THE IRRIGATION AGE. 



97 



Hollow Core Wall for Hydraulic Fill Dams 



In a Hydraulic Fill dam the prob- 

 lem of the drainage of the shiic : ng 

 water is of controlling importance. The 

 sluiced material should be such that 

 it will not retain the sluicing water 

 for an undue time. If the material 

 is such that it will not deliver tlie 

 water with reasonable rapidity a de- 

 cided settlement with consequent cracks 

 is bound to ensue when the fill ulti- 

 mately dries out. 



The sluicing water on the fill is 

 maintained in a summit pool by hand- 

 made levees. It is found that in 

 depths downwards to 5', the material 

 in suspension becomes comparatively 

 solidified and it will then hold its shape 

 and consistency. The sluicing water, 

 however, must necessarily be under con- 

 stant drainage if rapid construction and 

 solid banks are expected. 



A Hydraulic Fill dam during con- 

 struction generally lias water in the 

 impounding reservoir above it wh cii 

 rises at substantially the same rate ;i^ 

 the increasing height of the dam. but 

 a little below its level, thereby reducing 

 the drainage head in that direction. 

 Assuming that there is no core wail, 

 the sluicing water is forced to pass 

 largely through the down stream fill 

 unless drainage tubes in some form 

 are provided. The passage of the 

 drainage water through such a mass of 

 material is slow, and hence full ad- 

 vantage cannot be taken of the other- 

 wise rapid method of hydraulic con- 

 struction. 



Again, the material of the fill will 

 not take its final set until the fill is 

 complete. The fill is therefore saturated during construction, and 

 saturated material is always of greater bulk than dry material. 

 This fact accounts in a measure for the excessive settlement in 

 hydraulic fills. 



All this is controlled by building a Hollow Core Wall through 

 the center of the embankment, and providing it with numerous 

 drainage gates of simple construction. A facing of broken stone 

 or gravel should be placed next to the upstream face of the 

 core wall. 



It is evident at a glance that with this construction we have 

 accomplished two things: 



First, we have provided an effectual water-barrier whereby when 

 the lower prism of the dam is once drained it is forever protected 

 against re-saturation. 



Second, the problem of drainage is entirely under control and 

 can be hastened or retarded at will. Drainage head is secure-.! 

 in two directions, namely, towards the core and towards the toe. 

 The material more quickly receives its final set and unexpected 

 settlement is thereby avoided. The time of construction is greatly 

 hastened. 



Moreover, in the usual form of construction the levees on the 

 outside edge of the pond frequently give way and permit a 

 localized washout on the slope of the fill. The central drainage 

 into the Hollow Core Wall permits of instant relief of excessive 

 water and makes a washout impossible. 



Again, if the sluicing material is such that it settles rapidly, the 

 surface water can be quickly drawn off into the Core Wall. 



Once the fill is completed the drainage gates into the Core Wall 

 from the lower prism are permanently opened. This insures an 

 absolutely dry prism; a result never before reached. 



The above is a mere outline of the functions of the Hollow 

 Core Wall in relation particularly to the Hydraulic Fill during 

 construction. Tjie advantages named in a previous advertisement 

 in connection with an ordinary rolled earth dam apply in full to 

 the Hydraulic Fill when the same is completed and in permanent 

 service. 



The above notes are fairly illustrated by the sectional drawing 

 herewith presented which roughly represents a Hydraulic Fill 

 Dam in process of construction. The Hollow Core Wall is car- 

 ried up to and a little above the ultimate embankment and pro- 

 vides interior inspection through the heart of the fill. 



This topic is more fully treated in our Circular on EARTH 

 DAMS. The introduction of the Hollow Core Wall entirely changes 

 the basic problem of an earth dam, whether of rolled earth or 

 hydraulicked into place. These points will not admit of discussion 

 in an advertisement. 



Respectfully submitted, 



AMBURSEN HYDRAULIC CONSTRUCTION CO. 



ENGINEER-CONSTRUCTORS, 88 Pearl St., Boston, Mass. 



All inquiries from Canada should be addressed to 



Ambursen Hydraulic Construction Co., 



405 Dorchester St., West, Montreal, P. Q. 



HYDRAULIC FILL DAM WITH~HOLLOW CORE: WALL JN PROCESS OF CONSTRUCTION 



SPECIAL NOTICE 



We take pleasure in announcing 

 that we have perfected an arrange- 

 ment whereby Messrs. Lewis & 

 Wiley of Seattle, Washington, be- 

 come associated with us in all work 

 involving the sluicing of earth for the 

 construction of dams or for any 

 other purpose. The reputation of 

 the above concern was made in the 

 famous re-grade of Seattle, where- 

 by the hills of that city were cut 

 down and used for fill on the water 

 front. A similar contract has been 

 carried out by this company in Port- 

 land, Oregon, and a third one is now 

 in progress in Seattle. 



Messrs. Lewis & Wiley are un- 

 doubtedly the foremost concern in 

 the world in this special line of 

 work, and we deem ourselves for- 

 tunate in securing their association 

 with us. 



AMBURSEN HYDRAULIC 

 CONSTRUCTION CO. 



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