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PROPOSED DECISION - Canadian StriplPhase II Bond Release August 1, 1991 Page 3 On June 20, 1990, a partial inspection focusing on erosional stability was performed at the Canadian Strip Mine. In attendance were Cathy Begej and Susan McCannon of CMLRD, Mark Humphrey, of the OSM WTC in Denver, Jeff Zingo, of OSM Albuquerque Field Office and Bill Hill, Greystone Development consultants. Greystone is the permitting liaison for Wyoming Fuel Company and they prepared the request for Phase II Bond Release. Mark Humphrey had worked extensively with a classification system on erosion developed by Ronnie Clark and described in USDI-BLM Technical Note X346, Erosion Condition Classification System. This document describes a method for quantifying the degree of erosion at a site and the subsequent organization of the data into erosion classes entitled stable, slight, moderate, critical or severe erosion conditions. In addition, the document suggests that the moderate erosional condition class would be disruptive to cropland and forestry post-mining land use, and that the critical and severe erosional condition would be disruptive of all post-mining land uses, including rangeland and fish and wildlife habitat, the designated post-mining land use at the site. The classification system evaluates erosion condition based on seven categories: soil movement; litter movement; surface rock fragments; pedestalling; flow patterns; rills and gullies. Each category is broken Into five levels of erosion. If a category was present, the maximum score possible was listed in a column entitled "possible factors'. Observations were rated and listed in a column entitled 'identified factors'. At Canadian Strip, all five of the participants present on June 6, 1990, rated the east facing slope upslope from Pond 2 to become familiar with the system following instruction from Mark Humphrey. Later, Mark Humphrey, Cathy Begej and Bill Hill evaluated the drainage bottom leading into Pond 2, while Jeff Zingo and Susan McCannon evaluated the west facing slope above Pond 2, Cathy Begej evaluated the areas reclaimed prior to 1987. The areas are shown in Figure 3 and the results are shown on Table 2. Most evaluations rated the property as having a "slight" erosional condition. Usually, only five of the erosion condition categories were observed. Very few pedestals or gullies were found at the site. An effort was made to distinguish between recent, active erosion and past erosion. For instance, it was assumed that a highly revegeted rill was formed in the first year, before any vegetative growth appeared. This rill would not be counted as an erosional feature. Clumps of grass on hilislopes frequently showed some soil deposition upslope and 1/4" to 1/2" of exposed roots on the downshope side. This feature was evaluated in the soil movement tategory. Raindrop imprints were visible on clumps of dirt or areas without vegetative cover. Wyoming Fuel Company had used large, 2" wood chips as a mulch. These were frequently aligned between drill rows or in the bottom of rills found on slopes. Recent movement of wood chips was assigned to the category of litter movement, along with all other organic matter but scat (antelope pellets).