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 @ 

The PANDA probe is giving us and the construction team very useful insight with immediate feedback on the compaction being achieved on a major new rail construction project in QLD. We have two teams working daily using PANDA DCP’s and the Automatic Hammer on the rail formation, enabling real time decision making with confidence, based on the highly repeatable results.

Federico Velasquez

Senior Geotechnical Engineer, CMW GeoSciences

I felt the training was very thorough. If anyone doesn’t know how to use a PANDA after that session, they shouldn’t be using one at all.

Sam Bamford

Laboratory Division Manager, Protest Engineering

We purchased a PANDA 2 machine after using one from another laboratory. The information obtained has saved money on numerous jobs. It is reasonably priced and the after-market service has been great. Highly recommend using Insitutek.

Brett McDonald

Department of Transport and Main Roads, QLD

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