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October, 1959

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Bates Colliery is situated in the town of Blyth immediately adjacent to the river and harbour, and thus lies in that part of Northumberland where considerable coal reserves are available under the North Sea. This region, and its extension seaward, is the main area for development, and important reconstructions are in progress in the Ashington area and at Bates. These developments are being carried out to offset the inevitable decline in reserves from regions further south and along the western outcrop of the Northumberland coalfield.

History

Prior to Vesting Date, Bates and some nearby collieries, were owned by the Cowpen Coal Co. Ltd.

The orginal shafts (South and North) were sunk some 150 years ago and the nearby coal was worked by room and pillar methods.

In 1932 the Company sunk a third shaft (Bates) and went over to conventional longwall single units with conveyors to central loading points on the main transport roads. The transport system consisted of main-and-tail and endless-rope haulages.

One of the many interesting features of this colliery is that coal has always been transported by ship to its destination, and until recently there was no adequate rail connection out of the pit. The ship-loading devices, or staithes, although over 30 years old, are still of considerable engineering interest.

It is worth recalling that by having the winding shafts and the staithes conveniently sited, charges to the Railway Company were cut out and the Cowpen Coal Co. Ltd. is thus said to have had an "edge" of about 2s. per ton over rivals for the Blyth trade. As a result of this "edge", the Company never worked short time during the depression.

Prior to reorganisation

A concentration policy was commenced before Nationalisation by bringing coal from both the Plessey and Beaumont seams to a main pit-bottom located at the Beaumont seam level.

The 14-cwt. tubs were wound up the Bates shaft, four tubs per wind, in double-deck cages, by an electric winder; Bates has always used electrical power and there has never been any steam plant at the colliery.

On reaching the surface the coal was conveyed to a SimonCarves washery where the +3½ in. size was hand cleaned, the 3½ to 1¼ in. size washed in a 125 t.p.h. Baum box and the -1¼ in. sold untreated. (This plant is still being used while awaiting the completion of the new washery.)

Stone was also wound up Bates shaft and tipped on the surface to reclaim land from the river for railway sidings etc., and some was taken to the dirt heap at nearby Isabella Colliery.

Clean coal was loaded into end-tipping railway wagons and shunted through the sidings to the ship-loading booms. This successful method of ship loading is being retained in the new scheme. Coal is discharged from the railway wagons into two 20-ton hoppers and from there to the two loading booms via jigger feed conveyors. The two 42 in. loading conveyors are each powered by 50 h.p. motors and run at a speed of 320 ft. per min. The booms are extensible and can load ships of varying sizes.

Summary of the development plan

It is expected that the plan will result in an increase of output from 2,000 to 3,600 tons per day, and at a later stage, when new seams are opened out, output will be considerably greater. The total cost of the scheme will be in the region of 3¾ million pounds.

Workings at the colliery have so far been confined to the Plessey and Beaumont seams, the latter lying at a depth of 725 ft. below O.D. at the shafts. It is estimated that reserves in these seams to a distance of 44- miles seaward is 31 million tons, which at planned output should last for 36 years.

The policy of concentration was commenced by bringing the coal to a single trunk road in the Beaumont seam via strategically placed drifts. Work was then undertaken to make the trunk road suitable for locomotives. By suitable caunching the roadway was graded so that the maximum gradient to be negotiated was 1 in 230.

After Vesting Day the development plan was drawn up, and in 1951 work had started on enlarging and grading the Beaumont main roads to take doubletrack locomotive haulage and 3½-ton minecars.

A new 24 ft. diameter shaft (No. 3 shaft), necessary to wind the minecars to the surface, and ultimately for Ventilation purposes, was started in June 1952 and completed in January 1955. The sinking of this shaft and the driving of shaft sidings was carried out by the Cementation Co. Ltd. It is worthy of note that the make of water from the shaft is now negligible despite its close proximity to the River Blyth.

As the whole project has been prepared on the assumption that the colliery will be further developed later to a lower horizon, the new shaft was sunk to 1,000 ft. below O.D.

The shaft and new headgear are designed for two winders operating from different levels but at present only one winder has been installed to wind from the Beaumont level.

No. 3 shaft pit-bottom has been completed, but until a new heapstead is built it will not be suitable for coal winding, consequently the 3½-ton minecars are tipped in the pit-bottom and the coal is reloaded by conveyor into tubs for winding up Bates shaft.

A start was made on the surface works in 1955, following the completion of the sinking. A contract for the preliminary stages of the civil engineering work was carried out by Holland & Hannen and Cubitts (Scotland) Limited. This included the construction of the winding engine house for the new shaft, a canteen, an electrical sub-station, certain approach roads and the diversion of a main sewer crossing the site. This stage of the work was followed by a further preliminary contract for the driving of concrete piles, which was carried out by West’s Piling and Construction Co. Ltd.

The main stage of the work was reached early in 1958, when a contract was awarded to the Norwest Construction Co. Ltd. for the construction of more than a dozen buildings, including a new coal-preparation plant, heapstead and workshop buildings, together with the replacement of much of the existing railway siding system and the demolition and clearance of existing buildings.

Mott, Hay and Anderson are the consulting engineers for the project and Watson and Coates are the advisers on architectural matters.

Other items in the building programme are a cooling tower and reservoir, new fans, lamp cabin, time office and and an office block.

Underground, the locomotive haulage roads are being driven and the Plessey roadways, ultimately the return airways for both seams, are being enlarged, All stone from the drivages and pit dirt from the washery is taken out to sea and dumped beyond the three-mile limit.

The scheme is expected to increase the overall O.M.S. from 27 to 36 cwt. and the extra men needed to achieve this will be 400 face men, 270 others underground chiefly on development work, and a reduction of 32 surface men.

The main part of this programme, i.e., up to the operation of the coal preparation plant, should be completed in 1960 when coal can be wound up from No. 3 shaft, and the increase in output built up until 1962. All the surface work should be completed and in operation by the end of 1960.

At the time of writing, the general position was as follows :— No. 3 shaft and winder in operation (winding dirt, thus allowing maximum coal output from Bates shaft); construction of heapstead started; foundations for the coal-preparation plant completed.

At this stage it is worth noting that the whole scheme is built round the Plessey and Beaumont seams which are only 3 ft. and 2 ft. 6 in. in thickness, respectively.

Site problems

The problems encountered at the planning stage of the scheme, especially on such a congested site with little room for expansion were numerous and complicated.

Many factors had to be taken into account at the initial stages including the following :—

(a) The work involves virtually the complete replacement of the existing surface facilities. Most of the new buildings could be sited in positions which would enable them to be completed and brought into survice before demolishing their existing counterparts. The general run of the sidings, however, is set at an angle to the existing layout, and this has necessitated careful phasing of the trackwork.

(b) Although the scheme would initially result in output being raised to approximately 3,600 tons per day, it had to be planned on the basis of a much greater future tonnage.

(c) The present preparation plant, although efficient, could not cope with any increase in output. Therefore until the new plant was ready, the full winding capacity could not be utilised.

(d) Any considerable increase in output would also be held up until a new fan was installed.

(e) The colliery site is on low-lying ground adjoining the estuary of the River Blyth, and the ground consists of filled material extending to depths varying up to 20 ft., and unsuitable for heavy foundations. Below the made up ground lies Coal Measure sandstone which serves as a base for the cast-in-situ concrete piles which are required to support the buildings. The main stan’ding water level is subject to tidal variation and is very close to the surface, so that where it is necessary to excavate to rock level, as, for example, in the mass concrete foundations for the new headgear and winding engine, continuous pumping was required.

(f) A main sewer ran through the site; this had to be diverted.

(g) There are two rights-ofway, one through the pit yard and one round the foreshore, which had to be maintained.

(h) Underground development work was limited at the start as there was only one shaft available for drawing both coal and stone. When No. 3 shaft was completed it was possible to switch stone winding over to it and thus speed things up.

(i) Another limit on the amount of stone brought out of the pit was imposed by the fact that the stone barge, as a rule, only made two trips daily.

(k) Due to the fact that all coal is shipped, a considerable amount of standage room must always be available.

(l) Space must be provided for stockpiling.

Surface development—Phase I

The first stage of the development programme at Bates Colliery was a comparatively small one. Work commenced at the beginning of June 1956 and went on until April 1957.

The contract, carried out by Holland & Hannen and Cubitts (Scotland) Limited, consisted of erection of a sub-station, a new winding house, foundations for the new structural steel headframe, a canteen building, the diversion of a main sewer, together with general site works in the way of earth moving, brick retaining walls, drainage and concrete paved areas. Whilst the difficulties encountered in connection with civil engineering work were of no great magnitude, the following points are worthy of mention.

Sub-station (Fig. 11)

This is a brick building structure with a precast concrete roof, superimposed on a reinforced concrete basement. The two main features in the construction were (a) the multiplicity of ducts running transversely under the basement and linking up the installations on either side, and (b) the large number of ducts passing through the walls and roof of the basement structure.

As a result of (b) above, the shuttering to the basement walls, in particular, become exceedingly complicated.

As the normal ground water level was some 4 ft. above the basement floor slab, asphalt tanking was essential and the quality of the workmanship throughout the construction is apparent in that after some two years, there is not the slightest sign of water penetrating anywhere into the basement.

Headframe foundations

These four large mass concrete blocks were taken down to approximately 20 ft. below ground level where they are keyed for about 2 ft. into the fissured and laminated sandstone. Into the top of each foundation block is embedded a structural steel bolt setting frame about 5 ft. square by 7 ft. 6 in. deep carrying six 24- in. diameter holding-down bolts. These frames are inclined in two directions to accommodate the sloping legs of the headframe and their positioning called for extremely accurate setting out. Subsequent erection of the headframe proceeded without a hitch and no significant error was found in this rather tricky piece of positioning.

Winding engine house

The main electric motors and winding drum are carried on a reinforced concrete raft supported on three massive r.c. columns extending down to bedrock. The enclosing brick structure surmounted by a flat precast concrete roof and the general architec tural treatment gives this rather functional building an attractive appearance. The interior of the building is bright and spacious, with quarry tile floors, terrazzo dados and cement glaze wall treatment above. The roof soffit is sprayed with Limpet asbestos which materially assists in reducing the level of noise in the building.

The lighting in the engine house, installed by the National Coal Board, is designed to overcome any stroboscopic effects which might suggest that the winder was stationary when it was, in fact, moving. This has been achieved by using three sets of fluorescent lights, each on different phase.

Sewer diversion

An existing 36 in. sewer crossed the site of operations in such a manner as to foul some of the proposed new buildings. It was decided, therefore, to construct a new length of sewer and finally break into the existing sewer at each end and seal off the offending section.

The difficulties in constructing the new sewer—apart from the normal complications in finally breaking into the existing pipe— were mainly (a) the nature of the ground which, being mainly loose shale and pitwaste overlying rock, necessitated close trench sheeting throughout and heavy timbering, (b) the fact that the new length was constructed in a very confined area and in close proximity to existing buildings and installations and (c) tidal water backed up the existing sewer regularly throughout the period of construction and owing to a number of faulty joints in this old sewer, flooded the new cut, and so continual pumping was required.

Canteen (Fig. 12)

This a very pleasing modern building with loadbearing brick walls and a light-weight roof on lattice girders. The front elevation is wholly glazed down to cill level. A special feature is the very striking decorative wall tiling in the main dining room, which is also a practical hard wearing finish.

General

The external works were all fairly straightforward and the only point worth stressing is the fact that the weather broke only one week after the commencement of the contract and the whole of the work was carried out in most unfavourable conditions.

No. 3 winder

At the present time only one winder is installed at No. 3 shaft but the complete reorganisation has been prepared on the assumption that the colliery will be further developed at a later date by means of a second pair of cages working to a lower horizon. The second winder will be indentical to the one at present in operation.

The cylindrical drum winder is fitted with a balance rope and driven by a three-phase, 3,300 V. induction motor running at 420 r.p.m.

The main drive from the motor is through single reduction gearing and the two pairs of curved suspended post brakes are oil-pressure operated.

The depth of the wind is 738 ft., the single-deck cages carry one 3½-ton minecar, and the designed speed will result in 86 winds, or an output of 300 tons of coal per hour.

Other features of this winder are geared rope reels for easy adjustment of the rope lengths and an emergency pinion shaft brake hydraulically operated and interconnected with the main braking system.

Electrical parts were manufactured by Metropolitan-Vickers Limited, and mechanical parts, i ncluding the braking system, by Robey and Co. Ltd.

Electrical reorganisation

The increased mechanisation both underground and on the surface at this colliery and the subsequent load demand, rendered the existing 2,750 V. distribution system insufficient. It was therefore necessary to erect the new surface substation with an adequate capacity to cater for all future development.

Fig. 13 shows the arrangement of the E.H.T. and H.T. switchgear and transformers in the substation.

All the existing and proposed surface buildings and equipment will be fed via 3 kV ring main distribution systems from two 2,000 kVa 20/3.3 kV transformers. The busbar couplers in the systems are all castell inter-locked.

The underground distribution will be at 6.6 kV to eliminate excessive voltage drops in the supply cables. The supply will be taken from two 2,000 kVa 20 kV/6.6 kV transformers. In order to maintain standbye supplies at a minimum cost one of these transformers is equipped with secondary windings capable of giving output voltages of either 6.6 kV or 3.3 kV and so in an emergency can supply the underground or surface distribution switchboards.

A feeder is taken down the newly sunk No. 3 shaft to the Beaumont Level and into the Beaumont districts. It is intended to run another 6.6 kV feeder down the No. 2 Bates shaft to the Plessey inset and into the Plessey districts. The two feeders will eventually form a ring main system being interconnected by means of cable run in the Beaumont/ Plessey drift.

Acknowledgments

For permission to publish this article we are indebted to Mr. W. J. Charlton, Area General Manager. No. 2 (Mid-Northumberland) Area, N. C.B. Northern (N. & C.) Division and we should very much like to express our thanks to Mr. R. H. Charlton, Area Deputy Production Manager (Planning), Mr. J. Moss, Area Planning Engineer, and Mr. P. Coen, Manager of Bates Colliery for their assistance in the preparation of the article.

(To be continued)

Drawings and Photographs accompanying the article