From tomorrow (18 April), work will begin to shore up a collapsing quarry face in the Vale.
Building the barrier at L'Epine will allow the minor lane next to it to reopen.
The road was closed without warning last June because it was considered dangerous.
The Vale Constables were told by Guernsey Water that the barrier, or 'bund' is a sizeable structure.
The stone will be brought in by tractor, so parking in the access road will be suspended on weekdays.

Work on Guernsey's Victor Hugo Centre may begin by Easter '27
Channel Islands mobile portability issues to be resolved soon
Channel Islanders in the Middle East told to follow local warnings
Freehold of Guernsey's Premier Inn for sale
Unprecedented demand for cesspit emptying in Guernsey
Food will not be exempt from GST in Guernsey
Victor Hugo Centre fund reaches £7.5M
"We want our schools to be smartphone-free environments"