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PROPOSED DECISION - Canadian Strip/Phase II Bond Release <br /> October 1 , 1990 <br /> Page 4 <br /> class would be disruptive to cropland and forestry post-mining land use, <br /> and that the critical and severe erosional condition would be disruptive <br /> of all post-mining land uses, including rangeland and fish and wildlife <br /> habitat, the designated post-mining land use at the site. <br /> The classification system evaluates erosion condition based on seven <br /> categories: soil movement; litter movement; surface rock fragments; <br /> pedestalling; flow patterns; rills and gullies. Each category is broken <br /> into five levels of erosion. <br /> At Canadian Strip, all five of the participants present on June 6, 1990, <br /> rated the east facing slope upslope from Pond 2 to become familiar with <br /> the system following instruction from Mark Humphrey. Later, Mark <br /> Humphrey, Cathy Begej and Bill Hill evaluated the drainage bottom leading <br /> into Pond 2, while Jeff Zingo and Susan McCannon evaluated the west <br /> facing slope above Pond 2. Cathy Begej evaluated the areas reclaimed <br /> prior to 1987. The results are shown on Table 4. <br /> Most evaluations rated the property as having a "slight" erosional <br /> condition. Usually, only five of the erosion condition categories were <br /> observed. Very few pedestals or gullies were found at the site. An <br /> effort was made to distinguish between recent, active erosion and past <br /> erosion. For instance, it was assumed that a highly revegetated rill was <br /> formed in the first year, before any vegetative growth appeared. This <br /> rill would not be counted as an erosional feature. Clumps of grass on <br /> hill slopes frequently showed some soil deposition upslope and 1/4" to <br /> 1 /2" of exposed roots on the downslope side. This feature was evaluated <br /> in the soil movement category. Raindrop imprints were visible on clumps <br /> of dirt or areas without vegetative cover. Wyoming Fuel Company had used <br /> large, 2" wood chips as a mulch. These were frequently aligned between <br /> drill rows or in the bottom of rills found on slopes. Recent movement of <br /> wood chips was assigned to the category of litter movement, along with <br /> all other organic matter but scat (antelope pellets) . <br /> TABLE 4: Summary of Erosional Stability Observations <br /> Identified Possible Erosion <br /> Factor Factor Percentage Condition Class <br /> East Facing Slope N/A N/A 20-40 Slight <br /> West Facing Slope <br /> Observer 1 14 71 20 Stable <br /> Observer 2 38 85 44 Moderate <br /> Valley Bottom <br /> Observer 3 13 71 18 Slight <br /> Observer 4 16 43 37 Slight <br /> Northern Part of <br /> Property 12 72 17 Stable <br />