Where sedimentation tanks were present in the system, the sediments were sampled from the bottom of these tanks, immediately prior to the discharge pipe. At the other sites, samples were collected from the leachate volume measurement points, where sediments had collected, or, if necessary, sediment-rich leachate collected from the bottom of the sedimentation tanks was centrifuged (Beckman J2-21m centrifuge, 15,000 rpm for 10 min). After direct collection, or separation by centrifugation, the samples were kept frozen until further processing. Where sediments could be sampled directly, approximately 1.5–2 kg of sediments (wet weight) was sampled, and further processed. Where the sediment was collected from the leachate, approximately 100 g of sediment was separated from around 40 L of sediment-rich leachate.
Samples were dried at 40 °C, and subsequently sieved to 2 mm. More than 90% of the dry sample weight had a grain size