.#«* ^ refill- ^ *^^» w **" :^S^- ^< o > cv ,• o " ° * "v> ^ ^ ^v * ^SSl^ • *U> at * Aw A. * « S .\ V 5 ° ^°^ '^^&' n ?^ "-^^ ^ '0 V i>o s*.iak;%> y.-^k^ /y«^*^ c°*.iSK>>o •cf lll/ ; > *^ : *l§lk ' ^°- vial zaS"" V.....V"" 6 : afc. v* » ^ ' Bureau of Mines Information Circular/1985 Analysis of Dredge Safety Hazards By Stephen A. Swan UNITED STATES DEPARTMENT OF THE INTERIOR C S m > c 7& Mines 75th an^ Information Circular 9008 Analysis of Dredge Safety Hazards By Stephen A. Swan UNITED STATES DEPARTMENT OF THE INTERIOR Donald Paul Hodel, Secretary BUREAU OF MINES Robert C. Horton, Director Library of Congress Cataloging in Publication Data: b oc D % D Swan, Stephen A Analysis of dredge safety hazards. (Information circular /Bureau of Mines ; 9008) Includes bibliographic references. Supt. of Docs, no.: I 28.27:9008. 1. Dredges— Safety measures. I. Title. II. Series: Information cir- cular (United States. Bureau of Mines) ; 9008. TN295.U4 [TN345] 622s [622\32'0289] 84-600309 /H CONTENTS Page 1^ Abstract 1 Introduction 2 Dredge fatalities 2 Dredge operations 3 General hazards analysis 3 Pipeline hazards 6 Railing hazards 6 Ladder hazards 7 Electrical hazards 10 Wire rope hazards 10 Fire hazards 11 Personal flotation device 11 Conclusions 14 ILLUSTRATIONS 1 . Single workboat 4 2. Pipeline without walkway 4 3 . Safe walkway 5 4. Walkway safety hazard 5 5. Power cable along pipeline 6 6. Well-maintained railing 7 7. No railings 7 8 . Dragline pinch point 8 9. Ladder or stairway 8 10. Poorly constructed ladder 9 11. Unsafe ladder 9 12. Power cable 10 13. Fire hazard 12 14. Failure to wear personal flotation devices 13 15. Improper storage of personal flotation devices 13 16. Abuse of personal flotation devices 14 TABLES 1. Mining dredge fatalities, January 1973-June 1983 3 2 . Location of dredges included in hazard analysis 3 UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT ft foot yr year pet percent ANALYSIS OF DREDGE SAFETY HAZARDS By Stephen A. Swan ABSTRACT Bureau of Mines research has not included analyses of mining dredge safety since 1948. Because of the increasing use of dredges, 63 fatal accidents and several hundred nonfatal injury accidents involving dredg- es were examined. Also, 31 working dredges and 3 dredge manufacturers were visited to acquire qualitative information. Drowning accidents represented 59 pet of the fatalities and are delin- eated in detail. Also, countermeasures against other hazards are discussed. 1 Mining engineer, Twin Cities Research Center, Bureau of Mines, Minneapolis, MN, INTRODUCTION The Bureau of Mines concern about min- ing dredge safety is longstanding. S. B. Ash studied safety practices related to California gold in the early 1930' s. 2 In the 1940 's, R. W. Fatzinger visited hy- draulic and dredge mining operations in Alaska and California. He also reviewed 10 yr of accident data pertinent to such mining in the United States. The data, covering the period 1933 to 1942, includ- ed those related to 36 fatalities and 3,700 injuries in dredge mining. 3 It is generally assumed that dredge op- erations are "safe" — certainly much safer than other mining and construction opera- tions to which they are usually compared. It is true that personal injury rates for dredge workers, normalized in terms of worker-hours, dredge operating hours, or tons of material moved, are lower than those for many other mining operations. 4 Still, over the 10-1/2-yr period that ended in June 1983 63 people were killed and almost a thousand injured in mining dredge operations in the United States. The research discussed here included field visits to a selected sample of min- ing dredge operations, an examination of dredge-related injury data in the files of the Mine Safety and Health Administra- tion's Health and Safety Analysis Center in Denver, and field visits to a selected number of nonmining dredge operations. In all, field visits were made to 31 dredge operations. Three companies whose principal business is the manufacture of dredges and dredge components were also visited. Design considerations for safe- ty were discussed, as were training and product liability questions and the acci- dent experience of company field repre- sentatives during erection, initial oper- ations, and maintenance of delivered dredges. The information was analyzed in five separate categories which appear to be the most important in terms of developing countermeasures for these accidents. These categories include drowning, slips and falls, electrical, mechanical, and fire. DREDGE FATALITIES To try to quantify were taken from the Health Administration's since January 1973. fatal accidents that mining dredges during people (average) died was also an annual ave 95 nonfatal injury acci the hazards , data Mine Safety and accident records Table 1 shows the occurred on U.S. those years. Six each year. There rage of more than dents, as well as 2 Ash, S. H. Safety Practices in Cali- fornia Gold Dredging. BuMines B 352, 1932, 31 pp. ■^Fatzinger, R. W. Safety Practices in Dredging and Hydraulic Mining. BuMines B 450, 1948, 76 pp. ^Mine Safety and Health Administration. Annual and Quarterly Injury Reports. several hundred noninjury accidents. Note that about 59 pet of the fatalities in the table are drowning accidents. There were more drownings from boats and walkways (mostly pipeline walkways) than from the dredges themselves. Machinery accounted for a smaller number. An ex- ample of such an accident is one in which a worker was repairing a dredge-to-shore conveyor belt. The belt was started while he was working on it, and he was knocked into the water. Five of the fa- tal accidents were from electrocutions. Twenty-one fatalities involved shore- or dredge-based support equipment, including a rollover of a front-end loader, a fall- ing crane boom, a fall into a hopper, and conveyor accidents on land. DREDGE OPERATIONS The majority of the dredges visited were extracting sand or gravel. Others in the sample included units engaged in recovering phosphate, gold, ilmenite, and coal. Dredges involved in land reclama- tion after mining and settling pond maintenance — for example, in recreational area development, specifically units en- gaged in making lakes for fishing and water sports — were also included in the analysis. Of the 31 dredges visited, 18 were built by manufacturing firms whose prin- cipal business is the design and manufac- ture of dredges. Thirteen units were built by the owners or by local machine shops not primarily engaged in dredge de- sign and construction. The 31 dredge op- erations included in this analysis were located in 10 States (table 2). Three of the four Alaskan dredges were mining gold. TABLE 1. - Mining dredge fatalities, January 1973- June 1983 Total Drowning: Boat Dredge Walkway Machinery Other Total Electrocution (shore or dredge) Mobile machinery (shore). Fixed machinery (shore or dredge) Total TABLE 2. - Location of dredges included in hazard analysis Sites fatalities 11 visited 4 10 1 6 6 5 1 5 4 37 4 2 5 Ohio 5 8 3 1 13 63 GENERAL HAZARDS ANALYSIS Many dredges depend upon a workboat to transport personnel and materials between the dredge and shore (fig. 1). It is im- portant to note that most of the dredge operations that depend upon a boat had only one such boat. Several fatal acci- dents might have been avoided had a sec- ond boat been immediately available to enable persons who might have rendered aid to get to the dredge quickly. In these accidents the only available boat was tied up at the dredge, and the victim was the only person on the dredge. Some dredges have workboats but do not depend upon them to transport people be- tween dredge and shore as a normal prac- tice. The crew moves between the dredge and shore by walking the pipeline. Fig- ure 2 is an example of such a pipeline. Several dredgemasters reported that they had "knocked a guy off the pipeline" when they started the pumps. If access be- tween the shore and the dredge depends primarily upon walking the pipeline, it follows that a safe walkway must be pro- vided. Figure 3 shows a safe walkway separated from the pipeline. Infrequent- ly, however, the design of the walkway is such that there are large gaps between one section and another (fig. 4). In ad- verse weather negotiating a gap of this size can be particularly difficult and hazardous undertaking for the dredge worker. FIGURE 1. - Single workboat. FIGURE 2. - Pipeline without walkway. FIGURE 3. - Safe walkway. FIGURE 4. - Walkway safety hazard. PIPELINE HAZARDS A more specific hazard associated with pipelines is related to moving the line and making repairs where the job of mak- ing connections between sections involves the danger of crushing or pinching injur- ies. Although several dredges provided work platforms on the pipeline buoyancy structures, many do all the work from workboats, sometimes using people who have little skill in boat operation or safe mooring. Another hazard area related to the pipeline involves power cables carried along the pipeline. One obviously un- satisfactory arrangement is shown in fig- ure 5. If the insulators that carry the line are inadequate, or if the line droops into the water, chances of break- ing or electrical shorts are greatly increased RAILING HAZARDS As on the pipeline walkways, railings make an important safety contribution on dredge decks. Many dredges had strong, well-maintained deck railings (fig. 6). Some, however, had no railings at all (fig. 7). A need for guardrails inboard was evident on the type of dredge that mounts a dragline in a deck well. Two of the dredges visited had arrangements sim- ilar to that show in figure 8. Note that as the dragline swings , a pinch point is created between the cab and the deck. Several accidents have occurred when maintenance people were not aware of this FIGURE 5. • Power cable along pipeline. V FIGURE 6. • Well-maintained railing. FIGURE 7.- No railings. potential hazard. The problem is not one of having maintenance done during drag- line operations, because most companies require that the dragline be stopped during maintenance. The accidents that have occurred involved people doing deck- work and inadvertently stepping into the well. LADDER HAZARDS Figure 9 is an example of a ladder (or stairway) into a lower hull area of an otherwise well-constructed dredge. Note the absence of handrails. Tripping and bumping hazards are also visible in the stairwell area. Ladders for abovedeck maintenance are frequently designed with little thought about the safety of their use. Figure 10 shows such a ladder, made of round stock welded to an I-beam. The spacing is in- appropriate, the toe room is inadequate, and the footing is poor. Often it was not a cost problem that led to poor lad- ders, but simply lack of attention to the details of safety design. Figure 11 shows another ladder welded to an A- frame. The rungs are not evenly placed, and the ladder is quite difficult to ne- gotiate. Some of the lower rungs have been removed because they constituted an- other hazard to people working near the base of the A-frame. FIGURE 8. • Dragline pinch point. \ FIGURE 9. - Ladder or stairway. FIGURE 10. - Poorly constructed ladder. FIGURE 11. - Unsafe ladder. 10 ELECTRICAL HAZARDS Electrical hazards are common on many smaller dredges. Figure 12 shows poor handling of a power cable. Even on larg- er dredges, electrical safety is some- times given inadequate attention. Dis- tribution boxes are poorly placed and im- properly mounted. Cables are routed with little regard for insulation protection, not to mention the trippling hazards cre- ated. Common safety practice must be followed. WIRE ROPE HAZARDS Wire rope breakage on dredges is not uncommon. Both broken positioning lines and broken digging ladder control lines were observed during field visits. On one occasion, the end of a snapped rope violently struck and entered the opera- tor's compartment. It would undoubtedly have injured the dredgemaster had he been in his usual position at the time. There are several countermeasures. One is the proper handling of the equipment so that the rope is not overloaded. Another is regular inspection and replacement of work or damaged rope. A third is more careful design to ensure that the rope size is appropriate to the loads experi- enced during the majority of the opera- tions. Finally, proper guarding of the cables and drums can be invaluable to en- sure that a broken cable does not injure FIGURE 12. - Power cable. a worker. Although some of the ropes and sheaves observed during the study were well guarded, most were not. Many drums, 11 including drums immediately adjacent to the operator's compartment, were not guarded. FIRE HAZARDS Fires on dredges do not appear to be a common occurrence, but when one did occur, the results were frequently ex- tremely expensive and dangerous. In most of the operations visited, the fire pro- tection practices appeared to be substan- tially less well developed than those in shore-based plants. Scenes like that shown in figure 13 were very common. Flammable debris (oily rags, cartons, and fluids) were frequently observed in areas where ignition was possible. The train- ing given to most dredge workers relative to fire prevention and fire suppression was minimal. The available fire suppres- sion equipment was not always easily ac- cessible and properly maintained. PERSONAL FLOTATION DEVICE Perhaps the single greatest hazard on dredges is related to the simple fact that work is done over water. Only one of the 31 dredges vistied required water survival training and demonstrated water survival proficiency as conditions of em- ployment. All except two of the dredge operations required the wearing of a per- sonal flotation device (PFD) , according to the written safety rules of each com- pany. However, in only a few cases was the wearing of PFD's observed to be enforced. In the majority of operations visited, no one was wearing his PFD. Scenes like that depicted in figure 14 were common. On some of the very smallest and oldest dredges it was apparent that the avail- able PFD's were never worn. On some of the largest it was not uncommon to find PFD's stored as in figure 15, not well- maintained, not inspected, not fitted, and not assigned to individuals. Some- times the PFD's, even new ones, were ly- ing in dirt and grease as shown in figure 16. A few of the dredges had the PFD's as- signed to individuals; these PFD's were well maintained and regularly inspected and were worn while working over water at all times except when the person was in- side the dredge control house. However, at most operations the dredge workers complained that the PFD was uncomfort- able, too old to be of any use, or a work hazard because it tended to catch on things. In short, a multitude of reasons were offered in defense of not wearing a PFD. 12 FIGURE 13. - Fire hazard. 13 •v* i ■ .**. — — <,-*tz Jt \ \ \ \ \ \ \ FIGURE 14. - Failure to wear personal flotation devices. FIGURE 15 - Improper storage of personal flotation devices. 14 FIGURE 16. • Abuse of personal flotation devices. CONCLUSIONS More attention needs to be given to published safety requirements, including those in American National Standards In- stitute Standard A10.15 and in the Code of Federal Regulations. The three dredge manufacturers visited appeared to have studied and considered the standards in terms of design improvements. Beyond that, all three expressed the general view that safety is the responsibility of the operator, not the manufacturer. 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