SEVENTH ANNUAL MEETING 99 



gallon storage reservoirs. It is located just north of the Univer- 

 sity campus on land given by Northwestern University. The 

 plant is built so as to use the present pumping station, and 

 with the exception of the operating building, will be sodded 

 over and covered with shrubbery. 



The "Hypo" Treatment Plant being used in the meantime 

 has been maintained without additional labor and with a cost 

 for chemicals of about 25c per day. The plant consists of a 

 mixing machine for making the "Hypo" into a thin paste with 

 water. The mixer is set so that the overflow drains into two 

 wooden tanks, eight feet in diameter and three and one half 

 feet deep. The mixing and dilution tanks, arranged in pairs 

 and used alternately, drain into a two-inch wrought iron pipe. 

 Power for mixing and stirring the dilution tanks is furnished 

 by a Pelton wheel. The dilution tanks are set about three feet 

 above the floor and are tapped on the sides about two inches in 

 the clear above the bottom, with 24 inch galvanized iron pipe. 

 The piping leads to an orifice box and is so arranged that the 

 solution can be drawn from either tank or both tanks at once. 

 The orifice box sets on the floor of the well house and feeds 

 into ^4 inch galvanized iron pipes leading to the grids. Below 

 the orifice box, a valve is set and below this valve a T through 

 which a pressure pipe is connected. The grids consist of 24 

 inch galvanized iron pipes, Ts and plugs, each lateral pipe hav- 

 ing two ^4 i nc h holes drilled in and placed on the down stream 

 side of the pipe. One grid is placed over the top of the shaft, 

 the other in the 36 inch T at the side of the well. By placing 

 the grids at these points, the water is treated when it enters the 

 well, and has about twenty minutes contact before reaching 

 the suction of the pumps. At present 50 pounds of the chem- 

 ical are being used with 1,420 gallons of water. After this 

 mixture has been thoroughly stirred in the dilution tanks, it is 

 allowed to stand for at least one hour before being drawn off. 

 Considerable insoluble matter is always present which would 

 otherwise cause stoppage in the orifice box and valves. 



Each gallon of the above solution contains .0352 pound of 

 hypochlorite, analyzing 37 per cent available chlorine. From 

 the following formula, the engineer operates his orifice box : 



N — Nn, of gallons pumped per minute. 

 1,000,000 



— M or number of minutes to pump 1,000,000 gallons. 



N 

 Q=No. of pounds of "hypo" to be added to each 1,000,000 gallons. 



