## 2 Materials and Methods
### Surface Leaching Tests  
The surface leaching tests have been carried out in SGI in Linkoping, Sweden, and the analysis of the leachate is carried out by ALS Scandinavia AB. The experiments were performed according to standard SS-EN 15863 according to the European Standard used for evaluating the leaching behaviour of monolithic soil under dynamic and changing environmental conditions [92], see Figure 2. The tests entail the following procedure. A stabilized test sample with a known surface area is lowered into a water bath. The water is then changed after 6 h, 1 day, 2.25, 4, 9, 16, 32, and 64 days, see Tables in Appendices: Tables 1, 2 and 3 for surface leaching, and Tables 2, 4 and 3 for cumulative surface leaching. At each water change, the leachate is analysed under fixed experimental  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample ID** & **Sample Water Ratio (\%)** & **Bulk Density (t/m3)** & **Dry Density (t/m3)** \\ \hline
1\_5 & 60.8 & 1.62 & 1.01 \\
4\_1 & 75.3 & 1.49 & 0.85 \\
5\_4 & 107 & 1.40 & 0.68 \\
3\_5 & 63.5 & 1.62 & 0.99 \\
6\_5 & 45.2 & 1.77 & 1.22 \\
8\_5 & 45.5 & 1.72 & 1.18 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Parameters of the six soil specimens tested for permeability using permeameter in SGI.  
conditions and the concentrations are evaluated for heavy metals (As, Pb, Cd, Cr, Hg, Ni, and Zn), PAHs (16 pcs), PCBs (7 pcs), and organotin compounds (TBT).  
The surface leaching was performed as a triplicate test with specimens having designations within the test series. According to this standard, the release of pollutants is evaluated as a function of time when the contaminants are immobilised from a monolithic soil mass during a period of active contact with a leachate aqueous solution. The samples were named Bach1, Sample 6, Sample 7, and Sample 8A. Three tested specimens were fabricated using the dredged material collected from various test points.  
The chemical analysis of the dredged masses was carried out during sampling of soil on leaching. The test method is performed in accordance to the standard SS-EN 15863 to evaluate leaching behaviour in monolithic material using regularly shaped test portions of soil samples with a periodical renewal of leachate from 6 h to 64 days. The main idea of this approach consist in exposing the soil material to a water leachate for a certain period of time, then analysing the obtained solution with concentration of contaminants. The requirement of the minimum size of 40 mm in all directions is satisfied in the current experiments where the sleeves for soil samples had the dimensions of 50 mm. The aim of the chemical analysis was to determine the background levels of the chemical elements (heavy metals, PAHs, PCB, and TBT) and compare them to level from the leached concentrations from the tested soil specimens in the end of the experiment. In addition, the test aimed to identify, which of the sample points within the sample area in the harbour was the most contaminated and, therefore, would be used in surface leaching tests.  
In previous projects, the ultrapure Milli-Q water has been used obtained from the extra purification water systems; however, it results in a biased outcome due to the content of extra pure water. Therefore, the later projects, such as those run in the Arendal 2 and Ostrand, have been tested with the leachate from the respective local area. In this study, the leachate from the Port of Oslo has been used to adjust local environmental setting. The sample point 1_2 was selected for surface leaching based on the materials of the experiments. According to this method, the specimen is suspended using the nylon ropes so that surface leaching can take place on the entire surface of the soil specimen.  
Figure 2: Process of surface leaching test on soil specimens. Photo source: [PERSON].