GROUND-WATER REACHING SEWERS 143 



" Kalamazoo, Mich. Some ground-water finds its way into 

 the system, estimated from data taken before the sewers were 

 open for public use, to be 20 per cent of the capacity of the 

 sewers. 



" Norfolk, Va. No accurate estimate made, but ground- 

 water forms at least 60 per cent of pumping. From informa- 

 tion given elsewhere in the returns, the maximum flow is found 

 to be about 167 gallons daily per inhabitant connected with the 

 sewers. Of this, the ground-water, estimated at 60 per cent, 

 equals 100 gallons. 



" Schenectady, N. Y. The sewers are laid through wet 

 ground and quicksand in some instances. The Erie Canal 

 seepage also affects them to a small degree. Measurements 

 made at about the time that the system was completed indicate 

 that the infiltration of ground-water amounts to about 5 per 

 cent of the capacity of the mains." 



Mr. Stearns also says that he has recently examined two 

 new systems of pipe sewers which were built with the intention 

 of excluding the ground-water, and in both cases the amount 

 of water collected by the sewers was considerable. In one of 

 the cases, where the population connected with the sewers 

 was small, the amount of ground-water was probably in excess 

 of the sewage proper. 



In the sewerage works of Canton, 0., built in 1893, a 20-inch 

 outfall with no connections was gaged for subsoil water, and in 

 a length of 2400 feet a flow was found, due to infiltration, of 

 31,712 gallons in 24 hours, or at the rate of 70,000 gallons 

 per mile per day. In the same system of about n miles 

 there was a flow to the disposal works between midnight and 

 6 A.M. of about 73,000 gallons, which is at the rate of 26,500 

 gallons per mile per day (Engineering News, Vol. XXX, 

 p. 61). 



In the design for Taunton, Mass., 20 per cent for infiltra- 

 tion was added to the estimated flow in a 24-inch pipe passing 

 through a swamp. 



In North Brookfield, Mass., 1580 feet of 1 2-inch pipe was 



