Environmental Impact Assessment Review for Daberas Mine
New slimes dam
August 2002

Why this information document? 

Several changes have occurred to Namdeb’s mining operations at Daberas since the completion of the initial Environmental Impact Assessment (EIA). The EIA accompanied the feasibility phase of this project in 1998. 

This document informs Interested and Affected Parties of these changes, while at the same time inviting people to comment. EnviroScience has been tasked with a review and update of the initial Environmental Impact Assessment, including informing key stakeholders of the new developments at Daberas Mine. 

The Daberas mining operations

Daberas Mine is positioned in Namdeb’s Orange River Licence area, approximately 50 km upriver of the Orange River mouth (Figure 1). Here ancient, diamond bearing gravel terraces on the north-bank of the Orange River are targeted for mining in an open-cast fashion. Mining operations at Daberas commenced in 1999 and the expected life of mine is 16 years. 

Only the most important technical details will be presented here, for further information, please contact Antje Burke (contact details below).

GENERAL	
Project Proponent	•	Namdeb (PTY) LTD	
Environmental Consultant	•	EnviroScience	
Locality	•	Orange River, Diamond Area 1 (Figure 1)	
Process of environmental review	•	Site visit 
•	Compilation of updated and new mining information
•	Assessment of alternatives for major changes to previous mine planning concept 
•	Consultation with key stakeholders through this information document and Namdeb’s Environmental Steering Committee
•	Update of previous  Environmental Assessment and Management Programme report
•	Submission of updated EIA report to authorities 	

THE CURRENT PROJECT	
Extent of proposed  mining area	•	Approximately 352 ha	
Project time frame	•	Slimes disposal over 3 years, life of mine until 2015	
Mining method 	•	Conventional dry mining with excavators, transport with haul trucks to two screening plants, and back-filling of mined out areas where feasible.
•	The eastern (zone 2 - inlet) and north-western most deposit (hub and outlet) are presently mined.
•	A tailings dump has been created north-east of zone 2, a waste rock dump is being created north-west of the hub.
•	Undersize material from the Screening and Dense Medium Separation plants is disposed in a slimes dam.
•	Small slimes dams have been created north of zone 2, west of zone 5 and east of the outlet (Figure 2).   	
On site facilities	•	Office block and workshop are positioned on rocky outcrop north of the through road from Oranjemund to Sendlingsdrift.
•	This includes a Lilliput system for sewage disposal, wash-bay, and fuelling facility with appropriate bunding and disposal points. 	
Accommodation	•	Accommodation is provided at existing Daberas Hostel.	
Roads	•	Namdeb private road from Oranjemund to Sendlingsdrift runs through the centre of the mining operations.
•	Main haul road to the east follows northern outline of deposit, several smaller roads traverse the north-west section of the deposit (Figure 2).	
Power supply and telecommunications	•	Power supply from RSA across the river at Daberas farm and then along private Namdeb road.
•	Fibre optic telecommunications line, largely on existing telephone poles, from Oranjemund along Namdeb road to Daberas.
•	Reticulation within project area along haul roads and just north of the outline of the deposit.	
Water intake	•	Water is sourced from a pump station at the Orange River, and pumped to three reservoirs; one near the office block, one near zone 2 (inlet) at the current screening plant, and one at the screening plant at the hub/outlet.
•	About 600 m3/hr are required to supplement the freshwater losses at the screening plants and for domestic use.   	

NEW DEVELOPMENTS	
Increased mining volume  	•	Substantially more material (78 million tons compared to 40 millions tons) is planned to be mined which will result in more tailings and thus the need for larger dam capacity for slimes disposal.  	
Slimes dam	•	Initially a total of five medium-sized slimes dams was envisaged to be distributed throughout the mining area.
•	These will not be adequate and a large slimes dam replacing three, staggered small ones, positioned south-west of the office block is envisaged (Figure 2). 
•	Approximately 9.2 million m3 of slimes need to be disposed. Some 1.2 million m3 will be deposited into the current slimes dam and into mined out areas towards the end of the mine’s life.	

PROJECT ALTERNATIVES	
Slimes dam	•	Six alternatives were considered for the disposal of slimes at the western part of the deposit (hub and outlet).
•	The alternatives are:
•	open valley dam at original dam site
•	impoundment dam at original dam site
•	ring dyke (open valley dam build with slimes) at original dam site
•	co-disposal and smaller open valley dam at original dam site
•	disposal of fines in gullies north-west of deposit 
•	disposal of fines directly into Orange River 	
The disposal of fines into the Orange River or into virgin territory north-west of the deposit is considered environmentally not acceptable, and a more detailed evaluation of alternatives will focus on the remaining four options. Technical specifications below:	
1. Open valley dam	•	wall on down slope side, open towards dolomite outcrop
•	final maximum dam wall height 36 m 
•	material required for wall: 3.3 million m3, consisting of overburden
•	maximum capacity: 8 million m3
•	the remaining 1.2 million m3 will be pumped into the old dried out slimes dam and backfilled into mined out areas
•	time to final decommissioning uncertain, longer than for option 4	
2. Impoundment dam	•	wall on all sides, thus protecting dolomite outcrop from impact
•	final maximum dam wall height 36 m 
•	penstock system required (risk of failure, high maintenance)
•	material required for wall: 4.3 million m3, consisting of overburden
•	maximum capacity: 6.8 million m3 - not adequate, will require an additional dam site
•	time to final decommissioning uncertain	
3.  Ring dyke (open valley dam built with slimes)	•	wall on down slope side, open towards dolomite outcrop 
•	final  maximum dam wall height 21 m
•	penstock system required (risk of failure, high maintenance)
•	time to final decommissioning uncertain, but longer than option 4
•	material required for wall: 250000 m3, consisting of overburden
•	maximum capacity: 8 million m3	
4. Co-disposal and small slimes dam 	•	wall on down slope side, open towards dolomite outcrop 
•	if co-disposal is successful, final wall height reduced 
•	final maximum dam wall height 24 m
•	time to commissioning approximately 1-2 years after mine closure
•	material required for wall: 800000 m3, consisting of overburden 
•	maximum capacity: 4 million m3	

Environmental matters…

The Daberas deposit is positioned in an area of high environmental sensitivity, largely because of occurrence of many plant species restricted to the lower Orange River valley, and concentration of archaeological sites. An unique assemblage of plant species is associated with the targeted gravel terraces east of the road, while grass covered sand plains prevail in the western section of the deposit. Dolomite outcrops in the project area are of particular  conservation value because of range restricted plant species and pre-historic rock edgings (petroglyphs). There are also some pre-historic graves in the project area. Some of the most valuable sites have been fenced off and are put out of bounds. Option 1 and 3 of the slimes dam may affect some individuals of rare succulents (Juttadinteria cf albata) on the dolomite outcrop in the centre of the project area. 

The future dam will be positioned to the immediate north of the main road from Oranjemund to Sendlingsdrift, and will thus be very visible. Landscaping the stepped, lower sections of the  wall may be an option to ameliorate a negative visual impact.

What next?

Would you like to comment on the posed developments at Daberas? Your comments will be, as far as possible, incorporated in the environmental assessment. A summary of the EIA will be distributed upon finalisation of the EIA report (November 2002).

In order to proceed with the impact assessment, please submit your comments by 12 September 2002.

Thank you for your contribution!

This document has been compiled with input by the Daberas project team.