SITE OPERATION 



The basic elements of a gravel removal operation are excavation, trans- 

 portation, and material processing. The details of equipment selection, 

 scheduling, and operation procedures are dependent on the composition of the 

 gravel, the season of operation, the topography, the haul distance, and the 

 environmental characteristics of the site. 



EXCAVATION 



The two basic gravel removal techniques used at the 25 study sites were 

 scraping and pit excavation. Table I identifies the technique used at the 

 respect i ve si tes. 



R i pp i ng and Blast i ng 



Frequently, site operators prefer removing gravel in winter because 

 water levels are low and access is easier. However, winter mining means 

 excavating gravel in a frozen, possibly ice-saturated condition. At the 

 study sites, if the gravel deposits were well above water levels and were 

 low in frozen moisture, excavation by scraper was normally not difficult. 

 Ripping frozen gravel was required at at least three of the sites (Middle 

 Fork Koyukuk Ri ver-Upstream, Prospect Creek, and Phelan Creek). It is not 

 known if blasting was utilized to remove gravel at any of the sites. 



Scrap i ng 



Scraping at larger sites is usual ly done with be! ly-dump scrapers. At 

 smaller sites or remote sites, or both, D-9 or smaller caterpillar tractors 



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