The images date from 1900 and 1901 and highlight the dirty and often dangerous work of the men sent underground to burrow out the Girdleness Outfall Scheme.

Salvaged from a rubbish tip by Scottish Water worker Bob Nicoll, the images reveal the men hard at work, above and below the city’s streets, as they have rarely ever been seen.

“I’ve had the pictures for the last 15 or 16 years,” said Bob.

“They were part of some old archive stuff due to be thrown out but I felt they needed rescued from that as they show an amazing part of the city’s industrial history.

“I stored them at a pumping station in Aberdeen and one day was showing one of my colleagues from Scottish Water the pictures.

“He suggested we put them out on social media for people to see.”

The tunnels were designed to discharge 81 million gallons of waste per day which equates to 300 gallons per day for a population of 270,000.

The workers sent down to burrow through the earth had to blast about 40,000 tonnes of rock in order to create a trench for the pipelines.

With no hydraulic diggers or power tools, they relied on manual labour, digging in the darkness with little light or quality air.

The bricklayers of the 1870s were paid between ten and 15 shillings (50p to 75p) per 12ft length of the sewer tunnel, depending on how thick the brickwork was.

The best men could earn £4 and ten shillings a week. General labourers earned half the bricklayers’ pay.

Work on the system, which extends into Girdleness, Aberdeen Harbour and through the city centre, began in early 1901 and was finished in 1907.

It was adapted into Aberdeen’s modern sewerage system in 1985 and continues to serve the south and west of the city today.

“It’s amazing to see the work that went into building the sewer over 100 years ago,” said Bob.

“I’m pleased I saved the pictures from the rubbish tip.”

(Images courtesy of Bob Nicoll and Scottish Water)