Phase 2A: De Hoop Dam
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14-Feb-2008 3:08 PM
  
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PHASE 2A: DE HOOP DAM FACT SHEET

Locality
Province: Limpopo
District: Steelpoort
Position: Latitude: 24° 57’ 29” South
Longitude:  29° 57’ 25” East
Nearest towns: Steelpoort: 40 km
Roossenekal: 38 km
Nearest railway station:  Roossenekal: 38 km
1:50 000 maps: 2429 DD Jane Furse & 2529 BB Roossenekal


Dam Classification
Category: III
Size class: Large
Hazard potential rating: High


Reservoir Information
Full supply level (FSL): RL 915,00 m
Design overflow flood level (1:200 year flood): RL 917,90 m
Safety evaluation discharge level (SED): RL 921,47 m
Lowest drawdown level (LDDL):  RL 875,00 m
Reservoir yield: (domestic, 98% confidence) 80 x 106 m3/annum
  At FSL            at LDDL
Reservoir capacity: 347x106 m3   15x106 m3
Reservoir surface area: 1690 ha 190 ha


Hydrology
Drainage region: B400
River: Steelpoort River
Catchment area: 2865 km2
Mean annual runoff: 116 x 106 m3
Mean annual precipitation: 706 mm    


Structural Information
Type of dam: RCC Gravity
Type of spillway: uncontrolled central ogee
Overall length of wall:
  Length of spillway:
  Length of right NOC:
  Length of left NOC:
  Outlet works:
1 015 m
110 m
98 m
790 m
17 m
Crest levels:
  Spillway:
  NOC left flank:
  NOC right flank:

RL 915,00 m
RL 921,00 m
RL 921,50 m
River bed level: RL 850,00 m
Lowest foundation level: RL 840,00 m
Max height of NOC above lowest foundation: 81,5 m
Crest width: 7 m – right flank
6 m – left flank
Upstream slope: vertical
Downstream slope: 1 V : 0,8 H


Volumes
Hard excavation:
145 000 m3
Soft excavation: 97 000 m3
RCC: 500 000 m3
Mass concrete: 200 000 m3
Structural concrete: 50 000 m3


Spillway
Crest length: 110 m
Total freeboard: 6 m
Design flood discharge: 1 140 m3/s nbsp (Check 1104 m3/s also given on dwgs)
Spillway discharge at NOC: 3 616 m3/s
Safety evaluation discharge (SED): 4 463 m3/s


Inflow Flood Peaks
Return Period (Years): Inflow peak (m3/s):
2 94
5 206
10 332
20 502
50 804
100 1 100
200 1 460
Safety evaluation flood (SEF): 5 350
Regional maximum flood (RMF): 3 520


Outlet Works
Twin stacks of multi-level off-takes
Combined capacity:
20 m3/s
Service outlet valves:
2 x 1 000 mm sleeve valves
2 x    600 mm sleeve valves


Route R555 (Provincial Road P169-1) Realignment
Length of realignment: 2 0 km
Design speed: 100 km/h
Minimum horizontal curve radius: 450m
Maximum gradient: 4,94%
Vertical curve length: 180m
Road width: 2 x 3,7 m lanes with 3,0 m shoulders
Road reserve width (minimum): 40 m
Bridges:
  Steelpoort River upstream of dam
  Masekete Spruit
  Steelpoort River downstream of dam
  Total bridge width


3 spans of 20m each
Single 20m span
2 spans of 20m each
13,95m


ORWRDP Phasing Schedule

Phase

Component

Construction

Commissioning

1 Raising of Flag Boshielo Dam 2004 – 2006 2006
2A De Hoop Dam 2006 – 2010 2009
2B Flag Boshielo to Mokopane pipeline 2008 – 2009 2009
2C Steelpoort Weir and abstraction works 2008 – 2009 2009
2D 2nd pipeline from Steelpoort Weir to Mooihoek 2010 – 2011 2011
2E 2nd pipeline parallel to Lebalelo Scheme > 2025  
2F Connect Lebalelo Scheme to Olifantspoort 2012 – 2013 2013
2G 2nd pipeline from Flag Boshielo to Mokopane > 2025  
2H Incorporate Lebalelo Scheme 2008 – 2009 2009

Note: Implementation of Phases 2B to 2H to be regularly reviewed.

>> Print Fact Sheet [PDF - 36 KB]










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