Surface water management is a hugely important issue on all construction sites. The impacts of construction on the surrounding water courses can be devastating and the knowledge and understanding around this has grown significantly over recent years. Developers have more strategies at their disposal than ever before to ensure they mitigate the effects of their activities on the local ecosystems and water courses. Ultimately, protecting themselves from fines and reputational damage, by protecting the surrounding environment.

But why is surface water management necessary?

Silt is found in soil, clay, sand and gravel. Whilst animals and plants have adapted to live in moderately silty soil, too much silt can upset ecosystems. All water courses carry a certain sediment load, which they are able to transport and deposit in many places. However, when the sediment load becomes too high, issues start to arise. Sediment movement dislodges small animals and deposition can damage and kill aquatic life, by smothering and suffocating those living in the bottom of the stream. Further to this, the build-up of sediment means there is less space for animal and plant life, interfering with their food intake particularly. Another result of deposition is how muddy it makes the water courses (also known as turbid). This is a problem because it reduces light penetration, which makes it much harder for plants to photosynthesize. This being arguably the most important process for all aquatic life!

Flood Risk and Water Supply

These impacts aren’t limited to just the ecosystems – they can affect us humans just as much! Extreme weather events are happening more frequently than ever, and poor surface water management is a large contributor to this problem. In England and Wales, it is estimated than over 4 million people are potentially at risk of flooding. The speed of surface water run-off has a huge impact here. Peak flow, which is the highest level of water during a storm, needs to be managed by slowing the run-off down and increasing the time it takes to enter the water courses. However construction activities can increase the speed of run-off, consequently increasing the risk of flooding.

Another issue that is growing during these times is water availability in the UK. Increasing population, with subsequent housing and infrastructure growth, is putting substantial pressure on water availability. Although currently during ‘normal’ periods of weather we have sufficient water supply, when it comes to prolonged dry spells, we run into problems of insufficient supply. This can actually be mitigated to an extent by reducing the contamination of surface water run-off. Lowering the pollution is a much more favourable option than the costly treatment that is essential to make polluted water safe for use.

How is construction activity contributing to this?

Construction activities often lead to losses of topsoil, which usually acts as an important filtering mechanism for  surface water run-off. This loss means the run-off is contaminated with more silt sediment than it would normally be. There is also an increased surface water flow to the water courses surrounding, due to the vegetation removal and soil-stripping. So to begin with, there’s more sediment-dense surface water runoff. Then activities often reduce the area of vegetated land available for the disposal of silty water. Construction sites produce a large volume of water and a high rate of surface water run-off, which is why it must be managed. Traditional drainage systems are designed with speed in mind, with treatment seldom a priority. This leads to rapid pollution and movement of large volumes of water. Therefore, it’s essential to plan your surface water management. Take a look at our blog here to learn how to manage this naturally and sustainably using our straw: Using Baled Straw To Manage Runoff On Your Construction Site | Baled