Geotechnical investigations were needed for preliminary design of the horizontal directional drilling (HDD) necessary to connect the offshore cable to an onshore vault. Utmost attention to detail was needed in order to support the project team’s commitment to making the high-profile offshore wind project a benefit to the community and stakeholders.


Energy generated by the turbines would be transmitted by multiple submarine transmission cables that would make landfall at one of two potential landfall sites. The submarine cable landfall is the critical link connecting the offshore submarine cable to the onshore electrical vault before continuing to the onshore interconnection substation further inland. GZA led a subsurface investigation program consisting of 100-foot-deep geotechnical test borings and an extensive geotechnical and thermal resistivity laboratory testing program. The work entailed classification of the subsurface conditions, in support of the HDD cable landing and associated support of excavations. GZA interpretated subsurface conditions and potential obstructions that could impede the HDD process. The work was completed in a compressed time schedule during the winter months, to reduce the impact on seasonal tourism. Coordination with local officials for protection of natural resources and for the health and safety of the public were paid the utmost attention.


The project was completed on time and on budget and with a positive impression of the project team for the public.