The Sociedad Quimica y Minera de Chile S.A. (SQM) is one of the world’s largest producers of specialty fertilizers, iodine, lithium, and other industrial chemicals. In particular, the company notably extracts natural resources through evaporation and crystallization of naturally occurring brine solutions at its Atacama Desert Salar Plant, developing them into products such as sodium nitrate, potassium nitrate, potassium sulfate, and other specialty blends.

The Atacama Desert, a virtually rainless and sun-drenched plateau atop the Chilean Andes, is an ideal location for SQM’s operations as it is home of the world’s 3rd largest expanse of salt flats. In 2004 the company opted to increase its potassium chloride production with the addition of two 300,000 square meter evaporation ponds whereby operational and environmental concerns dictated the use of a geomembrane impervious system.

Cross-section
The engineered cross-section consisted of the in-situ natural subgrade followed by a puncture protective 300 g/m2 non-woven staple fibers geotextile and a 0,75mm enhanced flexible and puncture resistant Polyvinyl Chloride (PVC) geomembrane.
A post-harvesting minimum 40cm sacrificial layer of salt is to remain at all times in the bottom of the pond in order to prevent accidental mechanical damages from heavy equipment. The side slopes were further protected by an additional layer of puncture protective geotextile, covered by a 0,5mm High Density Polyethylene geomembrane.

Solmax was thus mandated by SQM to pre-fabricate over 200 rolled panels at its Varennes Plant through its dielectric process, each panel measuring 10 m x 300 m and weighing in excess of 3000 kg! Factory welds were specified in accordance with the PVC Geomembrane Institute (PGI) 1104 Specification Document, including 100% air lance non-destructive testing.

Site installation, also managed by Solmax, required a mere 30 day period, which is equivalent to an average daily production rate of 20,000 m2/day, a very high rate by any standards, which was one of the governing parameters in choosing PVC. Site assembly under scorching ambient conditions (40C+) was performed through automated hot air double-welding and air channel non-destructive continuity testing, while final inspection called for a full geo-electric area survey including well over 60 km of double-welds, yielding only two factory pre-fabrication leak defects!