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General Description

From 1944 onwards the Bensham Seam workings, as shown on Plan No. 1, advanced slowly southwards as succeeding easterly offshoots were worked and then abandoned, until the 3rd East District was gained. Here further progress south was halted because of a deterioration in the seam in that direction and the 3rd East then became the main winning. Its progress, however, in turn was held up for a year, after it had advanced some 840 yards from the 3rd East Junction while the rise side of flooded workings in the Yard Seam, 50 feet above, were proved by boreholes from a rise drift, thereby relieving the water pressure head. This did not, and indeed could not, drain the water from the main portion of the old workings, which lay to the dip side of the point of contact.

Following this, work was resumed in the Bensham Seam and, just prior to the explosion, two working districts, known as the 3rd East and 3rd North Fiats respectively and having a common ventilation system, were in production.

Plan No. 2 shows the extent to which these two Flats had been developed at this time. The 3rd East, with three producing places, extended for a distance of six pillars east of the terminus of the 3rd East Conveyor. The 3rd North Flat, with five places on production, had advanced eight pillars to the north of the conveyor road. An attempt to develop places to the south of the conveyor road had to be abandoned, because the gradients proved to be steeper than the maximum on which the shuttle cars could legally be operated. The coal from the 3rd East Flat was discharged from the shuttle cars on to the end of the conveyor and that from the 3rd North Flat sideloaded at the junction of the 3rd North road with the conveyor road.

On the opposite side of the latter point, there was a charging station which was used by both Flats. This was constructed of brick side walls on which rested "H" section girders to support the roof. At the entrance to the charging station from the conveyor road there were two motor generators and beyond them, through a steel ventilating regulator, two charging racks, one at either side. In order to change batteries, shuttle cars had to enter and leave the charging station at its bottom end, which connected with the district return airway. The shuttle cars from the 3rd North Flat reached this return airway by crossing the conveyor road at the next stenton inbye of the end of the conveyor.

Plan No. 2 also shows the roads which were being maintained in the Flats up to the time of the explosion, viz, those required for transport or as airways. As has been stated, the finished stentons were only loosely stowed, and any shown as stowed and drawn-off, therefore, were unlikely to be airtight unless finished off with stoppings.

Ventilation

The workings in the shaft area had been ventilated by one main intake airway, which was also the haulage road, and by one main return airway When development first started in the Bensham seam, it was realised that the surface fan would have to be augmented accordingly, and in due course booster fan of 61,800 cubic feet per minute capacity at a water gauge of 42 inches was installed in the main return airway at a point 700 yards distant from the shaft and just outbye the junction of the Bensham and Low Main Seams main return airways. The fan was in operation at the time o the explosion, and approximately half of the quantity it was passing was drawn from the Bensham Seam.

The workings from the booster fan inbye to the large faults were ventilated by a continuation of the same main intake and by dual returns, one on each side of the former.

As development proceeded beyond the faults, however, the system was changed to dual intakes and one return, which latter was to the west of and parallel to the intakes. The second intake was not continued beyond the point where advance in a southerly direction was halted, and as a consequence of this the 3rd East District was ventilated by a single intake, viz, the 3rd East Conveyor road, with a return airway in a parallel road one pillar farther to the south. These airways were separated throughout by brick stoppings or doors. Originally no stoppings were built in the stentons on the opposite side of the intake, but this was rectified later when it was found that the intake air was cutting across the pillared area and thereby becoming contaminated to a slight extent by firedamp. When the work of building these latter stoppings was completed, the total quantity of air entering the 3rd East District was 22,000 c.f.m., of which approximately 9,000 c.f.m. reached the first working place in the 3rd North Flat.

So far as the ventilation of the two Flats was concerned, a door and a screen erected on the conveyor road just inbye of its junction with the 3rd North road turned the intake air up the latter, round which it coursed, being directed through canvas tubes into the individual headings by a number of forcing auxiliary fans, each of 3,000 c.f.m. capacity. From the 3rd North Flat it passed on to the 3rd East Flat, the working places of which were ventilated in the same manner, and thence into the return airway.

The efficient ventilation of each working place depended on the proper siting and advancement of the auxiliary fans, and to ensure this an official was appointed by the management. Full records, as required by the Coal Mines (Ventilation) General Regulations. 1947, were kept and in conformity with No. 14 (5) of the same Regulations, a plan was prepared each week showing the positions of all the fans and their associated tubings.

Electrical Apparatus

The electrical lay-out of the district and the charging station is shown on Plan No. 3, which purports to show the installation as it existed five days before the explosion took place: of necessity the location of some of the apparatus is by description. The incoming supply, at 625 volts A.C., was by a double wire-armoured cable along the conveyor road to a district switch about 300 yards outbye of the charging station. From this switch the cable continued 275 yards further inbye to a section switch controlling the supply to the 3rd East Flat and the turbine pump situated therein. Supplies for the 3rd North Flat and for the charging station were teed off the busbars of this section switch. Current to the 3rd North Flat and the charging station control switch could not be cut off if the turbine pump was required to run, except by disconnecting the two circuits at the section switch busbars.

The supply to the 3rd East Flat from the section switch was by double wire-armoured cable to a bank of four gate-end switches controlling, respectively, the auxiliary fans, a coalcutting machine, a Joy loader and a small pump. The supply for the turbine pump was teed off en route. The Joy loader shown in the stenton opposite the pump was not connected to any apparatus.

Similarly. the supply to the 3rd North Flat was carried by double wirearmoured cable up the 3rd North road to a bank of five gate-end switches situated two pillars in to the right in the seventh level. These switches controlled, respectively, two auxiliary fans, two Joy loaders and a coalcutting machine. A drilling panel was fed by double wire-armoured cable from the busbars of these switches. The only other electrical apparatus in the district consisted of four shuttle cars.