B. SPECIFIC GUIDELINES 



Specific site planning should proceed based upon the selected gravel 

 removal method. 



I. Scraping in Active and Inactive Floodplains: 



a. Material sites should be mined to ensure that after the ma- 

 terial is removed, sufficient gravel remains to maintain the 

 low-flow channel configuration (refer to Section VI B 2) 



b. Since it is most efficient to work scraped sites in a dry 

 condition, the average depth of the groundwater table during 

 the desired period of mining and the effective use of river- 

 training structures should be assessed (refer to Appendix C on 

 river-training structures) 



2. Pit Excavation in Inactive Floodplains and Terraces: 



a. Pits should be considered when a large amount of gravel 

 (>50,000 m ) is required from a river that does not have large 

 exposed gravel deposits. If scraping is conducted in a situ- 

 ation where more gravel is required than is accessible within 

 the guidelines for scraping, overmining may result with corres- 

 ponding habitat and channel alterations. In these cases, it is 

 preferable to go to inactive floodplains or terraces and exca- 

 vate a deep pit (refer to Appendix D on pit design). 



b. Pits should be located in areas where they will have a low 

 probability of diverting channels into the mined area. This 

 means they should be located on terraces, inactive floodplains, 

 or stable islands with the recommended buffer. Terraces are 

 preferred because of the reduced probability of channel diver- 

 sion. 



22 



II. SITE PLANNING 



