Offshore Cone Penetration Testing and Sampling Support

Client

Alpine Ocean Seismic Survey

Services Provided

Offshore support for CPT testing, Offshore Quality Assurance and processing of CPT results, Offshore support for vibrocore and borehole sampling , Offshore geotechnical testing and soil classification

A worker in safety gear stands on a weathered wooden deck near equipment suspended over the ocean by an orange crane structure, with blue sky and scattered clouds in the background.

Location

Offshore New Jersey

Project Practice Areas

Geotechnical

Type of Facility

Offshore Wind Farm

Project Specifics

Ocean Wind is New Jersey’s first utility-scale offshore wind farm.

The wind farm will consist of nearly 150 turbines and will be constructed approximately 15 miles off the coast of southern New Jersey. Ocean Wind is scheduled to be operational in 2024 and ultimately will supply 1,100 megawatts (MW) to more than 500,000 homes. The objective of this phase of the project was to investigate offshore soils at selected locations for the inter-array cable and three separate export cable routes. The investigation included ball and piezocone Cone Penetration Testing (BCPT, CPTu), Thermal Resistivity Testing, vibrocore sampling, and borehole sampling.

Geosyntec Scope of Services

Geosyntec was requested by our client to provide personnel to support offshore CPT and sampling activities. The CPT support included quality assurance (QA) checks and data processing. QA checks confirmed testing was performed in accordance with project specifications and tolerances. The team also provided technical documentation for on-vessel changes in procedures as well as supporting documentation for cases in which cones were lost and left at the seabed or when bumpovers were required. CPT processing included the determination of derived parameters such as corrected tip resistance, friction ratio, normalized pore pressure ratio as well as estimated properties such as undrained shear strength, relative density/ friction angle and provide a preliminary estimate of stratigraphic units and provide preliminary graphs for measured and calculated test data.

Notable Accomplishments

Geosyntec had multiple personnel BOSIET certified to be able to perform the offshore work safely and effectively. Several deployments occurred during the 2020 global COVID pandemic. Geosyntec was able to follow quarantine requirements and provide multi-week offshore support on short notice when our client’s staff was unavailable due to ever-changing travel restrictions, with none of the involved Geosyntec personnel impacted by COVID. Following our offshore work performing CPT support, we developed procedures and data analysis tools to perform CPT QA and process CPT results while offshore.

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