An order 1 (ultra-detailed) soil survey was completed on 

 a corridor bordering the Clark Fork reach from Warm Springs 

 Ponds to just below Perkins Lane Bridge. A mapping unit 

 legend was developed to delineate mine waste deposits from 

 natural soils. Tailings deposits were further separated by 

 depth, amount of vegetation, and soil texture. Mapping units 

 were also separated according to the geomorphic setting, 

 being either above the 100-year floodplain, in the 100-year 

 floodplain, or roughly within the mean annual floodplain. 

 Natural soils and tailings-affected units were classified 

 using the Soil Taxonomy (Soil Survey Staff 1975) . A total of 

 18 map units were delineated on 1981, 1: 6, 000-scale aerial 

 photographs . 



To determine the chemical and physical variability in 

 the tailings deposits, two detailed soil investigation plots 

 were located near the river at sites where tailings deposi- 

 tion was extensive. Data from these sites were encoded and 

 used to produce maps of tailings thickness, surface eleva- 

 tion, and surface soil pH and electrical conductivity (EC) . 

 It was found that soil pH levels were highest in the natural 

 soil, with much lower pH found in tailings deposits. 

 Tailings deposits less than 8 to 12 inches thick had higher 

 pH levels than thicker tailings layers. Soil salinity tended 

 to be higher in tailings than in natural soils, but this 

 parameter differed less than pH. 



A streambank survey was conducted to assess the 

 condition of the channel banks within the study area. The 

 river bank condition was rated according to bank angle, 

 percentage of protective cover, kind of cover (gravel, 

 vegetation) , and depth of tailings. A two-man mapping team 

 floated and/or waded to obtain the data. The bank angle was 

 measured relative to the river, with a vertical bank equaling 

 90 degrees and an undercut bank less than 90 degrees. This 

 was done to find areas where the river was undercutting and 

 eroding its banks. The protective cover was ranked using a 

 rating from one to four, with one being less than 25 percent 

 cover, two between 25 and 49 percent, three between 50 and 79 

 percent, and four being greater than 80 percent cover. The 

 classification and rating system of bank conditions was 

 developed into a legend similar to the method described by 

 Platts et al. (1983), and a map of the river bank mapping 

 units was produced. The majority of the streambank within 

 the study corridor was in good shape, with probably 10 

 percent or less in the very erosive category. 



Several remedial measures may be employed within the 

 demonstration area. Contaminants would be removed from along 

 the streambank, and willows would be used to improve bank 

 stability. Mine waste removed from areas susceptible to 

 erosion would be redeposited on-site in more stable 



3-54 



