To monitor this excavation, extensive instrumentation has been installed. Soil Instruments supplied Inclinometers and De-airable Vibrating Wire Piezometers to its sister company ITM, who installed the instruments, in conjunction with Geotech Specialist of Cork who formed the holes.

The work started after completion of a trial excavation alongside the main site to determine the construction characteristics of the boulder clay strata, with lenses of sands and gravel overlying Limestone bedrock. From the trial the angle of excavation was determined along with the soil nailing spacing. The trial excavation instrumentation was also supplied and installed by ITM-Soil, to determine the instrumentation requirements for the main works.

Before excavation started on the main works, instrumentation was installed every 20 metres on both sides. Inclinometers were installed for measuring lateral ground movement, along with De-airable Vibrating Wire Piezometers at 12m, 8m and 4m depths to monitor negative pore water pressure in the boulder clays during the excavation. The piezometers were all terminated to dataloggers for the automated recovery of data; these were downloaded daily by the main contractor.

All the instruments are now installed and providing data. During the next phase of the works, we may instrument some of the soil nails with Strain Gauges, for a research project by University College Dublin in the use of soil nails in boulder Clay strata.