Environmental Hydrogeology of Ramotswa South East District, Republic of Botswana

Bundesanstalt für Geowissenschaften und Rohstoffe

by Michael Staudt

Edited by Dr. H. Vogel January 2003

TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ...... 1

ABSTRACT ...... 1

1 INTRODUCTION ...... 2

2 PHYSIOGRAPHY AND GEOLOGY IN BOTSWANA ...... 3

3 CLIMATE AND WATER AVAILABILITY IN BOTSWANA ...... 5

4 PHYSIOGRAPHY AND CLIMATE IN THE PROJECT AREA ...... 7

5 GEOLOGY IN THE PROJECT AREA ...... 10

6 HYDROGEOLOGY IN THE PROJECT AREA ...... 12

7 METHODS AND MATERIALS ...... 13

8 RESULTS ...... 15 8.1 Environmental hydrogeology maps ...... 15 8.2 Groundwater classification ...... 18 8.3 Groundwater quality ...... 20 8.4 The case of nitrate ...... 27

9 DISCUSSION AND CONCLUSIONS ...... 34

10 REFERENCES ...... 35

11 APPENDICES ...... 37 I Borehole location map ...... 38 II Map of potential environmental hazards ...... 39 III Groundwater flow direction map ...... 40 IV Results of the chemical analyses of the main elements ...... 41 V Results of the chemical analyses of trace elements ...... 44 VI Logs of selected sampled boreholes ...... 48

LIST OF FIGURES

Page Figure 1: Botswana - administrative districts and location of the Ramotswa study area ...... 2 Figure 2: Physiographic regions and annual rainfall distribution in Botswana ...... 4 Figure 3: Drainage basins in Botswana ...... 5 Figure 4: Depth to groundwater in Botswana ...... 6 Figure 5: Consolidated water demand estimates (1990 to 2020) ...... 7 Figure 6: Mean monthly rainfall in Ramotswa (1959 to 1998) ...... 9 Figure 7: Mean annual rainfall in Ramotswa (1959 to 1998) ...... 9 Figure 8: Geological map of the study area ...... 11 Figure 9: PIPER diagram ...... 18 Figure 10: Water reaction (pH) levels in the study area ...... 20 Figure 11: Groundwater temperatures in the study area ...... 21 Figure 12: Electrical conductivity in the study area ...... 21 Figure 13: O2 values in the study area ...... 22 Figure 14: TDS values in the study area ...... 23 Figure 15: HCO3 concentrations in the study area ...... 23 Figure 16: Sulfate concentrations in the study area ...... 24 Figure 17: Chloride concentrations in the study area ...... 25 Figure 18: Sodium concentrations in the study area ...... 25 Figure 19: Magnesium concentrations in the study area ...... 26 Figure 20: Sources and pathways of nitrogen in the environment ...... 28 Figure 21: Nitrate levels in the study area ...... 29 Figure 22: The Ramotswa sewerage system ...... 31 Figure 23: Nitrate levels in selected boreholes in 1983 and in 2001 ...... 32 Figure 24: Trend line for DWA well 4422 ...... 33 Figure 25: Trend line for DWA well 4349 ...... 33

LIST OF TABLES

Table 1: Landforms, geology, vegetation, and soils in the study area ...... 8 Table 2: Stratigraphy of the Transvaal supergroup in the Ramotswa area ...... 10 Table 3: Summary of aquifer and borehole statistics for the Ramostwa wellfield ...... 13 Table 4: Legend of the borehole location map and status of the boreholes ...... 16 Table 5: Typical point and area hazards ...... 17 Table 6: Groundwater classification according to FURTAK & LANGGUTH ...... 19 Table 7: Sanitation facilities by housing types in 1985 ...... 30 Table 8: Sanitation facilities by households in 1991 ...... 30

ACKNOWLEDGEMENTS

I extend a heartfelt thank you to my two supervisors, Dr. Horst Vogel and Prof. Dr. Klaus- Dieter Balke. Dr. Vogel’s practical help and guidance in Botswana, as well as his continued help and supervision, made this project and my experience a very positive one. I also like to thank Professor Balke for his supervision at the University of Tübingen (Germany) and for his offer to carry out this project.

I thank my dear friend Benjamin Mafa for his hospitality in Botswana and the insights he gave me into the every-day life of his beautiful country.

Special thanks go to Fredrick “Pine” Dithapo and Jerry Setlhomo, my field assistant and technician respectively. Without their help the project would not have been possible. Thank you so much, and all the best to you.

I also thank the following persons for their help: Antje Wolff for her support in using the ArcView GIS software and for printing the maps at BGR HQ, Susanne David for her introduction into the soils of the Lobatse Estate, Susanne Stadler for converting the GeODin- software files into the PDF format and for sending off my literature to Freiburg, Dr. von Hoyer for his background information on the Ramotswa wellfield, Mrs. B.M. Ghandi at the SE district council for her useful information, Dr. Siewers for carrying out the chemical analyses of the groundwater samples at BGR HQ, the Hydrogeology Division at the DGS, in particular Thomas Kellner; the Chemistry Division at the DGS, in particular Teddy Ditsabatho, the Cartography Division at the DGS, the staff of the Geological Information Center at the DGS, Jason Hawley and Dave Baker from Africa Surveys Botswana (Pty) Ltd. for the GPS precision survey, Katharina Beger for her pre-Botswana information and advice, the drivers and workers of the DGS, and finally all people who contributed to this work in one way or another, in particular the inhabitants of Ramotswa and Taung (Ramotswa station).

ABSTRACT

Since its independence from Britain, Botswana has experienced enormous economic growth. When it gained independence in 1966 it was one of the poorest countries in the world. There were no programs in place to provide for education, health, telecommunication, roadway development, or water systems. The discovery of diamonds one year later changed everything and set into motion intense economic development that is still unabated. In fact, during the 1980s and 1990s, Botswana had one of the fastest growing economies in the world due to its mineral wealth.

But Botswana also has its problems. The relationship between accelerated economic growth, a growing population (1,326,796 in 1991), and environmental limitations such as adverse climatic conditions, present a formidable challenge for sound water management. Hence, identifying those areas where groundwater has been, or is going to be, impacted upon by anthropogenic activities can help planners address Botswana’s looming water-management crisis by focusing on land-use planning programs and monitoring vulnerable areas.

One vulnerable area is the village of Ramotswa, which experienced one of Botswana’s worst cases of groundwater pollution during the 1990s. The successful promotion of pit latrines and the location of Ramotswa on top of Botswana’s most productive dolomite aquifer meant disaster as human wastewater polluted the shallow aquifer in no time at all. As a result, the

1 entire wellfield had to be abandoned in favor of surface water from the dam in the nearby capital city of Gaborone.

In 2001, the Environmental Geology Division at the Department of Geological Survey (DGS) decided to carry out an environmental hydrogeology mapping exercise in Ramotswa because the Ramotswa aquifer is the most productive in a country where water resources are scarce. During the exercise, groundwater samples were taken from a total of 31 boreholes. Among these, 11 featured elevated nitrate levels. The recorded maximum nitrate concentration was 442 mg L-1. It is assumed that the observed concentrations are still due to human waste. An additional area of pollution was found in the industrial complex at Ramotswa station.

Fig. 1: Botswana - administrative districts and location of the Ramotswa study area

1 INTRODUCTION

This study was carried out as part of a technical co-operation project between the Department of Geological Survey (DGS) in Lobatse (Botswana), and the Federal Institute for Geosciences and Natural Resources (BGR1) in Hannover (Germany).

The study objective was to establish the quality of the groundwater resources in Ramotswa (Fig. 1),

1 BGR is the German acronym for „Bundesanstalt für Geowissenschaften und Rohstoffe“

2 and to produce environmental hydrogeology maps based on the collected environmental data sets for regional and urban planners. The borehole location map (Appendix I) pictures the present distribution and accessibility of all boreholes in the project area. The environmental hazard map (Appendix II) depicts the areas and point locations where potential groundwater hazards and hazards to the settlement such as fuel stations, industrial zones, septic tanks and/or flood-prone areas exist. The groundwater flow direction map (Appendix III) gives a description of the potentiometric surface in meters above mean sea level (m a.m.s.l.), and highlights the groundwater flow and the distribution of watersheds. In addition, the third map describes groundwater quality (chemistry) as per October and November 2001, when fieldwork was carried out.

2 PHYSIOGRAPHY AND GEOLOGY IN BOTSWANA

Botswana is a landlocked country covering an area of approximately 582 000 km2. It is situated between latitudes 20-29° east of Greenwich, and longitudes 18-27° south of the equator. The “Tropic of Capricorn” (23.5° S) divides the country into a tropical North and a subtropical South.

Geomorphologically, Botswana is part of the so-called “Plateau Africa”. Hence, the relief is flat to gently undulating with an average altitude of 1000 m a.m.s.l. The highest point is Otse Hill (1491 m a.m.s.l.), close to Lobatse. Generally, Botswana may be divided into three physiographic regions, namely the sandweld, the hardveld, and the Okavango delta northwest of Maun (cf. Fig 2).

The so-called sandveld comprises two thirds of the country. The thickness of the sand stratum varies, but it may reach 500 m. The region features fossil and mobile sand dunes. The predominant vegetation is shrubs and grassland.

The sandveld region receives the least amount of rainfall (250-300 mm/a), therefore surface water is strictly limited. The Kalahari is dotted with many pans, which hold water during the rainy season. Most settlements are near those pans where wells may be dug to extract the groundwater beneath the pans. In addition to the pans, fossil river systems (mekgacha) occur in the Kalahari. It is believed that these were active river systems in pluvial times. Today some high-yielding aquifers are found beneath such formations.

The hardveld region consists of hills and alluvial river plains. This region is located in the eastern part of Botswana where rainfall is higher, and where the majority of the population lives. The region is characterized by hills of different type and origin. The vegetation is shrub and/or tree savanna, depending on the location. The formation of erosion gullies is a prevalent process wherever the vegetation cover is removed. This process is favored by the high rainfall intensity and shallow soils.

The oldest rocks are the Archaean basement complex rocks of the Zimbabwe and the Kapvaal cratons with an age of approximately 3000 Ma. The two cratons are linked together by the intercratonic Limpopo Belt. They are comprised of igneous and metamorphic rocks, mainly schists (greenstone belts) and gneisses, marbles and quartzites. Surface outcrops are found only in the eastern part of the country. In addition, volcanic rocks were formed, for example the Kanye Volcanic Formation and the Lobatse Volcanic Group

Between 2900 and 2500 Ma igneous intrusions, mainly granites and dolerites, were formed. The Gaborone granite complex, a large intrusive granite body, can be found in the southeast of Botswana. The Gaborone granite complex is overlain by younger sedimentary rocks - starting with the Transvaal Supergroup, followed by the Otse Group, the Waterberg Group, and the Palapye Group. These sequences were probably deposited between 2500 and 1700 Ma. They consist of different lithologies such as sandstones, shales, conglomerates, and quartzites, reflecting the

3 different cycles of transgression and regression during the sedimentation process. Most outcrops (inselbergs, kopjes) occur in the east, forming hilly regions.

Fig. 2: Physiographic regions and annual rainfall distribution in Botswana

Between 630 and 500 Ma the Damara orogenic belt was formed during the Pan-African orogeny. These rocks consist of successions of volcanic and sedimentary rocks, metamorphites and granitoids.

In the Phanerozoic eon, the Karoo Supergroup was deposited comprising successions of sedimentary and volcanic rocks, which have a widespread outcrop within the Southern African subcontinent. In Botswana they unconformably overlie about 70% of the Archaean and Proterozoic rocks. In the Ecca subgroup, Botswana’s coal resources are located.

The largest part of the country consists of the Kalahari sand beds, which are the youngest sediments in Botswana. They cover 70 % of the land surface. These wind-blown sand sediments were deposited in the Kalahari basin depression during the last thousands of years. The Kalahari basin depression is encircled by highlands including the Drakensberg in South Africa, the Namibian highlands, and the Bie plateau in Angola.

3 CLIMATE AND WATER AVAILABILITY IN BOTSWANA

Botswana’s climate is basically continental semi-arid with hot summers and dry, cold winters. The country lies within the high-pressure belt of the southern hemisphere in the interior of the subcontinent far away from oceanic influences. Rainfall is unreliable, unevenly distributed, and highly variable. Mean annual rainfall in Botswana varies from approximately 250 mm in the southwest to more than 650 mm in the Kasane region in the north (Fig. 2).

The effectiveness of these rains is strongly reduced due to the high evaporation rates in summer. Annual evaporation rates are three to four times higher than the amounts of annual rainfall in most parts of the country. Because of the semi-arid climate, the high variability of rainfall, and the high evaporation rates, there is recurrent shortage of water.

Like in other countries, the total water resources of Botswana include surface and groundwater. As far as the surface water is concerned, the Okavango river and its inland delta (Fig. 3) hold 95 % of the total surface water available. The other river systems are ephemeral, except for the Kwando-Linyanti-Chobe system in the Kasane area.

Figure 3: Drainage basins in Botswana

The volume of groundwater storage is assumed to be 100,000 Mm3 with a low mean annual recharge rate of 2.7 mm/a for the whole country (in 1992). The total surface runoff in Botswana is estimated to be approximately 1.2 mm/a. Comparing this figure with other countries it becomes clear that Botswana is one of the countries in the world where water is very scarce indeed. Any large-scale extraction of groundwater as, for example, at the diamond mines in Orapa, Letlhakane, and Jwaneng, constitutes mining of a non-renewable resource.

Yet, traditionally, groundwater is the main source of potable water. Figures estimated by the BNWMP in 1992 indicate that 64 % of the consumed total water in 1990 was from groundwater. The Batswana have tapped water for generations through digging wells. These hand-dug wells are known as Petse in Setswana.

Today, Botswana has one of the fastest growing economies in Africa and is therefore a country in need of additional water resources. Several programs have been evaluated to account for this high demand for water, for example the Gaborone dam and the North-South water carrier project. Water is in highest demand in the east of the country where most urban growth is taking place along the urban axis Francistown–Gaborone-Lobatse. However, aquifers in this part of the country are very shallow and thus highly vulnerable to pollution (Fig. 4).

Fig. 4: Depth to groundwater in Botswana (Busch & von Hoyer, 1995 - modified)

It is estimated that the water consumption will increase by up to 85 % or even more by the year 2020 (Fig. 5). Such a high demand cannot be satisfied from dams only but by also tapping into every possibly available groundwater resource. However, rapid population and economic growth have caused a major increase in the incidence of water pollution.

Groundwater is a most vulnerable resource and once polluted it is likely to remain polluted for some time. The most common type of contamination is bacteriological accompanied by elevated nitrate levels as a result of the use of pit latrines and leaking septic tanks. But, with the help of remediation measures, the establishment of groundwater protection zones, the enforcement of existing and possibly new laws, and with the establishment and maintenance of sewer systems, groundwater can be spared from further pollution (BNA, 2001).

4 PHYSIOGRAPHY AND CLIMATE IN THE PROJECT AREA

The study area is located in the South-East District (Fig. 1). While it is the smallest district in Botswana in terms of area, it is also the most densely populated. The capital Gaborone as well as Lobatse lie in this district. Ramotswa acts as the administrative headquarters of the SE district.

The study area includes the settlements of Ramotswa, Ramotswa station (Taung), Boatle, and surroundings. The size of the study area is approximately174 km2. The Ngotwane river (cf. Fig. 3) to the east forms the international boundary with the Republic of South Africa (R.S.A.). It also served as the eastern project boundary.

350

300

250

200

150 1990 2000 100 2010 CUBIC METERS IN MILLIONS 2020

0 Total Wildlife Livestock Rural villages Major villages Urban centres Mining Energy Total domestic Other settlements Irrigation & Forestry CATEGORY

Fig. 5: Consolidated water demand estimates for the period 1990 to 2020 (Source: Botswana National Atlas, 2001)

The Ramotswa study area is part of the hardveld region (Fig. 2). The topography is fairly hilly, which is typical for SE Botswana. The altitude of the plains ranges from 1000 to 1050 m a.m.s.l, whereas the altitude of the surrounding hills varies from 1068 to 1189 m a.m.s.l. The hills and escarpments are remnants of erosion cycles which began in the Tertiary.

The dominant Ngotwane river valley follows mainly N-S trending structures through the study area. The valley is approximately 125-150 m wide and features riverbank terraces of different age. The clayey and sandy river alluvium was deposited in the last thousands of years and is up to 20 m thick. River infiltration into the aquifers occurs beneath the Ngotwane river bed. The overall hydraulic gradient is 1:300 along the course of the river.

Other rivers are the Taung and the Boatle, which are tributaries to the Ngotwane river. All rivers are ephemeral and belong to the Limpopo river basin (Fig. 3). The entire catchment area is approximately 4200 km2 big out of which 1200 km2 lie in the SE disrict. The estimated long-term runoff of the Ngotwane river up to the confluence with the Limpopo river is 8300 m3/d.

The vegetation cover in the study area is predominantly mixed shrub and tree savanna (Table 1). But over time the indigenous trees have been cut down and used for construction or as firewood. Shrubs are also cut down for fencing of fields or plots, causing local denudation.

Land forms Geology Vegetation Dominant species FAO soil classification Alluvium Alluvial deposits Shrub/Tree Acacia tortilis Calcaric Cambisol Savanna (A4) Alluvium Alluvial deposits Tree Savanna Acacia tortilis Gleyic Luvisol (A7)

Alluvium Alluvial deposits Tree Savanna Acacia mellifera Calcic Luvisol (A9) Alluvium Alluvial deposits Grassland different grass Eutric Gleysol species (A31a) Hardveld Basic igneous and Shrub Savanna Combertum Chromic Luvisol metamorphic apiculatum (B3) rocks Hardveld Sedimentary Tree Savanna Croton gratissimus Eutric Regosol (D1a) rocks Hardveld Sedimentary Tree Savanna Acacia tortilis Ferric Luvisol (D7-d) rocks Hardveld Sedimentary Tree Savanna Acacia erubescens Calcic Luvisol (D9) rocks Hardveld Acid igneous and Tree Savanna/ Peltophorum Eutric Regosol (G1a- metamorphic Shrub Savanna africanum c) rocks Hardveld Acid igneous and Tree Savanna/ Combertum Ferric Lixisol (G2d) metamorphic Shrub Savanna apiculatum rocks Hardveld Steep hills and Tree Savanna/ Acacia mellifera Lithic Leptosol (R) rigdes on various Shrub Savanna rock types

Table 1: Landforms, geology, vegetation, and soils in the study area

The rainfall pattern is strongly seasonal (Fig. 6), as is generally the case in Botswana. Mean annual rainfall amounts to approximately 475 mm (Fig. 7). In good years however the annual rainfall may exceed 1000 mm, while in poor years it may be as low as 125 mm. Rains fall mainly in short, high intensity events. Occasionally, heavy rainfalls provide the bulk of the annual precipitation.

Rainfall is the primary source, which replenishes water resources in the study area. Flooding in the Ngotwane and Taung rivers is the result of high intensity storms, creating hazardous conditions in the study area. These high intensity storms in combination with overgrazing and the cutting down of trees and bushes also results in gullying, which can be found mainly in the southern and western parts of the study area.

Areas containing good-quality soils are used for growing crops, mainly maize and sorghum. These crop areas are found in the alluvial plains near the river, north of Ramotswa station, and along the road to Boatle. Because of lack of rainfall, crops fail frequently. In general, the soils thin towards the south where vegatation is sparse, revealing shallow and stony soils (e.g. Lithic Leptosol).

The by far most important form of landuse is livestock grazing, mainly cattle but also goats, sheep, and donkeys. Although the recommended stocking rates are 3 to 6 livestock units per hectar, the present stocking rate in the study area is much higher, around 12-14 livestock units per hectar. This results in overgrazing and soil degradation.

120

100

60 Mean monthly rainfall precipitation in mm

0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Fig. 6: Mean monthly rainfall in Ramotswa (1959 to 1998) Source: Department of Meterological Services, Gaborone

ANNUAL PRECIPITATION

1200

1100 1054

1000 902.8 900

800

700

600 ANNUAL

500 Precipitation in mm 400

300

200 122.3 100

0 1959 1961 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997

Fig. 7: Mean annual rainfall in Ramotswa (1959 to 1998) Source: Department of Meterological Services, Gaborone

5 GEOLOGY IN THE PROJECT AREA

The geology in the Ramotswa study area is made up of three lithological supergroups, namely the Otse-Waterberg, the Transvaal, and the Lobatse-Ventersdorp supergroups (Fig. 8; Carney et al., 1994; Key, 1980 and 1983). These were deposited onto the old cratons in different sedimentation cycles.

The Otse-Waterberg supergroup covers the extreme southwest of the study area. This supergroup consists of three undeformed red bed sequences, which occur in a restricted outcrop between Lobatse and Ramotswa. It is overlain by sedimentary rocks of the Lobatse-Ventersdorp supergroup. These rocks are the youngest in the study area with an age of approximately 1800 Ma.

The Transvaal supergroup (Table 2) covers the middle eastern and southern part of the study area. The Transvaal supergroup is one of the major early Proterozoic basinal deposits which was formed in the Bushveld basin. The western margins of the Bushveld basin extend into eastern Botswana in an arc including Lobatse, Otse, and Ramotswa. In Botswana the strata rests unconformably above the Lobatse volcanic group and is locally unconformably overlain by the clastic sedimentary rocks of the Otse-Waterberg supergroup. The Transvaal supergroup rocks are intensely faulted by steep normal faults and low dipping slides. Bedding planes dip at moderate angles towards the center of the basin. Within the Transvaal there is a unique startigraphy, largely floored by the Black Reef quartzite overlain by carbonates, and succeeded by a cyclic arenaceous/argillaceous succession containing volcanic interlayers. The age of the Transvaal strata is approximately 2200 Ma.

FORMATION LITHOLOGY Woodlands Fine-grained silicious rocks Sengoma quartzite Upper massive and pure quartzite; bottom shales Sengoma argillite Upper dolomitic and banded carbonates; bottom shales Ditlhojana quartzite Quartzite Ditlhojana volcanic Massive andesites and rhyolites Ditlhojana shale Shales Tsokwane quartzite Massive and flaggy quartzites Lephala Chert clasts, Bevet’s conglomerate Ramotswa shale Siltstones and shales Magopane Bedded chert and minor dolomite Matholobota Inter-layered dolomite and chert Ramotswa dolomite Dolomite with minor chert (stromatolithes) Black Reef quartzite Quartz and pebbles in quartz matrix

Table 2: Stratigraphy of the Transvaal supergroup in the Ramotswa area (Key, 1983). (The Lephala and Ramotswa dolomite formations are the two main aquifers in the study area)

The Lobatse-Ventersdorp supergroup covers the middle western and northern part of the study area. This supergroup consists of volcano-sedimentary sequences widely distributed in the eastern parts of Botswana. The age of the Lobatse-Ventersdorp supergroup is approximately 2700 Ma. These rocks are the oldest in the study area. The Lobatse-Ventersdorp supergroup is always overlain by the Black Reef formation of the Transvaal.

Figure 8: Geological map of the study area (Key, 1983)

6 HYDROGEOLOGY IN THE PROJECT AREA

The Ramotswa wellfield lies partially in the village and extends over an area of 29 km2. Due to the importance of the Ramotswa wellfield as a back-up supply for the capital Gaborone and for local water supply, a number of studies have been carried out in the project area over the past 20 years (e.g. BRGM, 1985; Selaolo, 1985; Institute of Hydrology, 1986; Water Surveys, 1994). A review of the monitoring performed by the Dept. of Water Affairs (DWA) and the Dept. of Geological Survey (DGS) has lately been summarized by GEOTECHNICAL CONSULTING SERVICES (2000).

There are two primary aquifer systems in the study area, namely the Ramotswa dolomite and the Lephala formation (Table 2). Both aquifers are considered to be in local hydraulic connection via the predominately N-S trending fracture zones. The dominant feature of the system is a marked anisotropy associated with high density fracturing. In the dolomites, the active groundwater circulation has favored local karstification along structural lineaments producing high transmissivities and storativities.

The Ramotswa dolomite aquifer consists of two different karst zones, a shallow and a deep zone (Institute of Hydrology, 1986). The upper karstic zone has a variable thickness of 20 to 50 m and receives recharge from the river and percolating rainwater. Dolomite solution appears preferentially along fractures. The deeper karstic zone has a thickness of beween 25 to 50 m and recharge is probably from across the border in South Africa.

Within the dolomite aquifer, areas of major linear karst and unfractured dolomite country rock have to be distinguished. While high yielding wells can be found along the major linear karst, low yielding boreholes are common in the country rock,. During field work the boreholes in this zone rapidly depleted at low pumping rates. While carrying out the short pumping tests, T values of 5 to 50 m2/d were recorded. The mean value was 10 m2/d for the country rock. The storativitiy is estimated at 3 x 10– 3. Away from the river, dry boreholes were common.

Hence it comes as no surprise that the main production wells are located in E-W direction along the major linear karst in the southern part of the study area. The linear karst there features a dense fracture pattern with different fracture directions. This fracturing, in combination with infiltration of river water and the intersection of minor side valleys in E-W direction, has produced favorable conditions in terms of permeability.

The production wells 4336, Z4400 and 4349 are located in this area (cf. Appendix VI). Borehole logs (Appendix VI) perfectly highlight the 3 subdivisions described above, namely the upper aquifer extending to a depth of about 30 m followed by a zone of less water-bearing fissures between 30-50 m depth, and a deeper aquifer of variable thickness between 45 and 100 m depth. The exceptionally high transmissivity of production well 4336 of 5000 m2/d should not be considered representative (cf. Table 3). Because the other two wells 4349 and Z4400 have a much lower transmissivity of 1400 m2/d and 540 m2/d respectively.

The Lephala formation aquifer outcrops in the southern edge of the project area, where the rocks are faulted against the dolomites, and in the north-east of Ramotswa. The Lephala aquifer is similar to the Ramotswa dolomite aquifer but is unaffected by karstification.The formation is characterized by two fissured zones which are separated by a less fisured zone, a thickness of the upper zone of 30 to 40 m, and a thickness of the lower zone of approximately 30 m.

In the Upper Argillites, water is usually found at 20 to 30 m depth with rest water levels of 10 to 20 m representing confined conditions. The most southerly group of wells (boreholes 4358, 4340,

4885, 4972) draw their supplies from these rocks. Low yields of 20 to 25 m3/h were recorded with specific capacities of 5 to 10 m2/d. The transmissivities ranged from 25 to 50 m2/d, and the storage coefficient was an estimated at 10– 4.

The production wells Z4406, 4373, and 4347 draw their supplies from the Lower Argillites.Water is encountered in a narrow fracture zone at 40 to 50 m depth. Again, the main supply was encountered at 60 to 80 m depth. These fractured features are most likely filled with manganese, pyrites and/or quartz. The piezometric surface was usually located at about 10 m depth. Specific capacities were similar to those of the deep zones in the dolomites, that is transmissivities of 80 m2/d for Z4406, 110 m2/d for 4373; and 135 m2/d for 4347.

Yields of the boreholes in the Lephala formation depend on their proximity to the river, the intersection of the fissured zones, and the extent of the secondary infills. Recharge may be restricted to surface runoff via fractures or infiltration from the river.

BEDROCK AREA/TEST RAMOTSWA DOLOMITE LEPHALA FORMATION

Aquifer statistics: Specific capacity (l/s/m) 2.7 3.5 Average transmissivity (m2/d) 1170 492 Storage coefficient 5,7 x 10-2 8,7 x 10-4

Borehole statistics: Number of boreholes 34 10 Median yield (m3/h) 8.73 37.56 Median T value (m2/d) 6.38 45.11

Table 3: Summary of aquifer and borehole statistics for the Ramostwa wellfield (Source: Dept. of Water Affairs (DWA) and Dept. of Geological Survey (DGS))

7 METHODS AND MATERIALS

This study was carried out in several stages. Prior to the beginning of actual fieldwork in Ramotswa, introductory desktop studies were carried out in Lobatse. These included reviews of the available literature and maps on the geography, the geology, and the climate in the project area as well as searching through the DGS borehole archive2. The latter was aimed at producing a preliminary borehole location map that was needed in order to obtain an idea about the number and spatial distribution of the boreholes in the study area.

Well census

The preliminary borehole location map formed the basic means of orientation in the field while carrying out the well census. The aim of the well census was to discover and determine the existence of all boreholes and wells in Ramotswa and the surrounding areas. While the locations of the DGS monitoring boreholes and the DWA production wells are well known, more boreholes were found after talking to residents.

Once located, the site of the boreholes was determined by means of a hand-held GPS 12XL

2 In the borehole archive all boreholes existing in Botswana have been registered since the early 20th century.

(www.garmin.com). While carrying out the well census, the initially manually produced preliminary borehole location map was transferred into the ESRI (www.esri.com) GIS3 software (ArcView) environment (Appendix I). Similarly, all borehole parameters such as construction details, lithologies, water levels, water yields, water strikes, usage, coordinates, and owner data, were entered into the GeODin (www.geodin-system.com) digital data base (Appendix VI).

Identification of environmental hazards

In a second phase all environmental hazards to groundwater were identified in the field, and determined to be mainly anthropogenic. They were differentiated as point hazards, such as pit latrines, and areal hazards, such as cemeteries. Again, the location of all hazards was determined by GPS so as to produce a digital environmental hazard map (Appendix II).

Groundwater sampling

During the third stage of the field survey, groundwater from all accessible boreholes was sampled for hydro-chemical analyses. All in all, a total of 31 boreholes were sampled, 21 of which were also sampled for trace elements4. It was most unfortunate that a number of extra boreholes could not be sampled either because of vandalism or inaccessibility due to plentiful rains.

Prior to pumping for a groundwater sample, the groundwater level was determined with the help of a dipper. At the same time the height of the casing and the diameter of the borehole were recorded. Before the pump was lowered into the borehole, the borehole log (whenever available) was checked in order to determine the most appropriate depth level to place the pump. Unfortunately, archive records were often incomplete or nonexistent. Because in such cases one could not know the depth of the water strike, the pump was installed in the middle of the overall borehole depth.

Most of the boreholes were not equipped with a pump. In these cases a submersible pump (Grundfos MP1) was employed, which was driven by a mobile power generator. To reach the desired depth, 3-m-long PVC tubes were used and put together. For security reasons, the pump was never placed at very shallow depth; nevertheless the drawdown had to be observed regularly. Based on the depth of the well and its casing diameter, the volume of the water column was calculated and a minimum pumping time calculated based on pumping yield [L/s].

Once pumping began, a series of field parameters [electrical conductivity (EC), water reaction (pH), water temperature (degrees Celsius), dissolved oxygen concentration (O2), and total dissolved solids (TDS)] were measured employing field electrodes (www.wtw.com) in a flow cell. Parameter values were checked every 10 minutes, and from time to time the flow cell was cleaned. As soon as the readings had stabilized for a period of at least 15 minutes, the groundwater sample was taken and filled in a 250-ml PVC bottle. The samples earmarked for the analysis of the trace elements were filtered through .45 µm filters and acidified. All samples were immediately put into a cooler box and later stored in a fridge in the DGS chemistry laboratory.

Also while sampling, the HCO3-concentration was determined by means of volumetric

3 All coordinates are in the Universal Transverse Mercator Projection (UTM) and in decimal degrees. The study area falls within UTM zone 35. 4 Boreholes in the vicinity of conspicuous groundwater hazards such as waste deposits and industries were also sampled for trace elements.

titration using a H2SO4-solution of known concentration. For titration, a 50-ml water sample was taken. The concentration of HCO3 in mg/L was calculated from the measured volume in ml of the titrant5. To verify the result, titration was repeated 2 to 3 times, and then the mean value was determined. Because of the prevalence of pH values < 8.2, CO3 was absent in all samples, that is undetectable. After completing the sampling campaign all samples were forwarded to the BGR HQ in Hannover for routine analyses.

Borehole precision GPS survey

After the groundwater sampling campaign was finished, the boreholes were surveyed to determine the precise elevations of the sample points in m a.m.s.l. This part of the work was done in collaboration with Africa Surveys Botswana (Pty) Ltd., a surveying company in Gaborone. Because of the high costs involved only 17 locations were surveyed. The elevations of the remaining boreholes were extracted from GEOTECHNICAL CONSULTING SERVICES (2000). Since the difference between the two data sets was only about 0.3 m, the accuracy level needed for the production of the groundwater flow map (Appendix III) met the requirements.

Map production

A key objective of the study was to produce three digital environmental hydrogeology maps, namely a borehole location map, an environmental hazard map, and a groundwater flow direction map. As mentioned above, these thematic maps were produced in the ArcView (Vers. 3.2) software environment. In addition, the Ramotswa Development Plan Map (Enneco, 1996) was digitized so that its information could also be inserted into the newly designed environmental hydrogeology maps.

8 RESULTS

In line with the study objective - namely to establish the quality of the groundwater resources in Ramotswa and to produce environmental hydrogeology maps for regional and urban planners - the results of this study encompass the three above mentioned thematic maps plus the results of field and laboratory work on various environmental aspects and impacts concerning groundwater quality in Ramotswa.

8.1 ENVIRONMENTAL HYDROGEOLOGY MAPS

Like in other environmental hydrogeology studies carried out by the Environmental Geology Division (e.g. Beger, 2001), all three thematic maps are in A0 format. This format allows good and easy readability. Because of the limited space available they are however again attached in A4 format to this report (Appendices I to III). All three maps are at 1:25.000 scale.

5 HCO3-concentration in mg/L = (Volume of the consumed H2SO4- solution in ml) x (0,052 N H2SO4) x 61.000 divided by the volume of the water sample (50 ml)

Borehole location map

All 64 boreholes identified during the field survey are presented in the borehole location map (Appendix I). In order to separate out the various types of boreholes, and the state and conditions they were in, a site-specific legend was developed (Table 4). In addition to the location of the boreholes, the map depicts the topography in the form of a 3D model, which was derived from the available detailed contour data.

LEGEND BOREHOLE STATUS DESCRIPTION working borehole borehole with water abstrartion, pump equipped borehole not in use borehole with no water abstraction blocked borehole blocked borehole due to vandalism or filled up collapsed borehole borehole no longer stable down to the end depth dry borehole borehole with no more contact to groundwater working borehole with handpump handpump with contact to groundwater dry borehole with handpump handpump with no more contact to groundwater observation borehole DGS observation borehole, sampling possible blocked observation borehole DGS observation borehole, no sampling possible production well, not in use DWA production well blocked production well DWA production well, inaccessible or blocked working wellhouse pump equipped wellhouse wellhouse, not in use wellhouse, no water abstraction blocked wellhouse blocked wellhouse due to vandalism or filled up dry wellhouse wellhouse with no more contact to groundwater

Table 4: Legend of the borehole location map and status of the boreholes

From the borehole location map it is clear that the bulk of boreholes is located along the Ngotwane river in the most easterly part of the study area. Another concentration of boreholes is in the area of Ramotswa station. In this area the boreholes are located next to the river Taung, or else, along smaller tributaries.

Several old boreholes were discovered in the countryside, which nowadays are mostly collapsed or dry. Two exceptions are a hand pump and the well house at the cattle kraal. These two locations (4154, WH1) plus the pump-equipped boreholes in the plantations (4379, RST1, RST2) are the only boreholes used for active water abstraction in the study area. Since the shutdown of the Ramotswa wellfield in 1997, water delivery is from Gaborone dam through Water Utilities Corporation (WUC).

Environmental hazard map

In the case of the environmental hazard map it was mainly the village of Ramotswa and the industrial area in Ramotswa station, which were surveyed (Appendix II). As mentioned above, two types of hazards were identified, namely point and area hazards (Table 5).

The point hazards are presented in the map by a single symbol, whereas the area hazards are labeled with their own legend pattern. In addition, as also mentioned above, land-use information contained in the Ramotswa Development Plan Map (Enneco, 1996) was digitized and entered into the environmental hazard map.

From the field survey it became evident that pit latrines constitute a major hazard in terms of

16 groundwater pollution. For 1991 it was estimated that out a total of 3636 sanitation facilities, 2432 were private pit latrines (Enneco, 1996). It is assumed that the number may have risen to approximately 3.000 today. Because of their large number they were however not depicted on the map.

Septic tanks are also still in use and have been identified in the industrial area of Ramotswa station, namely at Bolux, Tswana Steel, and White Dove Garments. Yet, these places will soon be connected to the sewerage system, as has already been the case with all public buildings.

Point hazards: Area hazards: Pit latrines Septic tanks Filling station Cemeteries Fuel/oil/gas storage Old dumping site Brick production Hazardous waste sites Car repair Animal farms Tannery Industrial area Dry cleaners Sewage pipeline network Hospital Sewage plant Cattle kraal Old pits, mining area Railway station Flood-prone area

Table 5: Typical point and area hazards

Besides these hazards, the industrial complex of Tswana Steel in Ramotswa station was identified as an environmental hazard. Leaking fuel tanks were found there, the soil was stained, and the open-air production may present a danger to the environment because of unfiltered gases. During rainfalls, harmful substances may easily be washed into the ground.

Another crucial site is the old waste disposal site, which is situated on a hill in the southern part of the study area. In future a new dumping site based on newest standards will be used however. Its completion is planned for the end of 2002.

Groundwater flow direction map

The groundwater flow direction map shows the groundwater level in the Ramotswa project area in m a.m.s.l. (Appendix III). The groundwater contours for the Ramotswa dolomite aquifer were constructed with the help of the hydrologic triangle method. The piezometric contours are in 5 meter intervals.

No attempt was made to develop a groundwater model for the whole area. Instead different drainage areas and watersheds were distinguished. In general, the water flows in a north-northeastern direction following the main slope and the course of the Ngotwane river.

In addition to the groundwater flow direction and groundwater levels, the map highlights the hydrochemistry of the groundwater samples taken in late 2001. This, in combination with the environmental hazard map, allows for the closing-in on potential sources of contamination.

8.2 GROUNDWATER CLASSIFICATION

The results of the laboratory analyses (Appendices IV, V) were interpreted and classified by means of a Piper diagram (Fig. 9). To plot the results in the form of a Piper diagram, the software program GW chart (www.usgs.gov) was employed and afterwards brightened with a graphic application. The ionic balance and the error for each sample were also calculated in order to verify whether the results were reasonable.

Legend 100 10 100M 80 80 4154 4155 c O 3 C 4160 N 60 60 a + + l 4163 M C g + 4165 4 O S 40 40 4166 b e 4340

4347(UN2) 20 20 4348 a 4349 0 g 4371 0 4379 d 4422 20 20 4885 4886 4887 40 40 4972 80 20 f 20 80 4995 60 60 N RST1 60 40 a O 3 40 60 C S + H O

RST2 g K + 4 M 80 80 3 RST4 O 40 60 C 60 40 RST5 RST6 100 RST7 20 80 80 20 WH1 Z4401 Z6423 80 60 40 20 20 40 60 80 Ca NO + Cl Z6424 3 Z6501 Watertypes in the Ramotswa Wellfield

Figure 9: PIPER diagram

2+ 2+ - As was to be expected, magnesium (Mg ), calcium (Ca ), and bicarbonate (HCO3 ) were the most important ions (Fig. 9). Thus, the dominant groundwater type was of Mg-HCO3 and Mg-Ca-HCO3 facies. Only the boreholes in the Ramotswa station area were mainly of the Cl-Na-HCO3 water type. According to FURTAK & LANGGUTH (1967), the groundwater in the Ramotswa project area may also be classified as (normal) alkaline earth freshwaters or alkaline freshwaters (Table 6).

GROUNDWATER TYPE SECTION SAMPLE NUMBERS: (cf. Fig. 9) NORMAL ALKALINE EARTH FRESHWATER mainly bicarbonatic a 4155 4160 4163 4165 4422 4972 WH1 Z4401 4166 4340 4347(UN2) 4348 Z6423 Z6424 Z6501 4371 4349 4887 bicarbonatic-sulfatic b 4885 mainly sulfatic c 4379

ALKALINE EARTH FRESHWATER WITH HIGHER CONTENTS OF ALCALIES mainly bicarbonatic d 10 RST1 mainly sulfatic e 4995 RST7 RST2 RST5

ALKALINE FRESHWATER mainly (bi)carbonatic f 4154 100M 4886 mainly sulfatic-chloridic g RST6 RST4

Table 6: Groundwater classification according to FURTAK & LANGGUTH (1967).

8.3 GROUNDWATER QUALITY

Water reaction (pH) levels

The water reaction of the examined groundwater samples was in the range of pH 6.4 (min.) to 7.7 (max.). The mean value was 6.98. All values above 7 are indicative of the Ramotswa dolomite aquifer, while the smaller values mostly reveal waters from the Lephala aquifer, or else, zones of transition (Fig. 10)

8,0

7,7

7,5

7,0

6,5 6,4

6,0

5,5 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501 Borehole No. 4347(UN2)

Figure 10: Water reaction (pH) levels in the study area

Temperature

The observed groundwater temperatures ranged from between 22.6 to 26.7° C (Fig. 11). The average temperature was 24.4° C. Groundwater temperature mainly reflects the diurnal fluctuation of the daily air temperature.

Electrical conductivity [EC]

Electrical conductivity varied from a minimum value of 258 to up to 6070 µS/cm. Since high values greater than 2000 µS/cm are indicative of pollution, the very high values recorded at borehole 4379 and at the Ramotswa station boreholes suggest pollution (Fig. 12).

Dissolved oxygen (DO)

The dissolved oxygen contents varied from 0.0 to up to 4.4 mg L-1, with the vast bulk of the samples showing low levels of smaller than 2.0 mg L-1 (Fig. 13). Such low oxygen contents are typical for

20 anaerobic (anoxic) groundwater conditions. The recorded very high values at boreholes WH1, 4154, and 4379 respectively, were due to sampling. Because these boreholes were equipped with pumps, recording was not carried out in the flow cell. Hence, the groundwater samples taken had contact with the atmospheric oxygen.

27 26,7

24 T in [° C]

23 22,6

20 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501

Borehole No. 4347(UN2)

Figure 11: Groundwater temperatures in the study area.

7000

6070 6000 5670

5000 4520

4000

3330

3000

EC in [MikroS/cm] 2550 TVO Theshold value is 2290 2000 2000

1000

258

0 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501

Borehole No. 4347(UN2)

Figure 12: Electrical conductivity in the study area.

5,0

4,5 4,4

4,0

3,5

3,0

2,5 in [mg/L] 2 O 2,0

1,5

1,0

0,5

0,0 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501 Borehole No. 4347(UN2)

Figure 13: O2 values in the study area.

Total Dissolved Solids (TDS)

The recorded TDS values ranged from 122 to up to 2872 mg L-1 (RST4). The mean value was 782 mg L-1, which was strongly influenced by a number of high TDS levels. In fact, a total of 6 boreholes exceeded the acceptable upper limit6 of 1000 mg L-1 (Fig. 14) according to the Botswana standard for drinking water (BOS, 2000). Out of these, three even exceeded the maximum allowable limit of 2000 mg L-1.

- Bicarbonate (HCO3 )

The concentration of bicarbonate ranged from 234 (min.) to 734 mg L-1 (max.). The calculated mean concentration was 493 mg L-1. As was to be expected, the dolomites showed a very high level of HCO3, while the slates and quartzite of the Lephala formation had smaller concentrations (Fig. 15).

- Sulfate [SO4 ]

The observed sulfate concentrations were mostly below the acceptable limit of 250 mg L-1 (Fig. 16). But three boreholes, namely RST 4, 5, and 6 respectively, had elevated levels that were above the maximum allowable limit of 400 mg L-1 (BOS, 2000). This was indicative of pollution.

6 The Botswana standard for drinking water (BOS, 2000) defines 3 classes based on upper concentration limits and ranges, namely Class I (Ideal), Class II (Acceptable), and Class III (Max. allowable).

3500

3000 2872 2683

2500

2139

2000

1582 1500 TDS in [mg/L] WHO guideline value 1207 is 1000 mg/L 1084 1000

500

122

0 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501 4347(UN2) Borehole No.

Figure 14: TDS values in the study area.

800 733

700

600

500

400 in [mg/L] 3 HCO 300 234

200

100

0 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501 Borehole No. 4347(UN2)

Figure 15: HCO3 concentrations in the study area

Chloride [Cl-]

No elevated chloride concentrations were observed in Ramotswa proper (Fig. 17). But concentrations much higher than the acceptable concentration of 200 mg L-1 (BOS, 2000) were analyzed for the Ramotswa station industrial complex. The latter suggests man-made pollution.

Sodium [Na+] Sodium did not show elevated levels in Ramotswa proper (Fig. 18). But again the boreholes RST 4, 5, and 6 in Ramotswa station, which are in the direct vicinity of Tswana Steel and a scrap yard, revealed high values. In all three boreholes the levels were higher than the maximum allowable level of 400 mg L-1 according to the Botswana drinking water standard (BOS, 2000).

600

504 500

455 WHO guideline value 400 mg/L 419 400

300 in [mg/L] 4 SO

200

100

0 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501 4347(UN2) Borehole No.

Figure 16: Sulfate concentrations in the study area.

Calcium [Ca2+] All samples had calcium concentrations, which were more or less ideal 80 mg L-1 to acceptable 150 mg L-1 (BOS, 2000) (Appendix IV).

Potassium [K+] The potassium levels were low throughout. None of the collected groundwater samples came close to any of the limits stipulated in the Botswana standard for drinking water (BOS, 2000).

1200

989 1000

813 800 695

600 562 in [mg/L] - Cl

400 316 WHO guideline value 250 mg/L

200

0 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501 4347(UN2) Borehole No.

Figure 17: Chloride concentrations in the study area

800

724

700

600

523 507 500

400 Na in [mg/L]

300

WHO guideline value is 200 mg/L 200

100

5 0 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501 4347(UN2) Borehole No.

Figure 18: Sodium concentrations in the study area

Magnesium [Mg2+]

In the case of magnesium, several boreholes in the study area that is in Ramotswa proper and in the Ramotswa station area, showed elevated values (Fig. 19). The maximum allowable limit according

25 to the Botswana standard for drinking water is 100 mg L –1. The magnesium concentrations in 7 boreholes (RST2, 4, 5, 6, 7, and 4379, 4348) exceeded this limit (Appendix IV).

Iron [Fe 2+]

Iron concentrations exceeded the WHO recommendation (WHO, 1998) of 300 µg L-1 by far in all boreholes except for two (Appendix V). Four boreholes, namely 4166, 4887, 4340, and 4160 respectively, even far exceeded the maximum allowable level for drinking water in Botswana of 2000 µg L-1 (BOS, 2000).

Most likely these high levels are due to ferruginous rocks, which are widely represented in the study area. In addition, they may also be attributable to anoxic (reducing) groundwater conditions as was indicated in places by the smell of H2S.

200

180 172

160 154 150

140

119 120 Max. Allowable of SABS 112 115 is 100 mg/L 111

100 Mg in [mg/L] 80

20 11

0 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501 4347(UN2) Borehole No.

Figure 19: Magnesium concentrations in the study area.

Aluminium [Al3+]

Four boreholes revealed Al levels above the maximum allowable level of 200 µg L-1 (BOS, 2000), which is also the recommended WHO threshold level for drinking water (WHO, 1998). Boreholes RST1 (427 µg L-1) and RST2 (407 µg L-1) respectively had levels that were even twice as high as the maximum allowable level (Appendix V).

Arsenic [As3+ or As5+]

Four boreholes along the river Ngotwane revealed arsenic levels (Appendix V) above the Botswana standard for drinking water of 10 µg L-1 (BOS, 2000). Interesting to note is that

26 three of them are aligned in a row in the northern part of the project area (Appendix III), and also that the As concentration rose in flow direction from 11.5 µg L-1 at borehole no. 4887, to 21.9 µg L-1 at borehole no. 10 (4165), and finally to 51.1 µg L-1 at borehole no. 4886. Around the last borehole there was an illegal scrap yard. The fourth borehole (4166) with an elevated As concentration is located south of Ramotswa.

Manganese [Mn2+, Mn3+, Mn4+]

A large number of groundwater samples revealed manganese concentrations that exceeded the WHO recommendation of 100 µg L-1 (Appendix V). Even the Botswana maximum allowable level of 500 µg L-1 was exceeded by three samples (4166, 4885, 4340). All three are located south of Ramotswa along the border to South Africa.

Like in the case of iron, this was probably due to geology. For example at one borehole black liquid was encountered, which was identified as manganese hydroxide. Most likely the manganese hydroxide stemmed from an underlying manganese-bearing slate.

Nickel [Ni2+]

Three boreholes (RST1, 2, and 5) close to the railway line in the Ramotswa station area also exceeded the maximum allowable limit for Nickel (BOS, 2000) of 20 µg L-1 (Appendix V).

8.4 THE CASE OF NITRATE

In many places around the world public water supplies do exceed the maximum - -1 recommended nitrate (NO3 ) concentration of 45 mg L nitrate for drinking water (WHO, 1998) including both rural and urban areas in Botswana, where the maximum allowable limit is also 45 mg L-1 (BOS, 2000). By and large the major entry routes of nitrogen into groundwater are municipal and industrial sewage including feedlot discharges and animal wastes, runoff from fertilized agricultural fields, and plant residues (Fig. 20).

Because nitrate pollution is a serious problem with groundwaters in Botswana, nitrates serve as the key indicator of overall groundwater quality in all environmental hydrogeology studies carried out by the Environmental Geology Division (Vogel, 2002). The major cause of groundwater contamination in the residential centers of mainly eastern Botswana is effluent from pit latrines and septic tanks (Hutton, 1976; Lagerstedt, 1992; Lagerstedt et al., 1994; Carling & Hammar, 1995; Jacks et al., 1999). A case in point is the village of Ramotswa, which experienced one of Botswana’s worst cases of groundwater pollution in recent history. This followed the successful campaign by government to encourage villagers to build pit latrines. Available information suggests that by early 1997 the problem had become so bad that the Ramotswa wellfield had to be abandoned as a source of drinking water (Norwebb, 1996).

Amongst the 31 boreholes sampled in late 2001, 11 revealed nitrate levels that exceeded the Botswana standard of 45 mg L-1 for drinking water. The maximum value was 442 mg L-1, recorded in private borehole no. 4379. In the other boreholes where the upper limit of 45 mg L-1 was also exceeded, the concentrations ranged from 64 to up to 188 mg L-1 (Fig. 21).

Looking at their spatial distribution and correlating the spatial distribution pattern to the prevailing groundwater flow direction in the Ramotswa area, it may be concluded that unpolluted water enters the study area from the south (Appendix III). The southern well field revealed no nitrate contamination. The first borehole in northerly direction where an elevated nitrate level of 72 mg L-1 was recorded was borehole no. 4349, which is located within the village.

Figure 20: Sources and pathways of nitrogen in the environment (Source: FREEZE & CHERRY, 1979 - modified)

The prevailing groundwater flow direction in the Ramotswa study area is in northwesterly direction. Hence, polluted groundwater is being carried towards the Ngotwane river. The nitrate levels in the boreholes located in the river plain ranged from 65.5 to 188 mg L-1 with

28 the, above mentioned, peak of 442 mg L-1 at borehole no. 4379. Fractures and cavities in the Ramotswa dolomite and in the upper karstic zone are contributing to the transport of polluted groundwater in this direction.

The groundwater flow in the Ramotswa station area is separated from the broader groundwater flow by a watershed in the form of the Sepitswane hills. These hills, together with the hills at Taung (e.g. Bojanjwe hill), form a small drainage basin and the groundwater flows in a NNW direction parallel to the river Taung, until it merges with the river Ngotwane north of the study area. In this area pollution due to pit latrines (Taung residential areas) and septic tanks (industrial area at Bolux, Tswaa Steel, and White Dove Garments) is evident.

500

442 450

400

350

300

250 in [mg/L] 3

NO 188 200 177 148 150

110 103 111 92 100 WHO guideline 72 66 64 value 45 mg/L 50

0 10 4154 4155 4160 4163 4164 4166 4340 4348 4349 4371 4379 4422 4885 4886 4887 4972 4995 WH1 100M RST1 RST2 RST4 RST5 RST6 RST7 Z4401 Z6423 Z6424 Z6501 4347(UN2) Borehole No.

Figure 21: Nitrate levels in the study area.

Clearly, the hydrogeological conditions (dolomite, karst) in the Ramotswa project area are unfavorable for sanitation practices such as pit latrines and septic tanks (cf. Lewis et al., 1980, Tredoux, 1993). In fact, they are considered to be the major source of nitrate pollution ni eastern Botswana. While 146 septic tanks were in use in Ramotswa in 1985 (Table 7) almost all septic tanks in the study area have been replaced over the last 10 years with connections to the newly built sewage system (Fig. 22). In late 2001 only a very few were still in use mainly in the industrial area of Ramotswa station (Bolux, Tswana Steel, White Dove Garments).

Yet, the fact that nitrate levels were still high at the end of 2001 highlights a persistent pollution problem. Most likely the problem emanates from the still large number of pit latrines. In 1991, 2432 pit latrines were in use that is 66% of all households used pit latrines then (Table 8). Given the fact that the population grew over the last two decades7, the number of pit latrines has most likely increased further.

7 From approximately 14000 inhabitants in 1981 to 20680 in 2001.

Hence, the nitrate pollution problem in Ramotswa will not be solved unless all pit latrines are replaced with flush toilets that are connected to a properly functioning sewage system. But up to late 2001 not even the new sewage system was in proper working condition. At several places the new sewers were leaking, ironically because of damages caused by excavators who were still working on the completion of the system.

Livestock may be another source of nitrate pollution. In places where livestock is highly concentrated, animal waste may contribute to groundwater pollution. A case in point was the cattle kraal next to borehole WH1 (Appendix III) where the watering site was less than 50 m away from the well house. Here the nitrate concentration was 148 mg L-1 in late 2001 (Appendix IV).

Housing type Population Housing units Pit latrines Septic tanks No sanitation

Traditional 2995 467 139 2 326 Low cost 8621 1397 716 5 676 Medium cost 4226 709 458 77 174 High cost 750 118 92 22 4

TOTAL 16592 2691 1405 146 1180

Table 7: Sanitation facilities by housing types in 1985 (Source: WLPU, 1985)

Toilet facilities No. of households %

Private flush 370 10.2 Private pit 2432 66.9 Neighbours’ pit 384 10.6 Communal flush 1 0 Communal pit 1 0 Movable 1 0 None 434 11.9 Not stated 13 0.4

TOTAL 3336 100

Table 8: Sanitation facilities by households in 1991 (Source: Enneco, 1996)

The primary health hazard from drinking water with nitrate-nitrogen (NO3-N) occurs when nitrate (NO3) is transformed to nitrite (NO2) in the digestive system (Vogel, 2002). While NO3 is not very toxic, NO2 is toxic. The nitrite oxidizes iron in the hemoglobin of the red blood cells of humans (and other warm-blooded animals) to produce methemoglobin. Methemoglobin lacks the ability of hemoglobin to transport oxygen to body tissues. This creates the condition known as methemoglobinemia (“blue baby syndrome”), in which red blood cells carry insufficient oxygen to the individual body cells thus causing the veins and skin to appear blue (“internal suffocation”). This condition is especially serious in infants.

Water with nitrate levels exceeding 1.0 mg L-1 should not be used for feeding babies. In adults, high nitrate levels in drinking water may cause digestive disturbances (Tredoux, 1993).

Figure 22: The Ramotswa sewerage system – Source: Enneco, 1996 (not to scale)

In ruminant animals such as cattle, sheep, and goats, nitrate is also converted to nitrite by bacteria in the rumen (Vogel, 2002). Nitrate poisoning occurs when nitrite is absorbed through the rumen wall into the bloodstream. When enough hemoglobin is converted to methemoglobin, the animal begins to suffer from oxygen starvation. The blood of cattle that have suffocated from nitrate poisoning is usually dark chocolate-brown. Pregnant females that survive nitrate poisoning may abort due to lack of oxygen to the fetus.

Although data was very sparse indeed, an attempt was nevertheless made to possibly identify temporal trends of the development of nitrate pollution in the study area. In the case of seven boreholes, namely 4995, 4972, 4886, 4885, 4166, 4163, and 4160, nitrate data were available for the year 1983, the time of exploration. These were compared to the data collected for this study (Fig. 23).

The boreholes in the south, namely 4885, 4166, 4160, and 4972, revealed no increased nitrate concentrations. But the nitrate concentration in borehole 4995 turned out to be 20 times higher than the initially recorded level. In the case of borehole 4163 it was even 55 times higher. These boreholes are situated north of the village. Surprisingly though, borehole 4886, also located in the north, had a smaller concentration in 2001 as compared to the1980s.

188 4995 9.2

0.04 4972 0.5

0.02 4886 5

0.08 This study 4885 0.5 Initial value Borehole No.

0.14 4166 0

110 4163 2

8.72 4160 2

0 20 40 60 80 100 120 140 160 180 200

NO 3 in [mg/L]

Figure 23: Nitrate levels in selected boreholes in 1983 and in 2001

In the case of two more boreholes, namely 4422 and 4349 respectively, a little more data could be gleaned from the DGS borehole archive. This allowed for the drawing of tentative trend lines (Figs. 24, 25).

As far as borehole 4422 was concerned an increase in nitrate concentration is visible (Fig. 24). There may also be a small difference between summer and winter levels (29/12/1992 vs.

01/06/1993). The latter appears even more apparent with borehole 4349 (Fig. 25). There is a conspicuous difference between winter and summer concentrations, namely lower levels in June 1993 (29 mg L-1) and higher levels both in December 1992 and November 1993 (82 and 72 mg L-1 respectively). Possibly nitrate concentrations are higher at the onset of the rainy season because nitrate stored and accumulated in the unsaturated zone is flushed through the soil profile into the underlying aquifer. Supporting information to this effect comes from India, where a lot of nitrogen was built up in the soil during the dry season (Jacks & Sharma, 1983, cited in Lagerstedt, 1992). After the onset of the rains, the mineralized nitrogen was flushed down into the groundwater.

NO3 in borehole 4422

200

29.12.92 150 05.11.01 02.06.93 100 10.05.84 02.08.89 in [mg/L] 3 50 NO

0 10.05.84 10.05.89 10.05.94 10.05.99 Date

Figure 24: Trend line for DWA well 4422 – Source: DGS

NO3 in borehole 4349

29. Dez 92 80

12. Nov 01 70 10. Nov 93

50 28. Aug 91 in [mg/L] 3 40 NO

30 2. Jun 93 1. Feb 90 1. Mrz 90 20 21. Dez 89 12. Jun 90

10 2. Aug 89 18.20. Aug 83 8. Jan 90 0 10. Sep 84 18.08.83 18.08.88 18.08.93 18.08.98 Date

Figure 25: Trend line for DWA well 4349 – Source: DGS

9 DISCUSSION AND CONCLUSIONS

The results of this study confirm that there still exist groundwater pollution problems in Ramotswa. The problems as well as complementary environmental hydrogeology information have been documented in the form of digital thematic maps (Appendices I to III). These maps allow planners and other officials in charge to pinpoint and address the problem. Because the maps are in digital form, they may also be updated easily.

The most obnoxious groundwater pollution problem is due to high nitrate concentrations in several boreholes. The latter is attributed to the continued use of pit latrines. In fact, at sites where the soil is very thin, and given a mean depth of the pit latrines of 1.7 m (WLPU, 1985), human waste may enter directly into the aquifer. Clearly, pit latrines in the study area ought to be replaced with facilities connected to the new sewerage system. But the latter also must be maintained properly.

The industrial complex in the Ramotswa station area turned out to constitute another area of concern. In this area the boreholes RST2, 4, 5, 6 and 7, were found contaminated. High nitrate levels and elevated concentrations of sulfate, sodium, and chloride were identified. This was indicative of anthropogenic pollution, as were the observed nickel and possibly the aluminium levels.

Hitherto rather puzzling are the observed elevated arsenic concentrations along the river Ngotwane. From the available information no conclusion may be drawn at this stage as to the origin of this heavy metal contamination. It is planned however to resample these boreholes soon as part of the forthcoming borehole drilling program for groundwater quality evaluation. The objective of this program, which has already been approved within the scope of the National Development Plan (NDP) 9, is to thoroughly determine groundwater pollution levels in the Ramotswa area and to contribute towards the reduction of groundwater pollution in this village.

This will also help alleviate a further matter of concern that became glaringly obvious while carrying out this study, namely the lack of reliable data for the Ramotswa wellfield. It was impossible to build up a strong argumentation with so little usable, previously generated data at hand. This was particularly evident in the case of the attempted trend lines. While one would have wished to establish trend lines for many boreholes, only a very few were possible. And even these raised doubt with regards to data reliability.

Against this background it is recommended to regularly sample all DWA boreholes at least once a year and to store the data properly. Ideally, sampling ought to be done twice a year so as to identify possible seasonal changes in nitrate concentration. Similarly, the observation boreholes ought to be monitored regularly and the recorded data interpreted.

Last but not least, the groundwater protection zones and previously made recommendations (WLPU, 1985; Water Surveys, 1994) ought to be strictly observed. This, and the elimination of the existing pollution problem, may allow for the renewed use of Botswana’s most important aquifer in future.

10 REFERENCES

Beger, K. (2001): Environmental Hydrogeology of Lobatse. South-East District, Republic of Botswana. Report by the Environmental Geology Division, 45 p. including attachments, Dept. of Geological Survey (DGS), Lobatse, Botswana.

BOS (2000): Water quality – Drinking water – Specification. BOS 32, Botswana Bureau of Standards, Gaborone, Botswana.

BNA (2001): Botswana National Atlas. 1st edition, Dept. of Surveys and Mapping, Gaborone, Botswana.

BRGM (1985): Siting of boreholes for Ramotswa. wellfield extension. Draft Final Report by the “Bureau de Recherches Geologiques et Minieres” (BRGM), Borehole location and hydrological investigations.

Busch, K. & Hoyer, M. von (1995): Groundwater Pollution Vulnerability Map. Republic of Botswana, Scale 1: 1000000, Dept. of Geological Survey (DGS), Lobatse, Botswana.

Carling, M. & M. Hammar (1995): Nitrogen metabolism and leakage from pit latrines. A minor field study from south-east Botswana. M.Sc. thesis, 54 p. plus appendices, Lulea Univ. of Technology, Dept. of Environmental Planning and Design, Division of Waste Management and Recycling, Lulea, Sweden.

Carney, J.N., Aldiss, D.T. & Lock, N.P. (1994): The Geology of Botswana. Dept. of Geological Survey (DGS), Lobatse, Botswana.

Enneco (1996): Ramotswa Planning Area Development Plan. Report of Survey by Enneco (Pty) Ltd., Ministry of Local Government, Lands and Housing, Dept. of Town and Regional Planning (DTRP), Gaborone, Botswana.

Freeze, R.A. & Cherry, J.A. (1979): Groundwater. 1st edition, 604 p., Prentice Hall.

Furtak, H. & Langguth, H.R. (1967): Zur hydrochemischen Kennzeichnung von Grundwässern und Grundwassertypen mittels Kennzahlen. Mem. IAH-Congress, 1965, VII, Hannover, Germany.

Geotechnical Consulting Services (2000): Groundwater Monitoring Project. Final Report, Vol.19, Ramotswa wellfield, Gaborone, Botswana.

Hutton, L.G., Lewis, W.J. & Skinner, A.C. (1976): A report on nitrate contamination of groundwaters in some populated areas of Botswana. Report no. BGSD/8/76, DGS, Botswana. Institute of Hydrology (1986): Ramotswa Wellfield, Southeastern Botswana, Digital Model Study and Storage Estimates, Gaborone, Botswana.

Jacks, G. and Sharma, V.P. (1983): Nitrogen circulation and nitrate in groundwater in an agricultural catchment in southern India. Environmental Geology 5(2): 61-64.

Jacks, G., Sefe, F., Hammar, M. & Letsamao, P. (1999): Tentative nitrogen budget for pit latrines, Eastern Botswana, Environmental Geology, 38(3): 199-203.

Key, R.M. (1980): Gaborone Geological Map, Scale 1: 125 000, Quarter degree sheet 2425D, DGS, Lobatse, Botswana.

Key, R.M. (1983): The geology of the area around Gaborone and Lobatse, Kwaneng, Kgatleng, Southern and Southeast Districts. DGS, Ministry of Mineral Resources and Water Affaires, Gaborone, Botswana.

Key, R.M. (1998): National Geological Map of Botswana, Digital Database, DGS, Lobatse, Botswana.

Lagerstedt, E. (1992): Nitrate contamination in the groundwater and nitrogen circulation in an area of south-east Botswana. M.Sc. thesis, 55 p. plus appendices, Stockholm University, Stockholm, Sweden.

Lagerstedt, E., Jacks, G. & Sefe, F. (1994): Nitrate in groundwater and N circulation in Eastern Botswana. Environmental Geology 23: 60-64.

Lewis, W.J., Farr, J.L. & Foster, S.S.D. (1980): The pollution hazard to village water supplies in eastern Botswana. Proc. Instn, Civ.Engrs 2(69): 281-293.

Norwebb, B.T. (1996): Nitrate levels - Ramotswa Wellfield. Dept. of Water Affairs (DWA), Gaborone, Botswana.

Selaolo, E.T. (1985): Evaluation of aquifer hydraulic parameters in Ramotswa, S.E. Botswana. MSc Thesis, University of London, University College London, England.

Tredoux, G. (1993): A preliminary investigation of the nitrate content of groundwater and limitation of the nitrate input. Report to the Water Research Commission (WRC), No 368/1/93, 76 p., Pretoria, R.S.A.

Vogel, H. (2002): The soil nitrogen cycle. Report by the Environmental Geology Division, 25 p., Dept. of Geological Survey (DGS), Lobatse, Botswana.

Water Surveys (1994): Groundwater Pollution Vulnerability Map of the Ramotswa and Mogobane Area. Map 3.5 including Report No.4, Scale 1:50000, Water Surveys (Botswana) (Pty) Ltd., Gaborone, Botswana.

WLPU (1985): Ramotswa Wellfield Pollution Study. Watermeyer, Legge, Piesold & Uhlmann (WLPU), Final Report, Dept. of Water Affairs (DWA), Gaborone, Botswana.

WHO (1998): Guidelines for drinking water quality. World Health Organization, 2nd ed., Vol. 2, 1996, and Addendum to Vol.2, Geneva, Switzerland.

11 APPENDICES

Appendix IV: Results of the chemical analyses of the main elements

Sample No. K Na Cl Mg Ca SO4 Fe(II) Mn NO3 Br NH4 NO2 [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ]

Z6423 8.5 19.3 16.9 48.3 31.5 4.22 0.12 0.15 2.0 Z6424 5.1 17.9 29.1 46.0 66.4 4.10 27.5 0.19 0.09 0.08 4166 4.8 8.5 3.6 19.0 25.9 0.54 4.69 0.696 0.14 0.04 0.84 0.01 4347(UN2) 2.6 15.6 20.7 28.7 29.0 17.0 0.382 0.388 3.61 0.12 Z6501 1.0 21.5 36.6 46.8 59.5 50.3 0.24 0.24 0.03 4972 1.7 26.5 26.7 37.7 54.3 32.0 0.04 0.24 0.17 100M 1.6 81.3 34.6 20.0 29.1 27.7 0.34 0.26 0.01 RST7 4.4 158 316 111 94 58.7 111 1.73 0.02 0.22 4886 2.6 157 97.9 32.2 41.5 7.53 2.34 0.505 0.02 0.55 0.19 0.15 4995 6.0 66.6 79.7 57.8 59.7 19.9 0.538 0.098 188 0.27 RST4 3.9 724 989 150 137.8 455 0.389 0.066 103 5.21 0.04 RST5 4.6 523 813 172 181.3 504 0.004 0.148 64.3 4.28 0.06 RST6 6.7 507 695 115 128.9 419 0.903 0.062 41.8 3.39 0.01 10 5.6 83.8 51.6 37.2 44.8 22.7 1.93 0.316 12.2 0.33 0.15 4887 3.2 20.3 28.9 50.6 36.1 0.23 4.49 0.071 0.43 0.33 1.5 4163 0.1 9.1 42.2 84.2 56.2 32.4 0.592 0.017 110 0.04 4379 0.1 28.5 148 154 107 62.6 0.659 0.013 442 0.04 0.08 4422 14.8 29.6 52.6 85.8 107 47.7 0.689 0.245 177 4371 4.0 19.3 24.5 73.6 84.9 18.4 0.661 0.004 65.5 4155 1.0 13.9 19.3 37.1 46.2 11.8 0.927 0.025 38.4 0.10 0.01 4885 1.2 37.1 78.2 53.9 93.1 97.0 1.45 0.737 0.08 0.43 0.01 4348 1.7 50.9 4.07 112 44.5 114.4 0.746 0.167 17.8 0.05 Z4401 3.6 5.0 2.26 11.4 16.7 0.05 0.03 0.02 0.32 4164 1.7 17.2 15.6 78.3 55.4 43.1 0.469 0.098 9.05 0.15 4349 2.2 15.8 23.1 73.0 79.0 16.2 0.480 0.005 72.0 0.01 4340 0.9 29.6 57.7 44.9 77.9 66.0 4.87 0.626 0.16 0.35 4160 0.8 22.5 8.99 79.6 74.9 10.2 3.76 0.123 8.72 0.12 0.02 0.04 RST1 2.6 89.8 126 40.6 75.9 54.9 1.64 0.147 2.48 0.83 RST2 3.8 176 562 119 187 106 0.887 0.060 91.8 2.80 0.01 0.15 WH1 0.7 26.0 73.4 58.5 110 7.87 0.027 0.004 148 4154 1.7 171 16.7 14.4 6.95 0.51 2.02 0.028 0.10 0.20 0.97

TVO (1990) 12 150 250 50 400 240 0.2 0.05 50 0.5 0.1 EU max. (1998) 12 175 50 100* 250 0.2 0.05 50 0.5 0.1 WHO (1998) 200 250 400 0 0.1 50 Botswana 200* 800 600 3 5 45*/100 Max. (1998) SABS Max. 400 40 600 100 200 600 1 1 9 2 10

Sample No. PO4 Al BO2 Ba Cd Co Cr Cu Li Ni Pb SiO2 [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ]

Z6423 0.03 Z6424 4166 0.1 0.043 15.4 4347(UN2) 0.09 0.009 0.007 13.2 Z6501 4972 100M RST7 0.03 4886 0.03 0.86 0.021 0.081 0.012 29.3 4995 0.02 0.21 0.072 0.013 0.042 0.021 53.8 RST4 0.04 0.32 0.037 0.007 0.023 0.106 0.037 34.6 RST5 0.03 0.26 0.037 0.008 0.032 0.099 0.101 35.6 RST6 0.29 0.016 0.018 0.075 0.036 31.5 10 0.49 0.179 0.045 0.012 25.6 4887 0.17 0.11 0.080 0.013 13.1 4163 0.08 0.015 26.3 4379 0.05 0.13 0.002 0.007 0.021 0.007 0.034 34.6 4422 0.04 0.15 0.020 0.012 0.005 0.023 27.6 4371 0.11 0.002 0.011 0.005 0.022 25.5 4155 0.06 0.12 0.001 0.012 22.5 4885 0.04 0.16 0.112 0.005 0.014 0.021 0.02 21.8 4348 0.06 0.56 0.010 0.005 0.019 0.029 0.04 29.0 Z4401 0.02 4164 0.15 0.052 0.015 0.022 27.8 4349 0.04 0.12 0.008 0.012 0.019 26.5 4340 0.13 0.125 0.021 0.017 19.5 4160 0.02 0.14 0.004 0.012 0.018 27.8 RST1 0.33 0.16 0.186 0.012 0.007 0.028 0.026 32.3 RST2 0.02 0.37 0.23 0.599 0.009 0.029 0.018 0.007 0.047 0.094 0.05 34.7 WH1 0.1 0.001 0.011 0.007 0.010 0.017 56.5 4154 0.02 0.25 1.04 0.030 0.070 21.2

TVO (1990) 0.2 0.05 0.05 0.04 EU max. (1998) 0.2 0.05 0.05 0.05 WHO (1998) 0.2 3 0.05 1 0.002 0.01 Botswana 5 0.05 1 Max. (1998) SABS Max. 0.5 1 0.5 0.2 0.5 0.1

Sample No. Sr Ti Zn F [ mg/L ] [ mg/L ] [ mg/L ] [ mg/L ]

Z6423 0.228 Z6424 0.180 4166 0.072 0.017 0.231 4347(UN2) 0.076 0.025 0.150 Z6501 0.170 4972 0.228 100M 2.690 RST7 0.887 4886 0.209 0.021 1.865 4995 0.298 0.526 0.234 RST4 0.711 0.526 4.460 RST5 0.867 0.094 1.400 RST6 0.626 0.732 1.790 10 0.128 1.19 1.260 4887 0.091 0.028 0.332 4163 0.043 0.864 0.217 4379 0.083 1.43 0.292 4422 0.127 1.08 0.105 4371 0.077 0.975 0.089 4155 0.052 1.32 0.333 4885 0.311 1.33 0.194 4348 0.086 0.862 0.334 Z4401 0.240 4164 0.084 0.705 0.153 4349 0.085 0.738 0.160 4340 0.255 1.34 0.183 4160 0.088 1.26 0.198 RST1 0.430 1.25 0.329 RST2 1.194 0.003 1.20 0.471 WH1 0.243 0.83 0.116 4154 0.094 1.09 0.460

TVO (1990) 5 1.5* EU max. (1998) 5 0.7* WHO (1998) 5 1.5 Botswana 5 3.0 Max. (1998) SABS Max. 0.5 5 1.5

Appendix V: Results of the chemical analyses of trace elements

Sample No. Ag Al As B Ba Be Bi (Br) (Ca) Cd Ce Co Cu (Fe) µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L

4166 0.002 7.7 14.4 27 50.3 0.018 <0.002 49 24700 0.016 0.016 0.93 0.69 4380 4347(UN2) 0.002 5.6 0.30 28 13.6 0.009 <0.002 136 29000 0.029 0.013 0.52 0.69 379 4866 0.003 4.8 51.1 297 29.3 0.055 0.002 522 43800 0.008 0.017 0.73 0.50 2150 4995 0.005 6.8 2.38 68 91.0 0.023 0.002 759 63500 0.43 0.040 1.58 1.19 529 RST4 0.028 6.4 5.63 82 50.5 0.091 <0.002 4640 130000 0.070 0.083 1.50 1.97 314 RST5 0.009 0.4 4.19 75 50.1 0.062 <0.002 4190 181000 0.099 0.004 8.50 2.75 37 RST6 0.011 33.0 4.12 77 22.3 0.003 0.004 3470 137000 0.066 0.040 2.41 2.06 1130 10 <0.002 43.7 21.9 152 205 0.30 <0.002 480 49500 0.067 0.10 3.59 0.85 2440 4887 <0.002 218 11.5 34 91.1 0.025 <0.002 403 40000 0.022 0.038 0.28 0.66 5670 4163 0.004 43.8 0.82 24 2.9 0.038 0.003 357 61500 0.024 0.032 0.12 1.40 729 4379 0.007 50.8 1.06 30 5.4 0.039 <0.002 1180 112000 0.10 0.037 0.17 2.91 792 4422 0.004 55.8 0.37 40 25.5 0.031 0.002 472 110000 0.030 0.054 1.14 1.79 792 4371 0.006 36.3 0.26 29 5.3 0.030 0.002 204 90300 0.072 0.024 0.17 1.01 788 4155 0.006 102 0.31 33 3.1 0.030 0.003 198 47600 0.020 0.26 0.22 0.97 1100 4885 0.011 64.0 4.08 43 124 0.008 0.002 424 98100 1.06 0.12 3.07 1.41 1780 4348 <0.002 75.0 3.30 161 12.4 0.038 0.002 88 46100 0.096 0.11 4.99 2.79 823 4164 <0.002 49.4 3.07 40 56.8 0.032 0.002 173 76900 0.030 0.029 1.60 1.34 498 4349 0.004 67.2 0.27 31 12.5 0.044 0.002 209 85200 0.082 0.020 0.16 0.96 538 4340 0.007 50.7 1.03 35 141 0.052 0.002 358 85100 0.040 0.12 0.50 1.38 5890 4160 0.011 42.1 0.78 36 8.4 0.038 <0.002 145 76600 0.034 0.10 0.19 1.03 4300 RST1 0.008 427 0.81 48 211 0.029 0.003 723 77600 0.061 0.086 2.33 1.19 2060 RST2 0.029 407 4.96 57 696 0.056 0.003 3000 201000 0.22 0.12 8.97 3.16 1110 WH1 0.003 31.4 0.84 25 4.2 0.024 <0.002 648 111000 1.76 0.019 0.39 9.51 14 4154 0.004 269 0.58 300 34.4 0.008 <0.002 233 7420 0.15 0.068 0.12 1.46 2250

TVO (1990) 10 200 10 1000 400000 5 2000 200 EU max. (1998) 10 200 50 1000 5 2000 200 WHO (1998) 10 200 50 5 1000 300 Botswana 3000 Max. (1998) SABS Max. 50 500 300 2000 1000 5 500 200000 20 2 500 1000 1000

Sample No. Ga (Ge) Hf (Hg) In (I) (K) La Li (Mg) Mn Nb Ni Pb µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L

4166 0.046 0.051 0.009 <0.01 <0.002 23.2 4110 0.008 0.9 20200 655 <0.002 1.84 0.45 4347(UN2) 0.026 0.024 0.003 <0.01 <0.002 16.8 2480 0.009 10.7 30500 384 <0.002 1.72 0.54 4866 0.035 1.79 0.015 <0.01 <0.002 73.3 2740 0.007 104 35400 551 0.002 5.14 1.46 4995 0.024 0.023 0.005 <0.01 <0.002 64.2 5860 0.029 53.9 62800 111 0.002 10.2 1.13 RST4 0.022 0.012 0.021 <0.01 <0.002 112 3980 0.035 113 155000 78.4 0.003 10.5 1.01 RST5 0.005 <0.005 0.036 <0.01 <0.002 69.2 4750 0.005 116 182000 174 0.054 65.1 0.02 RST6 0.010 0.052 0.021 <0.01 <0.002 177 6990 0.019 91.9 158000 69.4 0.010 13.7 1.61 10 0.043 0.94 0.007 <0.01 <0.002 44.2 5630 0.051 58.6 47800 372 0.005 4.60 2.51 4887 0.036 0.20 <0.002 <0.01 <0.002 45.6 3370 0.021 3.0 64900 84 0.002 3.59 0.24 4163 0.016 0.013 0.005 <0.01 <0.002 8.6 289 0.036 0.7 68700 20.2 0.003 3.61 2.19 4379 0.014 0.014 <0.002 <0.01 <0.002 8.4 461 0.034 1.3 180000 12.7 0.003 6.18 2.54 4422 0.020 0.045 0.002 <0.01 <0.002 17.7 16500 0.037 4.1 94600 262 <0.002 6.64 2.14 4371 0.007 0.023 0.007 <0.01 <0.002 22.2 3580 0.015 3.5 84500 0.1 0.003 4.86 2.17 4155 0.031 0.019 0.008 <0.01 <0.002 13.7 964 0.14 4.4 40800 22.6 0.004 3.48 2.74 4885 0.055 0.067 0.003 <0.01 <0.002 34.3 1300 0.069 27.8 61500 752 0.004 10.1 2.69 4348 0.032 0.030 0.002 <0.01 <0.002 61.3 1730 0.056 5.2 113000 164 0.003 8.02 1.80 4164 0.032 0.049 0.002 <0.01 <0.002 29.9 1820 0.018 6.4 77200 92.9 <0.002 5.46 2.13 4349 0.006 0.024 <0.002 <0.01 <0.002 28.3 2690 0.023 3.7 80900 2.1 <0.002 3.53 2.22 4340 0.063 0.073 <0.002 <0.01 <0.002 34.7 1170 0.057 28.7 52600 687 0.003 6.09 2.70 4160 0.050 0.041 0.002 <0.01 <0.002 18.5 1020 0.022 3.0 83000 136 0.004 4.26 2.57 RST1 0.051 0.059 <0.002 0.08 <0.002 100 2990 0.048 38.3 45900 172 0.003 21.2 2.56 RST2 0.036 0.022 0.003 <0.01 <0.002 109 4730 0.083 59.8 142000 67.2 0.008 81.4 6.07 WH1 0.002 0.068 <0.002 <0.01 <0.002 18.4 1020 0.046 16.3 60800 5.0 <0.002 4.99 1.00 4154 0.034 0.32 <0.002 <0.01 <0.002 27.4 2160 0.026 81.2 15300 27.7 0.002 2.88 2.23

TVO (1990) 1 12000 50000 50 50 10 EU max. (1998) 1 12000 50000 50 50 10 WHO (1998) 100 10 Botswana 500 Max. (1998) SABS Max. 10 400000 5000 100000 1000 500 100

Sample No. Rb Sb Sc (Se) Sn Sr Ta Te Th Ti U V W µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L

4166 4.78 0.043 3.39 0.35 16.6 55 <0.002 <0.005 0.011 0.11 0.014 0.41 0.023 4347(UN2) 2.97 0.032 2.92 0.53 20.5 75 <0.002 0.006 0.002 0.27 0.43 0.11 0.004 4866 3.71 0.21 7.32 0.78 16.8 248 0.004 0.030 0.010 0.29 0.27 0.53 2.02 4995 0.96 0.081 11.6 1.14 23.2 340 <0.002 0.010 0.005 0.38 3.33 7.63 0.037 RST4 4.44 0.11 7.10 15.4 10.1 863 0.005 0.032 0.009 5.88 35.0 6.40 0.017 RST5 6.58 1.19 7.59 19.0 0.36 1130 0.043 0.025 0.004 6.23 43.0 3.60 0.099 RST6 6.84 0.13 7.04 9.72 12.2 685 0.006 0.026 0.022 4.63 20.7 4.38 0.089 10 11.3 0.12 6.07 1.19 21.6 154 0.003 0.007 0.007 0.58 1.08 0.66 0.54 4887 5.58 0.27 3.34 0.66 23.6 110 <0.002 0.012 0.007 0.21 0.21 0.24 0.04 4163 0.38 0.11 5.84 0.72 17.7 47 <0.002 0.015 0.002 0.48 0.37 1.83 0.008 4379 0.80 0.29 7.13 1.79 18.4 87 <0.002 0.037 0.003 1.18 0.88 4.33 0.048 4422 5.18 0.10 5.83 2.45 31.7 124 <0.002 0.037 0.003 0.98 1.21 0.79 0.076 4371 1.68 0.049 5.12 1.09 17.7 78 0.002 0.028 0.010 0.37 0.91 0.59 0.012 4155 1.04 0.062 4.55 0.95 35.9 50 0.002 0.016 0.020 0.86 0.51 0.90 0.57 4885 2.94 0.25 4.51 0.93 17.3 308 0.002 0.015 0.011 1.87 5.56 0.40 0.014 4348 4.10 0.95 6.10 5.15 13.1 83 <0.002 0.020 0.009 1.90 6.27 2.22 2.99 4164 2.93 0.28 5.83 1.18 10.9 83 <0.002 0.011 0.003 0.89 1.55 0.62 0.16 4349 1.46 0.050 5.98 0.68 10.1 89 <0.002 <0.005 0.002 0.33 1.50 0.88 0.053 4340 2.35 0.31 4.83 0.20 20.6 260 <0.002 <0.005 0.007 1.44 3.45 0.26 0.015 4160 0.85 0.12 7.14 0.54 12.8 94 <0.002 0.007 0.005 0.44 2.20 0.15 0.018 RST1 3.80 0.41 8.03 0.82 5.32 422 <0.002 <0.005 0.004 1.37 1.58 0.53 0.009 RST2 4.84 2.15 8.04 3.77 14.7 1310 <0.002 0.008 0.005 3.06 14.9 3.88 0.019 WH1 1.21 0.050 12.4 0.97 16.9 245 <0.002 0.011 0.002 0.24 1.53 7.52 <0.002 4154 3.42 0.040 4.98 0.31 8.52 87 <0.002 <0.005 0.004 0.49 0.058 0.21 0.066

TVO (1990) 5 10 EU max. (1998) 5 10 WHO (1998) 10 Botswana Max. (1998) SABS Max. 50 5 500 4000 500 500

Sample No. Y Zn Zr Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Lu µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L

4166 0.013 9.5 0.057 0.002 0.010 0.002 0.009 0.003 <0.002 0.002 <0.002 <0.002 <0.002 <0.002 4347(UN2) 0.017 13.9 0.011 0.002 0.010 0.006 0.002 0.003 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 4866 0.038 6.8 0.043 0.002 0.008 0.002 0.006 0.004 <0.002 0.004 0.002 0.008 0.003 0.005 4995 0.13 474 0.016 0.006 0.029 0.006 0.018 0.008 0.002 0.012 0.003 0.008 <0.002 0.002 RST4 0.20 344 0.059 0.008 0.030 0.007 0.010 0.017 0.003 0.017 0.005 0.014 0.003 0.003 RST5 0.025 40.6 0.073 <0.002 0.004 0.002 0.007 0.002 <0.002 <0.002 <0.002 0.003 <0.002 <0.002 RST6 0.17 624 0.052 0.005 0.011 0.004 0.005 0.003 0.002 0.012 0.004 0.010 <0.002 <0.002 10 0.093 1230 0.059 0.010 0.042 0.012 0.032 0.009 <0.002 0.007 0.002 0.005 <0.002 <0.002 4887 0.028 13.4 0.028 0.005 0.014 0.004 0.017 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 4163 0.12 896 0.10 0.009 0.040 0.005 0.002 0.004 0.002 0.005 0.002 0.009 <0.002 <0.002 4379 0.075 1360 0.015 0.007 0.027 0.004 0.002 0.007 <0.002 0.003 0.002 0.005 <0.002 <0.002 4422 0.077 1040 0.038 0.008 0.038 0.011 0.006 0.006 0.002 0.004 <0.002 0.006 <0.002 <0.002 4371 0.047 979 0.028 0.003 0.015 0.004 <0.002 <0.002 <0.002 <0.002 <0.002 0.003 <0.002 <0.002 4155 0.11 1300 0.067 0.033 0.12 0.024 0.005 0.025 0.003 0.013 0.004 0.009 <0.002 <0.002 4885 0.13 1290 0.047 0.015 0.058 0.009 0.021 0.009 <0.002 0.007 0.002 0.007 <0.002 <0.002 4348 0.10 835 0.051 0.013 0.042 0.010 0.004 0.011 0.002 0.008 0.002 0.008 <0.002 <0.002 4164 0.026 683 0.036 0.004 0.017 0.005 0.012 0.002 <0.002 <0.002 <0.002 0.002 <0.002 <0.002 4349 0.061 750 0.025 0.005 0.020 0.004 0.004 0.003 <0.002 0.004 0.002 0.004 <0.002 <0.002 4340 0.053 1340 0.030 0.011 0.039 0.012 0.025 0.009 <0.002 0.005 0.002 0.004 <0.002 <0.002 4160 0.040 1260 0.022 0.004 0.019 0.005 0.003 0.008 <0.002 0.005 <0.002 0.002 <0.002 <0.002 RST1 0.054 1260 0.029 0.009 0.030 0.010 0.035 0.010 <0.002 0.005 0.002 0.004 <0.002 <0.002 RST2 0.17 1090 0.080 0.014 0.050 0.011 0.12 0.010 0.002 0.013 0.003 0.009 <0.002 <0.002 WH1 0.29 800 0.013 0.011 0.043 0.015 0.003 0.017 0.004 0.025 0.005 0.015 <0.002 <0.002 4154 0.017 1060 0.034 0.007 0.024 0.004 0.007 0.005 <0.002 0.004 <0.002 <0.002 <0.002 <0.002

TVO (1990) 5000 EU max. (1998) 5000 WHO (1998) 5000 Botswana 150000 Max. (1998) SABS Max. 5000

Appendix VI:

Logs of selected sampled boreholes

(developed in the GeODin software environment)

48 Depth: 0.00 (m above Datum)

0.0 2.00 CHERT, 0.00 Borehole diameter iron staining, 305mm 6.10 2.00 quartz pebbles 6.50 Casing left in borehole -10.0 4.00 brown, Steel CLAY, angular chert 4.00 fragments -20.0 6.00 grey, 6.00 CHERT 28.00 grey, DOLOMITE, -30.0 with or without quartz veins, groundwater 28.00 level (6.10) -40.0 32.00 greyish, CHERT, iron staining, 32.00 quartz veins -50.0 56.00 greyish, DOLOMITE, 56.00 different quartz content, -60.0 water struck 56.00 (56.0) 58.00 CHERT, 3-4 -70.0 cm diametwr 58.00 chert pebbles Borehole diameter 66.00 grey, 203mm white, Casing left in borehole -80.0 DOLOMITE, Steel 66.00 siliceous 70.00 black, CHERT, iron -90.0 70.00 staining 86.00 greyish, DOLOMITE, interlayers of -100.0 chert,quartz, 86.00 iron staining 88.00 grey, CHERT, iron -110.0 88.00 staining

-120.0

-130.0 144.00 greyish, DOLOMITE, interlayers of -140.0 chert, quartz, 144.00 iron staining

-150.0 150.00

Vertical scale: 1:900 Page 1 of 1

BH no.: 4155, monitoring BH with shelter

Location point: 4155, Ramotswa UTM Lo27 - Zone 35 Client: Easting (X): 38649,12 Author: Northing (Y): 7247354,64 Sampled Project: Ramotswa Ground level: 1023,29 m above Datum Date: 23/08/1980 End depth: 150.00 m below ground Depth: 0.00 (m above Datum)

0.0 2.00 SAND 0.00 Borehole diameter AND 305mm 4.80 GRAVEL, Casing left in borehole surface sand Steel -10.0 10.00 2.00 and pebbles 4.00 grey, DOLOMITE, silicious dolomite with -20.0 4.00 quartz veins 14.00 grey, 23.60 DOLOMITE, silicious Casing left in borehole dolomite, iron Steel -30.0 staining, quartz veins, groundwater 14.00 level (10.00) 16.00 grey, CHERT, iron -40.0 16.00 staining

Borehole diameter -50.0 50.00 216mm

-60.0

-70.0

86.00 grey, DOLOMITE, -80.0 iron staining, quartz veins, water struck 86.00 (23.6) 88.00 grey, -90.0 88.00 CHERT

-100.0 104.00 grey, 100.00 DOLOMITE, 104.00 as above

Vertical scale: 1:700 Page 1 of 1

BH no.: 4160, monitoring BH

Location point: 4160,Ramotswa UTM Lo27 - Zone 35 Client: wellfield consulting services Easting (X): 386483,09 Author: Northing (Y): 7246200,81 Sampled Project: Ramotswa Ground level: 1026.81 m above Datum Date: 28/09/2001 End depth: 104.00 m below ground Depth: 0.00 (m above Datum)

0.0 2.00 0.00 Borehole diameter TOPSOIL, 2.30 305mm 2.00 with pebbles Casing left in borehole 8.60 4.00 grey, Steel -10.0 DOLOMITE, 4.00 with clay 8.00 grey, DOLOMITE, with chert -20.0 8.00 pebbles 14.00 dark, grey, DOLOMITE, increased -30.0 quartz content, groundwater 14.00 level (8.60) 16.00 black, 16.00 SHALE -40.0

Borehole diameter -50.0 216mm 56.00 light, grey, 56.00 DOLOMITE

-60.0

-70.0

-80.0

-90.0

-100.0 100.00

Vertical scale: 1:700 Page 1 of 1

BH no.: 4163, monitoring BH

Location point: 4163, Ramotswa UTM Lo27 - Zone 35 Client: Easting (X): 386481,00 Author: Northing (Y): 7250657,06 Sampled Project: Ramotswa Ground level: 1018.36 m above Datum Date: 28/09/2001 End depth: 56.00 m below ground Depth: 0.00 (m above Datum)

0.0 0.00

Borehole diameter 203mm

Casing left in borehole Steel

3.30

4.00 TOPSOIL, groundwater 4.00 level (3.30) 4.00

Vertical scale: 1:30 Page 1 of 1

BH no.: 4164, monitoring BH

Location point: 4164, Ramotswa UTM Lo27 - Zone 35 Client: Easting (X): 387256,02 Author: Northing (Y): 7247480,31 Sampled Project: Ramotswa Ground level: 1023.53 m above Datum Date: 28/09/2001 End depth: 4.00 m below ground Depth: 0.00 (m above Datum)

0.0 0.00 Borehole diameter 10.00 254mm 6.70 TOPSOIL, Casing left in borehole groundwater Steel -10.0 10.00 level (6.70) 12.00 brown, 11.00 SANDSTONE, medium 12.00 grained 16.00 dark, -20.0 16.00 brown, CLAY Casing left in borehole 24.00 grey, Steel QUARTZITE 24.00 (sed.)

-30.0 34.00 dark, grey, 33.00 34.00 DOLOMITE 36.00 black, SHALE, iron 36.00 staining -40.0 39.30

Borehole diameter -50.0 203mm

60.00 grey, QUARTZITE (sed.), water -60.0 60.00 struck (39.3) 62.00 black, 62.00 SHALE

-70.0

-80.0

-90.0

100.00 QUARTZITE (sed.), with black shale -100.0 100.00 interlayers 100.00

Vertical scale: 1:600 Page 1 of 1

BH no.: 10, (4165), monitoring BH

Location point: 4165, Ramotswa UTM Lo27 - Zone 35 Client: Easting (X): 386243,80 Author: Northing (Y): 7251743,40 Sampled Project: Ramotswa Ground level: 1015.84 m above Datum Date: 28/09/2001 End depth: 100.00 m below ground Depth: 0.00 (m above Datum)

0.0 4.00 0.00 TOPSOIL, Borehole diameter 4.00 with pebbles 6.20 254mm 12.00 Casing left in borehole CHERT, Steel -10.0 interlayers of quarzite, 11.00 groundwater 12.00 level (6.20)

-20.0

-30.0

-40.0 42.00

Borehole diameter -50.0 203mm

Casing left in borehole -60.0 Steel

-70.0

-80.0

-90.0

100.00 greyish, SHALE, water -100.0 100.00 struck (42.00) 100.00

Vertical scale: 1:600 Page 1 of 2

BH no.: 4166, monitoring BH

Location point: 4166 Ramotswa Client: Easting (X): 386192680 Author: Northing (Y): 7245602398 Sampled Project: Ramotswa Ground level: 1024.724m above Datum Date: 28/09/2001 End depth: 100.00 m below ground Depth: 0.00 (m above Datum)

0.0 4.00 SANDY 0.00 Casing left in borehole CLAY 4.75 4.00 4.00

-10.0 18.00 greyish, DOLOMITE, groundwater 18.00 level (4, 75) -20.0

30.00 black, SHALE, -30.0 30.00 dolomitic

-40.0 40.00 40.00 CHERT

Borehole diameter 305mm

-50.0

-60.0

-70.0

76.00

-80.0 94.00 greyish, DOLOMITE, fissure fillingd of sand and quartz and -90.0 white specks, water struck 94.00 (76.00) 94.00

Vertical scale: 1:600 Page 1 of 1

BH no.: 4348, monitoring BH

Location point: 4348, Ramotswa UTM Lo27 - Zone 35 Client: Gaborone water supply Easting (X): 386621,68 Author: Northing (Y): 7246007,51 Sample d Project: Ramotswa Ground level: 1024.38 m above Datum Date: 03/10/2001 End depth: 94.00 m below ground Depth: 0.00 (m above Datum)

0.0 0.00

-10.0

-20.0

-30.0

-40.0

Borehole diameter 254mm

-50.0

-60.0

-70.0

-80.0

96.00 grey, DOLOMITE, -90.0 90.00 sometimes fissured, shaley,partly 96.00 white

Vertical scale: 1:600 Page 1 of 1

BH no.: 4371, monitoring BH

Location point: 4371, Ramotswa UTM Lo27 - Zone 35 Client: Easting (X): 387496,18 Author: Northing (Y): 7247677,70 Sampled Project: Ramotswa Ground level: 1022.48 m above Datum Date: 03/10/2001 End depth: 96.00 m below ground Depth: 0.00 (m above Datum)

0.0 4.00 dark, 0.00 4.00 4.00 grey, CLAY Casing left in 6.00 CLAY, borehole chips of 9.00 -10.0 dolomite, Borehole 11.00 groundwater diameter 431mm 6.00 level (4.00) 15.00

-20.0

-30.0 Casing left in borehole

-40.0

-50.0 Borehole diameter 381mm 54.00

-60.0

69.00 -70.0 Filter

-80.0

-90.0 90.00

-100.0 Borehole diameter 203mm

-110.0 120.00 DOLOMITE, solid and fissured, groundwater -120.0 120.00 level (69.0) 120.00

Vertical scale: 1:700 Page 1 of 1

BH no.: 4422, DWA production well

Location point: 4422, Ramotswa UTM Lo27 - Zone 35 Client: Water Affairs Easting (X): 387385,26 Author: Northing (Y): 7248086,74 Sampled Project: Ramotswa Ground level: 1018.94 m above Datum Date: 03/10/2001 End depth: 120.00 m below ground Depth: 0.00 (m above Datum)

0.0 0.00 3.00 3.00 CLAY Borehole diameter 254mm -10.0 Casing left in borehole 13.00

-20.0

-30.0

-40.0

-50.0

-60.0

-70.0

Borehole diameter 203mm -80.0

-90.0

-100.0

-110.0

-120.0

-130.0

-140.0 144.00 144.00 DOLOMITE 144.00

Vertical scale: 1:900 Page 1 of 1

BH no.: 4887, monitoring BH

Location point: 4887, Ramotswa UTM Lo27 - Zone 35 Client: BRGM Easting (X): 386556,55 Author: Northing (Y): 7251167,86 Sampled Project: Ramotswa Ground level: 1014.64 m above Datum Date: 03/10/2001 End depth: 144.00 m below ground Depth: 0.00 (m above Datum)

0.0 3.00 CLAY 0.00 Borehole diameter 3.00 WITH SAND 279mm 11.00 light, Casing left in borehole -10.0 grey, SHALE, 9.00 weathered, 11.00 fractures 15.00 light, -20.0 21.00 grey, SILTSTONE, mica,well 27.00 fractured, iron -30.0 15.00 oxides 30.00 black, SHALE, sandy, -40.0 interlayers of 42.00 grey siltstone, water struck (21.00), water Borehole diameter -50.0 30.00 struck (27.00) 203mm 32.00 black, QUARTZITE 32.00 (sed.) -60.0 37.00 grey, SILTSTONE, well fractured, pyrite, iron -70.0 37.00 oxide 38.00 black, 76.00 QUARTZITE (sed.), -80.0 interlayers of 38.00 black shale

-90.0 90.00

-100.0 100.00

-110.0

Borehole diameter -120.0 165mm 134.00 grey, SHALE, sandy, water -130.0 struck (42.00), water struck 134.00 (76.00) 135.00 grey, -140.0 SILTSTONE, pyritc, water struck 135.00 (100.00) -150.0 138.00 grey, 150.00 CHERT, with grey shale, fresh, rock 138.00 shattered 150.00 grey, 150.00 SHALE Vertical scale: 1:900 Page 1 of 1

BH no.: 4972, monitoring BH

Location point: 4972, Ramotswa Client: BRGM Easting (X): 386745737 Author: Northing (Y): 7244618248 Sampled Project: Ramotswa Ground level: 1026.044 m above Datum Date: 03/10/2001 End depth: 150.00 m below ground Depth: 0.00 (m above Datum)

0.0 0.00 Borehole diameter 279mm -10.0 16.00 CLAY Casing left in borehole WITH Steel 16.00 GRAVEL 16.00 -20.0 24.00 Borehole diameter -30.0 203mm

-40.0 42.00

-50.0

-60.0 Borehole diameter 165mm

-70.0

-80.0 84.00

-90.0

-100.0

-110.0

Borehole diameter 152mm -120.0

-130.0

-140.0 150.00 ANHYDRITE, must be Dolomite !!! water struck -150.0 150.00 (24.00) 150.00

Vertical scale: 1:900 Page 1 of 1

BH no.: 4995

Location point: 4995, Ramotswa Client: Water Affairs Easting (X): 385537561 Author: Northing (Y): 7252337495 Sampled Project: Ramotswa Ground level: 1033.06 m above Datum Date: 04/10/2001 End depth: 150.00 m below ground Depth: 0.00 (m above Datum)

0.0 3.00 0.00 Casing left in borehole 4.65 3.00 TOPSOIL 3.00

-10.0 Casing

-20.0 20.00 Filter,with vertical slits 24.00 24.00

-30.0

Borehole diameter 203mm -40.0 Casing

-50.0 65.00 DOLOMITE, groundwater -60.0 level (4.65), 60.00 water struck Filter,with vertical slits 66.00 65.00 (24.00) 66.00 70.00 -70.0 DOLOMITE, Casing soft, fissured?, 72.00 water struck 70.00 (66.00) -80.0

-90.0

-100.0

-110.0 Borehole diameter 165mm

-120.0

-130.0

-140.0

150.00 -150.0 150.00 DOLOMITE 150.00

Vertical scale: 1:900 Page 1 of 1

BH no.: Z6423, monitoring Bh

Location point: Z6423, Ramotswa UTM Lo27 - Zone 35 Client: Water Utilities Easting (X): 384569,62 Author:Pula Groundwater Developers Northing (Y): 7249989,09 Sampled Project: Ramotswa Ground level: 1037.35 m above Datum Date: 04/10/2001 End depth: 150.00 m below ground Depth: 0.00 (m above Datum)

0.0 9.00 0.00 Casing left in borehole GRAVEL, with 3.00 chert -10.0 9.00 fragments

-20.0 20.00

-30.0

Casing left in borehole

-40.0 Borehole diameter 203mm

-50.0 51.00

-60.0

-70.0 69.00

-80.0 84.00

-90.0

-100.0

-110.0

Borehole diameter 165mm -120.0

-130.0

150.00 -140.0 DOLOMITE, groundwater level (20.00), water struck -150.0 150.00 (51.00) 150.00

Vertical scale: 1:900 Page 1 of 1

BH no.: Z6424, monitoring BH

Location point: Z6424, Ramotswa Client: Water Utilities Easting (X): 382439887 Author:Pula Groundwater Developers Northing (Y): 7247200551 Sampled Project: Ramotswa Ground level: 1056.131 m above Datum Date: 04/10/2001 End depth: 150.00 m below ground