Transport officials planned to ask residents near the Auckland Harbour Bridge if their properties could be tested for heavy metals, without telling them contamination had already been found nearby.
Documents show a letter was drafted and signed in 2012 but wasn't sent.
Residents were never told about the contamination till RNZ found out about it three months ago.
The Transport Agency is now reviewing if there are any health risks at the properties.
Phil Pennington is looking into this
