Sustainability
BEING ‘RAIN READY’ ON SITE MEANS MANAGING SILT TO PREVENT POLLUTION AND PROTECT REPUTATION Most construction projects can expect to deal with rain at some point. This can create problems with silty surface water run-off that is harmful to the environment, reduces the amenity value of public spaces and potentially, results in fines and reputation damage. Frog Environmental Managing Director Richard Haine explains that better planning and a process-driven approach to preventing silt pollution is both costeffective and reputation-enhancing.
Silt, a combination of all sediment, including soil, mud, clay and sand, in water is the single main pollutant to the water environment from construction sites. Largely, this arises from the erosion of exposed soils by surface water runoff from rain, which carries the silt into public bodies of water such as rivers and reservoirs. In recent years, we have seen an increasing focus on the health of rivers in the UK. Public awareness and citizen science have grown significantly, with large numbers of volunteers joining river watch projects. Silt is a highly visible pollutant and is easily spotted in this context. In fact, many of the recent enforcement actions and fines that are being levied have come about from the public submitting video evidence using their smartphones. Historically, awareness of silt pollution from construction sites may only have
Richard Haine
Silt capture channels
18 Construction UK Magazine - August 2024
come with a letter from the regulator advising of a pollution incident. This type of reactive approach leads to environmental damage, additional costs and reputational risk: last year, a housing developer was fined nearly half a million pounds for silt pollution, and six figure fines are increasingly common. A significant cause of silt pollution is simply having too much water. If we cannot manage water quantity – the flow rate requiring treatment – it is highly unlikely that we will be able to achieve the desired water quality outcomes. This is because each treatment methodology, be it a tank-based system, a pipe reactor containing gel flocculant or a more humble silt sock, will have a maximum flow rate at which it can effectively treat water. Last winter saw recordbreaking rainfall. In fact, above average rainfall has been recorded most months from July 2023 to April 2024. Planning adequate water attenuation on-site and