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In 1928 the Nixon Navigation Company went into liquidation *6 . The precise history between 1928 and 1935 is not really very clear but it appears that the colliery was run by Welsh Associated Collieries 7 . In 1933 a Maclean or Tippler tip was started somewhat higher up the mountainside and slightly to the west of Tip 3. This is marked No. 4 on Figure 3.1. in 1935 Powell Duffryn took over the colliery and tipping continued on Tip No. 4 until 21st November 1944 when a major failure occurred in the tip and it was subsequently abandoned #9*. There is evidence that some surface drainage was installed relative to the stability of Tip 4 but it does not seem to have been in any way comprehensive and there is no evidence that drains exist beneath Tip 4 *10*. For a few months after the abandonment of Tip 4, tipping was carried out using horn rails on a site between Tips Nos. 3 and 4 next to the tram road or incline M1 *. After this, sometime early in 1945, a new tip, No. 5 on Figure 3.1, was then constructed uphill of No. 4; this was also a Maclean tip *12*. During the construction of this tip the Powell Duffryn Organisation were absorbed into the National Coal Board, formed in 1947. Tipping continued on this tip No. 5 until it was abandoned in 1956 due apparently to the economic difficulties of tipping at a great height and also due to the fact that the tip was on fire (started 1953) and was causing a public nuisance *13*. A new tip was then started on the northern side of the tram road and was constructed as a flat-topped crane tip, the crane being electrically driven; the position of this tip. No. 6, is shown on Figure 3.1. Tip No. 6 was started in 1956 but had to be abandoned at Easter in 1958 because of its encroach- ment on the neighbouring farmers' land and because it was causing interference with the tram road *14*. It is understood that no drainage precautions or investigation of the site, with this in mind, were undertaken before or during the construction of this tip *15*. It was then decided to start a new tip marked No. 7 on Figure 3.1 ; this was again a flat-top crane tip. Before construction was started an area on the north-eastern corner of Tip No. 4 was made flat with a bulldozer and a parting put in from the main incline to the edge of this platform *16*. it is apparent from the evidence that little investigation was carried out and also that there were no drainage measures taken at all with regard to this tip *17*. The tip continued in the valley between Tips Nos. 3 and 4 until in about 1962 it extended beyond the southerly end of Tip No. 3. Waste disposal was then continued on this tip up to 21st October 1966. There is much evidence suggesting that from as early as 1960 the National Coal Board had intended to abandon this tip and start another further to the west either between No. 4 and No. 7 or to the west uphill of Tip No. 5. A number of schemes were suggested but none came to fruition *18*. It is understood that there was a scheme for tipping to the west of Tip No. 5 as long ago as 1950 but this was never undertaken, and there is evidence that Tips No. 6 and No. 7 were in fact 'stop-gaps' while permission was being obtained for a major tipping scheme *19*. There is substantial evidence that natural springs and streams have been covered by tips, some by Tip No. 4 and others by Tip No. 7 *20*. Previous Movements of Tips There have been a number of major and minor movements in the complex of tips at Aberfan in the past (dates given here are as near as can be ascertained). Apart from the recent disaster the largest of these was the slide that occurred on 21 st November 1944 in the first Maclean tip. No. 4 *21 This was a very large slip which extended from the top of the tip in a 'tongue' stretching into the western half of field 8761, a total distance of 800 yards. There is much varying evidence with regard to the nature of this slip, the only common agreement being that rainfall had been heavy during the preceding days and that subsidence 98 Printed image digitised by the University of Southampton Library Digitisation Unit due to mining had affected or was affecting the area at that time; lastly that the failure happened and the slide was complete in a very short time probably during the night of 20th—21st November *H4, Dl\ K12, E6, 22*. There has been considerable evidence given of movements in Tip 1, principally from 1963 onwards. Some of this evidence is conflicting but it appears that there have been three types of movement, that is to say, firstly, repeated settlement of the top of the tip towards its front edge; secondly, there has been a flow of very wet fine material from the tip down the hillside below; and thirdly, there is evidence that in October or November 1963 a considerable amount of material moved out of the face of the tip and went down the hillside leaving a recognisable hole. There appears to be a conflict of evidence about the magnitude or the significance of this latter movement, but there is an indication of it in aerial photograph D5 (see Fairey Surveys, Fig. 8), taken on 10th November 1964 *D6, 23, 24, 25*. There is evidence that a number of minor movements have occurred on Tips Nos. 1, 5 and 7 over the years, other than that outlined above *D6, 26, 27*. The results of these movements can be seen in the shapes of Tips Nos. 1 and 5 to this day. There is also evidence which indicates that the top of Tip No. 7 did not advance very much between 1963 and 1966 although the toe continued to do so *28*; a number of the officials of the National Coal Board who were actively involved in the welfare of Tip No. 7 were unaware of this *29 *. There is a long history of tip movements at other collieries in South Wales, but of these, the one that occurred in 1939 at Cilfynydd is particularly relevant, and it has been referred to on a number of occasions during the Inquiry *30*. It has also been described in other publica- tions, and it gave rise to a memorandum prepared by the Powell Duffryn organisation which subsequently became the basis of the memorandum issued by the Divisional Chief Engineer of the National Coal Board, Mr Powell, in 1965. General knowledge regarding tip slips was rather limited although some knowledge of some of the larger slips in tips in South Wales was possessed by Coal Board officials *30 *. Records and Control The evidence shows that systematic inspection, other than from a mechanical viewpoint, of Tip No. 7 by qualified or authorised persons was not carried out *31 * neither was there any delegation of respon- sibility *32*, no instruction to individuals *33*, no survey records *34*, and most of the officials who became involved with tip stability, particularly in Area 4, did not have the necessary experience or training to carry out an analysis of this sort. The only officials who did have such attributes are given in reference *36*. No enquiries were made as to the stability or as to what to look for to determine the stability of Tip No. 7 *37*. The only reports with regard to the progress and stability of this tip were associated with the tip workers and at Area level with the Area Mechanical Engineer as a result of the memorandum issued by the Divisional Chief Engineer, Mr Powell *38*. There is evidence which suggests that in the days of Powell Duffryn, inspections of tips were both more frequent and more systematic *39*. Apparently the only working system in the National Coal Board with regard to tip inspection existed in the South Western Division Area 3, and this was not widely known or recognised *40 *. As the result of an incident at Ty Mawr tip in 1965 a document was issued in April of that year by South-West Division to all Areas requesting an immediate inspection of the active tips with regard to their stability. It contained a simple guide to the natural features and conditions which if pertaining might be of consequence. It was 99 answered by all Areas with differing diligence and interpretation, and as Printed image digitised by the University of Southampton Library Digitisation Unit far as Aberfan was concerned it was acted upon solely by the Area Mechanical Engineer who, with the exception of one or two senior officials at Area and Divisional level, was the only person actively concerned with it *41,42*. Flooding There are a large number of statements relating to the fact that flooding occurred in the village of Aberfan after heavy rainfall from as long ago as 1951 ; further, that this flooding was the direct result of the interference with streams on the mountainside by tip material and the resultant carrying down of this material, causing the blockage of culverts and the silting up of waterways. General evidence of flooding *44* has been given as has more specific evidence with regard to the blockage of culverts and drains by waste material, particularly from Tip No.

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