Hornsea outfall is a 1050mm x 143m cast iron sewer located on the main bathing area of the Blue Flag-rated beach.
The sewer was suffering from severe erosion, with surface water originating from the nearby Hornsea Mere ex-filtrating through holes and damaged joints along it’s length.
The Environment Agency and Yorkshire Water instructed Mott Macdonald Bentley to identify a suitable specialist contractor to design a solution for repair. DrainsAid were tasked with rehabilitating the pipe in order to prevent the leakage of water onto the beach, therefore preserving the beach’s Blue Flag status.
Upon inspection using a mainline crawler CCTV unit we established that there was significant debris in the pipe including sand, pebbles and general marine encrustation. This meant that before the pipe could be lined, we needed to cleanse the pipe.
We constructed a scaffold gantry over the seafront road in order to maintain traffic flow during the works and installed temporary pipework to control flows with pipes running adjacent to the existing outfall then discharging into the sea.
The key challenge with this installation was the restriction of works due to the tide times, this included very specific windows of opportunity for the cleaning and installation of the liner.
The chosen method of lining was Hot Cure using a glass-reinforced liner. Therefore, scaffolding had to be erected and a contract lift crane used in order to gain the required height and angle of entry for inverting the 140m liner.
Once inverted, water was used to push the liner into place and a large boiler was used to heat the water for the hot-curing process.