The air along Robertson Quay has finally been cleared. And the source of the offending stench a 1m-thick layer of sludge lining the bed of the Singapore River has been removed, giving the area a breath of fresh air. The years of muck that lined a 50m stretch of riverbed could have been due to dead leaves, litter and silt discharged from nearby worksites, especially after rain, said a PUB officer during a...