Does Freezing Affect Sediment Sampling Results?

Sewer sediment sampling is subject to errors, and these canoften make a significant contribution to the discrepanciesbetween predictions from mathematical models of pollutiontransport and what actually happens. Deep freezing ofsediment and cutting samples is the most reliable method ofsampling, unfortunately it is expensive and is limited mostlyto trunk sewers of diameters exceeding 800 mm. The impact offreezing sediment collected from filter backwash watersedimentation tank on the size distribution of particles below180 μm was investigated, demonstrating that the process had asignificant impact. Small particles are known to contribute toheavy metal content in sewer sediments, so they are the subjectof special concern.