Tweet

DESCRIPTION OF THE COLLIERY.

For more than 70 years Messrs. Thompson and Sons have worked coal in the district on the borders of Northumberland and Cumberland, both in isolated coalfields in the Coal Measures lying adjacent to a large dislocation of the strata known as the Stublick Dyke, and from two seams in the Carboniferous Limestone formation.

For the last four years operations have been confined to one of the seams in the Carboniferous Limestone worked by three collieries — Byron, in Northumberland; Roachburn, six miles to the south-west, in Cumberland; and Bishop Hill, one and-a-half miles south from Roachburn, also in Cumberland. Byron and Roachburn Collieries are considerable establishments, but Bishop Hill is a small colliery producing coal principally used for burning lime.

Mr. Thos. Croudace, who resides in Haltwhistle, is the certificated manager of all the collieries, and at Roachburn, Mr. Geo. Turner, who holds a second-class certificate, acts as undermanager and resides near the colliery. There was a sufficient staff of under officials at Roachburn Colliery, arranged on the Durham-Northumberland system.

The seam of coal worked at Roachburn Colliery, and at the adjoining collieries of Byron and Bishop Hill, lies in the upper part of the Carboniferous Limestone formation, and is known as the Acomb, Blenkinsopp, or Little Limestone coal.

Its average section at Roachburn Colliery is 3 feet 6 inches, and it usually lies on a hard ganister floor, and is overlaid by a good roof consisting of shale with sandstone bands.

The seam dips in a south-easterly direction, and the dip along the outcrop going south from Byron Colliery increases until at about a mile north of Roachburn Colliery it is 45°. The seam then flattens, and at the southern extremity of the area worked by Roachburn Colliery and where the pits are situated its angle of inclination to the horizontal is 35°,

Except in the valleys the line of outcrop, running in a north-east and south-west direction, crosses a moorland country lying at a considerable elevation.

At Byron Colliery, an old establishment, the coal comes to the surface by a drift near Greenhead Station on the Newcastle and Carlisle Railway.

Roachburn Colliery, near the site of an older colliery which had worked the rise coal, is a comparatively new place and lies adjacent to Messrs. Thompson and Sons' private railway which extends from Brampton Junction on the Newcastle and Carlisle Railway to Lambley Station on the Alston branch railway. Three hundred persons were employed underground in the various shifts, and the daily output was about 290 tons. The coal worked lies under land owned by the Earl of Carlisle.

At Roachburn Colliery (see plan on Plate I.) there are four shafts communicating with the seam. One of these shafts, 14 feet in diameter and 43 fathoms deep, is downcast for air, and is traversed by two cages. Another shaft, 9½ feet in diameter, in close proximity is upcast for air, and is surmounted by a fan. The remaining two shafts are a downcast for a rise section of workings and pumping shaft for the rise feeders.

In the direction of Byron Colliery; from the point at which the moss burst in, there was a shallow shaft, only 30 feet deep, on Denton Fell, called No. 7 pit, sunk to the coal near the outcrop. It was downcast for air, and was fitted with ladders, and a good road connected it with the working places. In addition to these opening to the surface, which are all that need be considered in connection with the accident, there were others lying between No. 7 shaft and Byron Colliery which could be reached by good roads underground.

From the bottom of the downcast and drawing shaft a main dip, driven at an inclination of 7½ inches per yard, and at an angle to the full dip of the seam, extends for 530 yards to a main level lying 55 fathoms below the shaft bottom. The main dip was being continued in an easterly direction for exploration purposes beyond the main level. The main level did not continue far to the south-west, but to the north-east it extended over 2,000 yards to the face of a district known as the Jubilee Winnings, and was being prosecuted in that direction for exploration purposes at the time of the accident.

The coal to the dip of the main level and in the Jubilee Winnings was of a soft friable nature, and had apparently been subjected to considerable heat and had lost the coking or caking property and most of its volatile matter and was practically unsaleable, although as regards thickness the seam was normal.

From the main level, inclines, locally known as "lanches," driven at about half the full rise, approached the workings in the seam, where good saleable coal was obtained, nearer the outcrop.

The coal was hauled up the main dip by an endless rope worked by an engine on the surface.

The haulage on the main level, as far as the foot of an incline known as the Chain Bank, 350 yards from the main dip, was worked on the main and tail rope system by ropes from an engine situated on the surface. Beyond the main and tail rope haulage the coal was led on the main level by ponies.

A lanch 1,000 yards from the main dip extended to the rise at gradients varying from 1 in 5 to 1 in 18, for 620 yards, and was worked as a self-acting endless rope incline, and a level from its upper end passed northwards through a whin dyke, 11 yards thick, shown on the plans, to workings beyond in two districts known as the Worthington No. 9 district and the Byron level district. This level, known as the Roachburn level, was at a lower level than a level known as the Byron level which approached from Byron Colliery and overlapped it, and about four years before the accident the two collieries had been connected underground by these levels being connected.

When the two collieries were connected the error in the surveys was found to be 11 yards.

Above where these levels overlapped on the Byron side of the whin dyke, in the Worthington No. 9 district lying under Denton Fell, was the point where the inflow took place (see plans on plates I. and II.), the surface there lying at an elevation of 800 feet above sea level and 613 feet above the main level.

The miners in going to and from their work used the cages in the Roachburn drawing shaft, the main dip, the main level, and the endless rope incline and the various extensions of the haulage roads to their working places. No. 7 shaft was not ordinarily used.

Before the connection had been made to Byron Colliery the air ventilating the workings from Roachburn Colliery on the north side of the whin dyke, had been carried forward on one side of a brick brattice in the single road through the whin dyke and returned on the other side, and then passed along a return air way maintained in one of the higher levels; after the connection was made the air ventilating both the Jubilee Winnings and the workings through the whin dyke passed into the Byron workings to a fan pit, along with air descending No. 7 shaft, and the return air way, no longer necessary, was not kept open.

The feeders of water pumped at Roachburn Colliery amounted in the aggregate to about 900 gallons per minute, and were dealt with as follows

The feeders below the main level were pumped to the bottom of the main dip by two electric pumps, one at P¹ and the other at P².

At the bottom of the main dip a large electric pump at P³ forced 600 gallons of water per minute to a delivery drift in the drawing shaft 7 fathoms from the surface.

A pumping engine on the surface dealt with feeders of water from the old rise workings amounting to about 300 gallons per minute.

The coal in the neighbourhood of the inrush was of good quality, lying at an inclination of 26 inches per yard, or nearly 360, was worked b our shifts of hewers, driving levels and bords from them 12 yards apart, and about 12 feet wide, to the full rise.

The coal was allowed to slide down the bords to the levels, where it was filled into tubs, lowered down a self-acting incline to the Roachburn level, taken along the level by ponies through the whin dyke, down the endless rope incline, then by ponies to the landing of the main and tail rope haulage, along the main and tail rope haulage road on the main level, up the main dip, and, lastly, up the shaft to the surface.

The bords were timbered by two parallel sets of pairs of gears (two props and a plank) placed two or three feet apart. The coal was 3 feet 6 inches thick, with a roof as already described.

It has been customary all along the outcrop to follow the coal right up to the surface deposits, and at several points subsidences of small area had taken place without any serious result. At the Inquiry it was stated that water collected in these subsidences, showing that the clay resting on the solid strata had not been broken through.

It will be noticed from the plans that a small tarn, or rather two small tarns, lay near the point where the inflow took place. These sheets of water were known as the Backstands Pond, and even in the driest summers always contained water. The maximum depth of the smaller tarn was stated by Mr. Croudace at the Inquiry to be about 2 feet 6 inches, but he bad not tested the depth of either tarn. The geological map, on the scale of one mile to the inch, shows that the tarns lay partly on a peat moss about 1,100 yards long by 330 yards wide, and the point of inflow was just clear of the moss as shown on the geological map.

The question of working the coal up to the outcrop in the neighbourhood of the point where the inflow took place had been considered by Mr. Croudace, and in the summer of 1907, five bore-holes, the position of which is shown on the plans on Plates I. and II., had been put down under the superintendence of Matthew Hilliard, one of the deceased men, who was an experienced borer, to check the accuracy of the surveys, and these boreholes indicated the nature of the surface deposits ; the sections obtained are shown on Plate II. The position of the only borehole which had passed through the coal seam, No. 5, was located underground, not by actually exposing the hole, but by hearing underground the noise of the rods when moved in it. The rods were left in it, and were there after the accident.

Consultations with Hilliard and the under-manager led Mr. Croudace to think it safe to work up to the outcrop, which was clear of the water in the tarns, and reliance was principally placed upon the thickness of clay, lying directly on the solid strata, to keep back any surface deposits.

The whin dyke could not be seen on the surface, although it is not improbable that it may stand up some little distance into the surface deposits above the solid strata. Where cut through in the mine at an approximate depth of 54 fathoms it was 11 yards thick, and consisted of a somewhat irregular mixture of basalt and sandstone. There were 35 yards of cinder coal next it on the Byron side, and then some yards of unsaleable coal devoid of the normal proportion of volatile matter. The whin dyke may have had some effect in confining the water in the tarns, it may indeed have been the cause of their existence, but nothing certain can be said as to its influence.

---

* Although situated in Cumberland, the miners employed at Roachburn Colliery were members of the Northumberland Miners' Association, and the deputies of the Northumberland Deputies' Association, as the colliery is so far removed from the West Cumberland coal field, and as the miners and deputies employed at an adjoining mine, Byron Colliery, situated in Northumberland, worked by the same firm, had for many years been members of those associations.