habitat diversity is reflected in a more diverse faunal community. Pit sites 

 are a viable alternative for material extraction in areas where changes to 

 the river hydraulics can be avoided or greatly minimized. When major hy- 

 draulic changes occur the effects on the environment can be damaging from 

 many standpoints. 



Scraped Si tes 



Scraped sites can occur essentially anywhere in a floodplain from 

 within the active channel to vegetated areas in the inactive floodplain and 

 terrace. Location of the site greatly affects the potential impacts that can 

 be expected from a scraped site. Although scraping implies that material 

 sites are operated by shallow removal of gravel, certain sites studied on 

 this project were excavated below the water table and thus resulted in 

 permanent flooding. These sites, however, were worked with scrapers or 

 bulldozers and not draglines or backhoes as might be implied by depth of 

 excavat i on . 



Scraped sites have several operational advantages; usually the sites 

 are dry, providing better working conditions and more efficient gravel 

 extraction. Additionally, excavated materials require less handling when 

 using scrapers to remove the gravel because only one machine is normally 

 used to excavate, transport, and deposit at the construction site. This is 

 not feasible using a bulldozer on a scrape or when digging pits with drag- 

 I i nes or backhoes. 



Given the same gravel requirement, the scraped site will generally 

 disturb a larger area than a pit site because the excavation is more shal- 

 low. In the study sites, the large area affected was often the greatest 

 problem of scrape-mining because there were few restrictions regarding 

 avoidance of channels and areas adjacent to channels. Locations of extrac- 

 tion sites are discussed in the subsequent section. 



Scrapes are generally situated in active floodplains adjacent to active 

 or high-water channels. Lowering these areas spreads water flow, at least 



560 



