The Environment Agency has recently issued updated guidance for the owners and operators of large reservoirs. An in-depth Expert Focus article for WaterBriefing suggests the water sector regulators, water companies and their supply chain partners should consider security, health and safety issues surrounding the sometimes overlooked area of service reservoirs.

A joint interview from Tom Willis from HUBER Technology and David Bull from Mott Macdonald explores how using stainless steel pressure-tight doors for walk-in access on service reservoirs, rather than roof covers, can deliver significant safety and security benefits, together with reducing whole life costs and carbon footprint.

Tom Willis/ David Bull: Beginning with the background, the water companies are responsible for hundreds or even thousands of service reservoirs within the distribution network - and the oldest of these assets often date back to the 1800s. Many of these structures are approaching the end of their asset life, requiring significant rehabilitation works or replacement.

Mott MacDonald Bentley (MMB) has successfully implemented the walk-in access method for water storage spaces for new service reservoir structures since AMP4 on behalf a number of the UK water companies.

The key design focus has been to ensure all reasons for access such as walk in entry, ventilation, instrument access and more are retained within the valve house completely eliminating the need for roof access covers enabling a step change to the safety and security of service reservoir assets.

Photo courtesy Costain: Yorkshire Water Bullamore Service Reservoir 

 For example, Yorkshire Water initially adopted this approach for three service reservoir replacement schemes in AMP4. Subsequently this method was incorporated into their Asset Standards as the required access method - the water company has since adopted walk in access services as standard practice on all its new service reservoirs. MMB has now used this walk-in access solution on 28 schemes in the UK -HUBER Technology’s TT7 pressure-tight doors have been used in all those schemes.

Photo: HUBER  TT7 pressure-tight door inside valve house 

Walk-in access – should this be the design of choice for all new service reservoirs?

It seems clear that walk-in access should be the default design of choice for all new service reservoirs in the UK. The approach is already commonly used across Europe, including Germany, Sweden, Norway, France, Italy, Switzerland, and Austria.

Roof access solutions involve working at height, the potential for accidental ingress of contaminants which can damage water quality, increased concerns over security risks and vulnerability to attacks by third parties. In conventional service reservoirs, the roof openings are an inherent weak point and whatever security arrangements are put in place still provide multiple points of entry with risk of direct access to the treated water. In addition, in the event that someone has been injured or taken ill, it is far simpler to take a stretcher in and carry somebody out via a walk-in entrance, rather than through a roof.

Nonetheless, currently in the UK, access covers on many of the water companies’ service reservoirs are multiple roof-based hatches – frequently up to ten covers on a single reservoir compartment in the larger examples.

Health and safety issues arising from roof access covers

There are a wide range of potentially significant health and safety issues associated with access via roof openings and ladders to floor level. These include built in working at height hazard, where slips, trips, falls, and falls at height are generally acknowledged to be some of the most common causes of industrial accidents; and a danger of falling objects where the immediate reaction of any sensible water provider is to isolate and then drain the tank, extract what had been dropped in and then refill it – wasting a significant amount of potable water in the process.

Other hazards include:

• Built in working over water hazard
• Laddered access
• Heavy tools carried up/down ladders or vertical lifting
• Problems with vertical emergency access
• Restricted access with confined space equipment
• Vertical escape route
• Cover sensor false security alarms
• Bacteriological contamination and ingress at cover mounting
• Issues with entering through an access cover
• Refurbishment and rebedding of roof security covers
• Multiple security sensitive openings

All of the above health and safety issues are completely eliminated when using the walk-in access method and Huber pressure tight doors.

Security – a key issue which can’t be completely guaranteed by regulations

In addition to health and safety, security of water company assets is an ongoing source of concern for the industry. In the UK, service reservoirs containing treated distributed water for public consumption are considered security sensitive assets and must comply with the restricted document Water UK publication ‘Specification for the Security of Service Reservoirs’.

Standards for intruder-resistant products are set under the Loss Prevention Certification Board’s (LPCB)security rating (SR) standard 1175 which has eight different ratings.

Water supply companies undertake security risk assessments to ensure that the assets are secured against unauthorised access. The risk assessments identify the appropriate LPCB ratings relevant to the reservoir. Products certified to this level must be capable of resisting attempts at forced entry – opportunistic or planned - The duration and list of tools changes depending on the different levels of security rating.

A typical service reservoir in the UK not only has roof access but, depending on the size, often several other ventilation and inspection hatches on the roof that would also be used for manual maintenance, all of which offer individual points of entry. Although this might make for ease of use, it also exacerbates how vulnerable the structure is to unwanted intrusion by third parties.

Other issues include reservoirs in urban areas representing an “irresistible challenge” for young people to gain entry, as well as those in remote locations with no security cameras, where it may well be in excess of the tested time limits of the security cover by the time a breach has even been identified, let alone necessary steps taken to address any potential impacts.

Covers to protect roof access are well-established and, for water supply reservoirs, typically have an array of features to attempt to mitigate security and malicious actions. However, a roof access reservoir design inherently builds multiple points of entry into the structure that need to be protected. Side access provides the opportunity to minimise the number of points of entry and to use more conventional security doors to protect entry to the treated drinking water space.

Walk in access via the valve house significantly strengthens reservoir security, with everything managed through a single walk-in entrypoint via the valve house, which is typically equipped with a security door, alarms, motion sensors, and CCTV. So, although the primary driver for using walk-in access is providing a safe means of entry and asset operation for maintenance, it also affords a significantly enhanced level of security to prevent unauthorised access.

Even if the security doors to the valve house were breached, the HUBER solid stainless steel, pressure-tight doors are near impossible to drill through and the water pressure from inside the service reservoir makes it impossible to open the door.

Whole life costs - a key consideration

While the initial investment for a stainless steel, pressure-tight door may be more compared to individual galvanised steel roof covers, there are considerable maintenance and H&S benefits and savings, including reduced operating costs and cost comparable construction. For example, on a service reservoir, you may need to install as many as 10 covers which have to be re-bedded for business security and ingress issues every 5 to 10 years.

Corrosion of galvanised steel products v stainless steel

In addition, when the additional operational and maintenance costs associated with products manufactured in galvanised steel are factored in, the balance undoubtedly shifts in favour of the walk-in entry stainless steel pressure-tight door solution. As a material, galvanised steel does not deliver the same benefits in terms of lifetime durability and failure as stainless steel which undoubtedly adds considerably to whole life costs, not forgetting the associated carbon footprint impacts.

Unlike stainless steel, products made from galvanised steel are more susceptible to corrosion and will almost inevitably have to be re-galvanised at intervals during their operational lifespan. In comparison, stainless steel pressure-tight doors are capable of outlasting the reservoir structures where they are installed.

Reassessing the operational and safety performance of service reservoirs

This is also an opportunity for water companies to reconsider what they want an asset to deliver in terms of operational and safety performance. By recognising the fundamental challenges that roof access on service reservoirs poses, such as working at height and other safety-related issues, the risks of accidental ingress which compromises water quality, and security risks from intruders, an innovative solution can be designed that minimises or even removes those hazards.

Designers of service reservoirs can ensure that, not only is the asset fit for purpose, but - as far as possible - will not cause harm to humans.

That responsibility extends beyond the nuts and bolts of the calculation to the decisions influencing the design and can include anyone from the client investment planners through to site contractors and builders.

If that influence affects the design of an asset, it is counted as a designer under the Construction (Design and Management) Regulations 2015 – and plays an important role in shaping how risks to health and safety are managed throughout a project.

The Regulations are overseen by the Health & Safety Executive (HSE) whose goal is to prevent workplace death, injury, or ill health. The fundamental principle of health and safety law is that those who create hazards are best placed to manage them.

Photo: HUBER walk in access door - open and lock position

From an HSE perspective, opting for walk-in access in preference to roof covers - whether as the client, the designer, or the contractor building the reservoir –would be viewed as a positive step towards eliminating known hazards. Roof access hazards by contrast can, at best, be reduced but generally are only informed or controlled.

While the challenges are commonly understood, they may often be accepted due to lack of awareness of an alternative solution. Innovation in its broadest sense doesn’t always have to mean new or disruptive, it can also represent a change of mindset, considering alternative approaches and doing things differently.

It’s essential that there is a better appreciation of the viable and reasonable alternatives to roof access already available, which bring all the attendant benefits of reduced safety risks and reduced bacteriological contamination, alongside increased security.

Future-proofing service reservoirs

Water companies have to secure and protect their assets for successive generations, not just the next five or ten years. Perhaps an unintended consequence of including greater side access is that it offers water companies a greater ability to future-proof service reservoirs.

The impacts of climate change, population growth, pressure on water resources, and aging reservoirs, especially in water-stressed areas, mean there’s likely to be a continued need to build and enhance these assets to strengthen and maintain the resilience of water distribution networks.

Inevitably, security standards will increase, and health and safety requirements are likely to follow.

Raising the minimum asset standards for service reservoirs from conventional roof manhole/access cover entry to side access will help support this. The walk-in solution will enable them to deliver more secure service reservoirs, reduce risks, and enhance health and safety.