Water Pollution And Construction: Causes, Remedies And Repercussions

• Published date: 28 September 2023
• Law Firm: Walker Morris
• Author: Rachel Turnbull

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Water pollution and construction: What are the main causes?

Water pollution incidents often arise on construction sites if proper planning and procedures are not put in place. There are typically three sources of pollution from construction sites which can impact on watercourses: silt pollution; the release of hydrocarbons or chemicals; and the release of other site waste into the water such as litter or building materials.

Silt. Silt pollution is the most common source of pollution on construction sites. It often occurs when greenfield sites are stripped back for cut and fill operations in preparation for construction activities. The impact of this activity can be underestimated by developers, but there are often clues ahead of development, that surface water management may be an issue. Signs include: the topography of the site, as steep slopes are likely to result in faster runoff; proximity to watercourses, as the closer the site is to a watercourse, the greater the risk that any run off from the site will end up in the watercourse; any existing measures (such as land drains, for example), which might indicate that surface water already needs some kind of management; and local resident information (often locals will be aware of surface water flooding or run-off issues in the past, and may even have referred to such issues during the planning process).

Removing topsoil and vegetation renders silt immediately vulnerable to surface water runoff. Use of heavy machinery which compacts the ground can exacerbate the problem, increasing the amount of water and silt which runs over land and enters surface water drainage channels and nearby watercourses. Use of plant and machinery also agitates topsoil and increases mobilisation of silt particles. Whilst measures such as wheel washing aim to prevent mud being transported onto the road, if not managed correctly they can inadvertently facilitate silty water leaving the site.

If soil particles remain suspended in the surface water and are carried off site, they can have significant impacts on the quality of local watercourses. Silt in the watercourse is often seen as relatively innocuous, perhaps because it's naturally occurring. However, silt can have detrimental effects on rivers and streams - smothering aquatic plants and invertebrates, blocking fish gills and...