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Investigative Methods for Controlling Groundwater Flow to Underground Mine Workings
Characteristic soils of the slightly drier forests are Aquic Dystrocryepts and Typic Cryaquepts. Seasonally, the soils are saturated within the upper 12 inches of the soil profile, but the depth to saturation drops to 24 to 40 inches at the end of the growing season in most years. The dominant plant association is subalpine fir/Labrador tea-Labrador tea. Small, grassy, wet meadows included in the wet forests are the wettest sites observed in the assessment area. In these small meadows, shallow ponding of water on the surface was observed. The ponded meadows occur along lowgradient drain-ageways, slumps, and in seepage areas (figure 6).
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| Figure 6—A wet meadow slump in map unit 1F. The slump headscarp is in the background. The slump deposit is saturated to the surface and has areas of surface ponding. The soil has 9 inches of fibric organic material over gleyed loam. Holm’s Rocky Mountain sedge, beaked sedge, and seepspring arnica dominate the plant community. |
In some locations, small areas of the wet forests and very wet, grassy meadows are intermixed in a fine, complex pattern that did not permit mapping the two types separately at the mapping scale used. These areas were mapped as a complex of the two types (figure 7).
The soils and plant associations that characterize these areas are similar to those of their respective components (map units 1F and 1H). The minor differences are described in appendix B.
All areas that were not mapped as water, or as any of the five riparian and wetland map units discussed above, were mapped as upland areas (map unit 3U). The unit includes forested and nonforested lands, and areas of rock outcrop and talus/scree. The soils of the upland meadows and forests are well-drained to excessively drained Typic Dystrocryepts, Andic Dystrocryepts, and Lithic Dystrocryepts. They formed mainly in colluvium (a loose deposit of rock debris that accumulates at the base of a cliff or slope) and glacial till. Water tables and saturated soils may occur below the 40-inch depth examined in this study, but this could not be ascertained from the soil profiles, vegetation, or aerial photos. The dominant plant associations are subalpine fir/grouse whortleberry-pinegrass and subalpine fir-whitebark pine/grouse whortleberry.
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| Figure 7—Map unit 1FH: A complex of small areas of wet meadows, saturated to the surface yearlong (foreground). Holm’s Rocky Mountain sedge and water sedge mixed with small, wet forested areas (background) having soils saturated within the upper 6 inches yearlong, dominated by Engelmann spruce, subalpine fir, bluejoint reedgrass, and willow. Soils of both components have thick organic surface layers. |
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