Officials from the Scottish Environment Protection Agency (SEPA) were called in after 40 lorry loads of soil rich in heavy metals were said to have been taken from site at Baird Drive, Murrayfield, to a dump designed for non-harmful in West Lothian.
Simon Cole, SEPA unit manage for the trams contract, told the Edinburgh Evening News: “We have been made aware of an issue at a construction site in the Murrayfield area.
“Following a visit, it is believed waste which has the potential to pollute the environment may have been disposed of improperly.
“As a result waste removal from the site has been suspended.”
Bilfinger Berger said: “We are working in partnership with SEPA across the project and have temporarily halted the removal of waste from a site in Murrayfield pending further analysis.
“All movement of materials is done following guidelines and protocols.”