Shovel Logging and Soil Compaction

SHOVEL LOGGING AND SOILCOMPACTION: A CASE STUDY By Rick F. Floch A PAPER Submitted to Departnent of Forest Engineering Oregon State University Corvallis, Oregon 97331 in partial fulfillmentof the requirements for the degree of Master of Forestry Completed May, 1988 SHOVEL LOGGING AND SOIL COMPACTION: A CASE STUDY BY RICK FLOCH GRADUATE STUDENT OREGON STATE UNIVERSITY ABSTRACT Shovel logging is a relativelynew ground-based method of yarding tinther. It involves moving logs from stump to landing by successive swinging witha hydraulic excavator modified into a log loader byreplacing the shovel bucket with a grapple. Loaders used in shovel yarding can weigh in excess of100,000 pounds so that the opportunity for soil compaction isgreat. This study measured the amountof soil compaction that occurs with shovel yarding. The study was done on the Quinault District of theOlympic N.F. in Washington state. The results show that 20.5% ofthe total area logged consisted of shovelpaths. Soil bulk densities in the shovel tracks whencompared to undisturbed areas within the unit showeda statistically significant increase of about 7.5%. Soil compaction did notseem to increase after the initialpass up to seven passes. Production rate for the shovelwas 7.8 net inbf/hour. Logging with the shovel cost$18.57/inbf less than yarding the same unit witha Washington 208 slackline yarder. Three methods of economicallyanalyzing the effects of soil compactionwere reviewed and the idea that the value of soil compaction involvesmore than just the dollar value lost dueto future decreased timber production was proposed. Values such as existence value, option valueand quasi-option value need to also be considered inany decision allowing soil compaction to occur. DEDICATION To my children, LUKE, JENNIFER, and JACOB and hopefully, their children. I only hope they will somedaybe able to forgive my generation forall we are stealing from them. ACKNOWLEDGEMENTS I would first like to thank theUSDA-Forest Service for providing me with theopportunity to participate in the two-year Advanced TechnicalSpecialty Development Program here at Oregon State University. Without this opportunity, this project wouldnot have been possible. - From the Quinault Ranger Station,I would especially like to thank RangerJohn Henshaw, who originally conceived the ideafor this study. Also, I would like to thank FrancisFriddle and Stewart Carlson - Sale Administrators who kept me supplied;Mel Davis for the initial work of pickingthe potential sites; Nancy Benson- silviculturjst, for spending timeon silvicultural prescriptions;Nancy Sturhan- soil scientist, for her thoughtsand conversation; Pam Trudeau - mother, researchassistant, and soil scientist- for her hard workand excellent conversation; Donna Witt- District BMA who arranged to letme stay near the study area; and finally forCharlene Hunt who did a mammoth job of preparingand sending me the scaling information. From the Timber Sale Purchaser- Mayr Bros. Logging Co. - I would like to thankGeary E. Lutz, shovel operator and Bill Hickson, WoodtsForeman for their cooperation, information and advice. iv I would particularly like to thankthe members of my graduate committee - Professors HenryA. Froehlich, Eldon A. Olsen and Rebecca Johnson.Their guidance and suggestions were crucial to thesuccess of this project. Also, I would like to thankDon Studier for the encouragement and support he gave me duringthe project and to Joel Krause, Toni Durstonand Toni Lowe, my fellow students who spent four verystrenuous days at Quinault helping with the datacollection.Without their help, the field study wouldnever have been done.Special thanks also to Phillip McColley,research scientist at the Wenatchee Forest ScienceLab in Wenatchee, Wa., who supplied the replacementnuclear densiometer at thelast minute. Finally, I would like toespecially thank my wife and three children for puttingup with the past 18 morths - particularly duringthe nionth I spent at Quinault and for themany late nights and weekends spent at my second home, PeavyHall Dungeon. V TABLE OF CONTENTS Page 1.0 INTRODUCTION 1 1.1 BACKGROUND 1 1.2 NEED 2 1.3 OBJECTIVES 2 1.4 SCOPE 3 1.5 LITERATURE REVIEW 3 1.5.1 SITE DISTURBANCE 4 1.5.2 SOIL COMPACTION 6 1.5.3 EFFECTS OF MULTIPLE PASSES 8 1.5.4 EFFECTS ON LONG TERN PRODUCTIVITY . 9 1.5.5 RESEARCH DONE ON SHOVELLOGGING ... 12 2.0 FIELD STUDY DESIGN 15 2.1 STUDY AREA SELECTION 15 2.2 STUDY AREA DESCRIPTION 15 2.3 LOGGING OPERATION DESCRIPTION 16 2.4 MEASUREMENTS TAKEN 18 2.4.1 SHOVEL PATHS 18 2.4.2 SOIL COMPACTION 20 2.4.3 TIME AND MOTION 24 2.5.4 PRODUCTION 27 3.0 RESULTS OF FIELD STUDY WITH DISCUSSION AND INTERPRETATION 28 3.1 SHOVEL PATHS 28 3.2 SOIL COMPACTION 34 3.3 TINE AND MOTION 42 3.4 PRODUCTION 47 3.5 THE VALUES ASSOCIATED W/SOIL COMPACTION . 53 vi TABLE OF CONTENTS (continued) Page 4.0 SUMMARY AND MANAGEMENT CONSIDERATIONS 65 4.1 SUMMARY 65 4.2 MANAGEMENT CONSIDERATIONS 66 5.0 ADDITIONAL RESEARCH NEEDS 70 5.1 COMPACTION/GROWTH STUDIES 70 5.2 ADDITIONAL SHOVEL LOGGINGSTUDIES 70 6.0 REFERENCES 72 APPENDI CES APPENDIX A - TIME/ACTIVITY REPORTFORM SAMPLE APPENDIX B - EMPIRICAL APPRAISALDATA APPENDIX C - NATURAL RESOURCEEVALUATION vii LIST OF FIGURES Page Figure 2.1: Scaled Map ofStudy Area 17 Figure 2.2: Track and Booni Dimensions of the Shovel 19 Figure 2.3: Diagram Showing Locationof Each Group of Bulk Density Measurements 22 Figure 2.4: Diagrant ShowingLocation of Measurements Taken Across Path Profiles 23 Figure 3.1: Location of ShovelPaths with Respect to the Number of Passes MadePer Pass 30 Figure 3.2: Plot ShowingAverage Depth Shovel Tracks Sunk Into the Surface of theSoil 35 LIST OF TABLES Page Table 3.1: Passes/Path,Length and Width of Paths Made by Cat 235Shovel 33 Table 3.2: Average DuffDepth 34 Table 3.3: Average DistanceFrom String to Ground Track Profile 36 Table 3.4: Soil Density UsingProbeless Meter (Backscatter Method) 38 Table 3.5: Soil Density UsingDouble-Probed Meter 40 Table 3.6: Comparison ofAverage Bulk Density in Tracks by Number of Passes 41 Table 3.7: Time Per Activityby Hours and Percent of Total Time 44 Table 3.8: Economic Comparisonof Two Yarding Methods 57 Table 3.9: Time Line With CashFlows From Table 3.8 59 1.0 INTRODUCTION 1.1 Background Shovel logging involves moving logsfrom stump to landing by successive swinging witha hydraulic excavator. The excavator, or "shovel," is modifiedinto a log loader by replacing the shovel bucketwith a grapple. Within the past tenyears, to reduce cost and increase production in forestoperations, shovel logging has seen widespread and increasinguse, particularly on the Olympic Peninsula of thestate of Washington (Fisher, 1986). Up until 1986, the Quinault RangerDistrict of the Olympic National Forest had permittedalmost no shovel logging. Areas that were flat enough to allow mechanized harvesting generally hadbeen logged with a highlead yarding system. This was to prevent unacceptable soil damage caused by tractorsand skidders making repeated tripsover typically very moist forest soils. At the request of John Henshaw, DistrictRanger on the Quinault Ranger District, this studywas undertaken as .a graduate student'sresearch project. Ranger Henshaw desired to knowmore about the environmental affects of shovel loggingon the Quinault 2 Ranger District, Of particular concern was the question whether the cost savings with shovelyarding, when compared to highlead yarding,was greater than the values lost due to increased compaction. 1.2 Need Loaders used in shovel yardingcan weigh in excess of 100,000 pounds. The potential for compactionwith this system can, thus, be quitesignificant. Because compaction can have substantialnegative long-term effects on tree growth and otherelements of the ecosystem, any decision about usingthis system must first carefully weigh theapparent up-front benefits of using this system againstthe possible adverse long-term effects that may result. To do this, the potentialcost savings with shovel yarding,the amount of compaction that may result and the valueof this compaction all need to be assessed. 1.3 Objectives The objectives of this researchproject are: For a shovel logged unit; Estimate the amount of compactionthat occurs. Estimate the production rate. Estimate the difference in loggingcosts between shovel logging and highlead logging. 3 4.) Compare the cost savings of shovel logging with the values lost due to increased compaction. 1.4 Scope This study reports on soil compactionresulting from logging with a shovel. It is designed to measure the production rate, unit cost and amountof sOil compaction that results when a Cat 235 hydraulic excavator is used to yard logs. It is a case study limited to one site, one specific typeof equipment, and one type of yarding method. 1.5 Literature Review Considerable research has been doneon the effects timber harvesting hason forest soils. Naturally occurring forest soils of the PacificNorthwest are generally low in bulk density and soilstrength and have high rates of infiltration. Because of this particular combination of characteristics, these soilsare easily compacted, disturbed and displaced during timber harvesting activities (Froehlich andMcNabb, 1983). Soil disturbance involves mixing ofthe litter and soil layer in place, whereas displacementinvolves horizontal movement of the soil. Soil compaction involves reducing porosity and subsequentlyincreasing bulk density. 4 1.5.1 Site Disturbance Research involving the effects of timber harvesting on soils frequently investigates the amount ofarea that is iuipacted or disturbed by the operation. In 1947, E.N. Munns reported that compactionto a depth of 10 inches using relatively lightlogging equipment in California was found to still existtwo years after logging had been done. On another logging job, he reported that tractor trailsand roads covered 25-40% of the logged area. Garrison and Ruinmel (1951) measuredground disturbance iimnediately after loggingwith tractors on ponderosa pines ranges in eastern Oregonand Washington. They reported 21% of a tractor loggedarea was disturbed with 50% of the disturbedarea considered deep disturbance.

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