The first spoil from the coal mine was deposited on the valley's lower slopes, east of the canal, but during the 1910s the first tip was started on the western slopes, above the canal line and the village. By 1966 there were seven spoil heaps, comprising approximately of waste. Tips 4 and 5 were conical mounds at the apex of the slope, although Tip 4 was misshapen from an earlier slip; the remaining five were lower down; all were directly above the village. Tip 7 was the only one being used in 1966. About high, it contained of spoil, which included of tailings—waste from the chemical extraction of coal, fine particles of coal and ash which took on properties similar to quicksand when wet.