Contract No. S-10-647-NPNC

Evaporation Failure: Forensic Analysis Fenix Plant Catamarca, Argentina

West, Lafayette 15 April 2016 BACKGROUND

• Solar batteries in high demand • FMC owns a lithium plant in Argentina • Needed to increase lithium production • Lithium naturally occurs in groundwater • Process: Pumping to pond, evaporate, concentrate. • Solution: build large shallow evaporation . Project Location: Catamarca

• 4,000 m-msl (12,000 ft-msl) • 10 cm/yr (4 inches/year) Project Location: Catamarca PROJECT SCALE

115 Ha 1C (288 ac) 1B • Ponds 1C & 2A unlined 1A • Did not work • Solution: line the ponds (30 mil HDPE) 51.3 Ha 2A (128 ac) 2B 2C POND CHARACTERISTICS

• 3-ft deep • 830 acres total area • About $40,000/acre • ~$35 million construction cost BACKGROUND

• Earthwork construction dates: Oct 2010-May 2011 • Liner work: Aug 2011 - Dec 2011 • Pond Filling: Oct 2011 - Jun 2013

1.2 miles • “Heavy” rain: Jan 2012 & 2013 OBSERVATIONS (Ponds 2B & 2C)

2C 2B 1.5 km

700 m OBSERVATIONS (Pond 1A & 1B)

1A 2,000 m

1B

570 m SOME MORE OBSERVATIONS

Pond 2A (1 year after subgrade preparation) $35 MILLION LATER…

• Leaks continued • FMC hired consultant to fix the problem (2014) SOLUTION IS THE PROBLEM

Salt Soil

Water

Brine Consultant Diagnostic

• “…The increased precipitation in the area contributed not only to increases in directly applied fresh water, but indirectly from the three rivers serving the basin of the salar.” Consultant Diagnostic

• “The fluctuating groundwater levels resulted in subsurface water movement which introduced more fresh water into the subsurface beneath the ponds and also contributed a flushing action with the influx and movement of the groundwater which created some additional solutioning but also particle dislodgement…”. Does it make sense?

6 km Does it make sense??

Hydraulic Gradient (i): From 0.2 m per km (0.02% or 0.0002) to 1.28 m per km (0.128% or 0.00128) Hydraulic gradient (i) = 0.0002 to 0.0013 Permeability (k) = 114 m/d - 940 m/d Velocity = k*i = (940 m/d) ( 0.0013) = 1.2 m/d t = 2.2 years/km

t = 120 years/km Does it make sense?

Salt dissolution by groundwater & Surface Infiltration

rainfall

1.2 m 0.1-0.5 m

Halite

Liner

Seasonal high gw

“fresh” water dissolves halite Brine creating voids/subsidence Does it make sense?

2 km

1.2 m

h 0.1-0.5 m Hydraulic gradient (i) = 0.0002 to 0.0013

Permeability (k) = 114 m/d to 940 m/d Velocity = k*i = (940 m/d) ( 0.0013) = 1.2 m/d

NaCl Coefficient of Diffusion (D) = 1.6×10-9 m2s-1

Groundwater mound (h) = 0.1 m

It would take ~1 day for infiltrated “fresh” water to reach 50% of the brine concentration Question: Why is surface rough?

• are NaCl, Na2SO4, & CaSO4 • Sodium sulfate can exert pressures up to 20 MPa during crystallization (Steiger, 2005) • Appropriate environment for dissolution (voids) and crystallization (enlargement) Sources of fresh water

t1 t2 t4 t3

t0 Capillary Pressure Capillary

Saturation 1.0 Another source of fresh water

Increases temperature from 25oC to 65oC

HDPE Geomembrane Heat Source

t4

t3 60 cm

2 cm/day Why did the ponds collapse?

• Exposed geomembrane for months resulted in weakening of foundation

Salt

void Stresses increase by about 1.5 MPa/oC

From Flatt R.J. (2002), Salt damage in porous materials, Journal of Crystal Growth, No. 242, pp 435-454 Some evidence

• Exposed geomembrane provides credence to proposed mechanism

KC3

KC1 Why did the ponds collapse? Why did ponds collapse?

• Weight of salt does not exert enough pressure to induce collapse (10-20 kPa) Why did ponds collapse?

Salt layers are very hard/stiff Why did ponds collapse?

Brine feeds the crystallization process (i.e., more crystal growth and subsidence)

Brine Salt/liner gap Brine below salt Salt

void Why it is important to understand the cause?

Otherwise we may propose invalid expensive solutions (e.g. a cutoff wall) Continuation..

Otherwise we may propose invalid expensive solutions (e.g., raising the base) CONCLUSIONS

• Avoid making easy conclusions • Always question your models • More importantly: never settle for an answer that you cannot later defend QUESTIONS?

David Espinoza, Ph.D., P.E. [email protected]