that a career in explosives engineering – whilst hard work – will always offer new, exciting and challenging opportunities that are perhaps not comparable to those in many other professions.”

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RVA’s expertise highlighted in industry magazine

The specialist expertise of RVA Group has been highlighted in leading industry publication Process Engineering. In the March – April 2011 issue, RVA considers the evermore challenging arena of process plant decommissioning…

“The difficult economic conditions of recent times have affected widespread processing sectors with quite overwhelming results. Unprecedented pressures have been placed on chemical, petrochemical, pharmaceutical and manufacturing companies across the globe, and very few have proven recession-resistant.

This is not to suggest there will be a permanent exodus of the processing industry, even in the UK alone. However it cannot be ignored that the number of production facilities being mothballed, rationalised or permanently closed down remains staggering. The specialist area of decommissioning may therefore be a great step into the unknown for most organisations, yet it is perhaps equally an inevitability for many.

The challenge is how to deal with the decommissioning – and in many cases decontamination, dismantling and demolition – of facilities safely, whilst at the same time cost-efficiently and with minimal environmental impact.

It should not be expected that the majority of businesses are competent to proceed with such projects without specialist external guidance. Decommissioning is not always a straightforward process and cannot be viewed merely as an extension of normal operations or the reverse of commissioning and construction. Nor should it be rushed in an attempt to achieve an accelerated exit. Decommissioning is an inherently hazardous activity and should be managed by appropriately experienced professionals, and the most important way to ensure a project’s success is getting the team right from the start. A specific set of skills and competencies is required to ensure the management of safety is proficiently catered for, and that the achievement of safety excellence is at the top of the ‘to do’ list.

The careful use of an organisation’s own engineering and production staff is in most cases a positive and value-adding move. Effective decommissioning is underpinned by a thorough preparatory and planning process whereby assets, procedures, decontamination and isolation details are comprehensively documented on an ongoing basis so that everything can be accounted for, and the plant can be brought to the required ‘known state’. No one will know this plant-specific information better than the people that have been running it, so key personnel should be involved from the outset.

However projects of this nature and scale tend to lie beyond most companies’ usual remit, and there will be areas of expertise that cannot possibly be fulfilled in-house – it is not reasonable to expect a skilled production manager for example, to become a qualified decommissioning engineer overnight. Instead the knowledge-based management support of external engineering consultants should be sought, so that any given project and its inherent risk, is competently managed.

By law, all UK demolition projects must be carried out in accordance with Construction Design Management (CDM) regulations. Revised in 2007, the regulations are not just a matter of paperwork compliance. Instead they govern the planning, coordination and management of projects to secure the health, safety and welfare of all involved. A competent and relevantly experienced CDM coordinator must therefore be appointed to oversee the project in this respect, and ensure consistency of standards.

Outside of the UK, whilst the legislative terms and job titles may differ, the principles, roles and responsibilities remain the same – manage safety to the highest achievable standards.

Beyond this there is no such thing as a ‘one size fits all’ approach. Every project has to be assessed on its own merits to ensure that a suitably skilled project team – comprising demolition, explosives, chemical, structural and mechanical engineering experts for example – is assembled for the job.

Because the decommissioning process is frequently brought about due to site closure or corporate rationalisation, it is commonly viewed as an unwelcome event and as a consequence, minimal resources are often allocated to what is an incredibly complex and high-risk activity. This can result in poor environmental, health and safety (EHS) performance, and ultimately commercial failure.

Even with the best intentions at heart, when money is tight some companies will take shortcuts, but the global downturn doesn’t mean that hazards are any less onerous, or that legislation can be flaunted. Safety should always be the number one priority.

Safety plans should be compiled in conjunction with other contractual documentation to ensure a cohesive output that does not conflict with risk management and the goal to achieve EHS excellence. Independent and specialist auditing of sites and methodology further helps to ensure best practice, but operations should be reviewed and revised as site works progress because ‘change of state’ can be rapid.

Organisations will understandably be focused on closing down their factories and plants in the swiftest and most cost-effective manner possible, due to the financial pressures that will no doubt have led to the said situation. However in truth a large majority of clients will not know where to turn next.

A feasibility and option study should provide a clear view as to the true liability, or indeed opportunity, of a decommissioning project. The findings and specialist recommendations given by independent experts with an experienced ‘demolition mindset’, could then provide companies with sufficient data and indeed confidence to pursue an innovative route that they perhaps previously deemed impossible, or may even have been wholly unaware of.

Sometimes dismantling elements of a plant for scrap whilst mothballing remaining structures is the preferable route, whereas in other scenarios complete site clearance proves the safest and optimum financial solution. Not only can direct liabilities such as hazardous material containment, security and maintenance costs, and local authority building rates be removed, but in some instances it is even possible to generate sufficient funds from scrap materials to completely cover the cost of the project.

Clearly not all decommissioning work will be self funding or cash generative, but cost-effective solutions can be devised that will help to mitigate a financially difficult situation. The recession has caused many companies to postpone important dismantling and decommissioning projects, as they simply deem them unaffordable, however they will have be tackled at a later date and in most cases at an increased cost.

The goal should always be to maximise return on assets where possible and indeed safe to do so. However factors such as plant age, former process, recovery cost, testing, market forces and commercial competition will all form part of the decision as to what should and should not be salvaged. In some instances it is efficient to recover individual items of plant for resale, however in other circumstances the dismantling of entire processes for reinstallation elsewhere, is possible.

Most importantly, organisations need an early project cost magnitude indication. This information can then be used to compile sanction grade estimates, funding applications and even determine the programme and extent of a project. Once again, specialist expertise and commercial understanding is invaluable in this respect, as factors such as plant resale value, scrap and credit recovery, market conditions and the possible effect of legislative changes, need to be incorporated alongside the direct project costs. However it is crucial that confidentiality, supply chain independence and trust are assured from the outset, so as to protect the commercial security of those involved.

Overall, making use of external expertise should be seen as a value-adding and team strengthening exercise, rather than a loss of control. Furthermore the sooner a specialist consultancy can get involved, the greater the benefit derived. Because it is the duty of the project management and engineering experts to provide safe, environmentally sound, commercially secure and cost-effective outcomes to project, companies can continue to do what they do best – run their business.

Because increasingly larger and more sophisticated world-scale installations are reaching the end of their life – and because legislation and environmental pressures are becoming evermore stringent – it could be argued that decommissioning is becoming an evermore complex practice.

Yet ever-advancing technology and improved knowledge does mean that project solutions are increasingly innovative, cost-effective and safe. The use of explosives for example is now much more precise, and specifically designed equipment is now commonly used to access hazardous areas where previously operatives may have been unavoidably placed at risk.

With an almost bizarre twist, preparing plant and machinery for dismantling and demolition can be less onerous than actually operating it throughout its life cycle, so long as the company has adequately planned for the situation and the best team is assembled for the job.”

To view the full article in print, visit http://digital.centaur.co.uk/processengineering/pe_032011/

 

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Cementing Overseas Relationships

Working with local consulting engineers PPA, RVA is developing the demolition and site clearance plan for the Moni cement works owned by Cyprus Cement Public Company, a member of the Galatariotis Group.

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St Pauls Developments

Decommissioning of Multi-Purpose Plant

  Case Study - St Pauls Developments (687.2 KiB)

RVA was selected by this client to support them in the closure and clearance of this 70 year old site in readiness for future regeneration and development.

The site, which still held top tier COMAH status at the beginning of the project presented a number of challenges to the RVA team. Having had several owners over the years making varying products, a wide range of hazardous materials were identified and bringing the plant to a ‘known status’ was a significant task.

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