Mr Watson said his yard had been closed temporarily because he wanted to ensure the safety of his staff, customers and neighbours.
"There's no evidence that any harm has been caused, but expert advisers tell me that if samples have asbestos readings, there is a possibility that contamination might become airborne thorough dust".
"I am now working with the Wanganui District Council to implement an agreed remediation plan, so that we can move back into the depot at the earliest," he said.
Mr Watson said he and his wife Andre had plans to build a house on the site and preliminary plans had been drawn for the house.
It was expected that further residential subdivision would occur, but plans had yet to be drawn up.
As well as the district council, Horizons Regional Council had been notified.
Neighbours had yet to be notified, but Mr Watson said that depended on an assessment of what the effects of the contaminant might be.
Any area capable of creating dust is being dampened down with sprinklers but he said it was thought that there was no risk with the current status of the site.
"The National Environmental Standards require councils to work with landowners in such events, and we're sure the district council will be doing so with us."
Mr Watson said his company had never worked with asbestos at this site.
"Any asbestos contamination must have been caused or allowed by an earlier owner. The science around the cause and extent has yet to be completed."
Meanwhile, the business has relocated to its previous office site in No3 Line and its contact numbers remain the same.