Advice for installation of a treatment plant in a flood zone
Installing a treatment plant in a flood zone should be done by a professional
This guide highlights some key aspects to consider when undertaking an installation in a flood risk area.
Flooding has a major impact on our environment. Climate change, increased countryside development and removal of trees have all impacted on flood risk over the last few decades.
This therefore poses the problem as to what to do with sewage treatment systems and off mains treatment solutions in areas of flood risk.
No. there is currently no system specifically designed for a flood risk application. However. There are some that will be better than others in the event of flooding. Active sludge systems don’t have filter material in them, and therefore, when flooded, there is less risk of filter material being blocked. On the flip side, there is a slight increase risk of bacteria getting “washed away” in the event of a system being fully flooded.
Sewage treatment plants with external air blowers are also advantageous in areas of flooding. This is because the installer is able to move the air blower to a location higher than the flood line.
It is unlikely you will be able to seal a treatment plant to prevent flood, subsequently, the best option is to allow the system to flood but as described previously, move the air blower to a location out (or above) the flood zone. Doing so will prevent the air blower from failing, which in turn will keep oxygen levels high in the water.
The benefit of keeping the air blower running is 2 fold:
A non return valve, installed at a river or stream can have a short term benefit if the river or stream level rises and falls quickly. However it is not a good measure to prevent water from coming back into the treatment plant. For example, if the water in the river rises, and the outlet is underwater, a non return valve will close, preventing the water from coming back into the treatment plant. Then there is nowhere for the water to get out of your treatment plant and you would have to stop using any water or the system will flood anyway.
The best method of dealing with a sewage treatment plant discharging to a river that occasionally floods is to install a pump station after the treatment plant.
A pump station is a chamber with a pump in, the pump automatically lifts the water to the desired location. Because the pump itself will have a non return valve, water cannot come back into the treatment plant from the river or stream.
If in doubt, seek specialist advise from a local installer.