Oil is made up of hydrocarbons, one type of hydrocarbons are polycyclic aromatic hydrocarbons (PAHs), these are toxic and so the amount that is able to be dumped at sea is controlled by OSPAR.
Looking at the sampling data for variation 2 of MLA-2020-00506, the OSPAR(explain action levels) action Level 1 for polycyclic aromatic hydrocarbons (PAHs) is 0.1mg/kg, yet many of the boreholes are return levels above 100mg/kg, but there is no action level 2 for PAHs. I need to compare these to what the levels were in the real river bed BH01-15_Sediment Sampling Results.zip.
This is the data for the bore holes done for the Riverbank variation 2 - lots of PAHs, less of things that come down the river. So makes sense as this land is from an area where oil tanks and coke ovens were.
The average PAH concentration is 100mg/kG i.e. 100 ppm - means that for every 1million tonnes of sediment being dumped, 100 tonnes of PAHs are dumped, i.e. hydrocarbons into the sea - so the dumping nearly 2 million tonnes of material will result in at least 200 tonnes of oil dumped into the sea.