GEO3701 Project Year 2026 Geology for Engineers 2026

UNIVERSITY OF SOUTH AFRICA (UNISA)
College of Science, Engineering and Technology



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Geotechnical Desktop Study for the Proposed Dam and
Reservoir Development at Ga-Mathipa/Ragopola,
Fetakgomo-Tubatse Local Municipality,
Limpopo Province, South Africa
Geology for Engineers — Project, 2026


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Module Code: GEO3701

Module Name: Geology for Engineers

Semester: Project Year 2026




Submitted in partial fulfilment of the requirements for Engineering Geology (GEO3701)
at the University of South Africa.

,UNISA | GEO3701 Geotechnical Desktop Study: Ga-Mathipa/Ragopola Dam



Declaration

I hereby declare that the project work entitled “Geotechnical Desktop Study for the Proposed
Dam and Reservoir Development at Ga-Mathipa/Ragopola, Fetakgomo-Tubatse Local Munici-
pality, Limpopo Province, South Africa” is a record of an original work done by me. The results
embodied in this report have not been submitted to any other university or institute for the
award of any degree or diploma.




Name. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Surname. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .




Student Number. . . . . . . . . . . . . . . . . . . . . . . . Contact Number. . . . . . . . . . . . . . . . . . . . . . . . . . . .




Signature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Date.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .




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,UNISA | GEO3701 Geotechnical Desktop Study: Ga-Mathipa/Ragopola Dam



Contents


Declaration 1


1 Introduction 4

1.1 1.1 Purpose and Importance of Geological Investigation for Dam Works . . . . . 4

1.2 1.2 Role and Scope of a Desktop Study . . . . . . . . . . . . . . . . . . . . . . . . 5


2 Site Description 6

2.1 2.1 Site Access and Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6


3 Climatic (Weinert Area) and Topographic Data 7

3.1 3.1 Climatic Conditions and Weinert N-Value . . . . . . . . . . . . . . . . . . . . 7

3.2 3.2 Topographic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8


4 Identification of Geology 9


5 Identification of Problem Soils/Geology 11

5.1 5.1 Expansive (Heaving) Clays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5.2 5.2 Collapsible and Erodible Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5.3 5.3 Weathering Profile Variability . . . . . . . . . . . . . . . . . . . . . . . . . . . 12


6 Assessment of Discontinuities and their Engineering Implications 13

6.1 6.1 Primary Igneous Layering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

6.2 6.2 Cooling Joints and Fracture Sets . . . . . . . . . . . . . . . . . . . . . . . . . 13

6.3 6.3 Faulting and Shear Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13


7 Field and Laboratory Investigation Proposal 15

7.1 7.1 Geophysical Reconnaissance . . . . . . . . . . . . . . . . . . . . . . . . . . . 15




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,UNISA | GEO3701 Geotechnical Desktop Study: Ga-Mathipa/Ragopola Dam


7.2 7.2 Boreholes and Trial Pits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

7.3 7.3 In-Situ Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16


8 Occupational Health and Safety (OHS) Requirements 18


9 Environmental Consideration 19


10 Conclusions and Recommendations 20


References 22




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, UNISA | GEO3701 Geotechnical Desktop Study: Ga-Mathipa/Ragopola Dam



1 Introduction

The successful planning and design of civil engineering infrastructure depends on a sound
understanding of the geological conditions present at a site. Engineering geology applies ge-
ological principles to engineering practice by identifying and evaluating rock formations, soil
characteristics, groundwater conditions, geological structures and potential geohazards that
influence the safety, stability and long-term performance of a structure (Wessels, 2021:12). Ev-
ery engineering structure is founded on or within soil or rock, so a geological investigation is
an unavoidable part of project planning, site selection, design and construction. Understand-
ing the geology of a site allows an engineer to identify geotechnical constraints early, during
planning and design, and to build in mitigation measures that bring the engineering risk down
to an acceptable level.

This report presents a geotechnical desktop study for a proposed small dam and reservoir at
Ga-Mathipa/Ragopola, within the Fetakgomo-Tubatse Local Municipality in the Sekhukhune
District of Limpopo Province. The municipality lies within the Sekhukhune District Municipal-
ity and was formed in 2016 through the merger of the former Fetakgomo and Greater Tubatse
local municipalities (Fetakgomo Tubatse Local Municipality, n.d.). The dam is intended to
supply water to the surrounding rural communities and to support small-scale irrigation.


1.1 1.1 Purpose and Importance of Geological Investigation for Dam Works


Dam and reservoir projects place unusually heavy demands on the geology of a site because
the safety of the structure depends directly on the competence of the foundation and on
the behaviour of the reservoir basin once it is impounded. Rock type, degree of weathering,
the pattern and orientation of discontinuities, groundwater conditions, permeability, faulting
and the presence of problematic soils all bear directly on foundation stability, seepage loss,
differential settlement and, in the worst case, structural failure. A geological investigation
gives the engineer the means to anticipate these hazards, to estimate material properties
before construction begins, and to choose a design and construction method suited to the
ground that is actually there rather than the ground that was assumed.




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