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Additional Work in Depositional Zone

The depositional zone is located between the upper and lower roads. This section contains the steepest slopes on the slide-more than 45 percent. These steep slopes were caused by the eroded material from above, which was deposited in a "bulging" shape near the toe of the slide, hence the name "depositional zone" (figure 8). To control erosion in this steeper section, 15 check dams, constructed from native materials (rocks and dead trees), were added to the original work. This phase of work was completed
October 17, 2001.

Figure 8. Spider hoe excavator in
depositional zone, located between
the upper and lower roads.

Project Data

Changes were made during construction to the lengths and locations of some of the Eljen drains and lined ditches in the original plans and specifications. The final constructed lengths and locations of drainage systems are reflected in an as-built drawing in the final construction report. To obtain a copy of this report or more information related to this project, contact Terri Anderson at the Bitterroot National Forest, 406-363-7112.

Plans for Revegetation and Continued Monitoring

To develop a plan to meet the revegetation requirements in the settlement agreement, Thomas Parker of Bitterroot Restoration Inc. prepared a draft proposal, dated July 2001, to revegetate the McClain landslide within 5 years. His proposal included establishing native vegetation and fixing soil nutrients, providing for soil surface protection using erosion control blankets, and controlling runoff by using contour wattles, rock fill, or log cribs. In late summer and fall of 2001, the Forest Service botany crew started implementing this plan by planting 700 shrubs in bare areas throughout the slide, installing straw wattles, and strategically scattering logs to control surface erosion. The crew also installed two experimental erosion-control- blanket test plots in a raw area of the slide directly above the upper road. The revegetation plan implementation is likely to continue through 2005, with evaluation and modification of revegetation and erosion control measures each field season to improve their effectiveness and ultimately meet the settlement agreement objectives.

A plan to monitor the effectiveness of the Forest Service in meeting the requirements in the settlement agreement was developed and a general outline of the plan was included in the Environmental Assessment, March 2001. The results of this monitoring program will provide the basis for determining project effectiveness, and help determine whether or not additional mitigation measures are necessary.

List of References

Auqoneering &Womack&Associates, February 2, 1999 & Revised April 22, 1999. McClain Creek Landslide Remedial Study, Bitterroot National Forest. Laurel, MT.

Echotech Geophysical, August 2001. McClain Creek Slide-Resistivity Profiles. Missoula, MT.

McClelland, Doug. 2000. [Personal Communication]. December 12. Missoula, MT: U.S Department of Agriculture, Forest Service.

McKean, J. and Inouye, K. December 2000. Publication 0077 1804-SDTC. Field Evaluation of the Long-Term Performance of Geocomposite Drains. USDA Forest Service, San Dimas Technology and Development Center, San Dimas, CA.

Prellwitz, R. January 2001. Stability Analysis Report - McClain Creek Landslide, Bitterroot National Forest. Stevensville, MT.

Prellwitz, R. January 2001. Drainage Analysis Report-McClain Creek Landslide, Bitterroot National Forest (Supplement to the Stability Analysis Report-01/01). Stevensville, MT.

United States District Court, District of Montana, Missoula Division, November 1998. CV 96-61-M-CCL, STIPULATION FOR COMPROMISE SETTLEMENT AND RELEASE OF FEDERAL TORT CLAIMS ACT CLAIMS PURSUANT TO 28 U.S.C. 2677

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