The co-ordinates on Alec's phone where he buries the device are in CRAB Park.
Every TV series dealing with time travel creates its own rules and methods. Here, people are able to go back to a time they existed and exist as duplicates. In the 2016 series Timeless (2016) for example, while this was possible, it was frowned upon due to the likelihood of negative consequences. It was described in Pilot (2016) as being bad for the fabric of reality. Both series used a device called a lifeboat as a backup method for time travel.