Environmental risk assessment of acrylamide and methylolacrylamide from a grouting agent used in the tunnel construction of Romeriksporten, Norway.

Increased focus on the possible evironmental risk associated with large-scale use of grouting agents has revealed that leakage of chemicals from grouting activities may cause harm to the environment. Chemical grouting agents are used to reduce water leakages in e.g. tunnel constructions. The present study focuses on monitoring results and environmental risk caused by releases of non-polymerised monomers during use of the acrylamide-based grouting agent Rhoca-Gil (Siprogel). Drainage water from the tunnel Romeriksporten was monitored with respect to acrylamide and methylolacrylamide, as leakage of these substances was observed earlier in connection with similar constructions where Rhoca-Gil was used. Concentrations of acrylamide and methylolacrylamide in the draining water showed that these substances leaked out both in connection with the injection of Rhoca-Gil and in connection with after-injection using other grouting agents. Gel formation studies with Rhoca-Gil showed that a low degree of polymerisation (and hence, large leakages of monomers) can be expected if the product is diluted with water. Results from investigation of the environmental fate of methylolacrylamide showed that this substance is chemically transformed at the high-pH conditions of the tunnel. Ecotoxicological testing of the substances and an environmental effects assessment for the receiving water (River Alna and the Oslofjord) showed that the discharge of acrylamide and methylolacrylamide may have caused effects on the aquatic life in the river and in a limited area of the fjord.