The North Irish Sea Array, also known as NISA, is an offshore wind energy development project located off the coast of counties Dublin, Meath, and Louth. The project will significantly contribute to the development of a clean, renewable energy future. Once operational, the anticipated 35 to 46 turbines for the site are expected to produce clean renewable energy for approximately 500,000 homes and businesses.
The drilling operations utilized a piggyback system to gather core samples of the mudstones and stiff clays for physical sampling, classification, and stress testing. Once each borehole had reached its target depth, the RGS engineer deployed three probes: the PS Logger®, 3-Arm Caliper Gamma and High Resolution Acoustic Televiewer (HRAT)®.
The caliper was run first to check borehole integrity and to provide useful QC information for the subsequent PS Logging. The acoustic televiewer produced an unwrapped oriented image of the borehole wall, delineating bed boundaries and fractures, as well as giving deviation data for the borehole. The PS Logger® probe measured P and S wave velocities at 1m intervals at depths to 65m. The resulting strength parameters derived from the velocities were to be used to feed into the foundation design calculations together with data from other sources including CPT and laboratory testing.
