not be dropped from a height greater than about 0.3 meter (1 foot). 

 Maximum heights from which stones may be dropped on geotextile filter cloth 

 are specified for varying sizes of stone in Section IX. 



c. Underlayer Stone. Underlayer stone should be placed to a full zone 

 thickness in one operation in a manner to avoid displacing the underlying 

 material or placing undue impact force on underlying materials and support- 

 ing subsoils. The underlayer stone should be placed in a manner to produce 

 a resultant graded mass of stone with minimum voids. Rearranging of in- 

 dividual stones may be required to achieve this result. Placement by any 

 method which is likely to cause segregation of the various sizes is not 

 permitted. Unsegregated stone can be lowered in a bucket or container and 

 placed in a systematic manner directly on the underlying material. Casting 

 or dropping stone more than 0.6 meter or moving by drifting and manipu- 

 lating down the slope is generally not permitted (U.S. Army Engineer 

 Division, North Central, 1978). 



d. Cover (Armor) Stone . The SPM (U.S. Army, Corps of Engineers, CERC, 

 1977) and White (1948) show the placement of cover or armor stone as either 

 uniform, special, or random. 



(1) Uniform Placement . This is applicable only to concrete armor 

 units and cut or dressed quarrystones in that they are of a uniform size 

 and shape, and thus, lend themselves to an orderly placement pattern. 

 Since quarrystones (as opposed to cut stone) are of random size and shape, 

 uniform placement of quarrystone is impracticable. 



(2) Special Placement . This is only applicable to parallelepiped- 

 shaped stone and involves the longest axis being placed perpendicular to 

 the slope of the structure face. For special placement, the longest axial 

 dimension of the stone should be at least twice as long as either of the 

 other two dimensions. The special placement method and the associated 

 stability coefficient should not be used unless quarrystone meets these 

 dimensional specifications, and prospective contractors for the project can 

 assure the developer that they can obtain the quarrystone and place it with 

 the long axis normal to the face of the structure slope. 



In general, due to the turbidity of the water at a construction site, 

 the special placement method can only be used above the water surface, as 

 it is not possible to observe or place stones accurately below the water 

 surface using this method. Even then special care must be taken to ensure 

 proper orientation and seating at the interface of the change- in-placemenU 

 and at the slope-crown interface. 



The special placement method will require close inspection and clear 

 instruction to the contractor to ensure proper placement procedures. This 

 method requires more time than random placement and should, therefore, 

 increase the selection, handling, and placement costs of the quarrystone. 



(3) Random Placement . Random (formerly pell-mell) placement is a 

 term used to describe a variety of placement techniques ranging from 

 dumping the armor stone under water from a scow to careful, individual 

 placing of the angular quarrystone in the above-water section. Quarrystone 

 placement by a contractor cannot only vary above and below the water level 



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