THE SEWERAGE OF KANSAS CITY. 99 



basins out of ten are not enough to let all the exhalations that the sewers can 

 make escape, and whether the four persons taking these in, would not rather the 

 other six should share with them ; in such things we are often very unselfish. 



With regard to the noxious character of these exhalations both writers and 

 smellers are divided; all, however, agree in not calling for more. 



The quicker sewage can be disposed of, the less will it affect the public. The 

 small sewers do this, lor their smaller size gives a quicker flow and leaves less 

 margin for the accumulation of material to decompose. When the sewage has 

 acquired considerable volume it will be less liable to such accumulation in large 

 sewers, and accordingly the use of the combined system will be less objectionable 

 the nearer we approach the outlet. . 



This leads to a consideration of cost and size. The combined system of sew- 

 erage has cost an average per mile of $30, 146 in St. Louis, $25,000 in Brooklyn, 

 $34, 550 in Providence, $20,727 in this city. The separate system has cost in 

 Memphis $6,875 per mile. An estimate for the city of Baltimore gives $10,000 

 per mile. In Leavenworth the work so far has cost about $8,800 per mile, in- 

 cluding the main trunk sewer. This will be reduced by the extension of laterals, 

 which cost an average of about $6,000 per mile, including flush-tanks and 

 royalty. Such data are modified by local circumstances. It occurs in most 

 cities that natural water courses are closed in, and while they greatly increase 

 the cost of sewerage, they give value to the ground with which the sewer is not 

 credited; it also occurs that large sewers are built to form trunks for future exten- 

 sions, the result of which when made would be to reduce the average cost mater- 

 ially. It would be a fairer exhibit of comparative cost to compare the systems 

 simply by the actual cost of the sizes of sewers required for each. 



In considering this, but little stress has been given to the difference in rain- 

 fall in different locaUties. In England, where the combined system may be 

 considered as having its best growth, rains are frequent and the storms compara- 

 tively light; in London the record of three years showed 746 rainy days, and on 

 only four days did rain fall to the depth of one inch in twenty-four hours. Here 

 we have months at a time without rain, and then storms of great severity ; — as much 

 as three inches of rain having fallen in one hour, and a rainfall of two inches or 

 more per hour being so frequent that it is necessary to take cognizance of it in 

 our sewer construction. 



The sewerage of Brooklyn during its heaviest flow is estimated at one one- 

 hundredth of an inch per hour for the whole area of the city. In fourteen years 

 the record shows ten storms of one-half inch per hour, and ten more between 

 that and two inches, one of over two inches, and one of over three inches. 



An usual practice in American cities has been to provide for the sewers car- 

 rying one-half inch per hour, and the few storms giving more than this amount 

 to the sewers would seem to justify that provision. 



Late experience in Brooklyn and other eastern cities, however, shows that 

 this is inadequate, and the result of heavy storms has been the flooding of low 



