History of the Huddersfield Water Supplies (1939) - Chapter X
History of the Huddersfield Water Supplies (1939) by T.W. Woodhead
Table of Contents:
TESTING AND INSPECTION OF FITTINGS, PIPES AND MAINS INCRUSTATION.
The water is tested for pH value, or the intensity of acidity or softness, several times each day, and the strength of the lime water three times a day.
Testing and inspection of fittings are done by the Waterworks Department with a view of preventing waste, and all fittings such as taps, ball taps, cisterns, cylinders, etc., are tested at the Spring Street Depot and must be up to the standard laid down by regulations before being passed for use. In addition there is also a system of night sounding on consumers' stop taps and on the mains, by means of a stethoscope for detecting possible leakages. This system was introduced in March, 1938, and has proved successful in detecting a large number of burst pipes and fittings which required attention. When hot or cold water taps do not shut off properly and need re-washering, this is carried out free of charge by inspectors of the Waterworks Department, on notice being given to the Waterworks Manager, Town Hall, Huddersfield.
Having our supplies from so many different sources increases the difficulties of supervision and control ; further, the development of the district causing so many dead ends to the supply pipes requires that a careful inspection has constantly to be made to let out material which may accumulate in those positions, thus causing temporary inconvenience to consumers.
Another difficulty met with, especially in old mains, is the formation of limpet-shaped incrustations on the inner surface of the pipes and unless they are removed, they become confluent, the result being a considerable reduction in the bore of the pipe and of supply (5). The following account by Mr. Beveredge explains how this difficulty is dealt with in the mains of the Huddersfield area.
All cast iron pipes used for the conveying of water are treated inside and out with a bitumastic solution, known as "Dr. Angus Smith's solution," before leaving the foundry. The pipes are coated with this solution to protect the metal from the action of water. Some waters act more vigorously than others — this is particularly so with a soft water. No matter how carefully the coating is applied, in time, the water comes in direct contact with the metal with the result that nodular excrescences on the inner sides of the pipe are formed. In time, the surface becomes studded with these nodular growths and unless cleared away the carrying capacity of the pipe is greatly reduced. The growths also, to a certain extent, are responsible for the discoloured water supplied to consumers.
At one time, these growths were cleared away by scraping the pipe, but this method, in the majority of cases, did not prove a success as it exposed the whole of the inside face of the pipe to the water and in a few years, the pipe was as bad as ever. In many cases, it was also the cause of a "red water" being supplied to the consumers. After years of experiment, a number of firms have perfected systems of scraping or de-scaling the mains and at the same time re-coating the inside face with a bitumastic solution or a thin coat approximately 3/16" thick of cement mortar. These methods are a distinct advance on the old method of scraping only, as the bitumastic coating or cement lining gives to the pipe a further lease of life, which should, if the work is properly carried out, nearly equal that of a new pipe and at a fraction of the cost.
One of these systems of reconditioning of water mains has been used in Huddersfield with satisfactory results. Not only has the carrying capacity of the mains been increased and the character of the water supplied to the consumers been improved, but inspections of cuts taken from the mains show that the incrustation has been removed and the inside face has received an even coat of bitumastic solution.
The system used is known as the "Eric" system and is carried out in the following manner :—
The main is got down to at intervals of approximately 200 yards and cuts of approximately two feet are taken from the main. A wire rope is then passed through the length of main which is to be reconditioned. To the end of this wire rope are attached a series of scrapers which loosen the incrustation on the inside face of the pipe. After the scrapers have been passed through the pipe three or four times, it is flushed out with a copious supply of water and at the same time, a stiff wire brush of a diameter equal to that of the pipe is drawn through, which takes away any scales which may be adhering to the sides of the pipe and would not be carried away by the scouring action of the water.
After this work has been completed, the pipe is in a condition to be coated with bitumen. The pipe is completely filled with bitumastic solution and an electrode, which is connected to an Electric Generator on the surface, is slowly drawn through the pipes. As the pipe is coated with the bitumastic solution, it forms an insulation between the pipe and the electrode. This is immediately communicated to a suitable meter attached to the generator which is under the constant supervision of the operator.
The length of time taken to recondition 200 yards of main varies with the condition of the main, whether it is straight, or curved, or has branches off it, but at no time should the water supply to the consumer be off for more than eight hours on any one day.
One advantage this sytem has over others is that the face of the pipe to be coated need not be dry as the composition of the solution is such that the bitumen adheres to a wet surface, thus saving a considerable amount of time.
During 1937, 10,505 yards of mains were scraped and relined with bitumastic solution, and during 1938, 11,485 yards
FRESHWATER BIOLOGICAL RESEARCH.
At Wray Castle, Lake Windermere, the research station of the Freshwater Biological Association of the British Empire, intensive investigations are in progress relating to these problems, and the Hon. Director, Professor W. H. Pearsall, has kindly supplied me with the following brief account of work in progress relating especially to waters from the peat-clad moorlands of the Pennines. In this Professor Pearsall gives evidence of a different origin of "limpets" in iron pipes, to the usual one given above, and that these incrustations are not due to the action of water on the metal. It is often stated that after scraping encrusted pipes, the mains show no sign of deterioration. Prof. Pearsall writes as follows :—
The problems which affect the users and suppliers of Pennine waters are very numerous and it may be safe to say that they are usually connected with the presence of dissolved peaty materials in the water or with the associated scarcity of lime. In this, they are to be classed with the waters of large areas in northern Britain. In the Pennines, however, three problems seem to be particularly common. In some cases there are difficulties in filtering the water supply in summer, owing to the growth of algae either in the reservoirs or on the filter beds. These difficulties result in excessive cost or seasonal demands for labour. In other cases the reservoir waters may become excessively acid, resulting in such secondary effects as high plumbo-solvent power and in the necessity for acid-neutralising treatment. Enquiry into some of these cases has shown that the reservoir "water" may become really a weak solution of sulphuric acid. A third and especially common case, the blocking of the iron pipes and even valves by the production in them of incrustations or "limpets." These structures consist mainly of iron hydroxide and their presence in the pipe system not only causes low rates of supply of water, but also usually leads to-the water becoming unpleasant in taste and appearance.
It is not generally realised that all these problems and many more like them are biological and are due to reactions brought about by living organisms. Thus the dissolved substances which lead both to the excessive growth of algae and to the production of sulphuric acid are in both cases products of the decay of organic matter and both these effects are due to the special activities of certain groups of moulds and bacteria in the water. At the same time, their presence also depend upon the conditions (also due to micro-organisms) which cause peaty matter to appear in solution in the water. There is therefore, a very wide field for biological research on the problems leading to the solution and decay of peaty matter in freshwater, and, so closely are the various biological problems in water related, that the solution of many waterworks problems undoubtedly lies in quite unsuspected directions. A good example of this is the third problem mentioned above, the incrustation of iron pipes, on which some recent research has thrown a new light.
The actual cause of the incrustation is a bacterium which lives upon iron carbonate dissolved in the water, converting it to ferric hydroxide which is insoluble and which is deposited on the surface of the bacterial cells and on the walls of the pipe. An incrustation is thus gradually formed. These bacteria are, however, very widely distributed and they occur even where incrustations are never found. Hence, the real cause of the incrustations must be sought in the factors which cause the presence of iron carbonate in the water, and which thus permit the growth of the incrusting bacteria. Until recently, these factors were practically unknown, but much light has been thrown upon them as a result of research upon two separate and apparently quite unrelated problems, namely, the properties of lake muds in relation to the vegetation growing on them and the conditions controlling the breakdown of nitrogenous compounds in lake waters. Without going into the details of these researches, it appears that the breakdown of nitrogenous organic matter in mud by moulds and bacteria leads to the formation of ammonia, which under certain defined conditions leads to the replacement of iron from the mud. This iron goes into solution as iron carbonate and, under conditions which exist in some lakes and reservoirs, and not in others, it may remain in solution and get carried down into the pipe system. Such waters invariably contain the incrusting bacteria, and hence incrustations in the pipes will follow. In actual fact every condition which leads to the formation of these incrustations appears to be controlled by living organisms and it is possible to say that the production or otherwise of these incrustations depends wholly upon the biological condition of the reservoir and its drainage area. Many other examples might, if space permitted, be given of this close relationship between Waterworks problems and biological investigation.