Leakage of chemicals from two grouting agents used in tunnel construction in Norway: Monitoring results from the tunnel Romeriksporten

Chemical grouting agents are used to reduce water leakages encountered in t unnel constructions. The object of the work presented in this paper was to study the leakage pattern and the amounts of substances released during use of two different grouting agents. The acrylate-based grouting agent MEYCO MP 307 and the isocyanate-based product TACSS NF/020 were used in the const ruction of the tunnel Romeriksporten, Norway, in 1998-1999. Drainage water from the tunnel was monitored with respect to the chemicals expected to pos e the highest environmental risk. A total of 62 tons of MEYCO and 80 tons o f TACSS were used during the monitoring period. The proportion of the produ cts that appeared in the drainage water was estimated from monitoring data, data on water transport out of the tunnel, and the recorded amounts of gro uting agents used. Average leakages of acrylic acid, methacrylic acid, and P-hydroxyethyl methacrylate were estimated to be 1.2%, 0.6%, and 0.5% (w/w) , respectively, of the total amount of MEYCO used. Average leakages of di-n -butyl phthalate and hexadecyl dimethyl amide were estimated to be 0.16% an d <0.003% (w/w), respectively, of the total amount of TACSS used. The resul ts of the study showed that the use of grouting products in tunnel construc tion might lead to relatively large local releases of chemicals into the (a quatic) environment. However, the use of effluent monitoring and proper ris k management strategies can keep the risk for environmental effects within acceptable limits.