LIST OF TABLES. Table No. I. Urban Population of the United States ican Cities in 1874 and 1884.. IV. Showing Per Diem Per Capita Consumption of Page. 53 54 67 68 V. Illustrating Monthly Variation in the Consump- 69 VI. Illustrating Extreme Daily Variations in Con sumption of Water 70 71 73 75 X. Comparison of Sewer Gaugings. 78 VII. Hourly Variations in Water Consumption.. IX. Sewer Gaugings at St. Louis... XI. Gaugings of Water Street Main Sewer, Kala- XII. Illustrating effect of Increased Section, the Vol- XIII. Showing the Comparative Discharge and Veloc- XVII. Comparing the Discharge in various Cases as Given by Different Standard Formulæ...... 118 XXI. Bids on Sewer Construction, Schenectady, N. Y. XXII. Bids on Sewer Construction, West Troy, N. Y.. XXIII. Bids on Sewer Construction, Dayton, Ohio. XXIV. Cost of Thirty-Five Sewerage Systems... XXV. Actual Cost of Labor and Material... XXVI. Actual Cost of Labor and Material. XXVII. Actual Cost of Labor and Material.. XXVIII. Actual Cost of Labor and Material... SEPARATE SYSTEM OF SEWERAGE. CHAPTER I. INTRODUCTION. "Sanitary Engineering" has been defined as that branch of engineering which has for its object the improvement of the health of towns and districts, by bringing to them a supply of those things which promote health, and carrying from them those things which are injurious to it. The three principal requirements for the promotion of health are wholesome food, pure water, and pure air. An abundant and cheap supply of food is best secured by perfecting the means of transportation by land and water. Pure water may be supplied by suitable water works. The air is kept pure by removing from the districts those things which pollute it: that is, by removing all garbage, and by carrying out a proper system of drainage and sewerage. Although all of these works contribute to the health of a district, yet the subdivision of labor in these times has increased the number of specialties in the engineering profession and has limited the field of the Sanitary Engineer. By common consent the engineer who plans and executes works for improving the means for transportation is called a Civil Engineer; the engineer of a system of water works is called a Hydraulic Engineer: leaving the Sanitary Engineer the task of removing from any locality whatever may be detrimental to health; thus assigning to him the role of scientific scavenger. Man himself is the principal cause of the defilement of his surroundings. His presence brings pollution to earth, air and water. Nature provides a remedy which is efficient only to a limited extent. Refuse from the animal kingdom is food for the vegetable kingdom. But when human beings congregate in masses nature can no longer meet the demands. In country districts, where the population is sparse, the disposal of excrementitious and refuse matter is easily managed by each householder in his own way. And even if that way be unadvisable the only sufferers are himself and those of his own household, and no one else will care to interfere. The methods usually there adopted, however, become very objectionable wherever the people congregate in large numbers. The conditions of living become changed. The sanitary condition of the immediate surroundings of each individual concerns not only himself, but the whole community in which he lives; and what was before a personal matter now becomes a question of public policy. In all densely populated areas, as in large villages and cities, the disposal of the solid and liquid refuse becomes a serious problem. The Mosaic regulations (Deut. xxiii, 12-13) can not be enforced, and to store the filth of a city within the city is simply to invite disease and death. The use of the pits, dug in the earth, as receptacles for refuse, is in every way objectionable. The soil becomes polluted with sewage, and the air is filled with the noxious gases arising from the sewage soaked earth, and from the putrefying masses in vaults and cess-pools. The decomposition of so much refuse in such close proximity to the dwellings is detrimental to health in two ways. It uses up the oxygen from the air, and loads it with pestilential gases. If cess-pools are used at all, they should be water tight. This necessitates the constantly recurring trouble of carrying away the contents when they fill up, and only partly removes the difficulty. Need of Sewerage-An examination into the sanitary condition of a majority of our older cities and villages will show the great need of some kind of sewerage. Many of them have never taken any measures to rid themselves of the necessary accumulations of filth, incident to a considerable population. For generation after generation the refuse which should have been removed far from the dwellings, has been flung upon the surface of the ground, or into cess-pools, where the putrefying mass poisons the air, and appeals in more ways than one for a remedy. "The offense is rank." On one of the principal streets in one of our oldest cities it became necessary to remove several small houses to erect a large building. The interior of the block was thus exposed to view, and it simply made apparent the state of affairs in nearly every block in the city. Within the space of 150 feet long by 50 feet wide, there were four wells and seven vaults and cess-pools. It needs no chemical analysis to determine the impurity of water obtained under such circumstances, nor a very vivid imagination to conceive the foulness of the atmosphere in that locality. The earth upon which many of our cities stand is literally saturated with sewage. The vile odors which are exhaled from the polluted soil, and from the sinks of rottenness and putrefaction which it contains, contaminate the air in the streets, and are a constant reminder of the need of an efficient remedy. There they stand, reeking in the accumulated filth of past generations, never for a day free from malaria, and zymotic diseases; and yet the remedy is easily applied and the cost of it within the reach. of the poorest hamlet. Pollution of Streams.-A small water course running through a city without sewers is sure to become a nuisance. Every conceivable variety of filth and refuse will be thrown into it, and it will soon be simply an open sewer. In dry weather, when the flow of water is at its minimum, the bed of the stream will become an elongated, open cess-pool of the worst variety. The channel is sometimes cleared by throwing the accumulations of filth upon the banks: that is, the filth is spread over a larger surface instead of being removed. Periodical cleanings of the bed and banks of the stream will only mitigate the nuisance tem |