F. If winter active-channel mining is contemplated, an adaitional site 

 visit during winter should be conducted. Its purpose is to determine 

 the presence of water at or below the proposed site. 



Field Approach 



Material Availability. A variety of techniques are available to evaluate 

 grandular materials present at a site. These include borings, test pits, and 

 resistivity measurements. 



Biological Evaluation . The entire site should be walked (during which 

 time ground photos should be obtained) to subjectively assess the overall fish 

 and wildlife habitat quality in sufficient detail to make Decisions I through 

 4 in Section I B. It may be appropriate to make this a combined applicant- 

 agency site visit. 



Hydraulic Data. Cross Sections: Cross sections of the river channel (s) 

 and floodplain should be surveyed to provide input to the hydraulic analysis 

 and the level to which excavation can extend. The number, location, and length 

 of the cross sections should be based on the following criteria (Figure B-l): 



• There should generally be at least five cross sections; three or more 

 would generally be necessary to describe the site and one or more would 

 be required upstream and downstream from the site. 



• Cross sections through the site should be located at the upstream and 

 downstream ends as well as one or more in between to define the extent 

 of mi n i ng. 



• In addition to the locations necessary to define the site, cross sec- 

 tions should be located at each significant change in floodplain width. 



• The upstream and downstream cross sections should be located at least 

 two active channel-top widths from the upper and lower limits of the 

 material sites and associated buffers. 



108 



