Geotechnical Engineering Consulting for Wind and Solar Projects
Let’s Build on a Solid Foundation!
Assessing geotechnical uncertainty is at the heart of civil and foundation design of wind farms and solar parks. Our strong academics combine with decades of field investigation experience and design practice to qualify us to provide reliable and optimized solutions. We have reviewed and produced countless geotechnical studies for utility-scale wind and solar across North America and followed through with many of these studies to the construction phase. We are familiar with the key parameters, the geohazards to look out for, and what works and what doesn't. Our geotechnical consulting services include:
Desktop Studies
Before anyone sets foot within a project area, we can provide desktop studies that contain indications on the expected site geotechnical and geologic conditions. The quality and breadth of the information depends on available resources for the project area, which we augment using our extensive North American experience. However, no matter how little can be gleaned from public domain and commercial tools as well as published resources, a desktop study is well worth its cost. As outlined in this blog entry, the opportunity to make an impact is highest during the early stages of project development and drops quickly as a function of project advancement. The reverse is true for the cost of making changes: it starts low during project development and increases rapidly as a function of project advancement as project parameters become set in stone. Hence, desktop studies are really important.
Preliminary Investigations
We typically perform preliminary geotechnical investigations for project owners and developers. This is where limited exploration activities are carried out to develop preliminary design information typically used for initial pricing exercises by owners and developers. Depending on desktop study results and the proposed project layout, we can design a preliminary geotechnical investigation scope that achieves those purposes without missing critical and costly geohazards. We can then carry out the investigation and produce a preliminary geotechnical investigation report.
Design-Level Investigations
We are typically retained either by the developer/owner or the selected EPC contractor to take the preliminary investigation to design-level status. This is when every WTG location is explored and design parameters are developed for each location and for project components such as access roads, substation support structures, O&M building, etc. The deliverable product of this work is a final and full investigation report which forms the geotechnical design basis for the project.
Specialty Testing & Geophysical Surveys
These include Multi-Analysis of Surface Waves (MASW), Ground Penetrating Radar (GPR), Electrical Resistivity (ER) surveys, Thermal Resistivity (TR) testing, Pile Load Testing (PLT) and Electrical Imaging (EI). We only subcontract leading, reputable testing firms to perform these services and have established working relationships across North America. The reports of such specialty testing are included as appendices to the geotechnical report which we produce.
MASW Surveys
For utility-scale wind projects, MASW surveys are typically performed at a subset of WTG locations, preferably as part of the preliminary geotechnical investigation and immediately after drilling the preliminary investigation borings. They should be scattered around the project area with a conscious effort to capture the variability of geotechnical settings across the project area.
ER Surveys & TR Testing
We recommend that electrical and thermal resistivity testing be performed as soon as the layout of the collection system and the substation location have been defined. This should preferably coincide with the preliminary geotechnical investigation to allow for changes in the collection system configuration if necessary based on the ER and TR test results.
Ground Penetrating Radar
For utility-scale solar projects, GPR is useful in detecting depth of bedrock or assessing abundance of cobbles, if driven or helical piles are being considered.
Pile Load Testing
Geotechnical investigations for solar projects often involve pile load testing to characterize the resistance of piles, across the project area, to uplift, lateral and compressive loads applied by the PV racking structures. Such testing is essential to achieve optimized foundations for the facility.
Electrical Imaging
We sometimes recommend electrical imaging to assess presence of voids, particularly below wind turbine foundations. The results of such imaging lead to recommendations relative to potential grouting to fill such voids.
Geotechnical Basis Review
What if geotechnical investigations have already been completed and one or more of the project stakeholders are interested in a peer review of the geotechnical basis? That’s where we could come in to offer a professional review capitalizing on our knowledge and experience for the benefit of the project and everyone involved.
Construction Support (QA/QC)
We offer construction support services in the form of quality assurance / quality control (QA/QC) of geotechnical aspects such as review of data collected per specifications and approvals of foundation subgrades.