Project Description

Figure 1 Piles arrive and installation begins

Abigroup who were building the Adelaide Port River Expressway needed a cofferdam that was able to be de-watered in order to allow the construction of the bridge piers. The previous option used by Abigroup was second hand AZ36 sheet piles. This option could not provide an adequate water proof area for the construction to proceed in a timely manner. So forced with substantial delays on the first cofferdam, Abigroup decided to use ESC for the second cofferdam.

ESC was approached to help them find a solution. As a result ESC designed a custom sheet pile and called it the ESC3600-BP. This sheet pile was a variation to the catalogue issued BP sheet piles. The BP sheet pile is designed with an open clutch suitable for post installation grout sealing. The BP pile is for de-watering works, groundwater cut-off walls and pollution control situations. This pile with its light weight, wide profile and minimal clutches also provides an attractive commercial proposition for retaining walls and other applications.

The BP sheet pile in this case had to be 17 metres long and hold out vast amounts of water with a 6 metre head whilst using only one layer of struts to ensure the project site could move ahead with minimal obstructions whilst maintaining the design and construction criteria required by the client.

Figure 2 Custom Designed Cofferdam done by ESC

Figure 3 Custom Designed ESC Sheet Pile specifically made for this project

River depth was 10.0m, with 2-3m of soft silt material overlying a hard clay layer. Sheet piles were installed 2m into the hard layer to provide an effective cutoff for water seepage under the pile wall. The cofferdam was filled with gravel and then dewatered to depth of 6.0m below the mean water level. Post grouting was done with a non toxic cement grout mixture, which was critical as environmental considerations were paramount on the project as the harbour is home to a large dolphin population.

Figure 4 Completely dry excavation was able to be carried out due to the grouted clutches

Figure 5 The ESC design allowed the construction to be carried out unobstructed and in the dry

Details of Sheet Piles

Figure 6 ESC sheet piles were used in the cofferdam to the left. Second hand AZ sheet piles were used on the cofferdam to the right. Time saved with the ESC watertight clutches was immense and ensured that even though the ESC sheet pile cofferdam started some four months after the first cofferdam is was the ESC sheet piled one which was completed first.

Figure 7 The Bridge beams are being launched

Figure 8 The finished Bridge in all its glory