Discussion on Paper No. 6222: An Investigation Into a Proposal to Dispose of Power-Station Ash by Discharging It Into the Sea at Low Water.

Abstract

said that the idea of disposing of half-a-million tons a year of boiler ash from Blyth power station by placing it in the cooling water and sending it out to sea through a pipe had been novel enough to give rise to certain misgivings on the part of local authorities and other bodies concerned with the preservation of local amenities and inshore fishing. 67. The Authors' firm had studied the behaviour of fine sands, silts, and clays under wave action on ocean beaches for many years and had been satisfied that there was nothing to fear from the proposal and that the material would be removed by wave action and deposited in deep water at a considerable distance from the shore and that it would not return to the beaches. 68. They had recommended, however, that scientific evidence should be available in support of their views to allay the fears which had been expressed and which were likely to be sustained when the matter came for decision before a Parliamentary Committee. It was with this object in view that the tests and other investigations described in the Paper had been carried out.69. It seemed to him that the most interesting outcome of the model tests and investigations associated with them had been the information which they had provided about the action of density-or turbidity-currents in transporting suspensions of silt for considerable distances down the gentle slope of the sea-bed.70. Professor Kuenen had said that turbidity-currents of low density carrying only silt and clay might form an important factor in the distribution of these finer fractions on the sea floor. They explained the mechanics of a circumstance which was well known to engineers concerned with the stabilization and protection of coasts, namely that particles of fine sand and silt did not remain in loose uncemented form on ocean beaches subject to wave action.71. As the Authors had rightly pointed out, silt was found on the foreshores of estuaries where wave action was slight, but where estuaries opened out to sea it disappeared and only the coarser materials remained behind within the range of wave action.72. Vast quantities of silt and clay were eroded from the coast of the British Isles every year. Wherever clays or silty clays outcropped at foreshore level between the tides, they were scoured and eroded by the waves whenever they were exposed to wave action.73.