GEOLOGY OF THE NEW YORK CITY AQUEDUCT 



145 



and the bottom 274 feet a diameter of only 3^ inches. At first a 

 2^ inch working barrel was used to pump from the bottom and a 

 discharge at 32 strokes per minute averaged 24 gallons per minute 

 or 34,500 gallons per day. This was continued for about 15 days 

 and the total quantity pumped was 490,000 gallons. The ground 

 water level was lowered 17 feet at hole 34 and 4 feet at hole 32, 

 750 feet away. 



The 2% ii^ch pump was then let down to a depth of 200 feet 

 with a 2>^ inch casing reaching down to the Binnewater sandstone, 

 depth of 437 feet. The average discharge at about 40 strokes per 

 minute was 60-65 gallons per minute, or an average of 90,000 gal- 

 lons per day. It will be noted that the discharge was much smaller 

 than at hole 32 owing to the absence of gas. Pumping with a 

 334 inch pump was continued 16 days and 1,532,000 gallons of 























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Fig. 24 Diagram showing successive stages of ground water level between holes 32 and 



34 during pumping 



water were pumped in addition to the 490,000 gallons from the 2j4 

 inch pump. The ground water level in hole 34 was lowered 36 feet 

 in addition to the 17 feet by the 2^ inch pump, but rose 9 feet in 

 20 minutes, and 30.5 feet in the next five days. In the next 22 days 

 it rose 9.15 feet, or .42 feet per day. 



Reduced water level in hole 32, 750 feet away by pumping in 34, 

 15 feet, or i foot for each 120,000 gallons pumped. In the first 



