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1/4, sec. 15. The eastern area is interrupted in its northern part by <br />developments of unstable ground (Qug) and potentially unstable ground (Qpug). • <br />Both the eastern and western areas of stabilized ground developed in <br />predominantly shaly material at the bases of parallel ridges formed mainly by <br />sandstone sections in the lower- part of the Williams Fork Formation. <br />4.4 Hydrology <br />Dry Creek which flows slightly east of north is the main drainage in this <br />area and 005 Gulch is a major tributary to it. At the time of the early <br />September- and mid-October 1991 field visits 005 Gulch did not have any flowing <br />water in it other than in one or two local areas. Between Sta. 65+00 and Sta. <br />72+00, about 130 to 140 feet left, are several areas in the stream bed that <br />were either damp or included stagnant water. These areas might have been <br />related to spring activity or to local perched water tables within masses of <br />unstable ground (Qug) and potentially unstable ground (Qpug). <br />Conventional understanding of unstable ground ranging from minor slumping <br />activity to major landslides usually focuses on the role of water. It is safe <br />to assume that in 005 Gulch water has played a significant role in ground <br />stability. Unfortunately we do not have an historical record in the gulch of <br />the relationship between the development of unstable ground and the amount of <br />precipitation. Probably the relationship is direct. This uncertainty can be <br />offset in a practical manner by taking appropriate steps to develop <br />comprehensive drainage plans in the design of the haul road and pond <br />embankment. <br />• <br />12 <br />