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REPUBLIC OF BOTSWANA

ANNUAL REPORT

OFTHE

GEOLOGICAL SURVEY

DEPARTMENT

FOR THE YEAR

1987

PRICE: 1'3,00

i ,-

Printed by the Government Printing and Publishing Services, Gaborone, Botswana

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1

1. GENERAL -----

The Geological Sur'vey remained Vii thin the Ministry of

Mineral fhsources and Water Affairs and continued with its mai,n

functions of gathering, assessing and disseminating all data

related to the rocks, mineral deposits and groundwater

resources of Botswana.

The departmental organisational structure continued to

ccnsist of the Directorate, four operaticnal divisions of

Regional Geology (Field Geology) Economic Geology, Hydrogeclogy

and Geophysics together Viith an administrative division.

Support to the main divisions was provided by, the Chemistry

and Industrial Minerals laboratories, Drawing Office, Library

and Records, and Drilling Sections.

The staffing positicn within the technical and profes-

sional cadres rerrained satisfactory throughout the year. How-

ever Mr. Moremi Sekwale Deputy Director left the department

at the end of November to become the ,Director of the Department

of Water Affairs. Dr. Norman Lock continued as Assistant

Director and has been acting as Deputy Director as from the

beginning of December, 1927. Mr. MichaelMchunu Assistant

Chemist left the department at the end of his contract.

Drs Jean Roy and Jchn Dyck geophysicists seconded by CIDA

left the department at the end of their contracts.

Satisfactory work programmes were carried out and completed by

all divisions during the year. Within the Economic Geology

unit, work was directed towards evaluation of industrial

minera,ls mainly clays, carbonates and calcretes.

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2

Mineral Exploration by the Private Sector continued to be

very active throughout the whole country. This work was

directed at the discovery of precious stones, precious metals

and platinum group metals.

Within the Hydrogeology Division, the emphasis was on

·groundwater investigation projects. By year end three such

projects were near completion. These included the Serowe

Groundwater Resources Evaluation Project, the Kanye Dolomite

Groundwater Resources and Development Project Phase 11 and the

Lephephe-Mmamabula Groundwater Investigation Project.

Three research projects were also undertaken by the staff

of the Hydrogeology division during the year. These projects

consisted of a desk study on the groundwater facies in

. Southern Botswana, the hydrochemistry in the groundwater

basin~ further to the west up to the Namibian border and the

Groundwater Recharge Study.

Through desk top studies, groundwater resources were

indentified in the Waterberg Formation in an area between

Molepolole and the Limpopo river and within the lower Karoo

rocks in an area around Botlhapatlou east of Letlhakeng.

Finally a groundwater resource map of Botswana at a scale of

1:1 million was compiled and produced during the year.

Within the Regional Geology Unit, work WaS directed

towards regional mapping projects. Six quarter degree sheets

were investigated during the year theSe being Mmamabula -

Dj. bete (QDS 2326c, D and part of 2327C) Shashe (O.DS 2127 A) ,

Topisi (QDS 2227A) ,\ Matsitama (QDS 2126B), Mogogaphate (QDS

2128C) and Marico River (QDS 2426B).

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3

Compilation of maps and manuscripts for the Mmamabula -

Dibete and Shashe projects were underway by year end.

Manuscripts ior the Okwa Valley, Kanye (QDS 2525A) and

Metlobo (QDS 2524B) were submitted for editing. Bulletins

and maps still pending included Jwaneng (QDS 2424D), Mmathethe

(QDS 2525A) and Letlhakeng (QDS 2425A).

The Geophysics Unit devoted most of its efforts to foreign

aid projects. The Petro-Canada funded reflection seismic

survey in the Ncojane-Nosop basin and the Passarge basin was

started during the year. The EEC funded interpretation of the

1985-86 aeromagnetic data over eastern Botswana was completed.

Initial planning was carried out for an EEC funded air-

borne electromagnetic survey in Eastern Botswana and an EEC

funded gravity and magnetotelluric survey in the three basins

in western and central Botswana.

Borehole logging was carried out for auriferous sulphide

mineralisation in three holes in the Vumba Schist belt Project

area and for geological and geophysical information in three

water boreholes. Furthermore, a considerable amount of time

was spent on professional consultation and advice on ground-

water evaluation projects.

In the support section the Drawing Office continued the

produc tion of maps and diagrams accompanying geo-logical reports,

builetins and memoires. The Chemistry and Industrial Mineral

laboratories provided the analytical facilities to other

sections within the department. The drilling unit provided

all the drilling input required by the department even though

their work was hampered by the breakdown of most of the

drilling machines which are now very old.

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The two CIDA projects continued to run smoothly during

1987. These projects include the driller training project

which was extended during 1987 to allow the five drillers to

·undertake studies at diploma level in drilling mechanics and

hydraulics at various institutions in canada, and the locali­

sation of the Geophysics unit project. In 1987 one student

went to Canada to undertake studies in hydrogeological

Technology at Sir Sandford Fleming College.

Fieldwork for the final phase of the Vumba project

involving drilling on several anomali0s was finally completed

during 1987. The final report on this project is expected

sometime in 1988.

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5.1

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Hydrogeology Division

Introduction

The staff establishment remained unchanged during 1987 with 4 posts for rtydrogeologists and 6 posts for Technical Assistants. Under the departmental training programme 2 Assistant Hydrogeologists became familiarised with principles of Hydrogeo­logy, whilst 2 Technical Assistant Trainees continued with their two-year training programme. A third trainee was recruited in March filling a training post, that had fallen vacant.

There has however been considerable staff move­ment, largely in connection with the training and localisation programme of the Department. One Hydrogeologist returned from England with an MSc-degree in Hydrogeology and one Assistant Hydrogeologist left to take up studies in the same subject again in England. One Technical Assistant commenced a three-year study programme in Canada. In the area of the Drill Sample Store and Borehole Records Archive one IndGstrial Class was replaced by a Senior Admin­istration Assistant, better qualified for the work requirements.

The planning and implementation of groundwater projects together with the supervision and control of the. work done by consultants and contractors has again ta\{en the larger part of the work carried out by the Hydrogeology Division. Three groundwater investigation projects were close to completion at the end of the year: a) the Serowe Groundwater Resources Evaluation Project, b) the Kanye Dolomite Groundwater Resources Exploration and Development Project, Phase 11, and c) the Lephephe-Mmamabula-Limpopo C:roundw8ter Investigation Project.

Groundwater research activities took the second place in the dlvisional work programme. A desk study on the groundwater facies in southern Botswana was complr,d.ed, whilst simultaneously another study investigates the hydrochemistry in the groundwater' basins further to the west up to the border with Namibia. July saw the beginning of the Groundwater Recharge Study CGRES). This three-year research project, requiring a multi­disciplinary approach, is carried out in a joint venture with the Uni.versity of Botswana, the Fr ee University Amsterdam with backs topping from otner research institutes in the Netherlands.

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5 .2.1

5.2.1.1

19

With two desk studies groundwater resources were identified in the waterberg formation, stretching in a broad band from Molepolole as far as the Limpopo and another resource in the Lower Karoo near Botlhapatlou, east of Letlhakeng. For both aquifers further investigations have been proposed to the Ministry of Mineral Resources & Water Affairs.

The hydrogeological mapping programme, to which the Department has been committed for many years, has produced a synoptical documentation of the country's groundwater occurrences in the form of the Groundwater Resources Map of Botswana in scale 1:1 000 000.

May be less in the foreground, but work has just been as intensive in the year in the Borehole Records Archive and the Drill Sample Store and in the Groundwater Monitoring Programme. More areas have been covered with borehole location maps, as can be seen from the index map enclosed and many more borehole data have been entered on computer, making them more easily accessible for users. The Monitoring Programme continued to collect climatological and groundwater relevant data. Although this data may not lead to immediate conclusions on resources availability, it will however be invaluable in a few years for the assessment and management of water sources. With the approval of funds for the long term Ground­water Monitoring Project planning for the insta­llation of new observation networks commenced in August.

Towards the end of the year some valuable equipment was taken over from projects: a trailer mounted test pumping unit, an IBM-computer with printer and plotter, an automatic weather station, a Hewlett Packard desk computer with plotter and printer including special hydrogeological soft­ware. Staff of the Division was trained in the operation of the equipment in the projects. The range of hydrogeological work the Division can now cover has been much expanded, opening up a field for new activities.

Development Projects

Evaluation of Underground water Resources (GS 10)

Serowe Groundwater Evaluation Project

Project duration: October 1985 to October 1987 (field work).

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5.2.1.2

20

Total project costs: Pula 8.5 million. Consultant: Swedish Geological Company (SGC), Sweden. Drilling Contractor: ~GB Drilling Company, Botswana. All field work was completed in October 1987. Data evaluation and reporting, obviously a problem area for the Consultant, was still not completed by the end of the year.

Work carried out: An airborne geophysical survey of the project area, followed by ground geophysi­cal surveying over selected areas. Borehole siting. Drilling of 41 exploration and 5 produc­tion boreholes. Geophysical logging and test pumping of all boreholes, with packer testing in selected boreholes. Geological mapping aided by interpretation of satellite imagery and air photo­graphy. Systematic water ' sampling. Water level monitoring in strategic observation boreholes. Resources assessment with computerised aquifer modelling.

Draft Technical Reports submitted until the end of the year covered the following areas: explora­tion boreholes (siting, drilling, testing, logging)

Final Technical Reports completed cover: interpre­tation of satellite imagery and air photography, low altitude airborne geophysics and borehole logging techniques. Submission of the Draft Main Report is indicated for March 1988.

Preliminary conclusions: Considerable groundwater resources exist in the project area. Airborne magnetic surveying has been most useful for mapping of subcrop geology. Satellite and airphoto data have not provided an important input with enligh­tening on geology or structure.

Lephephe-Mmamabula-Limpopo Groundwater lnvestiga­flon Project

project duration: May 1987 to B'ebruary 1988. Total project costs: Pula 239 000. Consultant: AquaTech Groundwater Consultants, Botswana. Data compilation and interpretation was near completion at the end of December and writing of the Draft Final Report had commenced. Its submis­sion is scheduled for ~'ebruary 1988.

Work carried out: A comprehensive search through the Data Archives of the Geological Survey and all relevant reports with the objective of extracting all existing information on the geology and ground water occurrence of the Karoo graben between

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5.2.1.3

5.2.2

21

Lephephe and the Limpopo. Lithological logs were prepared from drill samples. The elevation of about 100 boreholes was determined and water samples collected from all equipped boreholes in the project area. Interpretation of SPOT-imagery and ai~photos and water analyses.

Preliminary conclusions: Large groundwater resources exist in the area and are partly rechar­ged from rainfall and surface water bodies. Water quality is good in most areas. Target areas for later exploration are determined.

Kanye Dolomite, Groundwater Resources Exploration

and Development Project, Phase 11

Project duration: September 1986 to February 1988 Total project costs: Pula 2,9 Million. Consultant: Bureau de Recherches Geologiques et Mineres (BRGM), France. ,Drilling contractor: Geotest (pty) Ltd., Botswana. Completion of drilling and test pumping work was delayed by 2 1/2 months, due to logistical and management problems of Geotest. This caused additional consulting costs. Work was finalised in October 1987. The Draft Final Report was submitted at the beginning of Uecember 1987, according to schedule.

Work carried out: Installation of an automatic weather station and a network for monitoring water table fluctuations, rainfall and soil moisture transport. Geological and structural mapping supported by SPOT-imagery and airphoto interpretation. Borehole siting. Drilling of 37 exploration and 7 production boreholes. Test pumping and geophysical borehole logging. Level­ling of all boreholes. Computerised aquifer modelling to determine recharge, storage and to design wellfield operation schemes.

Conclusions: Mean annual recharge is in the range of 20mm. 7 production boreholes plus another 6 high yielding boreholes, later to be transformed into production boreholes, can deliver 5800m3 /day in balance with recharge. At the beginning of wellfield operation higher abstraction is possible from aquifer storage. Year one: 15 000m3 /da¥; year five: 7 400m3 /day; year fifteen: 5 800m /day. The project has greatly added to the knowledge about fracture aquifers in Botswana.

Groundwater Resources Monitoring and Recharge

Studies (GS 04)

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5.2.2.1

5.2.2.2

22

Groundwater Recharge Study

Project duration: July'1987 to June 1988. Total project costs: P680 000. The project is carried out in a joint venture by the Geological Survey, the University of Botswana and the Free University Amsterdam. Work carried out: Literature research. Design of special equipment for soil moisture extraction and soil sampling to a depth of 15m. Installa­tion of an automatic weather station and gauging stations for stream flow. Sampling of 400 soil samples and determination of soil moisture and chloride concentrations. All investigations concentrated on the first study area, the Pitsa­nyane Groundwater Basin no~th of Lobatse. The area was mapped in detail for geology, structure and geomorphology.

Groundwater Resources Monitoring

Project duration: August 1987 to .December 1991. Total project costs: Pula 566 000. Funding of the project (DDF) became available in August 1987. Plans for the purchasing of monito­ring instruments were put into action. Selected future groundwater observation areas were surveyed, the borehole conditions noted and borehole head elevations measured.

Departmental groundwater exploration projects

Letlhakeng-Botlhapatlou groundwater investigation project, Phase 11

In a sandy facies developed in the Lower Karoo in the a6ea around Botlhapatlou approximately 196 x 10 m~ of good quality groundwater is stored which could be extracted. A project memo­randum proposing field exploration has been submitted to the Ministry of Mineral Resources & Water Affairs in October for funding.

Groundwater potential assessment in the Waterberg between Mochudi and Molepolole

Core drilling in search for Transvaal dolomite under Waterberg was continued. Starting in January, drilling had to be stopped in August as the rapidly ageing rig became uneconomical to drill in hard formation. Two sites were investi­gated, 450m cored and 218m drilled with down-the­hole hammer. Conclusions: The stratigraphy of the Waterberg has been refined. Transvaal dolomite only occurs in graben structures over a limited area along

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HYDROGEOlOGICAL RECONNAISSANCE MAP OF THE REPUBLIC OF BOTSWANA AT SCALE 1 : 500 000 PROGRESS IN MAPPING AS AT 1.1.1888

~~----+------r-----i------t------r-----i------r-----4------+~170

Published

L::J At pre~ r7l Awaiting production Ld In Drawmg Office

• .• 7· ........ .

ftTTTTnl Under production

l.!.J.illlj if) Drawmg Office

Under preparation

I-~~J Under revisIOn

·~' ., ". '"

• ~ ,........--

,. ~-'.' . ' .............

... ~ . ..,

... '~ .... "~'>., "",._"." '

" ..... -.~ .. ".

24

the southern limb of the Waterberg syncline. Where encountered the dolomites were found to be well fractured, partly karstified and weathered near contact w.i th the Waterberg. Two poten-tial sites for production borehole drilling were found. Further work planned: Drilling of one core bore­hole into the northern limb of the syncline, to investigate for possible dolomite occurrence there. On request by the Department of Water Affairs \DWA) a project memorandum was drafted for a groundwater development scheme in selected target areas of the Waterberg aquifer. DWA requested GS to supervise the work of the consultant in this project.

,' .. , 5:3";3;"" Groundwater potential assessment for the Water­

ber g forma tion eas t of lVlochudi " .. " .," ..... ',.

~ ... " ... " ,--, .... ,--..... , ,,'.:,· ..• ·5.4t~'.

.... . ....... ~ - ~"'.- '--~ ~ ... ,.' _ .. , "',-

'.'-.. ". ' ... -. -.'-' ,,' - .. .. -, ..

5.5

5.6

....•... '.

Data interpretation has almost been completed. Maps and diagrams have been drawn and report writing commenced.

Hydrogeological mapping programme

The cartographic processing of map sheets 9 and 10 of the Hydrogeologi.cal Reconna.issance Map Series, scale 1:500 000 has been completed . Drawing of map sheet '( has reached an advanced stage. One Hydrogeologist expert an:1 one Cartographer were seconded by BGR/Hannover (for a total of 6 man months) to assist the Department with the compilation of the Groundwater Resources Map of Botswana at a scale of 1: 1 m.illion. The map had reached first-proof-print stage by July and editing was finished during uecember. Map sheets 9 and 10, as well as the national map have a format larger than can be handled by Government Printers. As soon as funds can be secured printing w.ill be contracted out to a qualified printing company.

Groundwater monitoring

Monitoring of selected groundwater basins continued. With project finance becoming availabe in August implementation of plans for the installation of new observation networks was started.

Borehole Records Archive and Data Base

Drill Saople Store

The updating of records continued as a routine task. Borehole location maps were compiled for additional areas of the country in a continued

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GEOLOGICAL SURVEY DEPARTMENT PROGRESS IN COMPUTERISATION OF HYDROGEOLOGY WELL RECORDS AS AT 1.1.1988

13 15

© REPUBLIC OF BOTSWANA

}>\.::;.J Updated maps

~ Updated maps, t::LJ partially computerised

II<':'9l Updated maps, ~ computerised

o Partially computerised

26

ef:~ort to produce reliable location rnaps for the w~ole country.

DuI'irlg 19(37 thE' 2:c'chi\le regi;3 t,ered 300 pr i ,Ta te bore­holos and 370 Government b0reholes. This high nu~nb(?r o:f drilled h'.)r"(?l-.:.~)les rt-:,·flf':;i:"!".s GC)vt:'~('n!l1(J,'(lt I;.:, .inv'2,:.::t.i"Clg in gC'o:lnd"ivat,er ,:;:xplo('ati.on and '~hF-l impac t of t~'1e d,:cQugh t.

After compleU,on of the nevl cO~'e shed movir:g of the drill sBmples started. By the end of the year 17 pallets were stored, holding the samples from bcre­holes P1 to P700.

Professional advice to the public and the release of boreholFc and hydrogeologi.cal data ha8 again been an all year round task.

Government bcdies to which consulting services were provided are listed below: - Department of water Affairs: By being a meJl,ber 0:" the "Workir:g Group Ramotswa Wellfielci "me] Gaborone Dam Catchment Protection". Preparir:g a draft project memorandum fOl' a ground. water development project. to supply water to Mochudi and Molepolole. Writing corw,e:1ts for Draft Water Supply jVlanual by VIAK Consultants.

- Water A)Cportionrner:t Board: Geologi,cal Survey is a board member. Tecb1.ica 1 advice was given :i.n the following cases: water right application by BDC for Seleka farrr,; water right application by Shamrcc), and Mining & Development for Monarch ~ine; application by Debswana to extend water right for Orapa Mine; controlling of wellfie2d monitoring at Jwanerg, Orapa, paje.

- water Utili ties Corporation: by prepay·ing a draft TOR for a conC',ul tancy "Ramo'!.swa wellf ieJ rl opera tior! and Ironi torir.g". Ccmments on "Lobatsi:' water SupI=,ly Reful"tlishnwn t Study". "Franci.s town Water Supply StLdy" •

- MinisiTY of Mi.neral Resources & Water Affai.r,,: Geol()gical Survey was Cl mer ,ter of ihe fcllowj.r: g project reference groups: "Water Adlili.nistration Stdlly"; "Metsemotlhabe Transfer Scheme".

- Geological Survey is also a meRber of the following project referer..ce groups: "Okavangc Delta Integrated water Resources Developmert Study"; "Limpopo Catchm,'nt Water Utilisation Study". The Department is a member cf ti,e followirg:

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5.8.1

5.8.2

27

"Agricultural Resources Board"; "Intermini­sterial Consultative Committee on Environmental Studies".

Hydrogeological Research Programmes

Cooperation with national and international Institutions in hydrogeological research

The Groundwater Recharge Study is carried out in a joint venture with the University of Botswana and the Free University Amsteedam. This has strengthened the ties with the two universitiei.

The Federal Institute for Geosciences & Natural Resources (BGR) in Hannover started with a pilot project in July. Objective: the development of methods foe the siting of high yielding boreholes in fractured aquifers. Techniques originally developed and tested in West Africa are applied in crystalline bedrock areas of Eastern Botswana. The first phase consists of the structural in~erpeetation of specially processed satellite imagery with the aim of detecting tension featu­ees acting as groundwater conduits. Phase one will be completed in March 1988. Any further woek will depend on the results achieved. C. Marobela received training at BGR in imagery interpretation in the context of this project.

The production of the Groundwater Resources Map of Botswana was achieved through the secondment of BGR personnel. (ref. 5.4)

Departmental research peogrammes

C. Marobela peesented his MSc-Thesis entittled "A study of the hydrochemical facies of ground­watee in Southern Botswana". The study comprises the area south of the 24°S and east of 24°E under'la.'.n by crystalline baserne0t Pre-Cambrian arenaceous Bnd dolornitic rocks and sediments of the Karoo. In itl] W(2stern part the study area has a cover of Kalahari Beds. Conclusions of the study: Uroundwater chemistry shows a regional trend of evolution from fresh in the east to brakish and saline in the west. The regional groundwater ilow is dieected east to west. In the Transvaal and Wateeberg clastic sediments there is a chemical evolution from east to west in which the watee changes from Mg-Ca-HCO to Na-HC0

3 and Na-Cl-SO I , this change is att~ibuted

to ion exchange procgsses. The pcesence of Kalahari Bed cover has no effect on the ground­wa ter ch',rnis try. The Kalahari Beds are chemi­calcY inert and do not alter the quality of

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water passing th~ough them.

P. Phofuetsile completed all field work and data compilation for his MSc-study, investigating the hydrochemical facies of the groundwater in south-western Botswana.

G. Gabaake began with a hydrogeological /hydro­chemical investigation of the Western Ngamiland, in November. The aim is to study the regional groundwater flow regime and the influence of the Okavango Delta on the surrounding groundwater systems.

Staff

1 Staff assignment

Principal Hydrogeologist, Dr. M. von Hoyer -Heading the Division. Coordination of divisional work programme. Planning of war), programmes together with Senior Hydrogeologist. General Supervision of staff, control of performance and work progress. Supervision of consultants and contractors in the projects Kanye Phase 11, Lephephe-Mmamabula-Limpopo Phase I. Identifica­tion of new groundwater exploration and research projects, preparation of terms of reference and contract documents. Coordination of hydrogeolo­gieal mapping programme. Consulting for Govern­ment and public sector. Representation of the Department in various committees, working groups, proje2t reference groups. Control of several recurrent expenditure and DDF votes. Training of counterparts.

Senior Hydrogeologist, Dr. S. Keller - Supervision of consultants and contractors in the Serowe project. Planning of new projects, preparation of project documents in liaison with the PrincipaL Execution of the groundwater investigations in the Waterberg foemation east of IVlochudi. Teaining of counterpaets, profession~l guidance with individual reseaech studies. Deputising foe the Principal.

Senior Hydrogeologist, E. Selaolo (Shadow post) -PeoJect Supervisor and research assistant in "Groundwater Recharge Study" (ref. 5.2.2.1). Supervision and control of consultant and contra­ctor in the Kanya Phase 11 project, together with the Principal. Representation of the Department in the Agriculture Resource Board and the Inter­ministerial Consultative Committee for Environ­mental Studies. Attended: a) Seminar on "Natural Groundwater Recharge in Semi and Arid Areas" in

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Antalya/Turkey in March; b) Symposj um on·tlWater Resources Management" in Barcelona/Spain in· October; c) Workshop on "Use of Mod.els 'in Ground.- •. , water Pollution Studies" in Amsterdam/NethETlands in November.

Hydrogeologist, H. Timje - Completion of-the desk study "Letlhakeng-Botlhapatlou Groundwater-Ihv~~ti­gation, Phase 11". Writing of the project memo- . randum for a propocied groundwa ter explora tiori; project in the Botlhapatlou area. Finalis~tio~ of TOR for the project "Lephephe-Mmamabula.-.1,.impopo Groun~water Investigation Project Phase In; . followed by evaluation of tenders and the prepara­tion 0:: the contract document, together wit.t. the Principal. Supervision and control of the -ccnsultant in the latter project, togeth~~~wi1b the Principal. Compilation of data and backgrourid. information for the writing of a project memora"ndum" "Tshane groundwater investigation project"': " .

Hydrcgeologist, R. Hargreaves - In charge of the BoceholE' Recocds Archive and the Data Base', as.:., well as tte gcoundwater monitoring programme. . Planning, organisation, logistics foc ·above work areas. Supervision and ccntrol of Technical " AssiEtants wocking in the archive and the monito­ring progcammE'. Ocder and pucchase of instcumenta­tion, in liaison with thE' Pcincipal. Installation of a new IBM computeI' and peciphecals. Design of a new bocehole data base in coopecation with DWA. Design of impI'oved Borehole Data Record Sheet and Pumping Test Data Record Sheet. Pcofessional advice to Govecnment and public sector cegarding general hydrogeological information aDIl bor'ehole data. Training of Technical Assistants in archival work and use of the computerised-data base.

H~dcop;eoloP;ist C. Marobela - Graduated'from an M c-course In Hydrogeology (London Univecsity College) and returned to the Department in July. Aftec studying literature relating to th~ hydro­geology of fractured aquifers in the bas.ement ro.cks of Eastern Botswana, he received training in sa telli te imagery interpreta tion techniqu~~s· at BGR HaDno'ler. This 2 1/2month training was in, direct context with the research project being carried ' out by BGR which ai.ms at developing techniques to improve siting of high yielding boreholes in frac­tured environment by studying the tectonic frame­work of an area aided by satellite data .. Returning from BGR he commenced with writing a publication. which is based on the result~ of his MSc project.

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Assistant Hydrogeologist, P. Phofuetsile - Completed all field work and data compilation for the study of the hydrochemical facies of groundwater in South west Botswana. Commenced his studies for an MSc degree in Hydrogeology at the University College of London, in September.

Assistant Hydrogeoiogist, G. Gabaake - Supervision of core drilling, core logging and geological/hydro­geological interpretation of all data as part of the investigations for Transvaal dolomite occurrence under Waterberg cover in the area west of Mochudi. Report writing under guidance by the Senior. Since this project could not be completed due to technical problems with the drilling rig, there would have been insufficient data for writing an MSc thesis. Therefore a new subject was chosen, the hydrogeologi­cal/hydrochemical investigation of Western Ngamiland. Work for the study started in November.

Senior Technical i\ssistant, J. Keakile - Received training in the Serowe Groundwater Project in opera­tion and mai_ntenance of a new test pumping unit, which the Department took over at t;,e end of the pruject. Carried out test pumping for the Kanye project. Has been attached to the "Groundwater Recharge Study" since August, where he organi.sed and supervised soil sampling and the construction of stream fJow gauging stations.

Senior Technical Assistant, T. Ntesa~g - January to April worked in the Archive attending to registration of boreholes, filing of incoming data sheets. May to August, organisation and supervision of the moving of drill samples from the rondavels to the core shed for final storage. September to December, borehole levelling in designated n,oni toring net'."orks at Molepolole and Mochudi.

Senior Technical ASSistant, K. Leetile and Technical ASSistant, J. Phiri - Climatologic and hydrologic monitoring of groundwater basins at Lobatse, Ramotsw~ Mochudi, Letlhakeng, Serowe, Palapye, Maun.

Technical Assistant, A. Mogotsi - Upgrading of boce­hole location maps, data entry into computerised data base, data retrieval. Cartographic drawing for various departmental reports. Left for Canada to commence with stUdies at Sir SandfoI'd Fleming College, in September. (re£. 5.9.2).

Serior Ad~inistration Assistant, P. Kekopakgomo - Archival work, i.e. data search, entering of bore-

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hole data on code sheets. Work in the drill sample store, i.e. sample splitting, storage in containers, container labelling, final storage of sample contai­ners. Has been employed in the pOed, as from 23.9.87.

Industrial Class, M. Montsho and B. Mohamadi - Work in the drill sample store under the supervision of R. Hargreaves. Work carried out: receipt of samples from drilling companies and DWA, registration of private bor'eholes, sample splitting, storage in containers, container labelling, final storage of contain~rs on trays and pallets, updating of records for samples stored. M. Montsho was transferred to field crews at the end of September. He is replaced by P. Kekopakgomo.

5.9.2 Staff Training

Hydrogeologists

E. Selaolo was involved in thE' decision mal,ing on the divisional level. He shared the supervision of consultant and contractor in the Kanye Project with the Principal and was solely responsitle for this sector during a three months leave of the Principal.

C. Marobela returned from London University College in July, having obtained an MSc-degree in hydro­geology. He received training in the interpretation of specially processed satellite imagery at BGR, Hannover between September and middle of November.

P. Phofuetsile commenced with a 12 months course in hydrogeology at the London University College, in September.

G. Gabaake received further in-service training by working closely with the Senior Hydrogeologist in the Transvaal Dolomite/Waterberg project.

Technical Assistants

T. Kgole successfully completed the second year of the course in GeologicaJ Engineering Technology at Cambrian College in Sudbury/Canada. He spent two months in the department on vacation attachment, where he undertook computer studies under guidance of R. Hargreaves.

A. Mogotsi started a three year course in Geological Engineering Technology at Sir Sand ford Fleming­College in Lindsey/Canada. The course began in October.

32

5.10

5.11

32

J. Setlhomo in January continued with training on the test pumping unit. From March to October he was trained by the Consultant in the Kanye Project on climatologic and hydrologic monitoring, drilling supervision, test pumping. The remainder of the year he trained in the Borehole Records Archive.

N. Ramotsoko was trained in the Kanye Project by the Consultant in the same subjects as J. Setlhomo. From June onwards he received training in archival work and data processing.

L. Kgosiemang was recruited as a new trainee in March. He commenced his training with cartographic drawing, which he completed in June. He was then attached to the "Groundwater Recharge Project" where he was trained in hydrologic monitoring techniques, soil sampling and laboratory work techniques.

A training course "Map reading and field navigation" was held in the department between June 8th and 18th. It was attended by Keakile, Setlhomo, Ramotsoko, Kgosiemang. The course test was passed by Setlhomo, Ramotsoko and Kgosiemang.

Publications

Nil

Reports R. HARGREAVES

G. GABAAKE

G. GABAAKE

H. TIMJE

33

Botswana Geological Survey Water Borehole Record System: A guideline to the computer storage of the data. Unpub­lished report, Geol. Survey, Lobatse, 1987.

Transvaal Dolomite Project. Geological and hydrogeological results of core borehole TDM 1 Matematema. Unpublished report, Geol. Survey, Lobatse, 1987.

Transvaal Dolomite Project. Geological and hydrogeological results of core borehole TDM 4 TDM 3 and TDM 4 (Bh. 5629). Unpublished report. Geol. Surv­ey, Lobatse, 1987.

Letlhakeng groundwater investi­gation project, Phase 11. Unpublished report, Geological Survey, Lobatse, 1987.

34

It is expected that three of the eleven students currently in Canada will comple1.e their courses in 1988 and return to the Geological Survey. The remainder are expected to return to Botswana from May to August for work attachments.

In addition,one Motswana from the Geophysics Division is studying micro-electronics at a college in England.

6.3 Development Projects

6.3.1. Aeromagnetic Survey of Eastern Botswana

An interpretation of the 1985/86 aeromagnetic survey of eastern Botswana, funded by the European Economic Community was carried out by Stolberg Ingenieurberatung of West Germany and interpreta­tion maps and a report were made avajlable to the public in September 1987.

6.3.2. Geophysical Exploration-Nossop and Ncojane Basins

The European Economic Community agreed in December 1986 to fund a gravity survey plus are-interpreTa­tion of the 1985/86 aeromagnetic survey and some Magnetotelluric work over interpreted sedimentary basins in western Botswana that have potential for hosting petroleum resources.

The work will be undertaken in 1988 and will include surveys in the Nosop and Ncojane and Passarge areas.

6.3.3. Reflection Seismic Survey

The External Affairs Department of Canada .through Petro-Canada International Assistance Corporation graciously agreed to spend Cdn.#6.8 million on a reflection seismic survey over the Nosop, Ncojane and Passarge sedimentary basins to add to an assess ment of the Petroleum Potential of Botswana.

Field work started in July 1987 and by 3rd Decem­ber a total of 913 kms of survey had been completed in the Nosop/Ncojane area. The sut'vey 'vias tempo­rarily suspended in December and will be continued starting in May 1988.

6.3.4. Serowe Groundwater Evaluation Project

This project continued throughou't 1987. Contribu­tions to the project from the Geophysics Division ranged from direct participation to the evaluation of technical reports. Towards the end of the year

35

35

the project was windjng down and geophysical input was minimal. The project is expected to be completed next year.

6.3.5. Kanye Dolomite Groundwater basin

This project was completed in 1987. The Geophysics Division contributed a considerable amount of consulting input to the project throughout the year and assisted in the critical evaluation of the final reports.

6.3.6. Vumba Greenschist Project, GS 17

The project is a continuation of the BGR funded evaluation of the mineral potential of the Vumba greenschist belt.

Several diamond drill holes were completed in 1987 to explain the cause of electromagnetic, induced polarization and magnetic anomalies located in previous years without finding mineralization of economic interest.

In 1987 the Geophysical Division logged three of these holes. with a Crone Pulse Electromagnetic instrument. The survey results indicate that one of the holes may have missed a body of sulphide mineralization.

6.4. Internal Projects

6.4.1. Makgadikgadi Gravity Survey

6.5.

Additional gravity work in the vicinity of gravity anomalies near Gweta which were located in the National Gravity Survey was carried out in 1984 and 1986. It is thought that the resultant gravity anomalies may be caused by concealed greenschists.

A diamond drill hole to :letermine the cause of the gravity anomalies was started in 1987. At year end the hole was at a depth of 152 metres and penetra­ted Kalahari sands and calcretes from surface to its current depth.

Cooperation with International Agencies

6.5.1. G.T.S.N. Seismic Station

The Seismological section of the United States Geological Survey is currently installing a new generation of seismic stations in Africa for the detection of earthquakes. One of the sites that

36

41

prior to his departure in September to commence a Ph. D course. The third project covers the map and bulletin for the Letlhakeng area (2425A) which have still not been submitted by Mr. M. Modisi who has been employed at the University of Botswana since 1985.

Y.3.1. Geological Outline of Botswana

7 .4.

This account is co-authored by Drs. Carney, Aldiss and Lock and will eventually be published as part of the burvey's bulletin series. It is aimed at a broad band of user levels serving both as an intro­duction to Botswana geology while at the same time acting as a comprehensive information base that will assist the reader who wishes to undertake in-depth geological investigations.

Thematic Studies

Falling within this category are investigations into topics of specific interest that may be either purely scientific or concerned with the prosecution of geological work in general.

7.4.1. Mogobane, Borehole I

Dr. Aldiss completed an Internal Report (DTA/18/87) on lithologies encountered in core from borehole Mog.1. This consisted of 125m of a turbidite seque­nce of alternating mudstones, siltstones, sandstones and pebbly wackes forming part of the Mogobane Form­ation (Lobatse Volcanic Group). A correlation between high gamrr:a-ray activity and niudstone layers was observed, but it was also noted that certain sands tones also had high gamma counts and a recommen ~dation was made that further investigations should be undertaken to discover the cause of this.

7~.4.2. Kalahari Borehole Monitoring Project

A project to monitor chip samples and the level and quality of water in boreholes drilled in the south­west Kalahari during the Petro Canada seismic survey waS initiated during the year, as a result of a suggestion made by the Hydrogeological Division. The work was carried out by B. Aboneng who was able to monitor 21 holes drilled to depths of 300m through strata of the Kalahari beds and Karoo Supergroup. The project is on-going and results are currently being assessed by Mr. Aboneng.

7.4.3. Archaean Lithostratigraphic Kevision

An investigation of 'basement' metamorphite litholo­gies was undertaken by.six members of the Division

42

fully employed in the year of 1986. In the year of 1987, over 4700 drill core/soil samples were analysed for base metals and arsenic.

8.1 .7 SEROWE GROUND WATER PROJECTS (Swedish Geological Company)

Serowe groundwater resouC'ces evaluation project was contracted out to Swedish Geological Company in the second half of 1985. Under the agreement, the Chemistry Laboratory carried out all the water analysis required for the project. A total of 84 - borehole water samples submitted by the Swedish GeolOgical Company were analysed and reported during 1987.

8.1 .8 KANYE AND MOLEPOLOLE/MOCHUDI GROU)JD vJATER PROJECT (Bureau de Recherches Geolog.Lques et Minieres):-

Kanya grou,'ld water project was contracted out to BRGM. In tie year 1986, the Chemistry Laboratory carried out a number of soil, rain water and borehole water samples for the evaluation and interpretation of geologi,cal, hydrogeological and climatical data. In 1987 over 400 borehole water samples were analysed including some important trace elements sut­mitted by BRGiVL

8.1.9 MMAMABULA GROUNO WATER PROJECT

The above ground water project was contracted out to Aquatech. Under the agreement, the Chemi,stry Laboratory provided the necessary analysis required by the project. A total of 154 borehole water samples were analysed during the year.

8.1.10 GROUND WATER RECwIRGE RESEi;f{';H HlOJECT (GRES PROJECT):

The above project was jointly undertaken by Geological 0urvey Department and University of Botswana. This project is expected to continue over a period of five years starting from 1987. The Pitsanyane basin was selected as the first study area as it is idealy situated between Lobatse and Gaborone for necessary technical baCKUp. The existing mobile laboratory waS redesigned in order to satisfy the requirement for the project. Instruments used for the project were calibrated and personnel were trained on various instru­ments and techniques. Expert advice "Jas provided in solving analytical techniques for the determination of low chloride content in soil samples. A total of 149 water-moisture samples were analysed during the period.

8.1 .11 POLLUTION OF PELENG RIVER A1W SURROUNDING AQUIFERS:

The proviSion of professional and technical advice to :~e mem~ers of public as well as other Government and Para-3tat21 o['gani.satio::1s 2.3 an al2. year rcund td.,sk a):-ld larg{:\ly c8ns,i:3ts of clnalysis of ',,\rater SatllI:ol~:>s and the intr.;,rpretatiorJ,'; of analytioal dat~ for human consumption atld pollutic'D p~lnL

50

I I 1I ii 'i li 1i

I' !,

I 50

point of view.

In 1985 the Water Apportionment Board commissioned the Geological Survey Department under the chairmanship of Deputy Director with representatives from BMC, Department of Water Affairs, Lobatse Town Council and. Local Governm;omt and Lands to establish a technical solution to the pollution problem caused by BMC effluent.

The Chemistry Laboratory was represented in all t'le meetings and valuable contributions were made in concluding the remai.ning problems. The wo('king group pa i.d several visl~s to the evaporation pond during construction including the first inflow of tannery effluent after the construction.

8.1 .12 GEOCHEMICAL/ROCK/MINERAL ANALYS IS RECOB-D,_ ARCHIVE

AND COMPUTER DATA BANK:

The compu-':;er data bank is growing with analytical data since 1985 when the Chemistry Laboratory was provided with Apple 11e computer and MAX software by Federal Institute for Geosciences and Natural Resources (BGR). The analytical data for geochemical, rock and mineral analysis are syste­matically stored in 3.3 diskette using MAX software.

The data were systematically stored in order to provide access to the Geologists for search, listing, statistical calculations, plotting etc. and eventual evaluation of geochemical anomalies etc.

8.1.13 ATTACH]vl],;NT:

Mr. M. Nyepi, a U.B. 3rd year vacational student was trained in various analytical techniques from 8th June to 8th August.

At the request of Botswana Power Corporation, Mr. R. Malejane, Senior Technician from Botswana Power Corp6ration was trained in trace eJ.ement analysis by Graphite furnace from 9th to 13th March. He was trained in theoretical baCkground, instrument handling, standardisation and analy­sis of copper and lead.

The late Mr. AJ.len JJurand of BRGM was trained in preconcentration of trace elements in ground water samples.

Two Dutch s tuden ts Mr. S. Spaans and Miss 1. van Haren working for thei.r' ~lSc thesis under the GrounJ water Recharge Research Project were trained in moisture balance, and determination of chloride in soil moisture by classical mr~thod.

51

i I d i

i I

I I

FGU. Kronberg

Geological and Geodetic Services (Botswana) (pty) Ltd.

HIFAB Internationals As, consultants.

60

- Northern Wellfield groundwater monitoring report (14) January - June 1987 14.1 Executive Summary.

- Northern Wellfield groundwater monitoring report 14 report 14.2 data compilation Oct. 1987.

- Inception - report on feasibi­li ty study on establishing a cement industry in Botswana.

- Geophysical borehole logging techniques used in Kanye 11 dolomite groundwater project Sept. 1987.

- Sanitation Sector management study final report, Nov. 1987.

Interconsult A/S consulting -Engineers

A national master plan for rural water supply and sani­tation the Zimbabwe experience March 1987.

SIA Farm Consultants (pty) Ltd.

Sir MacDonald and Partners

SMEC: Snowy Mountains Engineering Corporation Cooma NSW Australia.

- Economic and planning features of effluent disposal at Lobatse Nov. 1981.

- South East Botswana water development study.

- Metsemotlhata transfer scheme feasibility/preliminary design study draft final report Nov. 1987.

- Metsemotlhaba transfer scheme feasibility/preliminary design study interim report appendi­ces Sept. 1987.

- Metsemotlhaba transfer scheme feasibility/preliminary design study report progress report No. 3 & 4 1987.

- Metsemotlhaba transfer scheme feasibility preliminary design study draft final report maps and drawing Nov. 1987.

- Southern Okavango integrated water development phase I; Environmental impact study

61

Geophysical Prospecting.

Groundwater.

Industrial Minerals.

International Journal of Coal Geology.

59

Quarterly Journal of Engineering Geology.

Tectonophysics.

Transactions of the Geological Society of South Africa.

water Resources Research.

Three articles were received through the Inter-library loan system .

. 3. Consultants reports received aur i ng the year included the following:

Sir Alexander Gibb and Partner.

Anglo American Corpo­ration of S.A. Ltd.

Bureau de Recherches Geologiques et Miniers

Dames and Moore

Debswana

- Lobatse Water Supply refurbi­shment pre-investment study Vol. I report June 1986 ref: A 465.

- Lobatse water Supply refurbi­shment pre-investment study Vol. 11 Appendices June 1986 ref. A 465.

- Review of the long term ground water resources potential of the Northern Wellfield aquifer May 1987.

- Kanye dolomite groundwater basin, hydrogeological inves­tigation, resources assessment and development project phase 11 technical proposal TB10/1/4/85-86.

- Kanye dolomite groundwater basin, hydrogeological inves­tigation, resources assessment and development project phase 11: structural geology of the Kanye dolomite TB10/1/4/86-87.

- Drilling and long term pumping tests tender document.

- Eastern Botswana regional water study executive summary 1985 -03 -15.

- Technical data appendix moni­toring report No. 8 for period March to August 1987 for OrBpa Wellfields.

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61

- inception report March, 1986.

- Southern Okavango integrated water development phase I: Main Technical study inception report April 1986.

- Southern Okavango integrated water development phase I: environmental impact study interim report October 1986.

- Southern Okavango integrated water development Phase I: final report environmental impac t study Annexes June 1987.

- Southern Okavango integrated water development Phase I: Final report Technical study June 1987.

- Southern Okavango integrated water development Phase I: Draft final report environmen­tal impact study vol. 111.

- Southern Okavango integrated water development Phase I: Final report Technical study IV.

- Southern Okavango integrated water development Phase I: Final report technical report vol V.

- Southern Okavango integrated water development Phase I: Final report vol. IV. June 1987.

- Study of open water evaporation in Botswana final report March 1987.

- Southern Okavango integrated water development Phase I: Final report environmental impact study vol. I Project impact assessment Annexes A & B June 1987.

- Southern Okavango integrated water development Phase I: Final report technical study

'I

,Il

, 1 ' I' i i, i' i , . ii' !

it

11

ii

r j i ,\ :

I i " :

!

I i I I I, I' , . i I

Swedish Geological Company

Watermeyer, Ledge, Piesold & Uhlman consulting Engineers.

WCPU Consultants

Wellfield Consulting Services (pty) Ltd.

vol. I main report June 1987.

- Southern Okavango integrated water development Phase I: Final report 'technIcal study vol. I main report June 1987.

- Geophysical borehole logging techniques used in the Serowe project Technical report No. 6.

Serowe Groundwater resources evaluation project technical report No. 2 remote sensing activities.

- Surface water pollution study with particular reference to the Gaborone dam catchment area final report.

- Water administration study draft final report executive summary June 1987.

- Water administration study phase I January 1987.

- Environmental impact assess­ment Kolob'eng and Metsemotlha­ba dams and Bokaa dam final report June 1987.

- Water administration study phase I report Jan. 1987.

- Aquifer testing site NWF5 Jwaneng Northern Wellf:i:eld January 1988.

- Siting of borehole for five villages in Central District TB10/3/15/86 - 87. Final

.report January 1987.

- Aquifer testing site NWF5 Jwaneng northern wellfield.

- Botswana Power Corporation Morupule Power Project Paje Wellfield monitoring report 1986. .

63

DYCK, J .!-l.

GABAAKE, G.G.

KELLER, S.

KHE1MEYEH, H.

65

Geophysics equipment resources and equi.;)ment databa.se. JHD/4/87

Major func tions operational mandate for the Geophysics div.ision. JHD/5/87.

Biblioe;I'aphy of HydrJgeology in BO'~swana - unpublished reports. JLF/Ij/S7 Chr N.R. GG/1/87.

Transvaal Dolomite Project Geolo­gical and hydrogeological results of cO.ce borehole TDI11 /Matema tem3 unpubli,shed report GG/2/87.

Transvaal Dolomite Project Geolo­gical and hydro geological results of core boreholes TDM2; TDM3 and TDt'14 (BL 5629) unpublished report. GG/3/37.

Transvaal dolomite in the area between Molepolole and Mochudi' and theL r reh~vance to ground­water explocation. Results of core boreholes Sasakwe I and 11 SK/3/86.

Brickearth samples from farm Pumula 20-Jo near Lobatse on ODS 2525 B3. RK/7/S7 HK/19/87.

Resources of sand. and na tllraJ. stone for buildlne; purposes in the Fran'~ is tOVl:'"l a;~ea. HK/8/8? MN/1/87.

Hesources of sand and natural stone for building purposes in the Francistown area. HK/8/87 IVJN/1 /87.

Results of the core drilling on the NakalaDhala carbonates depos i ";s .. RK/9/87.

Some notes on the potential of carbonate resources for agricul­tural use. RK/10/S7.

Preliminary report upon the carb(~ nates of the Matsiloje ra~ge. RK/11/3? & MN/3/87.

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68

8.4 DRILLING SECTION

In May, 1987 three officers, T. SekgopO', ·M. M')latlhegi and

C. Mpelege return,'d fr'om the Hail (oybury Sch:)ol of Mines jn

Canada, havirg successfully completed a 9 mont~s .;uuY'se and

obtained di.plomas in Mec~allical Engi.neering, Diamond Drilling

Option.

Two other officers, M. Raditladi and M. Ntloedibe departed

for Canada in September to attend the same course.

Two industriRl class employees, K. Habitsi and B. Galeka­

no:,we passed pr"ctj cal. examtnations fer pY'()mot2.0:~ to the T5

g,·'ade. Un:"ort'J.na tely B. Ga h'Kar,oKwe was una ble to take the

post rl.ue to an acci:lent which re,,~lllted .i.n permanenl: disab.ility.

!Jrilling v{i th the two Deep Hele s'igE;, the Hydceq Gryphon

and the LongyeBl" 4.4 was ;3everely harnpl'Y'eci by b 1 'eakc1ovm,,'

whe~eF.u3 the newe.,:" tone rJgs prov.ided a good se·.c'vice t.o the

iepartment wit,hi~ their limitations.

DRILL PRC;)UCTION

The Hydreg Gt'¥phon was elrployed by the Hydrogeology

division tc pr(lve occurrences of 'l'ro YJ.,3vasl Dolomite bene:Ji',h

Wa ts'rDC?cg ,~;anc3 s tene 1 n the r'1ochc.d .i/fVlol epolole are8..

Two hol.22 were vertj.cally Gor'eel to a total depth of 457-70m and a i"ul'tllE'r' hole nar:\mer drilled tc 2'"'IBn,.

PRO-LINE AUGER ;=tIG

ThE Prc-Li.ne Pcj.g was employed p"gai.n by tte Hydrogeolcgy

division in cOfljtT!ction witL thE' Univers.ii.y of Botswana and

Free t...fni vel'S .·L ty, Ams tprdam ~'11 the groundwa ter resources

1.1.c,ni toring and. recl':i-3:cge study .in P.i tsanyanc-.

69

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I i I , I I I 1

69

A series of 18 holes of 5" diaroeter were augered to a

total depth of 130-80 ~etres.

LONG YEAR 44

The Long-year, on the Vumba Project, core drilled three

holes to a total dept~ of 552-20 metres.

The .rig then moved to Gweta for the Geophys,ics Divi,sion

where coeing commenced to a depth of 150~, to explain the

cause of a gravity anomaly. This hole was not completed

in 1936 and it will run into 1983.

2 TONE TDC 1G RIGS

The 2 ~one Rigs were employed by the indllstrial minerals'

section to ascertain cal~eete deposits at Ngopilo Hill.

Eleven vertical holes were cored to a total depth of 159-41m.

These rigs then moved to Metlobo where 2 holes were cored

foe the field mapping section to a total depth of 84-45m.

Also for the field mapping purposes a further 18 holes

were cored to a total depth of 523-29 metres in the

Mmamabula region.

OVERALL STATISTICS

Hydreq Gryphon

No. Holes 3

Meterage Cored

Meterage Hammered

PHO-LINE

457-70 metres

218-00

No. Holes 18

Meterage Augered 130-80 ~etres

LOW}Y E A 1,\

No. Holes 4

Meterage Cored

2 TONE RIGS

702-20 metres

No. Holes 31

Meterage Cored 767-16 metres

70