EXPERT REPORT CONCERNING GEOLOGIC AND HYDROGEOLOGIC ASPECTS OF TETRA4’S CLUSTER 2 VIRGINIA GAS PRODUCTION PROJECT, VIRGINIA, FREE STATE PROVINCE, SOUTH AFRICA

This expert report, prepared by Sustainable Surface and Groundwater Solutions (SSGS) for the Centre for Environmental Rights, reviews the revised groundwater component of the Environmental Impact Assessment (EIA) for Tetra4 (Pty) Ltd's proposed Cluster 2 expansion of a natural gas field near Virginia, Free State Province. The review concludes that the assessment is fundamentally flawed in its methodology, data interpretation, and numerical modeling, rendering it an unreliable basis for decision-making.

• The geophysical survey methodology was flawed because the seven traverses were oriented parallel to the target lineament, which contradicts standard practice of orienting traverses across a feature to gather informative data. Furthermore, the report failed to interpret magnetic data to assess the lineament's dip, and only two of five new boreholes intersected intrusive dolerite rocks, suggesting the attempt to target preferential pathways was unsuccessful.
• The drilling program is considered inadequate for the 187,000 ha area, as only five new boreholes were drilled. Only three of these five boreholes intersected water strikes, indicating the program may have failed to effectively assess preferential pathways and provide a representative sample of hydrogeological conditions.
• The interpretation of aquifer testing data lacks scientific justification. The report does not specify the aquifer types identified or provide the rationale for selecting specific analytical solutions—such as Theis, Neuman, or Walton's methods—for different data sets.
• The numerical modeling approach contains several critical errors: it uses constant head boundaries for rivers (neglecting possible infiltration zones), models known faults as porous equivalents instead of Discrete Feature Elements (DFEs), and includes a 30-metre-thick dolerite sill throughout the domain without providing supporting borehole logs or fieldwork data.
• Transport modeling is inadequate because it omits diffusion coefficients and fails to use multiphase models. Multiphase modeling is necessary to capture the migration of methane as both dissolved and free gas phases, including capillary and buoyancy-driven migration.
• Model calibration is questioned because up to 75% of recorded water levels may represent dynamic rather than natural static conditions. Additionally, a significant discrepancy of 21.63 metres was reported between simulated and observed water levels for borehole RTBH10 in the steady-state calibration, casting doubt on the validity of the transient calibration.

APA

de Lange, D. F., & Lukas, D. A. (2025). EXPERT REPORT CONCERNING GEOLOGIC AND HYDROGEOLOGIC ASPECTS OF TETRA4’S CLUSTER 2 VIRGINIA GAS PRODUCTION PROJECT, VIRGINIA, FREE STATE PROVINCE, SOUTH AFRICA. Centre for Environmental Rights. https://cer.org.za/wp-content/uploads/2026/04/Expert-report_Tetra4_de-Lange_10122025_rev1.pdf?x21779

Chicago

de Lange, Dr F, and Dr A. Lukas. EXPERT REPORT CONCERNING GEOLOGIC AND HYDROGEOLOGIC ASPECTS OF TETRA4’S CLUSTER 2 VIRGINIA GAS PRODUCTION PROJECT, VIRGINIA, FREE STATE PROVINCE, SOUTH AFRICA. Centre for Environmental Rights, 2025. https://cer.org.za/wp-content/uploads/2026/04/Expert-report_Tetra4_de-Lange_10122025_rev1.pdf?x21779.

Wikipedia

{{cite report |last1=de Lange |first1=Dr F |last2=Lukas |first2=Dr A. |title=EXPERT REPORT CONCERNING GEOLOGIC AND HYDROGEOLOGIC ASPECTS OF TETRA4’S CLUSTER 2 VIRGINIA GAS PRODUCTION PROJECT, VIRGINIA, FREE STATE PROVINCE, SOUTH AFRICA |publisher=Centre for Environmental Rights |date=October 2025 |url=https://cer.org.za/wp-content/uploads/2026/04/Expert-report_Tetra4_de-Lange_10122025_rev1.pdf?x21779 |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{delange2025expert, author = {de Lange, Dr F and Lukas, Dr A.}, title = {{EXPERT REPORT CONCERNING GEOLOGIC AND HYDROGEOLOGIC ASPECTS OF TETRA4’S CLUSTER 2 VIRGINIA GAS PRODUCTION PROJECT, VIRGINIA, FREE STATE PROVINCE, SOUTH AFRICA}}, institution = {Centre for Environmental Rights}, year = {2025}, month = oct, url = {https://cer.org.za/wp-content/uploads/2026/04/Expert-report_Tetra4_de-Lange_10122025_rev1.pdf?x21779}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }