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PROJECT REPORT July 2014

Productivity assessment for a Volvo MCT135C rubber-tracked skid-steer loader: a case study at the Slave Lake Mulch Research Area Steven Hvenegaard, Rex Hsieh

INTRODUCTION

In February 2014, Alberta Environment and Sustainable Resource Development (ESRD) completed a 30 ha fuel treatment within the Slave Lake Mulch Research Area near the town of Slave Lake, Alberta. We attached a MultiDAT1 to a Volvo MCT135C rubber-tracked skid-steer loader to capture real-time data from the machine while it was working. We then calculated its productivity rate and utilization rate.

METHODS

Machine Description The Volvo MCT135C skid-steer (Figure 1) is a 55 kW (74 hp) machine with a ground pressure of 33.5 kPa (4.9 psi). The skid-steer was equipped with a Wallenstein LX5300 log grapple.

Figure 1. The Volvo MCT135C skid-steer with the Wallenstein log grapple.

1 MulitDAT is a system for recording and reporting information about the activities of forestry machines.

http://www.castonguay.biz/

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Fuel Treatment Site The Slave Lake Mulch Research Area (Appendix A) is 4 km southeast of the town of Slave Lake, Alberta. This research area was designed to study mulch fuel treatments and the productivity of the equipment. The Volvo skid-steer was used in two study plots: 7A and 7B.

Crews from the Alberta Wildland Fuel Inventory Program measured the stand characteristics (Table 1) and collected fuel load data before the treatments began. The study plots were flat and dominated by Black Spruce (Picea mariana). At the time of mulching, the ground was frozen and covered with 50 cm of snow.

Table 1. Stem density and height of trees in the study plots.

Study Plot

Plot Area (ha)

Pre-Treatment Stand Density (stems/ha)

Average Tree

Height (m) >9 cm DBH <9 cm DBH Total

7A 1.5 663 7000 7663 5.9

7B 1.7 550 6000 6550 6.0

Fuel Treatment Activities In study plot 7A and 7B, a mulcher had worked in strips pushing over trees and mulching the felled stems and other woody debris. This is called strip mulching, and it is a common forest fuel treatment in high density Black Spruce stands with small-diameter trees. The mulch strips were 3.5 m wide with 3.5 m of standing timber between them. During mulching, felled stems became lodged in adjacent standing timber (Figure 2). The main function of the Volvo skid-steer was to pull felled stems and pockets of woody debris from the adjacent standing timber, and pile it in the mulch strip (Figure 3). This was called the cleaning phase.

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Figure 2. Felled stems and woody debris in the adjacent standing timber after strip mulching.

Figure 3. The Volvo skid-steer pulling debris from the adjacent standing timber.

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RESULTS

We collected data on the Volvo skid-steer for four days between February 22 and 26, 2014. This work was conducted in temperatures ranging from -15oC to -30oC. The productivity rate of the skid-steer in study plot 7A was 0.21 ha/PMH and 0.50 ha/PMH in study plot 7B. The machine utilization rate is equal to productive machine hours divided by total scheduled machine hours multiplied by 100:

(PMH/SMH x 100)

The utilization rate for the skid-steer was 75%.

DISCUSSION

The 3 m mulch strip created by the mulcher (Hurricane C250) in study plots 5A and 5B proved to be slightly too narrow for the mini-hoe to easily manoeuvre during the cleaning phase. Based on these observations, the mulcher (Lamtrac LTR6125T) in study plots 7A and 7B created 3.5 m strips to provide extra space for the skid-steer to manoeuvre during the cleaning phase. The wider mulch strips also reduced the number of stems and pockets of woody debris lodged in the adjacent standing timber.

From a fire behaviour perspective, a wider mulch strip may reduce the potential for crown-to-crown fire spread. Further studies will be required to determine the optimal width for a mulch strip based on the factors that influence crown-to-crown fire spread (tree height, crown bulk density, etc.).

In the Black Spruce stands that had short trees and low density, there was less woody debris accumulation and fallen stems in the adjacent standing timber after mulching. In fuel treatment areas with distinct differences in high density and low density Black Spruce, it may be cost effective to split the treatment plots and treat the low density stands without the cleaning and final mulching phases.

CONCLUSION

This assessment provides a snapshot of the potential productivity of the Volvo skid-steer during the cleaning phase of a mulch treatment in Black Spruce. We caution readers against relying on these results to estimate the cost of their fuel treatment project, or to expect a certain production rate from their equipment. Generally, productivity assessments are conducted over much longer periods, but because forest fuel treatments are small and variable this is difficult to achieve. We continue to look for opportunities to conduct these assessments for different machines and in different types of fuel treatments.

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APPENDIX A

Slave Lake Mulch Research Area

Map courtesy of Mistik Environmental Services Ltd.