Fire crews have been pumping sea water on to a cliff at Dawlish to bring down more than 350,000 tonnes in a controlled landslip.
The fire service was called in yesterday to prevent a potentially “catastrophic” collapse that could have posed a risk to workers repairing the line.
Network Rail had requested the assistance of the fire service after workers noticed a large area of soil and rock above the main line had slumped during the previous 48 hours.
Fire crews from Teignmouth, Middlemoor and Dawlish were on site throughout the night pumping water into the fracture line.
A meeting has taken place on site this morning to assess any movement in the landslip site overnight, as well as consider the pumping strategy for the next 24hrs, with the incident potentially lasting up to seven days.
Group commander Andy Rowse said today that crews had been at the scene overnight and the cliff face had slumped further. Two crews remain this afternoon as the pumping operation continues.
Cmmdr Rowse said the plan was for the loose material to be brought down over the rail line then moved by Network Rail out to sea so the line could be reinstated.
The line at Dawlish was destroyed during storms at the beginning of February svering the main rail link from the Westcountry.
Although the landslip has prevented work taking place beneath the affected area, Network Rail have said it is unlikely to have an impact on its April 4 completion date.
A spokesman said: “To safely clear the failing land mass, high pressure water - a similar technique used in clay mining - has been deployed to saturate the land and create a controlled erosion.
"This will enable the cliff material to be taken down in a planned and controlled manner to minimise damage to the infrastructure."