are frequently used. Scraped sites are usually dry when worked, however, 

 caterpillar tractors can work in shal low water (possibly up to 0.5m). 



P i t Excavat i on 



Pit excavation is generally done with draglines or backhoes. Dewatering 

 may or may not be necessary. At the study sites some of the more shal low 

 pits were dewatered, but deeper pits, e.g., Dietrich R i ver-Upstream, West 

 Fork Tolovana River, and Tanana River-Downstream were excavated underwater. 



Comparison of Techniques 



Some engineering and economic advantages and disadvantages of removing 

 gravel via pits versus scraping are listed below. 



Advantages of Pits Versus Scraping 



• Greater quantity from sma I ler area. 



• Can work within confined property limits (if necessary). 



• Less clearing required. 



• Less stripping required. 



• Can provide silt trap. 



Disadvantages of Pits Versus Scraping 



• Dewatering or underwater excavation required. 



• May provide less gravel per unit time than scraper operation. 



• Cannot be restored as closely to original condition. 



TRANSPORTATION AND STOCKPILING 



Transportation of gravel from the material site to the stockpile or 

 processing plant may be done with scrapers or front-end loaders and dump 

 trucks. Stockpiling gravel removal operations greatly reduces scheduling 

 problems. It is possible to load trucks directly for long-haul transport to 

 ultimate-use areas without stockpiling, but a great deal of coordination is 



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