Control and environmental program for cleanup and cover of sediments in Bukkevika, Arendal. Investigations of blue mussel and sediments.

Summary

In 2017, NIVA has carried out surveys of mussels and sediments outside Bukkevika in the Tromøysund close to Arendal. The investigations were carried out in accordance with agreement with Arendal municipality dated 30.11.2011. The sediments in the inner part of Bukkevika are capped with geotextile and covered by sand/rocks, and then sealed with coarser rocks. The outer and deeper part is capped with sand/rocks. Four mussel stations and three sediment stations were investigated. Metals (Pb, Cd, Cu), PCB and PAH were analysed in both mussels and sediments (surface 0-5 cm). This survey is a part of the control and environmental program in Bukkevika where water sampling, turbidity measurements and analyses of environmental pollutants in water already have been reported. The mussels had low concentrations of metals, PCBs and PAHs at all stations. Generally, pollutants were lower or approximately equal to the concentration when Bukkevika are compared to the three other stations north and south of Tromøysund. This indicates no leakage from the capped area of sediments in Bukkevika. The sediments had elevated values of metals and PAH compounds. However, there is no reason to believe that the leaching of pollutants from uncovered sediments in the vicinity to Bukkevika has given increased values in the mussels. Based on exceedances of EU-priority pollutants (anthracene, fluoranthene, benzo[b/j]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, benzo[ghi]perylene) and water region specific substances (pyrene, benzo[a]anthracene, chrysene, dibenzo[a,h]anthracene) in the sediments, NIVA recommends carrying out an environmental monitoring program with regular sampling of the sediments every 6 years. Although there were no exceedances in mussels, NIVA will recommend supplementary monitoring every 3 years as a control for detecting any future leaks from the landfill.