How to identify asbestos in the ground and what it looks like

When we think of asbestos containing materials (ACM), we generally think of dusty old pipe insulation or cement fiber board, or other old materials in cellars, attics, and plant rooms. Asbestos is not given anywhere near as much consideration when it comes to external works, especially excavation.

Since asbestos was widely used throughout the 20th century, whenever a building is being demolished the entire site must have the asbestos removed professionally to ensure the remaining structure is safe to destroy. If this is done properly and to Health and Safety Executive (HSE) guidelines, then the remaining materials are available to be reused, as a base course layer in ground build-ups for example.

The issue comes from the late recognition of asbestos’ danger to humans, and the subsequent, even later, banning of asbestos in construction. With this late banning of use (or re-use) of asbestos there was no regulation requiring the removal of Asbestos Containing Materials (ACMs) before demolition or reusing demolition by-products. The effect of this, alongside the natural life cycle of buildings, and the upward trend of redeveloping old sites, has led to a rapid uptick in projects encountering asbestos in the ground.

It may seem like the increased prevalence of asbestos while working in the ground is something that could be easily handled within the existing asbestos removal regulations, infrastructure, and guidelines, however there are several important differences in the way you should approach asbestos discovered in the ground versus above ground:

• Hard to spot – Most ACM found in the ground are the product of demolition (masonry rubble), and in many cases the rubble has then been crushed and graded before being used as an aggregate. As a result, any visually identifiable material such as pipe insulation or cement board will be so broken down that it is very hard to spot with the naked eye. This is further compounded by the effects of water and ground movement breaking down the asbestos containing material (but crucially, not the asbestos itself).
• Lack of traceability - The use or re-use of ACMs was not regulated fully until the year 2000. Therefore, any building that was demolished, or recycled aggregate that was imported before the turn of the 21st century could have asbestos containing material in it. For example, if there has been a series of redevelopments on a site over the last 120 years, the ability to trace the material in the made ground is even harder.
• Problems of scale - The disturbance caused by groundworkers excavating is vastly greater than that of electricians drilling for example. An excavator can move much more material in a day than an electrician or plumber might create in a lifetime, leading to significantly higher potential exposure to airborne asbestos fibers, especially if high-content material is disturbed.
• Uncontrolled environment – When dealing with ACMs indoors there is always the option to close the door to a room that has airborne asbestos fibers or a disturbed ACM which acts as a good barrier and control boundary. However, when dealing with asbestos in the ground there is much less control as you have environmental factors such as wind and limitations in your ability to cordon off an area.
• Likely to be wet and less hazardous: One of the few aspects of working with asbestos in the ground versus working indoors is that it’s less dangerous. The ground is especially wet or cloying (such as in clay soils), so in these conditions even dispersed asbestos fibers are somewhat encapsulated and are less likely to become airborne. However, it is important to note that if the soil becomes dry it will likely begin to turn to dust and will release the asbestos fibers.

To help with these complex issues, the Joint Industry Working Group, a leading civils and groundworks industry body, created a practitioners guide called The Asbestos in Soil and Construction & Demolition Materials. It brings together the combined knowledge and experience of industry leaders and experts to assist with interpreting the current legislation on asbestos with an emphasis on construction practices in-ground.