Contractor Trant Construction hired the two “shorlfo Super” pumps to de-water the three large tubular steel piles which will secure and stabilise the terminal’s new floating pontoon which is designed to ride up and down the piles so that it can rise and fall with the tides running in the Solent.
The piles, each 610mm in diameter and more than 30m in length, were driven approximately 25m into the sand and underlying clay of Portsmouth harbour before being filled with concrete to provide solid supports for the pontoon.
“Before pouring the concrete, we first had to pump out the silt and seawater from inside them,” explains Trant’s site manager Mark Blackler. “We chose Shorflo because we’ve used them before and they are a reliable company who supply good pumps.”
Shorflo’s Super-Silent Betsy pumps are built around the Hidrostal screw centrifugal impeller which is renowned for its operating efficiency and its ability to handle a range of materials. With a maximum capacity of 172³m/hr the four-inch D100 model is exceptionally fuel efficient, consuming only 1.1litre/hr when pumping flat-out.
At Gosport, the two pumps were supplied over two days and mounted on a barge so they could reach the piles located a few metres beyond the quay. One flooded the pile and one pumped out the sand and silt, discharging into two temporary settlement tanks mounted on the quayside. Here the silt was separated from the water which was then pumped back into the harbour.
The new £5 million terminal replaces the original floating pier which had reached the end of its service life. With an estimated 3.6million passengers using the facility every year, the client, Gosport Borough Council, ordered the new terminal to ensure it could cope with the steadily increasing passenger throughput.
The new pontoon was built in Deest, Holland, by specialist marine engineers Ravestein and floated down the Channel on one large barge with the pontoon being installed over one weekend .