The first excavation took place late last year following allegations about the deaths of 800 babies, and the manner in which they were buried, at the home came to light nearly three years ago.
Both of these tests have been ordered by the Commission of Investigation into Mother and Baby Homes, which was tasked with investigating these allegations of mass graves at the site in Tuam.
A team of archaeologists have returned to the site, and will carry out excavations for the next few weeks.
The team will conduct a more detailed examination than the first excavation, and also go deeper than the first.
Local historian Catherine Corless, who’d helped bring these claims to light, said that she had received little details about the latest search but had seen the team of archaeologists enter the site with a large digger.
The Bon Secours Mother and Baby Home in Tuam is just one of 14 Mother and Baby Homes being investigated by the Commission.
The Commission is due to publish a report into its investigation into these homes in February 2018.
That report will be passed onto the Minister for Children, with Katherine Zappone currently holding that role.
In a statement released at the time of the first excavation, the minister said the stories from people who had lived in the home was “very distressing”.
She said she hoped the Commission would help former residents and relatives of those who had died at the homes.