Is Your Penstock Containment System Actually Working?

It is critical that pollution containment systems are regularly tested and verified.

Across multiple sites, we repeatedly encounter the same issue:

Systems that appear to operate — but do not actually contain a pollution event.

Below are two common faults identified during servicing and emergency call-outs.

If you are unsure whether your system would perform in an emergency, we can assess and test your containment setup.

Fault 1: Valve Does Not Fully Close

We are frequently asked to service existing pollution containment valves, particularly penstock systems installed at outfalls.

A global aerospace engineering company in Wolverhampton requested an annual service of their containment valve located at the final discharge point into a balancing pond.

Findings:

• The valve appeared to operate normally (open/close)
• During confined space inspection, the valve stops were incorrectly set
• No evidence of prior adjustment or commissioning
• The valve had likely never been set to fully close

After adjustment, the valve was able to fully close mechanically.

However, this revealed a second issue:

The system achieved closure — but not containment.

The valve had originally been incorrectly specified, meaning even when fully closed, it could not reliably prevent discharge.

Key Risk

A valve that closes is not necessarily a valve that seals.

Without proper specification, commissioning, and validation:

• Flow may continue past the valve
• Containment may fail during a real incident
• Compliance may be assumed — but not achieved

We can review your valve specification and confirm whether it will achieve full containment under real conditions.

Fault 2: System Failure During Power Loss

Another common issue is reliance on site mains power to operate containment systems.

While servicing pollution control valves for a UK dairy facility, we identified a critical vulnerability.

Incident:

• A trailer charging point caused a short circuit
• This tripped the power supply to the containment system
• The valve controls became inoperable
• The system failed during an emergency call-out

A containment system without power is not a containment system.

This risk is particularly critical because:

• Spill events often coincide with power failure
• Fire scenarios may disable electrical systems
• Manual intervention may not be possible in time

Key Risk

Containment systems must be designed to operate independently of site power.

Without backup or stand-alone capability:

• Systems may fail at the exact moment they are needed
• Environmental and regulatory exposure increases significantly

If your system relies on mains power, we can assess fail-safe operation and recommend improvements.

Why Testing Matters

The purpose of a pollution containment system is to operate during an emergency.

By the time an incident occurs:

• It is too late to discover faults
• It is too late to correct design issues
• It is too late to prevent environmental damage

Containment systems must be proven — not assumed.

Best Practice Approach

We recommend:

• Regular servicing and inspection
• Functional testing under realistic conditions
• Verification of full sealing performance
• Independent power or fail-safe operation
• Alignment with CIRIA C736 guidance

How We Can Help

We support clients with:

• Containment system inspections
• Performance testing and validation
• Specification reviews
• Retrofit and upgrade solutions

Whether you are:

• Unsure if your system is compliant
• Experiencing performance issues
• Reviewing risk across your site

Request a system assessment
Speak to our team