ToggleBlok® Replaces Failed Bladder Containment System

The Incident

A recent request for support came from a drainage partner responding to a pollution containment event.

A heavy-duty inflatable stopper system had been deployed within the drainage network. During operation, the unit catastrophically failed — resulting in a cast iron manhole cover being forcibly ejected several metres into the air before landing on a nearby smoker’s shelter.

While fortunately no injuries were reported, the incident presented a serious safety risk alongside the original pollution concern.

If your site uses inflatable stopper or bladder systems, it is important to understand how they behave under pressure — we can review your current setup and advise on risk.

Assessment & Findings

Our immediate priority was to assess the system and determine whether it could be safely reinstated.

Key findings included:

• No evidence of a pressure relief or safety valve
• The stopper acting as the sole containment mechanism and fail-safe
• Complete destruction of the unit preventing full inspection
• Likely failure of pressure regulation and control systems

Based on the available evidence, the most probable cause was over-inflation due to control system failure, resulting in a sudden and uncontrolled release of stored energy.

Critical Risk:

Inflatable systems store significant energy under pressure. Without appropriate safeguards, failure can present a serious hazard to personnel and infrastructure.

Engineering Conclusion

Due to the lack of safety controls and the nature of the failure, we concluded that:

• The system design presented an unacceptable risk
• Safe operation could not be guaranteed
• Replacement — rather than repair — was required

The Solution

The client instructed us to replace the failed stopper system with a ToggleBlok® automated containment valve. Liml to toggleblok page

Unlike inflatable systems, ToggleBlok®:

• Does not rely on stored pneumatic energy for containment
• Uses a controlled mechanical actuation system
• Eliminates the risk of explosive failure
• Provides predictable, repeatable operation

This approach significantly reduces both operational risk and health & safety exposure.

Solutions like this can often be retrofitted into existing drainage systems — contact us to explore suitable options for your site.

Key Takeaway

This incident highlights an often-overlooked issue:

Containment systems must be assessed not only for performance — but for safety under failure conditions.

While inflatable stoppers can be effective in certain applications, they must be:

• Properly specified
• Adequately protected
• Regularly maintained and tested

Without these controls, they can introduce significant risk.

Need Advice on Your Containment System?

Whether you are:

• Using inflatable stoppers
• Reviewing legacy containment systems
• Working towards CIRIA C736 compliance

We can support with:

• System assessment
• Risk identification
• Retrofit solutions

Request technical input
Speak to our team