If you require a cofferdam (sometimes referred to as a temporary dams, portable dam or limpet dam) for a project that requires a dry working area then you are in the right place. OnSite has a vast experience in the supply and installation of cofferdams and are well positioned to offer advice, without obligation, on the temporary works element of your projects. Get in touch using the form below or e-mail us at: Waterways@OnSite.co.uk


Traditional Cofferdams vs OnSite’s PortaDam

Traditional cofferdams were constructed using sheet piling or earth bunds but these methods can prove costly and there may be access or other installation issues. Portable cofferdams offer cost advantages, are easier and quicker to install and can be removed quickly in the event of an increased flood risk. Our own system, PortaDam, is the UK leader in temporary dams, providing the most effective method for coffer damming. Portadam is a proprietary cofferdam system, with the structural design and performance, certified by numerous bodies to enable temporary works certification to be achieved. Read more about our temporary dam solutions here


About PortaDam

With almost 50 years of design and installation experience and thousands of meters installed Portadam is the most effective and safest temporary dam system available. The ‘A’ frame structure and tailored membrane creates a freestanding structure that requires no additional bracing or supports and the structural calculations have been certified by numerous reputable bodies.

Portadam has been successfully used in a wide variety of environments including some susceptible to flash floods, namely Welsh and Scottish rivers where the flow rates and volumes can increase significantly in a very short period of time.

For further information on how Portadam can satisfy your temporary works requirements click here



We have provided cofferdams for numerous different applications in rivers, canals, lakes, ponds, tidal estuaries and coastal locations.

Projects, among others, include:

  • Bridges and culverts for inspection and maintenance works
  • Canal banks, walls, and towpath works
  • River construction projects
  • Weirs and fish passes
  • Outfalls and infalls
  • Servicing, repair or replacement of water control structures

Below is a small sample gallery, for a breakdown of galleries by application visit our Portadam page here