Client:
Domestic
Scope of Works:
Contiguous Piled Retaining Wall
Nature of Site:
Restricted Access
Location:
Kingsdown, KENT
Year:
2019
Requirement:
L&J Projects Ltd were contacted by Dargan Construction Ltd to construct a contiguous piled retaining wall which would provide support for a new two-storey extension to a domestic property.
Due to the site being on a steep slope, the proposed extension would be dug into the slope creating a vertical face in excess of 6.0m which would require retaining.
The site was challenging due to minimal access and steep level changes from the site entrance to the works area.
Solution:
L&J Projects Ltd carried out an initial design study to determine pile diameters and reinforcement requirements based on an assumed geology profile (Chalk) to assist in selecting an appropriate pile construction method and rig type. With such a challenging site, considerable Engineering design was required early on to assess the feasibility of the project.
With pile diameters up to 450mm calculated and a Rotary Bored installation method chosen, a GEAX XD8 Piling Rig was chosen for its compact size and drilling capabilities. With the initial scope of works defined, L&J Projects Ltd compiled a tender package to ensure the project was in budget before any further costs were committed by the client. Production output was tendered at a maximum of 3 piles constructed per day to give realistic project costs to the client.
On Site:
Once the project was secured, L&J Projects Ltd commissioned two deep site boreholes to be drilled to confirm the initial design assumptions were valid. The final pile depths required were 1.5m deeper than the piling rig could achieve, with no other rig suitable for the project, L&J Projects Engineers worked closely with the Project Engineer. A solution was agreed to extend the height of the capping beam on top of the piles to meet the required specification. With the cost savings from the reduced pile length added to the reinforced capping beam works, the innovative solution was a no-cost extra to the client.
The program of works was complex due to the piles needing to be installed at varying platform levels around a very tight site. A 13.0T excavator and driver were required to create suitable access ramps and piling platforms and to clear the pile arisings away from the rig as works advanced.
On site, L&J Projects Ltd installed 47No 450mm diameter piles to depths ranging from 8.2 – 10.8m depth. All works were completed within program and on budget.
