There are serious consequences to not controlling silt and sediment on construction sites.
The risks are primarily environmental, as pollution will harm biodiversity, but will also create financial and reputational implications for those responsible for a development. Effective silt control also offers benefits though, making sites easier and safer to work on.
Silt – fine soil, sand or clay – is created when ground is disturbed by construction works or weather. If it is not correctly managed it can migrate to watercourses, creating a risk of pollution to biodiversity. If this occurs developers are liable for heavy fines for breaking legal requirements.
To reduce this risk, a number of measures have been developed, most commonly used in conjunction with one another. Silt control is most effective with dual methods of both barriers – to slow or stop the flow of water from carrying silt – and traps – to capture silt where it settles.
The importance of getting these measures right means there are a number of solutions available, to suit all project types.
To slow the flow of silt migrating in the first place, silt fencing is useful.
These are geotextile membranes, trenched into the ground to divert or filter water runoff and movement of water through soils. By capturing and stopping silt these prevent watercourses from being polluted, protecting important biodiversity.
Silt fencing should be installed as close to construction works as possible, to deliver maximum containment. It is particularly useful in the winter months when water causes more challenges on sites. However, it is essential that all measures are maintained year-round, with regular checks and maintenance to ensure their effectiveness.
Where even small volumes of silt or sediment could still reach water, further protection is required.
A sediment control barrier – in the form of mats – can be placed in the beds of bodies of water to catch sediment as it drops out of suspension in water. These can sit within the beds of rivers downstream from works, or in smaller, shallower burns.
Where complete protection is required, more robust measures are needed.
Silt curtains can be placed into watercourses, floating in the water to block or absorb materials ranging from fine sediment to heavy clay. Also formed from geotextile membranes, silt curtains are designed to completely block matter from reaching clean bodies of water.
Each of these measures will capture or contain silt, allowing it to be held ready for removal. What combination is most appropriate will depend on the ground and weather conditions and the individual site’s layout and proximity to watercourses. The anticipated volume, speed and direction of water flow will also dictate which is most optimal.
Our technical experts can help you to identify the right silt control measures for your works and advise on the proper installation and upkeep.
Stratec are experts in geotechnical products and solutions. Get in touch for more information or advice on how to protect your sites and optimise your projects.