Victorian slate extraction techniques generated vast amounts of slate waste - for every ton of finished slate produced, approximately nine tons of waste rock are extracted. It is estimated that the lifetime of the Oakeley concerns, more than 100 million tons of waste was generated. The restricted location of Oakeley on the slopes of Allt-fawr made disposing of this waste a significant problem. The original village of Rhiwbryfdir and the nearby monastery of Mynachlog were purchased by Oakeley and then buried under a massive waste tip. Space was also sought on the south bank of the Afon Barlwydd and in 1854 the Glan y Don (also known as the Pen y Bont) tip was established. This tip was accessed by a high viaduct that crossed the Ffestiniog Railway's Dinas branch, the London and North Western Railway's Conway valley line and the river. This tip became so large that a mill was built on top of it for further slate processing capacity in 1875.