Project

Redevelopment and remediation of the old gas works site in the Old Port area of Chester on the River Dee.

Scope of Works

Construction of a new riverside wall, incorporating a walkway and cycle path. The riverside wall was constructed from cellular cofferdams, formed from sheet piles, framed internally and filled with granular materials. Due to the access and ground conditions this was the only suitable way to provide the ground retention as required. This proved highly successful. Ale Piling carried out all of the sheet pile installation on this site, on the first phase for a main contractor and on the second phase the work was carried out directly by Ale Piling including supply of materials and installation of the frames to the cellular cofferdams.

Method

Due to the difficult access constraints on the site all of the work on phase one was carried out working from floating craft. No access to the pile line could be provide for plant on the land side due to the proximity of an electricity substation and no craneage could be used on the majority of the site due to the overhead HV cables present. All of the sheet piles on site, on both phases were installed using two of our side grip piling rigs. The work carried out from floating craft had to been sequenced to incorporate the 5m difference in the tides on the river. In location of the phase two works the sheet piles had to be backdriven using a crane suspended hydraulic impact hammer. Ale Piling also installed forty 250mm diameter tubular piles on site.

Project Images

Materials

LX 20 and LX12 sheet piles, 12m to 6m in length
12 m Long 250mm diameter tubular piles
7m long 65 mm tie rods
Twin welded 300mm steel channel

Ground Conditions

Made ground comprising of mainly granular material and sandstone blocks from a previous riverside wall. (The previous riverside wall had to be excavated and removed, to allow installation of sheet piles). Underlying sandstone and river deposits.

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