Homeowners in Kaiapoi may be forced to leave their houses as contaminated silt caused by liquefaction during the earthquake is cleared from around their properties.
Phillip Ball, who is co-ordinating volunteer help in the town, says the silty soil contains sewage from burst pipes and will become more of a health risk as it dries out and becomes dusty.
Mr Ball says homeowners may have to move out while the dusty material is removed.
He says some workers who didn't clean their hands properly have already become sick, and volunteers working on dried-out material will need proper carbon filter masks.
