2 BULLETIN 1067, IT. S. DEPARTMENT OE AGRICULTURE. 



in capacity and in excellence of design the pumping plants of this 

 section are unique, although among the many plants erected there 

 are some that are conspicuously superior to others. Department 

 Bulletin No. 652, "The Wet Lands of Louisiana and their Drain- 

 age," and Volume XI, No. 6, of the Journal of Agricultural Re- 

 search, contain much interesting information relating to the recla- 

 mation of these lands. 



This bulletin contains a short description of the various types 

 of drainage pumping plants found in the southern coast country, and 

 gives the results of tests that have been made since 1909 by the 

 Division of Agricultural Engineering, Bureau of Public Roads. 



TYPES OF PUMPS. 



DRAINAGE WHEEL. 



The first pumps used in the Gulf Coast country for artificial drain- 

 age were of the drainage wheel or scoop wheel type. Many of the 

 steam-driven drainage wheels are still in use in Louisiana. Large 

 wheels of this type range from 28 to 32 feet in diameter, with a width 

 of from 4 to 7 feet. In most localities, however, the cost of founda- 

 tions stable enough to hold the wheels rigidly in place has increased 

 the cost of the drainage wheels to such an extent that they have 

 been practically eliminated from competition with other cheaper 

 forms of pumping plant. Another point against the drainage 

 wneel is the difficulty involved in adjusting its height. Once set, 

 the depth to which the water may be lowered is definitely fixed. 

 As a rule these wheels are expected to pump against a maximum 

 head equal to one-fourth the diameter. The humus of the drained 

 land in time disappears as the land is. cultivated, and the level of 

 the land falls, the amount of shrinkage varying with the depth of 

 humus. As a result of this shrinkage it has been found desirable 

 after a few years to pump to a lower level. With a drainage wheel 

 this requires either lengthening the paddles or lowering the founda- 

 tions and power plant. 



CHAMBER- WHEEL PUMP. 



The chamber-wheel pump, certain types of which have been used 

 for drainage, is practically a meter, the discharge being propor- 

 tional to the speed. Because of the pulsations set up, due to the 

 alternate accelerating and retarding of the water that is being 

 pumped, there are well-defined limits of speed that may not be ex- 

 ceeded without injury to the pump. While the centrifugal pump 

 may be forced to an extent that is limited only by the power of the 

 engine or motor driving it, the limitations of capacity for the cham- 

 ber-wheel type are found in the pump itself. 



