474 



SEWERAGE 



SEWERAGE. Until within recent years American 

 sewerage systems have been modelled 



711 < 745 ** lor European examples and based 

 5Ln It-p"). ' UJWMI the experience of other countries, 

 using very much tho same material and 

 employing tho same methods of workmanship. I. 

 ex]x'iienco, however, has shown the need of new 

 methods to meet tho special conditions peculiar to 

 certain localities, as, for example, at Chicago, Mem- 

 phis, and Boston, or in summer sea-aide settlements. 

 It has also been found that the data regarding ruin- 

 fall and population derived from European ex|H-ri- 

 ence did not apply equally to this country, whore 

 the climatic conditions ore entirely different, as well 

 s the habits of onr people in respect to the more 

 general use of plumbing appliances, fondness for 

 bathing, and the enormous consumption of water for 

 manufacturing purixises. 



The rainfall of London averages 24 inches per 

 annum, ouly one-half as much as that of Boston, 

 while the consumption of water per head in London 

 is but one-third as much as in Boston. Again, the 

 rainfall in America is much heavier than in England, 

 sometimes amounting to nine inches in a single 

 month or two inches in twenty-four hours, in con- 

 trast to the "perpetual drizzle" of Great Britain. 

 In Pullman, 111., the average discharge into sewers 

 from each dwelling amounts to 100 gallons por day. 

 In New York City the total water-consumption per 

 head is nearly as large. 



There are still many towns without any sewerage 

 systems, though they have a public water-supply ; 

 while, owing to their rapid growth, many other cities 

 have found their sewers wholly inadequate. The 

 population is frequently scattered over large areas, so 

 that the section to be drained is so great that the 

 cost of laying sewers becomes enormous. Again, in 

 most large cities a considerable population of ignor- 

 ant foreigners who live in tenement-houses are not 

 accustomed to modern sanitary conveniences, and, 

 being careless and filthy in their'habits, they throw all 

 sorts of rubbish into drains and sewers, and conse- 

 quently make the cost of maintenance excessive. 



Recent Change*. The most notable recent devel- 

 opments in American engineering practice, Imvo 

 been : (1) In the substitution of much smaller 

 ewers than wore formerly used, and having them 

 constructed of such a shape and material, either 

 brick or tile, carefully laid with proper grade and 

 alignment, as to prevent an; deposits and to secure 

 a uniform and constant flow of tho waste mate- 

 rial (2) In the employment of flush-tanks, where 

 ewers are laid with but slight grade, so placed at 

 their upper ends that they will be thoroughly 

 scoured and kept free from all deposits. The au- 

 thorities of Paris have lately advised the expenditure 

 : l.OOO to supply no less than 3166 flush-tanks, 

 to discharge once or twice every twenty-four hours. 

 They have been used with great benefit iu many 

 other places, notably in Memphis, Tenn., under the 

 direction of Col. G". E. Waring. (3) In tho syste- 

 matic ventilation of sewers by perforated man-holes, 

 located at the street level, and always kept open. 

 (4) In the use of improved appliances for clearing 

 catch-basins and removing de|M>sits of silt or other 

 material when necessary ; and (5) In superintending 

 and regulating plumbers and other mechanics when 

 making connections from buildings with the sewers 

 s a security against careless workmanship. 



Formerly sewers were' often built of sufficient area 

 to contain a hay-cart or a row-boat ; now the ; 

 ence is given to much smaller conduits, and the cost 

 of construction has been thereby much reduced. 

 According to Prof. Parkes, the total amount of 

 excreta from a mixed population \vonld not exceed 

 twenty-five tons of solid and 91,200 gallons of fluid 

 natter for each 1000 inhabitants, every twenty-four, 



hours, and as this is delivered into the sower through 

 the entire day, it can be carried off through a very 

 small drain. In Paris t! from a barrack 



building containing 1000 soldiers was readily con- 

 veyed through u four-inch diain. Experiments at 

 Saratoga demonstrated that ti .;(;.- pro- 



ducts from a hotel with over 2000 occupants did not 

 fill a six-inch pi)>e. It is therefore entirely unnec- 

 essary and merely a great source of expense to build 

 colossal sewers like the Cloaca Maxima in Koine, and 

 which were formerly deemed indispensable; but 

 sewers are now proportioned to the actual needs of 

 a given locality. 



In European practice it is usual to connect honse- 

 drains directly \\itli sewers and to allow the former 

 to ventilate through the latter. Where- sewers are 

 properly constructed, well laid, and properly venti- 

 lated and flushed, there is no objection to this prac- 

 tice. American sewers, however, are so frequently 

 defective from bad construction, breakage, or the 

 accumulation, of deposits that it is deemed wise to 

 place an intercepting trap between each house and 

 the sewer with an air-inlet opening at the ground 

 level, and this rule is now generally enforced by all 

 boards of health. 



The recent introduction of public steam-heating 

 apparatus in many American cities, and the discom- 

 fort and damage caused by constantly turning up 

 street pavements to repair steam pipes, together with 

 the necessity of laying telegraph and telephone 

 wires underground, is steadily preparing the way for 

 the adoption of the Parisian pystem of laying all 

 sewer, gas, and water mains in an underground tun- 

 nel or conduit, where they will bo easily accessible 

 without disturbing street pavements, and this im- 

 provement will undoubtedly be brought about be- 

 fore long in ninny cities. 



There has been considerable discussion of lato in 

 this country ns to whether it is best to construct 

 small sewers to receive house-drainage alone, and to 

 make separate provision for rain-water, instead of 

 building sewers of sufficient capacity to receive both 

 forms of waste material. The former method has 

 advantages on the score of economy, and is adapted 

 for localities whom there is sufficient grade to tho 

 streets to carry off the surface water promptly and 

 where a suitable and safe outfall can be secured. It 

 is charged that large sewers are more apt to bo foul 

 from the difficulty of flushing them, that they create 

 more gases, and that they are more expensive both 

 to construct and to maintain. Tho opponents of tho 

 so-called "separate system "clnim that surface water 

 will usually be so contaminated as to be unfit for 

 discharging into an ordinary river or stream, and 

 therefore it must be treated" as house -waste and re- 

 moved to a distance. The cost of the two systems 

 of drains, it is claimed, will be greater than one set 

 of pipes, while the rain-water is essential to flush 

 and clean the sewers. Col. Geo. E. Waring has been 

 the principal advocate of the separate system, but 

 conservative engineers like Sir Bobert MwUaaon 

 take an opposite view. The general verdict seems 

 to be that no system is applicable to all conditions, 

 and that local considerations must have chief weight 

 in deciding what form of sewerage is to be adopted. 



The unsatisfactory results which have followed in 



London and Paris from discharging the sewage of 



reat cilies into the Thames and Seine rivers 



have led to the consideration of some other method of 



sewage disposal, and the irrigation system has b. t u 



widely advocated instead. Elaborate' rxpcri nts 



have been made at Berlin, Edinburgh, and near Paris 

 for disposing of sewage by irrigation. No nuisanco 

 has been created and, notwithstanding the popular 

 apprehension, the health of the neighborhood has 

 n injured, while very extensive crops have 

 been grown on the sewage farms, and have helped to 



