What Does Contaminated Soil Look Like?

Soil contamination is a critical environmental issue often found in urban areas where industrial activity, pollution, and human activity are common sources of contamination.

Recognising the signs of contaminated soil is essential for the overall environment. If you notice any symptoms of soil contamination, it may be necessary to call a soil remediation service to address the problem before it worsens.

There are some telltale signs of soil contamination, and some solutions as to what you can do if you suspect your site may be affected.

One of the most obvious signs of soil contamination is patches of discolouration. Soil can naturally appear in a variety of colours depending on the region and its organic composition, but sudden or unusual changes in the colour of the soil can indicate a problem.

If you see areas where the soil is darker or has an unusual texture compared to the rest of the site without an identifiable cause, you may be dealing with contaminated soil.

Discolouration can appear as dark oily patches, sometimes with a damp or wet appearance even in dry weather. This could suggest contamination by substances such as oil, heavy metals, or chemicals, particularly if the rest of the area is dry.

If soil contamination is present in only a portion of your site, it may still be early in its spread, making this a good time to address the issue before it gets worse.

Contaminated soil may feel different to the touch. A greasy consistency could be because harmful substances are present. If you notice a section of your site with soil that feels damp or sticky for no apparent reason, it's best to have a professional company test the soil for contaminants.

• Oil or fuel spills - Dark patches may indicate a spill of motor oil, or other petroleum products.

• Chemical runoff - Industries or agricultural activity nearby can result in chemicals seeping into the ground, changing the soil's appearance.

• Heavy metals - Contamination with lead, arsenic, or mercury can alter soil colour and texture, and can cause significant health risks.

An unpleasant smell coming from the soil is another indicator that it may be contaminated. Healthy soil should have an earthy, organic smell, but when the ground is contaminated, particularly on hot days, you may notice a sharper, bad smell that is unlike the natural odours you are used to.

The smell could be similar to that of chemicals, such as pesticides, industrial solvents, or petroleum products. In some cases, the contaminant itself may have a distinct odour. For example, arsenic-contaminated soil can produce a strong smell, even in very small amounts.

If you regularly notice an unusual smell on your site, especially on dry, warm days, it’s a good idea to have the soil tested. Contaminants often release hazardous compounds as they break down, and the odour may be one of the earliest signs of a problem.

• Decomposing chemicals - Many industrial chemicals release gases as they break down, causing noticeable smells.

• Leaking septic systems - Leaks from old or damaged septic tanks can cause the soil to emit strong and unpleasant smelling odours.

• Industrial pollutants - Factories and industrial facilities can release pollutants that find their way into the soil, causing smells ranging from metallic to chemical in nature.

One of the subtle signs of contaminated soil is the absence of wildlife and plant life. Healthy soil promotes a diverse ecosystem, attracting animals, insects, and birds. But when the ground is polluted, it can become hostile to these creatures.

If the soil is contaminated, plants may struggle to thrive and grow. Even if a few plants manage to take root, they often absorb toxic substances from the ground, which can then be passed along to animals that feed on them. This toxicity can cause animals to avoid the area altogether. Therefore, if your site appears unusually lacking in plants or wildlife, contamination could be the culprit.

Not only can contaminants prevent plants from growing, but they can also disrupt the delicate balance of the local ecosystem. The absence of any wildlife in an area that was once abundant with it should raise a red flag.

• Yellowing or stunted plants - Contaminants can damage plant roots, making it difficult for them to absorb nutrients.

• Fewer birds or insects - If you notice fewer animals visiting your garden, the soil may be releasing harmful toxins that deter wildlife.

• Dead patches of grass - Large dead areas of grass or plants that are failing to grow in what should be fertile soil can be signs of deep-rooted contamination.

Soil erosion can be a natural process, but when it occurs quickly and without an obvious cause, it may be a sign of soil degradation due to contamination. Erosion occurs when the top layer of soil is displaced, often leaving behind dips, holes, or uneven patches on your land.

Contaminated soil is often structurally weaker than healthy soil, making it more susceptible to erosion. Harmful substances can break down the soil’s composition, causing it to wash away more easily. Over time this can lead to significant changes in the land’s topography, making the ground uneven and harder to manage.

• Chemical breakdown - Certain contaminants can destroy the organic matter that holds soil together, making it erode more easily.

• Water runoff - Contaminated water flowing through the land can carry away soil, leaving behind barren or uneven patches.

• Subsidence - The collapse of contaminated soil beneath the surface could result in sinkholes or depressions in the land.

Water plays a considerable role in soil contamination. If your property has an older water storage system, contaminated water can seep into the surrounding ground, carrying pollutants with it.

Before the 1970s, many now banned substances were commonly used in households and industries. These contaminants, including lead and certain pesticides, can accumulate and eventually make their way into the soil. Over time, these harmful substances can build up to dangerous levels.

To determine whether your water system is contributing to soil contamination, it's a good idea to have your water tested by a professional remediation service. Testing can reveal the presence of harmful substances, allowing you to address the issue before it spreads further.

• Lead - A toxic metal that can cause long-term soil contamination.

• Old pesticides - Some chemical pesticides banned today may still be present in older systems.

• Industrial solvents - These can seep into the ground through water systems, leading to widespread contamination.

One of the most dangerous types of soil contamination that building owners should be aware of is asbestos-contaminated soil. Asbestos is a naturally occurring mineral that was widely used in building and manufacturing due to its durability, insulation properties, and heat resistance. It was later discovered that asbestos fibres are extremely hazardous when inhaled, causing severe lung diseases such as asbestosis, lung cancer, and mesothelioma.

While asbestos was banned in the UK in 1985, it can still be found in older buildings and materials, potentially contaminating surrounding soil.

Asbestos contamination in soil usually occurs when older buildings that contain asbestos are demolished or renovated without proper precautions. The debris from demolition, or improperly disposed of asbestos materials, can release fibres into the atmosphere which then settle into the soil. Over time, these particles can remain in the ground, posing a long-term health risk, especially if the soil is disturbed during construction or landscaping.

Asbestos-contaminated soil is most common in areas near old industrial sites, factories, and buildings constructed before the 1980s, but even properties in residential neighbourhoods can be at risk if proper demolition or disposal practices were not followed.

Unlike other types of soil contamination, asbestos-contaminated soil does not have obvious visible signs like discoloration or bad smelling odours. Asbestos fibres are microscopic and cannot be detected without specialised testing. But there are still a few signs to look out for:

• Proximity to older buildings or industrial areas - If your building is located near older structures that might contain asbestos, the risk is higher for contamination.

• Presence of debris - If you notice older construction materials such as roofing tiles, insulation, or cement fragments on your site, these may contain asbestos.

• Past demolition activities - Properties that have been demolished or have undertaken major renovations may have been exposed to airborne asbestos fibres, which could settle in the soil.

Even minimal exposure to airborne asbestos fibres can be hazardous, so it is essential to address any potential contamination quickly and thoroughly.

If you notice any of the signs we’ve covered, or if you suspect your soil is contaminated with asbestos or Total Petroleum Hydrocarbons (TPH) such as oils/fuels, you should take immediate action.

Soil contamination can pose serious health risks to the public and the local environment. The best course of action is to consult a professional site remediation service. They will be able to test your soil and water, identify contaminants, and advise you of the appropriate solutions.