LAND DRAINAGE BY MEANS OF PUMPS. 19 



results in any other case of underdrainage, as the problems to be 

 encountered are similar. A very large percentage of the bottom land 

 reclaimed by means of pumps is now very completely tile drained. 

 Nearly all the small surface ditches have been replaced with tile. 

 On some of the districts even the larger lateral ditches have been 

 replaced with large tile, and the plans for the drainage of new dis- 

 tricts now call for tile drains where formerly open ditches would 

 undoubtedly have been recommended. On the Langelier District, 

 near Havana, 111., practically all the open ditches, both large and 

 small, have been replaced with tile drains, until only about 2,000 

 feet of open ditch now remain. Thus far the system has been satis- 

 factory, although it has not yet experienced an extremely wet sea- 

 son. Future experience on this district will furnish valuable data 

 for guidance in the design of systems which are to include tile drains. 

 The replacing of open ditches with tile drains will reduce the main- 

 tenance charges on the interior drainage channels and will effect a 

 saving in land. The question of laying tile drains in the bottoms 

 of broad, shallow depressions to be used as floodways for storm run- 

 off deserves careful consideration in planning drainage improve- 

 ments of this character. By laying tile drains a few feet below the 

 bottoms of open ditches which are no longer deep enough to give a 

 sufficient depth of drainage the combination of ditch and underdrain- 

 age may be very cheaply attained. 



On account of the surface erosion and consequent sedimentation 

 in the main ditches small open surface field ditches or laterals empty- 

 ing into the main ditches are highly objectionable unless for some 

 distance back from the junction they are dug as deep as the bottom 

 of the main ditch. The difficulty could be avoided by the use of 

 some sort of permanent and stable masonry inlet ; otherwise small 

 ditches should be replaced by tile. 



GRAVITY SLUICEWAYS. 



In the case of districts where the river falls low enough during 

 the latter part of the summer to afford an outlet for gravity drain- 

 age, sluiceways, so arranged that they may be opened when desired, 

 should be built under the levee near the pumping plant. The sluices 

 should be composed of one or more parallel pipes laid nearly level 

 and provided with suitable valves. The length of the pipes will 

 naturally be 100 feet or more. Metal, concrete, or vitrified sewer 

 pipe may be used in their construction. Both ends should be pro- 

 tected with strong concrete bulkheads, and cut-off walls should be 

 placed around tin; pipes at intervals along their length to provont 

 seepage along their exterior surface. Cracking and failure of these 

 eno 1 bulkheads, one of the commonest accidents in drainage districts, 

 show that they must bo made with special care, amply deep, and of 



