SITE INVESTIGATION 



The import-ance of an adequate on-the-ground site investigation cannot 

 be overemphasized. At the Ugnuravik River site, the investigation stopped 

 with an interpretation of aerial photographs. Subsequent site operations 

 discovered that the gravel was merely a veneer and not present in sufficient 

 quantities to meet project needs. In contrast, before construction of the 

 Trans-Alaska Pipeline System rather extensive site investigations were 

 conducted which significantly increased the knowledge of site gravel quan- 

 tity and qua I i t y . 



Types of Data 



Several different types of data need to be obtained in a material 

 site i nvest i gat i on. 



Aerial Extent and Depth of Deposit . Estimating the volume of material 

 available depends on establishment of the aerial extent and depth of the 

 deposit in question. If this volume is less than the needed volume, the site 

 will be inadequate to satisfy the material needs. Hence, this is one of the 

 most important types of data to be obtained. 



Thickness and Aerial Extent of Overburden. Gravel sites frequently have 

 a covering of silt or organic material, over all or part of the site, which 

 must be removed in order to expose underlying gravel. Mining may not be 

 economical if more than about I m of overburden is present over most of the 

 site. 



Homogeneity of Deposit. A deposit which appears suitable on the surface 

 may be unsuitable at depth. This change in deposit quality frequently is a 

 result of fluvial processes involving channel shifting, alternating erosion 

 and deposition, and overbank flows associated with periodic flooding. Test 

 pits or borings from several locations within the site should be analyzed to 

 determine deposit quality. 



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