OBJECT

Water storage dam for mining plant.
Several small dams on 10 km lenght.

HISTORICAL.

The mining Company had to set a dam on a very permeable soil, at this period it had the following solutions:

• Excavated and substitued the permeable soil by clay
  • this solution was not applicable under the water table level.
• Performed a gouted curtain.
• Performed a slury trench with bentonite mud.
  • But this is no convenient for the enbankment of the dam (no strenght)
• Performed a slutty trench with self hardening mix.

The last solution was choosen.

Method.

Backhoe excavation to 12 m depth (thickness of the trench 0.90 m). Then making deeper with the Kelly system (Soletanche) to the bed rock (thickness of the trench 0.60 m). All excavation were made using a cement bentonite mix.

Charateristics of this work.

Difficulties:

• To find the right cement bentonite mix
  • The standard mixes used in Europe are not applicable with american cements.
• To adjust the mixing production with the excavating production.

Difficulté pour mettre au point le coulis. Le dosage réduit en ciment n'etant pas appliquable avec les ciments portland. ( Il a fallu doser à 250 kg /m3).

Difficulté à tenir le rendement des engins d'excavation au niveau de la production de coulis.

Solutions found.

• Cement bentonite mix:
  • Increasing the cement proportion to 250 kg/m3.
• Important modifications of the mixing plant.
  • Fabrication of the bentonite mud with 2 mixers of 4 m3 of capacity. Production 72 m3/h (working 7 days/ week).
  • Continuous fabrication of cement bentonite mix with 1 m3 mixer only (mud bentonite and cement screw). Producion 90 m3/h (working 5.5 days/week).
• Adjustment of the pumping system to send the mix to 3 km.

2 track cranes with the kelly system (Soletanche)
1 backhoe .
2 bentonite mixers (4 m3)
2 Cement bentonite mixers (1 m3)
300 tonnes ciment storage
Several pumps and tanks.

8 French

# 50 Americans