Waste collection is gradually resuming after Transpacific grounded its fleet of trucks following a fatal crash in Adelaide.

Transpacific is starting to resume waste collection across the nation after grounding its 2800 trucks after a fatal crash in Adelaide.

The company said it expected “all services will be fully operational over the next week”.

“We will work tirelessly to clear the back log,” Transpacific CEO Robert Boucher said in a statement on Thursday.

“We have made a strong commitment to all our employees, customers, communities, and shareholders that we will operate our fleet safely and to the standards which we expect of ourselves.”

Household garbage collection has been disrupted in parts of Sydney, Adelaide, Brisbane, Darwin, Geelong and Perth, the Transport Workers Union (TWU) said on Wednesday.

Transpacific, the nation’s biggest waste management company, grounded its entire national fleet while a third party inspects its trucks and maintenance records.

It comes after one of its sewage trucks slammed into three stationary cars at a major Adelaide intersection on Monday, killing a 41-year-old Ingle Farm woman and a 56-year-old Hallett Cove man.

The 28-year-old male truck driver, from Netley, and a 48-year-old woman, from Hahndorf, are both in a critical condition in hospital.

Police are investigating whether brake failure caused the crash at the the start of the South Eastern Freeway.

They have said it appeared the truck’s driver was travelling at considerable speed before the crash.