GROUND-WATER REACHING SEWERS 145 



used for 4000 feet in a location most unfavorable for tight work, 

 and that with these exceptionally adverse circumstances the 

 infiltration was only 50 per cent of the total quantity, or an 

 amount equal to the domestic flow, say: " The results obtained 

 under the extremely unfavorable conditions existing at East 

 Orange of a leakage of only 2.5 gallons per second (215,000 

 gallons in 24 hours) from 25 miles of vitrified-tile sewers, with 

 66,000 joints, is indicative that, under favorable conditions 

 and with careful workmanship, a system of such sewers may 

 be made nearly impervious, though in designing disposal work 

 it will probably be safe to allow for an infiltration of 15 per 

 cent of the flow of sewage proper." 



In connection with studies made on the pollution of Boston 

 Harbor, the State Board of Health of Massachusetts had tests 

 made on the infiltration of ground-water into sewer systems 

 of recent construction. These showed * that into 137 miles 

 of sewers, ranging in size from 8 inches to 36 inches diameter, 

 the leakage was at the rate of 40,000 gallons per mile per 

 day. 



In the course of his report, Mr. Goodnough, the chief 

 engineer, said that so far as he could judge by determinations 

 of the amount of night flow throughout the State, the leakage 

 into any large sewer system might easily amount to 70,000 

 gallons and at times when the leakage is extraordinary to as 

 much as 80,000 gallons per day per mile of sewer. He adds 

 that, in extensions of the Metropolitan Sewer System it seems 

 desirable to make provision for a leakage of as much as 80,000 

 gallons per day per mile of sewer. 



In the case of the joint trunk sewer from Elizabeth and 

 Newark to Staten Island Sound, unusual care was taken in 

 the construction, special jointing material (sulphur and sand) 

 being used instead of cement and in the 150 miles of main 

 sewer and tributary systems, the infiltration was at the rate 

 of 25,000 gallons per mile per day.f 



* Special Report on the Discharge of Sewage into Boston Harbor, 1900. 

 f Report Passaic Valley Sewerage Commission, Dec., 1907, p. 13. 



