DREDGING 99 



Fig. 31, page 91, furnished by the Essex County Park 

 Commission, shows a shovel making the first cut in the 

 Middle Division of Branch Brook Park. This work was 

 necessary in order to create an artificial lake. 



In park work much water is encountered in the excava- 

 tion for lakes, which must be removed through sewers or 

 else by low-lift centrifugal pumps. Fig. 32, page 95, 

 shows the same work at Branch Brook Park hi a more 

 advanced condition. This work was particularly difficult 

 by reason of large volumes of surface and ground water. 



By Dredge. Where large bodies of water must be 

 deepened some form of dredge will be necessary. The 

 accompanying illustration shows a clam-shell dredge re- 

 moving earth and vegetable growths at Weequahic Reser- 

 vation, one of the Essex County Parks. This lake is 

 adjacent to the Newark Meadows (salt marshes) and 

 originally was quite shallow. It was increased to a depth 

 of 8 feet in order to prevent the growth of water plants, 

 the excavated material being largely used for surface 

 dressing. (Fig. 33, page 101.) 



Fig. 34, page 105, shows a hydraulic dredge at work at 

 Lake Nokomis, Minneapolis. This dredge is mounted on a 

 timber hull, 80 feet long. It is electrically operated by 

 an alternating current of 2300 volts. The main pump has 

 a 15-inch suction and discharge, the pump revolving at 

 either 250 or 305 R.P.M. as desired. The two winding 

 shafts each run at 22 R.P.M. There are five drums used as 

 follows : one each for the right and left spud, one each for 

 the right and left swings, and one for raising and lowering 

 the suction ladder. The ladder and cutter dig to a depth of 

 28 feet. For a greater depth a plain suction sleeve is used. 

 The dredge is provided with 1600 feet of pontoons with 

 pipe and also 4000 feet of shore pipe. The illustration 



