15 pounds per square inch. If the discharge line is so long that one 

 pump cannot handle the material satisfactorily, it is discharged from pump 

 No. 5 to pump No. 6, which increases the pressure to 155 pounds per square 

 inch. The pressure at the end of the line will vary with its length and 

 the amount of solids in the suspension. 



When the General Arrangement drawing was made (see Figures) , there 

 were 7,950 feet of 28-inch pipe between the booster station and the point 

 of material deposit. One pump was satisfactorily handling all of the 

 material. These pumps were alternating in operation each week, as it was 

 necessary to vehuild a sand pump after one iceek's continuous operation. 

 At a distance of about 50 feet from the booster station, a 12-inch line 

 is connected into the 28-inch discharge line. This line has a valve which 

 can be opened at any time, and is used as a safety measure to relieve 

 pressure in case of a breakdown in the pumphouse. Shut -off valves or 

 plates are located before and after each pump in the system. These valves 

 can be closed when making repairs to the pumps. Throughout the system, 

 at each change in pipe dimensions, at each branch line, eductor or nozzle 

 are located gate valves, to shut down any part of the line for repairs or 

 change in directional flow. At one point on the water line and one point 

 on the sand line is located a spring-loaded check relief valve, so that 

 if a water hammer develops, the safety check valves will prevent a pipe 

 fracture. 



A 36-inch overflow line is connected to. the surge well, and extends 

 down to roughly the high tide water level. This line drains off any excess 

 water, and, in case of breakdown, can be used to discharge material accu- 

 mulating from the eductors and sluicing lines until they can be closed 

 down. 



The schematic general arrangement sketch (see Figures) will aid in 

 following the system for moving sand and material through the various 

 phases of operation. Other Figures indicate general construction and use 

 of the component parts of the system. 



To fully understand the plant operation, a breakdown of component 

 assemblies is advisable. Component assemblies consist of: main powerplant; 

 surge well; hydraulic giants; eductors and sluices; and booster pump 

 powerplant. 



The main powerplant is a semipermanent installation. All machinery 

 is mounted on concrete foundations and is enclosed by a sheet metal 

 structure. Within the main pumphouse are four major pumps; two carrying 

 seawater at high pressure to the central points of operation and two sand 

 pumps discharging the suspended material at high pressure. The four main 

 units are 28-inch centrifugal dredge-type pumps, direct -connected and 

 driven by General Electric induction-type motors, 6600 volts, 202 amperes, 

 60 cyle, 253 revolutions per minute at full load and 2,500 horsepower. 

 Pump No. 1 is a Fort Peck pump which has been modified by enlarging the 

 impeller diameter from 77.5 inches to 88 inches, to increase its capacity. 



