The material site was developed during construction of the Steese 

 Highway by scraping gravel deposits within and adjoining the main channel of 

 McManus Creek. A small gravel pit was also dug along the northwest boundary 

 of the site, in an area where the floodplain meets the valley wall. During 

 gravel removal operations, it was necessary to clear and remove the dense 

 vegetation at the 3-ha site. An estimated 75,000 m of gravel were made 

 available for use by these efforts, although a considerably smaller amount 

 is thought to have actually been removed. Large mounds of removed overburden 

 and unused gravels were left within the site. Site rehabilitation was not 

 performed following mining activities. The revegetation that has occurred is 

 attributed to natural reinvasion. Various aspects of this site are shown in 

 F i gure 89. 



Tanana River - Downstream and Upstream. The Tanana River is a large, 

 braided river fed by many glaciers in the Alaska Range. The Tanana River- 

 Downstream study site is adjacent to the Richardson Highway approximately 

 57 km downstream from the Tanana River and Delta River confluence at an 

 elevation of 260 m. The site was developed by pit excavation of the central 

 portion of a vegetated island located within the active floodplain of the 

 Tanana River. Excavation was conducted after March 1971 with approximately 

 510,000 m of material removed from within the 8-ha working limits. Cleared 

 and stripped surface materials were disposed of in waste areas along the 

 borders of the pit. Permit stipulations required a minimum 91 m buffer along 

 the highway and a minimum 50-m undisturbed buffer along adjacent side- 

 channels of the Tanana River. Maximum depth of excavation in this uncon- 

 nected, water-filled pit was approximately 9.4 m. The site was not reha- 

 b i I i fated. 



The Tanana R i ver-Upstream study site is adjacent to the Richardson 

 Highway approximately 9 km downstream from the Tanana River and Delta River 

 confluence at an elevation of 290 m. The gravel removal area was developed 

 by pit excavation of a vegetated gravel deposit adjacent to an active side 

 channel of the Tanana River. The pit was excavated in two parcels herein 

 cal led the upper and lower pits, which are segregated from the river by a 30 

 to 40-m wide vegetated buffer. A single channel at the downstream end of the 



63 



