Pollution investigation in Hjeltefjorden after a leak of cable-oil from a subsea high voltage power cable in 2013

Summary

This study is an assessment of possible environmental pollution in the fjord Hjeltefjorden outside Bergen (Norway) caused by a spill of cable oil from a damaged subsea high voltage power cable. The cable oil was of the type T3588 which is an oil of relatively low toxic properties. The oil leak took place from 9th to 23rd of August 2013 and the total amount that leaked out is estimated at approx. 15 cubic meters. During the active period of leakage, oil sheen was occasionally observed on the fjord surface above the leakage point. After the leak was stopped, samples of mussels and sediment were collected from several shoreline locations on each side of the fjord to investigate for possible oil contamination. The samples were analyzed for typical oil-related chemical contaminants (naphthalene and polyaromatic hydrocarbons). A mussel sample was spiked with T3588 oil and analyzed as a positive reference sample. The analyses of mussels did not show any oil related contamination whereas weak traces of oil contamination were found in some sediment samples. NIVA consider the sediment contamination most likely to be a result of older oil spill events in the study area. The present study thus concludes that it is unlikely that the oil spill from the broken power cable caused any significant pollution in the affected area beyond the period when the leak took place.