8 SEWER DESIGN 



quality of the air contained are those of fifty years ago, when 

 the laws governing the flow of sewage were not so carefully 

 heeded, and when the street-washings were hurried into the 

 sewer to form deposits. With equal care in the design there 

 seems to be no reason why the small or the larger sewer should 

 be the better ventilated. 



While it is true that two systems, one for sewage and one for 

 storm- water, over the same area, will cost about two-fifths 

 more than a single combined one, yet the assumption that their 

 lengths will be the same is not true. The need for storm- 

 sewers and their necessary length to reach a watercourse are 

 matters to be based on a study of the local conditions, but it 

 is safe to say that in any city there are many blocks which would 

 carry all the storm-water from the centre of the block to the 

 cross street at the end without any nuisance or damage, and 

 that therefore the construction of storm-water sewers in those 

 blocks would be a municipal waste. In a printed discussion 

 of some years ago,* Mr. Robert Moore of St. Louis, stated that 

 on the steep streets of Kansas City, Mo., the storm- water wash 

 in the gutters becomes a serious matter after it has run 500 to 

 600 feet, and that 1000 feet is the limit of endurance. Mr. 

 Chanute, in replying, said that from actual experience in 

 Kansas City he has yet to find the water at 1500 feet the unen- 

 durable nuisance mentioned. From his own experience the 

 author believes that in small cities water from 2000 feet of paved 

 street does not unduly gorge the gutter or cause any annoyance. 

 Mr. Homer of the St. Louis Sewer Dept, says f that while 

 there are in St. Louis sewer inlets which drain 1200 feet of 

 street satisfactorily, he believes that this is a greater length 

 than is generally warranted, since at the lower end the flow of 

 water in the gutters is inconveniently deep. 



On the other hand, it is more than likely that in a large part 

 of the city there are streets where the two sewers would have to 

 be carried at the same depth and in the same direction, and 



* Jour. Ass'n. Eng. Soc., Vol. III. p. 69. 

 f Engineering News, Vol. LXIV, p. 326. 



