1.3 Geotechnical Investigation



Identify the physical characteristics of the subsoil at the proposed wind turbine locations.


Inconclusive survey results, additional surveys required, results causing overly conservative foundation designs.

Forte’s Risk Mitigation:

At Forte we ensure top quality by

1) issuing a detailed specification which outlines clearly the required results and related format

2) monitoring investigations as they progress and

3) lead value engineering meetings at completion to promote optimised designs.

1.2 Geo -Pic3
1.2 Geo -Pic1

√ Specification to ensure best value survey for client  

√ Value Engineering to facilitate optimised foundations



Geotechnical Site Investigations are complex surveys. Defining the extent of required investigations requires understanding of the local terrain, knowledge of different investigation techniques and a keen awareness of the cost benefit analysis of using such techniques.

If handled correctly additional surveys can often be avoided, saving additional survey costs and avoiding delays to the wind farm engineering process.


1) Sign a) multiple work package (“EPC Manager”) contract or b) single-work package contract with Forte.

2) Issue all required information to commence survey

3) Arrange all accesses to survey areas with landowner

*Forte can execute the survey with its partner or manage the Clients appointed surveyor


1. Documentation Check (Desk Study)

Review of project documentation to identify what constraints are to be considered when conducting the survey. Review of national databases to identify the regional soil characteristics, historical activities in the local area and historical flooding patterns


2. Scope Definition and Specification Confirmation

  • After desk study completion, finalise the required scope and specification of deliverables.
  • The details will be shared with the client so they can provide feedback if desired.


3. Fieldwork

After obtaining access to site (action by client with support from Forte) survey will be conducted in accordance with specification.


4. Site Investigation Reporting

  • Sample Examination and Testing:
  • Soil Laboratory Analysis: testing of chemical properties of soils found
  • All survey information will then be processed and borehole logs interpretative reports prepared.


5. Value Engineering and Final Report Issuance

  • After issuance of the draft deliverables discussions will be held with the Forte foundation design team to provide clarifications to technical queries and to promote optimised foundation design.
  • Any errors or discrepancies identified will be rectified in revised reports and thereafter issued to the client.


1) Site Investigation Report:

Desk Study and Site Investigation findings report including the following: borehole logs and laboratory analysis results, summary of expected soil properties at each WTG location, expert opinion on conducting excavations and soil improvement measures required


2) Engineering Report:

After receipt of preliminary foundation design from the foundation design team, the soil behaviour of the ground when supporting the proposed foundation will be examined to confirm suitability.


3) Hydrogeological Survey Report (Optional):

Results of desk study into local regional water table behaviour including analysis of local databases and results of onsite investigations to determine maximum expected water tables at each wind foundation location within the wind farm site.

√ Result: Result: Identification of the physical characteristics of a representative sample of the soils below ground level so that it can be considered in the wind farm design..






Note: It is not possible to mitigate all geotechnical risks prior to the construction phase as even extensive surveys only provide a small representative sample but with best management practices geotechnical risks can be minimised.

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