Forensic Review of Solar Farm Piles Post Construction

Apr 3, 2020 | Compaction Control, Soil & Site Investigation

We always like getting involved in helping our clients solve difficult problems. This was on one of the world’s largest grid-connected PV power plants.  

Thousands of solar PV tracking panels across several hectares were built in NSW as a solar farm. However the project had been rushed to be finished. 

After noticing some of the solar panels were beginning to lean and ground subsidence around some piles, it was necessary to understand and quantify the problem and it’scause, identify where the focus of rectification efforts needed to be and to evaluate different rectification methods. Left unchecked, the panel frame could become distorted, cracking PV panels and preventing the tracking mechanism from operating. Further, there was a risk of pull-out failures due to the wind. 

Pull test and lateral tests were time consuming to carry out on the fully constructed and operational solar farm and required the PV panels themselves to be removed. 

Aurecon saw an opportunity with the PANDA® probe to: 

  • Better understand the problem (lack of compaction around the piles)
  • Triage the site to quantify the magnitude of the problem and focus rectification efforts 
  • Assess different rectification approaches against each other to better understand the problem (lack of compaction around the piles) 

Further, due to the solar farm being post construction, it was necessary to use a tool that could be operated underneath the panels and very close to the piles. 

The PANDA® Instrumented Variable Energy Dynamic Cone Penetrometer (DCP) is used to identify the strength vs depth profile for soil investigation and compaction control. If tip resistance was consistently high over the full pile depth, then there wouldn’t be an issue with the piles and they would pass the pull test and lateral test. 

For more information on the PANDA® Instrumented DCP and purchasing, rental and training options, please visit our website @ 

Our Plate Load equipment is getting a lot of use. We’re very happy with it. 🙂

Mary Flux

Director & Engineering Geologist, WANT Geotechnics

We find the Insitutek team extremely helpful and their knowledge of the equipment and its capabilities is a great resource for our staff.

Lucas Pardo

Principal, LR Pardo & Associates

The Light Weight Deflectometer (LWD) was first used in 1998 by the Minnesota Department of Transportation (Mn/DOT) at the Minnesota Road Research Project. Starting in 2005 the LWD has been used by Mn/DOT as an acceptance tool for the compaction of roadbed and miscellaneous embankment and trench construction, culvert treatments and other tapered construction.

Minnesota Department of Transportation (Mn/DOT)

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