CLASE ECHINOIDEA I Introducción

Forest duff is the material found on the floor of forests that typically consists of items in two layers. The upper layer generally includes things such as twigs, needles, leaves and other forms of vegetation that are dead, but have not yet decomposed. The second, lower layer includes partially to fully decomposed forest litter that rests on top of the mineral soil. Duff sampling at 9 locations completed in November 2011 in the Upper Flower Creek Timber Sale area indicated that asbestos concentrations in the duff ranged from no detectable limits to 12 million structures per gram of dry duff weight. While the area sampled is not within OU3, the results provide an indication of the asbestos levels that might be expected within OU3.

It should be noted that to the knowledge of the project team, the extent of asbestos in the two forest duff layers is not known. In other words, the distribution of asbestos in the undecomposed duff layer relative to the more decomposed layer is not known. Nor are the baseline levels of “naturally occurring” asbestos in the region known.

5.1 FOREST DUFF REMEDIATION TECHNOLOGY

The project team is not aware of any well-established technologies for removing forest duff from forested areas. However, there has been some research aimed at developing such technologies. The following sections summarize the findings from those efforts. 5.1.1 Remediation of Northern Europe Forests

In 2002 a study6 was completed the Nordic Nuclear Safety Research Group (a.k.a. Nordisk Kemesikkerhedsforskning). The purpose of the study was to identify technologies available for planning countermeasures in the event of a nuclear accident that caused widespread contamination of forests and forest duff. With regard to forest duff remediation, the study made recommendations that the top few centimeters of the organic layer (i.e. the whole undecomposed layer and the top portion of the decomposed layer) be removed during treatments. The recommendation for accomplishing this task was the use of a tractor-powered machine that was in development at FSL in Denmark, which is the Danish Forest and Landscape Research Institute (www.eldis.org). The machine could reportedly harvest the organic forest floor

6

Tools for Forming Strategies for Remediation of Forests and Park Areas in Northern Europe after Radioactive Contamination: Background and Techniques. 2002. Lynn Hubbard et al. Accessed at:

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layer with first requiring the total removal of stumps and other vegetation. The project team was not able to find further documentation of the equipment, but apparently it consisted of a rotating device mounted to the front of a wheeled piece of equipment such as a tractor or skidder. The rotating device scooped up the forest duff and fed it to a storage bin mounted behind the tractor. The depth of the rotating brush in the duff layer was controlled by a set of wheels.

Given the very steep terrain found in OU3, the project team does not believe the technology recommended in the Nordic study would be viable. In addition, the Nordic study recommended that the technique not be applied in areas that a prone to erosion. Again, given the steep terrain in OU3, the project team has concluded that attempting to remove the duff layer is not a preferred option because of the potential for significant erosion.

Another option identified in the Nordic study was “deep plowing” of forest soils. The use of large scale wheeled or tracked equipment with specially designed plows allows the plowing and removal of soil up to 1 foot deep. While all standing trees need to be removed to apply this technology, stumps do not need to be removed. The project team considered this technology within the context of OU3, but concluded it was not likely to be viable given the steep terrain in the region and soils that in many areas of OU3 are likely to be too shallow and rocky.

5.1.2 Combination Industrial Vacuum System and Portable Conveyor

The project team also considered industrial vacuum systems as a way to remove forest duff from OU3. Several industrial vacuum manufacturers exist including Vector in Milwaukee, Wisconsin and Multi-Vac in Union Grove, Wisconsin. The concept considered was that the industrial vacuums could be used in conjunction with portable conveyors to gather and transport forest duff to a central collection point. More specifically, an industrial vacuum system would be mounted on a wheeled or tracked vehicle and would include a large collection bin. The vacuum would then move around a contaminated site collecting forest duff. Periodically the vacuum would unload the material from the collection bin onto a portable conveyor system which would transport the material to a centralized collection point.

The project team is not aware of this concept ever having been demonstrated in actual field use. However, portable industrial vacuum systems have been used successfully and portable conveyor systems have been tested in the field. The two have not been used in conjunction with each other. Regarding the portable conveyor systems, field trials were completed in 2008, which tested the feasibility of using portable conveyors to move slash from timber harvest units to a centralized landing area. The tests were conducted in the Lake Tahoe area.

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The results of the test are described in detail in a USFS research bulletin7 and in abbreviated form here. Portable conveyors can be used in forest settings. They are made up with a number of individual sections with each section being about 10 to 15 feet long. Such conveyors are available from several manufacturers and are being used in construction, mining, and nursery industries for temporary material handling tasks.

The conveyors tested in Lake Tahoe field tests were powered by hydraulics or electricity and had the capacity to convey up to 20 tons of material per hour. They were set up in a quarter acre timber harvest area and used to convey logging slash up a 17 degree slope. The productivity of the conveying system ranged from 4 to 6 green tons per hour. While the system worked in general a problem encountered was that many of the slash pieces were too long or otherwise too big to fit on the conveyor with a good likelihood of falling off.

In the context of OU3, the project team believes such a system might have a better likelihood of being more effective because the material picked up by the industrial vacuum system will be smaller in size and therefore less likely to fall off the conveyor. However, given the low production rates observed in the trials and the much steeper terrain in much of OU3, the technical and practical feasibility of such a system is doubtful. A more detailed assessment of this possible technology is recommended in later phases of study.

5.1.3 Beneficial Land Cover

A third option considered was the use of a beneficial land cover. This concept would draw on the experience of a recent reclamation project near Aspen, Colorado8. In that project, a mix of biochar and native grass seeds were applied to a barren slope that was slowly eroding various toxins associated with mine tailings into Castle Creek at a location just upstream from Aspen’s water treatment plant. The application of the biochar and seed stabilized the soil in the slope and minimized erosion of soil into the stream. In the Libby situation, the contamination is found in the forest duff rather than the soil. Therefore, the utility of establishing a beneficial land cover is less clear. Further investigation is recommended.

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Tests of Biomass Removal Using Lightweight Portable Conveyors. June 2008. Bob Rummer, et al. Document Number 0851-2809-MTDC.

8 _{From Barren to Beautiful at Aspen’s Hope Mine. September 10, 2011. Accessed at:}

http://www.forestbusinessnetwork.com/7496/from-barren-to-beautiful-at-aspens-hope-mine/from-barren-to- beautiful-at-aspens-hope-mine200/

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