Case Study

Piling

Construction works at the new Athlone Art Gallery consisted of the renovation of a derelict 18th Century riverside warehouse plus the construction of a new build extension to the existing warehouse. Both new and old structures are located adjacent to the quay side of the river Shannon in the centre of Athlone.

Main contractor, Purcell Construction asked Taranto Ltd to provide precast concrete driven piles to the new structure plus limited headroom, bottom driven mini pile for the warehouse renovation.

In planning the works, we had to pay special attention to the limited access and working room available on site. Also, as both structures are adjacent to Athlone Cathedral, stringent limits on vibration were placed on all site works.

For the existing warehouse renovation Taranto Ltd installed 45No 220mm ΓΈ bottom driven, cast in-situ mini piles using a special modified Taranto Ltd mini piling rig. In several locations the existing foundation of the warehouse obstructed the position of the new pile position. This resulted in Taranto Ltd pre-drilling through the existing stone and concrete foundation at each pile location to depths of 6m prior to installing the bottom driven mini piles. The Taranto Ltd mini piles were installed to working loads up to 250kN for depths up to 12.0m.

Athlone Art Gallery

Solution

Main contractor, Purcell Construction asked Taranto Ltd to provide precast concrete driven piles to the new structure plus limited headroom, bottom driven mini pile for the warehouse renovation.

During the pre-drilling and piling works, Taranto Ltd continuously monitored vibration levels across the site, including monitoring the vibration levels of the existing warehouse structure through the use of several wall mounted vibration monitors. Throughout the works Taranto Ltd ensured that the stringent site vibration limits were not exceeded.

On completion of the mini piling works, Taranto Ltd dynamically tested the mini piles using a dynamic pile-testing rig specially modified for the limited headroom and access available on this site.

Taranto Ltd installed 53No 250mm2 & 300mm2 Precast concrete driven piles for loads up to 700kN for the new extension block. Again, access and site working room was very limited. Taranto Ltd utilised a medium sized top drive tracked rig and installed the 53No piles to depths up to 14.0m over a four-day period.

Several of the new pile positions were obstructed by existing low level stone wall. These were believed to be the original river Shannon quay walls. To overcome this Taranto Ltd pre-drilled the pile positions to 6.0m before installing 175mm diameter tubular steel top driven piles to working loads up to 700kN and to depths up to 14.0m.

On completion of the external piling works, Taranto Ltd carried out static pile testing to both the Precast driven piles and the tubular steel driven piles. Due to the limited working room and site levels, Taranto Ltd completed the testing works using a static reaction frame test. Using this testing method eliminated the need and expense of providing bulky kentledge weights to site.

Experience

The existing buildings, location, site access and restrictions on site vibration and movement provided several difficulties to the construction management team in the planning and organisation of this technical challenging construction project.

Taranto Ltd worked liaised with main contractor, Purcell Construction and project engineers, Arub Consulting, at the planning stages of the works to provide engineering solutions and cost effective method of construction which could provide the loading requirement whilst coping with the site access restrictions and other constraints.

As the works progressed, several unforeseeable problems were encountered, including the presence of previously unknown low-level structures and existing walls. Throughout the project, Taranto Ltd continued to work closely with the project construction management team to overcome the difficulties of this site and to progress the construction works in line with programme.