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CHAPTER SEVEN

Underground Problems and Changes on the Surface

Contents

Faults - The White Lodge Fault - The Old Irthlingborough Fault - The D 6 Faults - The F Main Fault - Washouts - The M District Faults - Thin Stone - The Pilot Plant - The Auxiliary Ventilation Shaft - The Second Finedon Tunnel - The Blacksmith’s Shop and Loco Shed - The Conversion of Electric Trolley Locos - The Restoration of Buccleuch Quarry. - Surface-to-Underground Communications

All mines are likely to encounter some dislocations of the strata which may force adjustments to the proposed layout of the workings.    These may be faults, where the strata have fractured and dislocated, washouts, where the seam has been eroded and replaced by overlying strata, or thin stone, where the thickness of the seam has been reduced to an uneconomic level.   The iron ore seam at Irthlingborough was, in comparison with many mines, reasonably horizontal, but there were a few examples of these particular problems.
Faults
The White Lodge Fault
The first fault encountered, during the driving of the Main Mine Tunnel, was the White Lodge Fault; this was already known, and had been taken into account when the tunnel was laid out (See Chapter One fig.6).    This fault, however, was distinctive in that, unlike most other faults encountered, it fell to the south with a downthrow (slippage) of some 21 yds. (19 m.).   The Mines Surveyor in 1916, H. F. May, interpreted it as shown in figure 1, but a slightly different, and no doubt more accurate, interpretation is suggested by S. E. Hollingworth (fig. 2) in the Memoirs of the Geological Survey of Great Britain, 1951.    This section was taken in the White Lodge limestone quarry, some 30 yds. (27 m.) to the west of the mine tunnel.    It has been suggested that this dislocation was caused by the action of the River Nene, which, having removed the strata overlying the Lias Clay, allowed the strata on the valley side to slip, creating the fault and simultaneously forcing the softer Lias Clay to rise in the valley, a phenomenon known as ‘valley bulging’.
The Old Irthlingborough Fault
The Company encountered a second fault, 40 yards (36.5 m.) north of the White Lodge Fault while driving tunnels in a southerly direction during 1920.    The tunnels were stopped on the line of the fault, which had a 12’ (3.65 m.) downthrow to the north.    Early in 1927 the Cement Company also stopped its limestone quarry along the line of the same fault while working in a northerly direction, leaving an end gullet which quickly filled with water. (fig. 3).   In 1950 the base of this gullet collapsed on the weak line of the fault, causing an ‘inrush’ into the mine which, while not dangerous, caused problems when it disrupted the mine ventilation system.   The weekly report of 11 February 1950 described the event :-
Eventually the subsidence stabilised, although by about 10 years after the original occurrence the hole had subsided a further two to three feet (about 1m.).   This has since been filled, and there has been no further subsidence.
The D 6 Faults
In the 1950’s the Company encountered several faults in an area north of the A6 bypass at Irthlingborough, close to the eastern boundary of its estate (see plan fig, 4).    These faults were all longitudinal, with downthrows to the north varying from 2’ to 8’ ( 0.6 to 2.4 m.), which required that all tunnels be stopped on the fault line.   Eventually, in most areas, the iron ore was mined from the north side.
The F Main Fault
By far the biggest throw to cause problems in the layout of the mine was the ‘F Main Fault’.    This was encountered in a developing tunnel driving north, in March 1953.    The extent of the throw of the fault was unknown at the time but it was predicted, from the strata encountered, that it would be a downthrow of several feet.    A downward drift 9’ ( 2.7 m.) wide was driven at a slope of 1 in 7.5 (fig. 5).    Over a year later, after having driven 30 yds. (27.4 m.), the iron ore seam was regained at a level 12’ (3.7 m.) lower.    To develop the mine beyond the fault required the installation of a winch for hauling up the wagons, one or two at a time, to be stationed on sidings from which they would be transferred to the surface by the main haulage.   There was no way that the main haulage locos could enter the workings down a drift of 1 in 7.5.
Washouts
Soon after encountering the F Main Fault the same developing tunnel struck the only complete ‘washout’ (fig. 6) recorded on the mine plans.   Clay completely replaced the iron ore seam for a width of about 60’ (18.3 m.); tunnelling continued through this feature to gain the seam on the other side.
The M District Faults
In October 1961 a downthrow fault was encountered in a developing heading in M district (fig. 7) in Burton Latimer parish. A drift, similar to that driven through the F Main Fault, was commenced, but it was soon discovered that a series of step faults was involved.   A second-hand Becket & Anderson Ltd. hoist was acquired from Cleveland, and fitted with a 15 hp motor to haul the wagons of clay up the slope.   Before the faulted area could be fully proved the mine closed, but a grid of borings, carried out in the autumn of 1964 in fields ahead of the workings, made it apparent that the seam was so disturbed that working the ore in that area would have been problematical.   Using the evidence of a well sunk on the northern boundary of the Company’s estate by Burton Latimer Urban District Council in 1901, to provide a water supply to the town, it was known that the ore would be lower than the general level of the mine by some 30’ to 40’ ( 9 to 12 m.).
Thin Stone

In various areas the workings encountered thin stone; in these cases tunnels had to be either stopped, or driven to a narrower width, both to prevent roof falls and to avoid the unnecessary mining of clay.   When this occurred the miners were paid on yardage rather than tonnage.
The Pilot Plant
One surface building, for the use of which there is little evidence, was the Pilot Plant.   It was situated on waste ground between the Offices and the Kilns, and was probably built in 1920 to perform an experiment on the grading, crushing and possibly washing of the ore; it had all but disappeared by 1947.   A few concrete ‘up stands’ in the undergrowth, to support pulley wheels, and an underground cistern were the only evidence by then of its former existence.   A laconic entry in the Weekly Report for 27 May 1944 gives partial evidence for its use.
This was evidently ineffective, because a later report states that Coveallen of Rushden were unable to repair the crusher rolls as the material was too hard and they required grinding.   This engineering firm, however, did not have the necessary dust-extracting apparatus, leaving the London Brick Company at Peterborough as the only firm in the area who might have been able to help; unfortunately they could not take on any ‘outside’ jobs at that time.

Apart from four photographs taken during its construction (fig. 8) and a mark on a plan (fig. 9) there is, so far, no other evidence of this enigmatic structure.

The Auxiliary Ventilation Shaft
The Weekly Report of 23 March 1950 stated,
It was not until early 1955, however, that this 80’ deep (24 m.) shaft was achieved.   A well-digger arrived from Leicestershire, and started a 4’ (1.2 m.) diameter shaft in the autumn of 1950, but he left the job after digging only 8’ ( 2.4 m.).   He was persuaded to return in July 1951, but had only reached a depth of 35’ (10 m.) when he again left, this time due to inclement weather in the autumn.   He failed to return, however, in the following spring, and no amount of incentives would entice him back.   Eventually, at the end of November 1954, the Manager from Blisworth Quarry was called upon to complete the work.   At 40’ (12 m.) down he discovered, in the boulder clay, a fossilised ammonite, 7.5" (19 cms.) across.   The Geological Society of London, who were given the fossil, showed great interest in this find, having deduced that it had been carried to the area as an erratic fossil from further east during the Great Ice Age.  When the shaft was completed a fan was duly installed and conditions in the Charging Station were greatly improved.   A member of the Survey Department, M. B. Shipp, accepted the challenge to be lowered from the surface in a kibble in order to record the strata in the shaft; this sequence was then used as the representative section V3 recorded on the Working Plan of the mine, and is now included on the Abandonment Plan.
The Second Finedon Tunnel
As early as 1956, when the Company began to work the area north of Thrapston Road, Finedon, it became evident that the ventilation fan at Irthlingborough would not be able to provide enough air to these workings without some auxiliary support.   For this purpose a second Finedon Tunnel was started, parallel to the one driven in 1938, to emerge eventually into Barlow’s Quarry at Finedon; this was to be fitted with an extractor fan at its mouth.   It was not until September 1965, when closure of the mine was imminent, that the fan house was completed and the fan installed.   The fan was purchased from Davison & Co. Ltd., Sirocco Works, Belfast, and was adapted with a 40 hp motor to produce 80,000 cu. ft. per min. (2,265 cu. m. per min.).   The Chief Engineer was anxious to establish whether the noise of the fan would cause annoyance to nearby residents; the fan was set in motion for a short time and it was established that, being in a gullet some 30’ (10 m.) deep, no sound could be heard at street level.   The very next day the fan was removed and the fan house demolished.
The Blacksmith’s Shop and Loco Shed
In 1939 it was noted that the number of wagons, or ‘trams’ as they were commonly called, available to the miners was becoming critically low.   At that time there were as many as 90 ‘cripples’ amounting to some 16% of the total stock.   Eventually, in early 1961, a combined Blacksmith’s Shop and Loco Shed was erected, using a redundant steel structure from one of the Company’s works in Wales.   This building (fig. 10) was always known as The Tram Repair Shop, and was situated on the eastern side of the ‘Bank’ between the Offices and the Top Weighbridge.
At about the same time, and using materials from the same source, small sheds were erected over the tracks adjacent to the top weighbridge and the area where men were moving and coupling full and empty wagons so that they could be at least partly protected from the weather.  

The Conversion of Electric Trolley Locos

Although no accidents were ever recorded from electric shocks caused by the trolley locos, there was always the possibility that this could happen, particularly if the connection was broken between the wheels of the loco and the rails which completed the circuit.    The locos were fitted with sand boxes so that, if necessary, dry sand could be placed on the rails to afford a grip when starting the loco from a stationary position in certain conditions.   If its wheels were to be standing on this sand, however, a poor connection would result and the current could, potentially, find its way through the body of anyone who inadvertently touched any part of the machine.   It was for this reason, and others, that H.M. Inspector of Mines revoked the Special Regulations dated 24 September 1949, which permitted the use of trolley locos, and required that by the end of 1963 the Company should introduce an alternative mode of propulsion.   The battery experts, D.P. Batteries of Bakewell (fig. 11), were engaged to advise on the possibilities of converting the existing trolley locos to battery operation, and, with their help and advice, battery compartments were constructed on four locos (fig. 12).   These vehicles now became unique in the world, there being no other Greenwood & Batley locos converted in this way.   Their batteries could be charged overnight in a new Battery Charging Station, built using materials similar to, and from the same source as, those of the Tram Repair Shop.   This structure was both the last to be built at Irthlingborough and the last to be demolished.
The Restoration of Buccleuch Quarry.
Even before the Second World War the Government had become concerned about the huge area of land already lost to agriculture as a result of iron ore quarrying, which left the land both devoid of topsoil and in ‘Hill & Dale’ formation.   A Government Committee produced a report in 1939, suggesting that restoration should not be left to the mineral operators or land owners; instead it proposed that a special body should be set up, to be known perhaps as The Ironstone Areas Restoration Board, to control the work of restoration in an area known as The Restoration District, which would include the counties of Northamptonshire, Lincolnshire, Oxfordshire, Warwickshire, Leicestershire and Rutland.   Due to the onset of hostilities, however, nothing further was done at that time.   After the war the Government again considered the problem; by this time 1,500 acres (607 Ha.) of Northamptonshire were affected.   Their deliberations resulted in the introduction of The Minerals Working Act 1951, which, in its preamble, stated the following:-
Whilst this did not affect land under which minerals were won by underground mining, it did affect the 69 acres (28 Ha.) of Buccleuch Quarry worked before the introduction of the 1951 Act.   The land was restored by the Wellingborough Urban District Council in 1956, using money from the Restoration Fund set up under the 1951 Act, with no input from the Company.   It was eventually handed back to the Company in a levelled condition but without topsoil, as this had not been set aside when the quarry was worked.
Surface-to-Underground Communications
Communication between the surface and the Deputies’ Meeting Stations underground was originally by telephone, but the mine’s humidity caused the almost 4-mile (6.4 kms.) length of telephone cable to perish quickly.   Walkie-Talkie radio connections were found to be impracticable due to the tendency of iron ore to block shortwave communication.   Towards the end of 1957 it was decided to install instead a revolutionary surface-to-underground radio link, known as a Reporter Radio Telephone, believed at that time to be the only one of its kind in the world.   It took the form of a permanent radio station, 90’ (27.4 m.) underground, near the Charging Station, with the call sign ‘Earth Base’.   This was linked by a TV-type coaxial cable to a 20’ ( 6 m.) metal aerial on the surface, in line with the antennae of the parent station 1.5 miles (2.4 kms.) away on the roof of the Electrical Fitting Shop.   A hand microphone was used to transmit messages which were preceded by an electric bell alarm.   Later a second radio station was established north of Thrapston Road, Finedon.

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