present in adequate amounts in exposed deposits. Pits should be considered 

 wtien more than 50,000 m are required. Refer to Scraping Guidelines (VI B 2) 

 and Pit Guidel ines (VI B 3) . 



2. Specific Guidelines for Scraped Sites 



a. Gravel bars adjacent to high-water and abandoned channels can 

 be scraped to a specified level at the edge of the channel and 

 should be sloped toward the channel to provide proper drainage. 

 An average maximum depth should be maintained in the channel to 

 provide for flow containment during periods of low flow within 

 the channel. The average maximum depth at any point along the 

 channel is the distance between the average thalweg profile line 

 and the channel-full stage at that point (Figure 13). 



-Sianne/ -Fu// 



Channel -Ful 



Average Maximum ^'^^^ 



Thalweg Profile 



Average Thalweg Profile 



Channel Thalweg 

 Cross Section A-A 



Figure 13. Definition of average maximum depth and channel-full width in a 

 channe I . 



Recommended values of maximum depth that should be maintained in 

 the channel are listed below for three ranges of channel-full 

 width. Values of half the recommended depths should be considered 

 minimum depths below which flow containment would be ineffective. 



65 



VI . SITE OPERATION 



