Encountering galligu is almost a rite of passage when working in areas like Runcorn, Widnes, St Helens, or near the Sankey Canal. Yet, many are unaware of this unique and often problematic material beyond these regions. Let’s dive into what galligu is, its history, and how it’s managed today.

What is Galligu?

Galligu is the byproduct of the Le Blanc process, an early industrial method used to produce soda ash (sodium carbonate). This process utilised salt from the Cheshire brine domes beneath places like Northwich and Middlewich. The chemical reaction left behind a thixotropic, sulphate-rich waste material known as galligu.

The properties of galligu are fascinating yet troublesome. It typically contains elevated levels of metals, with sulphates being the primary environmental concern. Its form can vary significantly, ranging from a sandy texture to something akin to toothpaste. What makes galligu particularly challenging is its thixotropic nature—it can appear stable but shift into a very soft or even liquefied state with minimal moisture changes.

Field Encounter with Galligu

We were recently on site to drill three windowless sampling boreholes for a proposed telecom mast on a road embankment. All three positions encountered galligu, to depths that varied from 5.5 m upslope to 2.4 m downslope, resting directly on glacial till.

The material sampled exhibited striking visual characteristics. It ranged from a creamy white to a dark blue or bluish-green with an immediate and sharp transition between the two colours. These samples will be sent for testing to assess their composition and potential environmental hazards. We will also save a few samples to add to our collection of unusual or problematic materials encountered during site investigations.

Managing Galligu: Challenges and Solutions

The presence of galligu poses significant challenges for land redevelopment, especially in former industrial regions. Its instability and chemical composition mean it often requires careful management to make the land safe for reuse.

Stabilisation is one of the most common approaches for dealing with galligu, and one that we have previously recommended on a site in Runcorn (https://www.gea-ltd.co.uk/blog/detail/ten-lock-flight-public-house-runcorn.html). This process typically involves mixing the material with stabilising agents to create a firm and durable substrate. Stabilisation is especially useful for preparing sites for hardstanding areas or industrial land use. However, every site is unique, and the variability in galligu’s composition demands tailored solutions..

Why Awareness Matters

Understanding galligu is crucial for anyone involved in site investigations or redevelopment projects in areas where this material is prevalent. Ignorance of its properties can lead to unforeseen complications, delays, or environmental risks. By sharing knowledge and best practices, we can improve safety and efficiency in handling this challenging industrial legacy.

Galligu serves as a reminder of the environmental impact of the Industrial Revolution—and the importance of thoughtful, informed land management in modern development.