Zeepipe Ready For Operation Environmental monitoring of the discharge of inhibited sea water at Sleipner Jaunary-March 1993

Abstract

The Zeepipe Ready For Operation program involved the discharge of some 1.5 mill. m³ of sea water inhibited with Na-bisulphite and glutaraldehyde at Sleipner. The discharges which took place during January and March 1993, were subject to environmental monitoring at sea performed by NIVA. The extremely bad weather conditions during the monitoring periods were favourable doe dispersion of the plume, but highly unfavourable for monitoring. The discharge plume was frequently detected, mostly at mid-depth. The plume was not deteted more than 200 m from the discharges point. The overrall biological impact from the discharges may be considered as being small. Chemical analyses of water samples collected near the discharg showed no inhibitor concentrations above detection limit, and no oxygen reduction. Screening toxicity tests and tests on primary production on the water samples did however show some impact. Analyses of samples from the pipeline showed low sulphite values, and glutaraldehyde values in the range 3-35 ppm.