This dataset contains the results of British Standard leaching tests (BS EN 12457-2:2002) in which deionised water or seawater were mixed with different types of waste, under standardised conditions. The results are for concentrations of metals (in units of mg/kg) and other constituents in the leachates. The wastes used in the leaching test were all legacy wastes (i.e. from facilities or industries no longer operational) of different types: coal and metal mining, municipal waste (landfill), smelting and steel slag wastes. In all cases the wastes were sampled from the coastal zone of the UK, defined as being within 500 metres of the current UK coastline. The wastes were collected between 2020 and 2024. In some cases wastes were collected from different locations within the same site, in others triplicate samples were collected from the same location at the same site, and for one site samples were collected in three successive years. Full details about this dataset can be found at https://doi.org/10.5285/843ebced-e75c-4963-9d0a-363c9d20ee15
