I was very interested in the damage to a bridge and embankment on the CTRL at Cobham as reported on 22 February. It reminded me of a problem I had to deal with at Lancashire County Council in 1947/48 with a burning road embankment.
This was on a route constructed pre-war making use of colliery waste.
Burning had been noticed by locals and was later reported to the divisional surveyor who assumed it was some material spread on the embankment to burn off the grass?
I was asked to take the borehole gang and drill along both verges and take samples, record temperatures and depths etc. A metre or two down it was obviously very hot material and at some 5m down the heat was damaging the steel boring tool.
The temperatures were recorded and advice sought from colliery engineers.
The conclusion was that the material had contained some burning slag and over the years the earth's moisture kept it smouldering. Rabbits had found it an ideal site to keep warm in winter and increase their breeding capacity and they supplied the extra oxygen!
The whole embankment had to be removed and reinstated with ordinary fill material.
Alan Whitaker (F), 9 Brou Close, East Preston, Littlehampton, BN16 1DB.