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Case Study: GRP Tank Covers - Maghera Sewage Treatment Works

  • GRP Tank Covers
  • GRP Tank Covers
  • GRP Tank Covers
  • GRP Tank Covers
  • GRP Tank Covers
  • GRP Tank Covers

Project Name

GRP Tank Covers for Maghera Sewage Treatment Works


Maghera, Co. Londonderry, Northern Ireland


GRP Conical Tank Covers for Sludge Holding Tanks to control odour in the sewage treatment works.


2 no. bespoke moulded 10.6M diameter GRP conical shaped self-supporting Tank Covers.


  • 1 no. 1000 x 1000mm hinged & lockable GRP manway access hatch with safety grille.
  • 1 no. 1000 x 1000mm hinged & lockable GRP pump access hatch with safety grille & split fall arrest.
  • 1 no. 150mm diameter GRP flanged connection with backing plate.
  • 1 no. 150mm diameter fresh air inlet with insect mesh.


Relinea were appointed by Ovivo Water to provide an effective odour control solution for two existing sludge holding tanks within the Maghera Sewage Treatment Works. It was recognised by the client that the odour had to be controlled due to the legislation of the 2012 Northern Irish Code of Practice on Odour Nuisance from Sewage Treatment Works.


The two sludge tanks to be covered were in full operation, hence the installation needed to be carefully co-ordinated with the client. To gain access within the sludge tanks, they would have had to be fully cleaned out, which would have proved to be very costly.

Relinea therefore had to design a system that could be installed without the necessity of accessing the tanks.


Relinea proposed a number of designs to Ovivo Water that would effectively control the odour emanating from the sludge holding tanks, while also allowing for ease of installation given that access into the sludge tanks was limited. In view of this, Relinea conclusively recommended a conical shaped bespoke GRP moulded tank cover to be employed, meaning that the tank covers could be built up in an area adjacent to the sludge tanks and then crane lifted in one piece into position.

The 10.6M conical shaped self-supporting tank covers were manufactured in chemical resistant resin ensuring a long maintenance free service, and were constructed using equal moulded segments which were bolted together and connected to the central ring. The tank covers were manufactured to carry a loading of 0.75Kn/m2 and met BS EN 1991-1 Standards. Installation of each cover was carried out within two days causing minimal disruptions to site operations. 

Each odour control tank cover incorporated a manway access hatch with integrated fall arrest, and a pump access hatch with an integral split fall arrest which ensured protection throughout the pump removal process.

Relinea delivered the project on time, on budget and to a very high standard to the complete satisfaction of Ovivo Water.