This site in the heart of the city centre was ripe for redevelopment and selected to create modern office space. On a corner site, spanning Dawson Street and Molesworth Street, the original building was demolished to create a new office with a triple basement providing storage, parking and state-of-the-art facilities for future occupants.
Murphy was selected to install secant and contiguous bored piles to act as a retaining wall for the triple basement, bearing piles to support the internal columns and a tower crane, as well as installing four well points. Due to the specifics of the project, Murphy selected three different Bauer piling rigs to deliver the required specifications for the building.
At planning stages, the client had specified a large quantity of small diameter piles to be installed. The expert Murphy engineers suggested using a smaller quantity of piles with a larger diameter instead. This would speed up the programme as less boring would be required. The design was proposed and the client agreed to it, saving further time and money on the project.
Due to the site itself being located in central Dublin, on a corner site, with access only on one side there were restrictions which were taken into account by Murphy throughout the project. Logistically, piling work throughout the project needed to pause to allow access to the site for deliveries. In addition, the restricted site did not have enough room for the three rigs at all times, so deliveries and removal of rigs were carefully coordinated to ensure minimal down-time for the rigs and crew.
One of the most important considerations was the movement of plant at the site. To overcome this a number of measures were put into place. All Murphy piling operatives are trained banksmen, signallers and slingers, and two were assigned to each rig. The foreman and engineer were also trained as banksmen, signallers, slingers and regular update meetings were held to inform all staff off the potential hazards. All rigs were fitted with mirrors and cameras, for 360 degree views at all times. In addition, the work was carefully coordinated, allocating each rig to a specific area to ensure each was working as far away from each other on the site as possible.
There were 213 piles in total, constructed in both 900mm and 1200mm diameter. Pile depths varied in length between 10m – 21m. The rock socket lengths also varied between 0.5 – 9m long. There were a number of these piles chosen for further monitoring. This involved placing an inclinometer tube inside the pile. This is used to determine whether the pile is deflecting during the dig. The four well points were constructed using 600mm diameter casing. A 250mm OD plastic pipe was installed and surrounded with gravel.
Murphy expertise meant that the project team were extremely well equipped to work with rock sockets that others would struggle with, which further speeded up the project for the client.
The safety, health, environment, sustainability and quality systems (SHESQ) implemented by Murphy received high praise from the client-side safety officer, which is testament to the high quality work of the Murphy team.