Stockton Colliery No. 3 Shaft
by Russell Rigby
University of Newcastle’s Hunter Living Histories
Recent erosion of North Stockton Beach has exposed a rare example of 19th century mining technology, and also dramatically highlights how the beach has retreated more than 100 metres in the last century since the completion of the breakwaters at the harbour entrance.
Stockton Colliery operated from 1885 to 1908. It was one of the ”Delta Collieries” which were located around Newcastle Harbour, and worked the thick high-quality Borehole Seam below the low-lying land, harbour and ocean bed. There was almost no solid rock above water level, and mining conditions were often difficult, with the ever-present risk of inrush of water. This was partially balanced by the proximity to the harbour, with the 2 largest Delta collieries (Hetton and Stockton) being no more than 250m from the wharfs. Now there are almost no visible relics of these mines apart from streets and parks named after former mine officials, memorials to mining deaths and tragedies in parks and churches, and some awkward street alignments.
Initially the Stockton mine had just 2 main shafts for coal winding and ventilation at the southern end of Stockton. A few years later the decision was made to sink another shaft. The No3 shaft was completed in 1895, after more than 3 years work, at the northern end of the mine workings, for ventilation and to provide an emergency exit from the mine in the event of a water inrush. The original top of the shaft was 6.7m above high water mark, in the dunes about 110m from the shore line at the time.
The mine workings extended from the Hunter River bank west of No3 shaft, eastwards under the ocean bed for 1000m beyond the low-water line.
The need for a second emergency exit for the mine had been emphasised following a roof fall in 1893 in the lower seam workings on the western side of Stockton, near the river bank about 400m from the shaft site. The debris in the fall included unconsolidated alluvial sediments from the river bed almost 60m below the surface – the upper seam had been eroded away. Substantial coffer dams and bulkheads were quickly constructed and normal work stopped in this section of the mine, but there was a lengthy dispute between the colliery management and Government mines inspectors whether the mine was safe to operate at all, and whether the inspectors had the power to suspend operations.
No. 3 Shaft site
For more than 20 years a vertical iron tube about 1m diameter has poked out of the sand on the beach in front of of the North Stockton Child Care Centre as the beach has eroded. Its exact purpose was uncertain, but it was quickly identified as part of the Stockton Colliery No. 3 shaft site. The tube was possibly the lining of a well sunk into the sand to get fresh water to use in the steam engines on-site. Even today many houses in Stockton close to the beach have spear-points for bore water to use in gardens.
More of the structure was exposed during beach erosion in late August 2017, until it collapsed and was washed away on Sunday, 3rd September. The same night the top of the surviving shaft casing was exposed right on the low-water line, about 10m further down the beach. The top of the casing is at about the level of a 0.35m low tide, so will only be fully exposed at very low tides, and relatively calm surf.
The shaft may have been exposed in 1995, but does not seem to have been noticed or recorded because of its location and the surf conditions at the time.
The shaft casing itself does not present any danger to beach users (less than the rocks and WW2 tank traps scattered along the beach) although the exposed iron ladder-way and other ironwork may need to be removed for safety. The shaft will probably be covered by sand soon as the beach recovers from the latest erosion event, but will be periodically revealed after erosion in future storms and with rising sea levels. The cast iron appears to be in good condition as it has been buried in sand below the water-table for almost all of the past 120 years.
Due to the waves breaking directly onto the shaft it was not possible to take detailed measurements of the shaft and the metal-work, or to take a sample. This may be possible before the beach builds up again but will any opportunity will depend on low tides and calm conditions. The approximate location (by GPS – accurate to about 5m) is:
6359040mN MGA zone 56 ,
0.35m RL AHD (from tide height).
Sinking the shaft
The details here summarise a section from a report by A A Atkinson presented to the Institute of Mining Engineers in London in 1902 – “Coal Mining under Tidal Waters, Hunter River, NSW”. The section dealing with the sinking of Stockton No3 Shaft was republished by F Danvers Powers in 1912 in his book “Coalfields and Collieries of Australia”, as an example of the technique for shaft sinking in water-saturated soft sediments.
The upper section of casing was 3 metres across, made up of 8 segmented rings of 30mm thick cast iron bolted together, with a smooth outer surface (“tubbing”). Each ring was 0.9m high. The bottom ring of the tubbing had a sharp cutting edge to assist penetration through the alluvium. To sink the shaft, the cast iron tube was forced down into the sand by loading up a 10m square platform on the top of the tubbing with sand and iron rails (as much as 1400 tons). Sufficient depth of water was maintained in the shaft to balance the pressure of the strata and control the speed that the tubbing was forced down while the water-saturated sand inside the tubbing was excavated with a grab bucket. Water baled from the shaft was recirculated to stir up the sand at the bottom of the shaft and decrease the resistance.
When bands of clay were encountered a large trepan chopper was used to cut up the clay, and divers were sent down the shaft to load it out, working underwater for 2-4 hours at a time in 20-30m depth of water.
After the top of the casing reached ground level the platform was unloaded, more rings of casing added and the process repeated until the casing reached down to solid rock about 60m below the surface, and finally to the Borehole Seam 78m below the surface. Because the loading required to overcome the resistance of the clay bands from 40m depth threatened to cause the failure of the 3m casing tube, a smaller 2.7m diameter section
(6 segments per ring) was “telescoped” inside. This required that the smaller tube was sunk from the surface after the original casing had been re-filled with sand. Once the casing had reached solid rock and the shaft was dry, the last sections of tubbing were added at the bottom of the shaft as it was deepened. Sinking the shaft took over 3 years to complete.
The Borehole Seam in this area has 2 coal sections each 3m thick, separated by 3.5m of shale, and both sections were worked at Stockton [section]. The upper workings were connected, and a sloping tunnel driven from the workings in the lower section. Initially there was a small cage installed in the shaft, but this was replaced by an iron ladder-way 4 years later.
There are newspaper reports of curious sailors from ships tied up at the ballast dolphins occasionally being found wandering around underground after climbing down the ladder.
The mine finally closed in January 1908. A timber head frame over the shaft survived for several years, and is prominent in the photo of Lord Kitchener of Khartoum inspecting possible sites for a fort in January 1910.
The top section of the tubbing was probably reclaimed, but once the water table was reached removing the shaft lining would be very unstable and unsafe to continue. This would explain why the rim of the shaft looks relatively undamaged. A section of the ladder-way is also visible. There is no evidence that the shaft was capped – just left to fill with sand.
Note: some references suggest that the No3 shaft site may be in the small ring road in Beeston Road, Corroba, about 400m north of the shaft site on the beach. The “ring road” is part of the street layout for the 1920s “Garden Suburb”, and has no relationship to the mine. Incidentally only the western part of the suburb was ever developed – the proposed eastern half would also now be in the surf zone north of the shaft, so there is a connection of sorts.
References and bibliography:
Atkinson A.A. (1902) “Working Coal under the River Hunter, the Pacific Ocean and its Tidal Waters, near Newcastle, in the State of New South Wales. (Trans. Inst. Mining Engineers, London, 1902.)
F. Danvers Powers (1912) “Coalfields and Collieries of Australia”; Critchley Parker, Melbourne
Annual Reports, Department of Mines
Tonks, E (1985) “Beneath Tidal Waters – the story of Newcastle’s Harbour Collieries”; Headframe Publishing
Ross & Pat Craig Collection, University of Newcastle Cultural Collections – https://hunterlivinghistories.com/2016/11/30/ross-and-pat/
Facebook – “Lost Newcastle”