OnSite, a member of South Staffordshire Plc, based at Blackpole, Worcester, working with main contractor The Water Services Support Group, has completed a challenging project for Southern Water to clear a blocked waste water outfall pipe by taking one of its Whale tankers offshore.
An initial sonar survey showed that sections were blocked up to 60% with silt and numerous scale nodules weighing 2 to 3 kg. The initial plan was to place a line full length for winching to follow.
The ingenious OnSite solution was to take one of their fleet of Whale High Volume JetVac tankers offshore on a sea barge, with a team of OnSite operatives and specialist industrial divers, to the pipe outflow point. The teams worked to completely clear the submerged 600mm x 627 metre outfall pipe and undertake internal pipe inspection and testing. Entry was limited to a single access point at the outfall.
Although the discharged waste water at the Southern Water, Hook Lane, Warsash, Fareham site is treated onshore, it still encourages organic growth on the inside of the outfall pipe. It was this growth combined with scaling and silt intrusion that over a period of time created the outfall pipe blockage.
The OnSite Whale tanker used on this successful project was a seven year old High Volume JetVac mounted on a DAF 32 tonne GVW chassis. The tipping tank has a nominal capacity of 14,850 litres (3,267 gallons). A high performance Uraca P3-45 jetting pump was specified. This pump can deliver up to 90 gallons per minute @ 2,600 psi through 150metres of jetting hose.
An 1800cfm vacuum/air conveying liquid ring pump ensures an effective loading capability through either the overhead loading boom or the 6” air operated rear inlet valve.
Commenting on this project, Ray Ryder, Fleet Manager at OnSite, said “This was a challenging project that required considerable logistical planning. The successful completion of this project was due in the main to the team efforts of our operatives and the industrial diving team together with the proven efficiency of our ‘floating’ Whale High Volume JetVac tanker to deal with demanding situations. The Machine met the requirements, and we were confident that it was more than capable of completing the job, despite being the oldest in our fleet. Whale build quality means that at seven years old it still has superior performance”