On the Sewerage and Sewage Disposal Works of the Borough of Dudley.”
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238 MARTEN ON THE SEmRAGE OF DUDLEY. [Selected (Paper No. 2503.) “ On the Sewerage and Sewage Disposal Works of the Borough of Dudley.” By EDWARDDIYMACE MARTEN, M.A., Assoc. M. Inst. C.E. THE difficulty of dealingwith the sewage of the. populous district which overlies the celebrated South Staffordshire ten-yard seam is enhanced by mining-operations.Wherever this coal is worked the surface is more or less affected, and subsides or is ‘‘ drawn,” sometimes gradually, but sometimes with such sudden- ness as to endanger life. Water-pipes of the ordinary description are frequently fractured by these movements, which often cause considerableleakage at thejoints. So much isthis the case that the Author’s father, Mr. Henry John Marten, M. Inst. C.E., many years ago found it necessary to design a special socket to obviatethe difficulty. Someof the canals whichintersect the districtare now carriedupon embankments, 20 feet in height, over ground which, within the memory of man, was on a level with their banks. It will readily be understood that these sub- sidences, which are of every-day occurrence in the Black Country, seriously interfere with the work of the sanitary engineer. The difficulties are not so formidable in the towns themselves as in the districts which surround them, since in most cases the value of the surface-rights in towns, and the necessity of afford- ing vertical and lateral supports to buildings, make any mining operations thereunder impracticable, and it is generally, but not always, found possible to construct and work a system of internal sewerage. It is mainlyin connection with outfall and intercepting eewers laid outside town limits that the troubles accruing from mining-operations are experienced. Whilst, moreover, themining in this district is a standing cause of leaky sewers, itis at the same t.ime emphatically a reason why they should be watertight. The South Staffordshire Mines Drainage Commissioners have spent large sums of money in draining the coalfield and in constructing works to prevent water finding its wayinto the mines, and they veryproperly watch with Downloaded by [ York University] on [19/09/16]. Copyright © ICE Publishing, all rights reserved. Papers.] IKARTEN ON THE SEWERAGE OF DUDLEY. 239 a jealous eyeany action which maypossibly add to their pumping- expenses. All sewers constructed outside the actual town district have to be laid in a thick bed of puddled clay, and sometimes are required also to beof cast-iron. Sewage-farming within the mining-areawould be attended with great difficulty, as even if a sufficiency of surface land could be acquiredwithout the vastexpense of purchasing the minerals below, anythingin the shape of irrigation wouldbe open to suspicion, aslikely to send water into the mines, and would probably be opposed by the Mines Drainage authorities on that ground. Precipitation, aided by artificial filtration, is practically the only process available for the central towns of this district, unless the sewage can be conveyed by some means over the inter- vening mining ground on to the non-mining terra jirrna which surrounds it. Precipitation, however, is also attended with con- siderable difficulties, because to enable the necessary works to be constructed, the first requirement is suitable land, the mines and mineralsunderlying which must be purchased. This adds con- siderably to the cost, and further difficulties are often experienced on account of the operations of adjoining mine-owners, which have a tendency to " draw '"the site and the structures erected upon it. The municipal borough of Dudley has a population of about 46,000, the town itself containing about 30,000 inhabitants, while theremaining 16,000 are scatteredamong themining villages whichlie within the borough boundaries. It is situated upon a ridge running nearly north and south, and forming a portion of the watershed of England, the natural drainage of the town beingpartly into the Severn basin, and partly into the Trent basin. Some of the houses stand at an elevation of over 800 feet above sea-level; and the lowest part of the ridge, where it passes through the town, is 660 feet above sea-level. The aistricts to be drained lie on each side of the main hill, extending as far down as 590 feet above sea-level, so that it is only possible to deal with the whole sewage of the town at anyone point, by means of long lines of intercepting sewers connected by a tunnel about4 mile in length through the ridge. To these difficulties, arising from the confbr- mation of the ground on which the. town is built, were added those arising from mining-operations around it. In 1876 the Corporationpurchased an estateknown as the Russell's Hall estate, 70 acres in extent, closely adjoining the western side of the town, and lying at a sufficiently low level to deal with the whole of the sewage from both sides of the ridge. Downloaded by [ York University] on [19/09/16]. Copyright © ICE Publishing, all rights reserved. 240 MARTEN ON THE SEWERAGE OF DUDLEY. [Selected It was proposed to bring the sewage to this land by means of intercepting sewers traversing both flanks of the hill upon which the town is built, and connected by a tunnel, and to deal with it there by means of a combination of filter-beds and irrigation. The estate consisted entirely of mining-ground, and the scheme was consequently opposed, both by the South Staffordshire Mines Drainage Commissioners, and by the late Earlof Dudley, who was by far the largest ratepayer in theborough, and who was advised that the diversion, as proposed by the Corporation, of storm-water as well as sewage on the land, would injuriously affect his mines in theneighbourhood, and the streams passing through hisestates, besides being unnecessarily costly and likely to create a nuisance. Mr. H. J. Martenwas consulted, and with the concurrence of Mr. George Taylor, the agent for the surface of the Dudley and Himley estates, prepared an alternative scheme which was laid before theTown Council in aReport, on July 25, 1876. This scheme, after a delay occasioned by the necessity of obtaining an Act of Parliamentcertain portions of the Earl's settled estates being affected by the covenants entered into with the Corporation -was carried out by Mr. H. J. Marten, assisted by the Author, during a period extending from June 25, 1879, to July 30, 1884. The town has been entirely re-sewered on the separate system, and upon the most modern principles. The gradients are in most cases so steep that practicallyno artificial flushing is required, and from the same cause a few ventilators carried up the sides of the houses in the higher partsof the town are sufficient, with the aid of the ventilating covers of the manholes, to keep the sewers free fromnoxious gases. The branchsewers areall stoneware, and the joints are made with tarred yarn and cement. Manholes are placed at everychange of lineor gradient. Only onecase of stoppagehas occurred since the systemhas been in operation; and on an investigation being made as to the cause, it was dis- covered that a butcher was in the habit of discharging hot fat intothe sewer. This was put astop to, and it hasalways workedwell since. The houseshave, toa large extent, been disconnected from the old drains, which are intended to be used henceforthexclusively for surface-water,which they convey to the streams and brooks, eleven in number,forming the natural outlets from the town. Only such storm-water as it is impossible to exclude is allowed to enter the new sewers. The old drains, as is usually the case, were found to be of immense size compared withthe work they wereconstructed to perform,and to have Downloaded by [ York University] on [19/09/16]. Copyright © ICE Publishing, all rights reserved. Papers.] MARTEN ON THE SEWERAGE OF UUDLET. 241 been putin without any attempt at system, andthe capital outlay which they represent would probably, if properly applied, have sufficed to put down three or four complete modern systems of internal sewerage for the town. The sewage, collected as above described, gravitates to an inter- cepting-sewer along each side of the ridge upon which the town isbuilt. Theseintercepting-sewers, whose flattestgradient is 5 feetper mile, converge upon the Russell’s HallEstate, the northern one being for the last 3 mile in a tunnel which is insome places more than 100 feet below the surface of the ground. The hillthrough which this tunnel passes has beenformed by an upheaval of the Upper Silurian Limestones, which here form an anticlinal, from the summit of which the coal measures have been denuded. No trouble, consequently, was experienced from mining operations in driving the tunnel, though the intercepting-sewers themselves suffered greatly from this cause. They had to be laid almost entirely in a thick bed of puddled clay, and as near the surface of the ground as possible, which added seriously to their length, as it was necessary to follow the contour of the land. To show the difficulties which have to be contended with in a mining country, the Author may mention that during the construction of the works, he found one morning that some 30 yards of the new sewer had disappearedbodily into the workings below, leaving nothing to be seen except a deep hole resembling the crater of a volcano. This accidentrendered necessary a somewhatcostly deviation from the line originally selected. At Russell’s Hall Estate, the liquid is first sent through rough strainers formed of broken blast-furnace cinders, and capable of removing the heavier solid matters ; it is then passed into a small reservoir or storm-water catch-pound, formed partly by excavation and partly byembankment, and capable of holding about 2,500,000 gallons.