Rhoca-Gil

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Rhoca-Gil is a type of industrial sealant produced by Rhône-Poulenc, used in the construction of tunnels to block the passage of groundwater into the tunnel. The sealant begins as a liquid, is then injected into cavities which need to be sealed, and polymerises, causing it to harden.

Process[]

Rhoca-Gil consists of two fluids, that are mixed, thinned out with water and then sprayed into cracks in the bedrock. One of the fluids contains acrylamide and . The mixed solution becomes a viscous fluid that penetrates cracks and holes in the rock, where the fluid reacts—polymerizes—to a tight plastic substance. When it is completely polymerized it is stable and will not exhaust any toxic compounds.

Controversies[]

In 1992 construction of the Hallandsås tunnel in Sweden began, with opening plans for 1995. Groundwater leaking into the tunnel was however a major problem, slowing the progress, and Rhoca-Gil was used. In 1997, fish and local cattle started dying as a result of Rhoca-Gil in its liquid form leaking into the water supply, contaminating it with acrylamide, a known carcinogen and mutagen. Furthermore, the contamination of the area led to a ban on agricultural products from the area, as well as a ban on using water from the area affecting local residents.

The main contractor, Skanska, along with Rhône-Poulenc and the Swedish Rail Administration had criminal charges brought against them. Some senior executives resigned. Construction was halted in late 1997. The main critique of the use of Rhoca-Gil was against Rhône-Poulenc for not pointing out the risks of using the sealant, as well as against Skanska for not informing local residents about the usage of Rhoca-Gil.

A similar incident occurred at the construction of Gardermobanen in Norway, leading to a ban of the substance in Norway in 1997.