IKITIAL STUDY OF BURIED COMMUNICATION 

CABLE FOR UNDERGROUND TIINES 

Robert L. Lagace and N. Albert Moussa 

ARTHUR D. LITTLE, INC. 

Cambridge, Massachusetts 02140 

SLWWRY DATA IREPORT 

Contract No. 50308037 

February 1982 

UNITED STATES 

DEPARTFIENT OF THE INTERIOR 

BUREAG OF MINES 

Arthur D Lit tie, Inc. 
TABLE OF CONTENTS 

LIST OF FIGURES 

LIST OF TABLES 

ABSTRACT 

A. OBJECTIVE 

B. APPROACH 

C. FINDINGS 

D CONCLUSIONS 

E RECOTQfENDATIONS 

PAGE 

APPENDIX I--GENERAL MINE ACCIDENT STATISTICS 13 

APPENDIX 11--MSHA ACCIDENT REPORTS FOR MINE FIRES All EXPLOSIONS 22 

APPEhiIX 111--SWIES OF FOUR SELECTED MINE FIRES AND EXPLOSIONS 44 

APPEM)IX IV--METHODOLOGY FOR CALCULATING CABLE BURIAL DEPTHS 58 

FOR ADVERSE ENVIRONMENTS 

Arthur D Lit tie, lnc. 
LIST OF FIGURES 

PAGE 

APPENDIX 

Figure 1-1 Trends Over Time for Occurrence of Underground Fires 16 

Figure 1-2 Summary of Mine Fatality Data 1958 to 1978 (Coal) 2 1 

Figure IV-l Qualitative Characterization of Buried Cable Thermal 60 

Exposure and Endurance 

Arthur D Little, Inc 
LIST OF TABLES 

APPENDIX 

PAGE 

Table 1-1 

Table 1-2 

Table 11-1 

Table 11-2 

Table 11-3 

Table 11-4 

Table 11-5 

Table 11-6 

Table IV-1 

Table IV-2 

Allen Corporation Study Xesults for Underground 

Coal Mines 

Frequency Distribution of Various Casualty Levels in 

Coal Mine Fires 

List of Selected Mine Fire and Explosion Accidents 

List of MSHA Accident Reports of Major & Minor 

Underground Coal Mine Fires 

List of MSHA Accident Reports of Underground Metal 

and Non-Metal Mine Fires 

List of Major Mine Explosions 1959 to 1979 

Preliminary Assessment of Communications Impact 

on Mine Fire Outcomes 

Preliminary Assessment of Communications Impact of 

Outcomes of Major Mine Ex:plosions 

Frequency Distribution of Various Mine Fire Durations 

IEEE Thermal Classificati.on System 

Arthur D Little, Inc. 
The objective of this project was to perforn a preiiininary study to 

determine the desirabflity/practicaiity cf burying ';he communication 

cables in underground mines in order to protect then from the effects of 

fires and expiosions . 

We conducted discussions with Government and industry specialists on 

the physics of mine fires and explosions, mine disaster fighting, rescue, 

and investigation activities, and on nine operations. In additim, we 

examined -,ublisheC experimental work and selected detailed NSHA accident 

reports on fires and explosions in underground mines. 

We found the overall desirability /practicality of cable burial must 

be regarded at this time as highly questionable, because of its be~efit 

limitations to special sceneries, its practical operational shortcomings, 

and the evailability of alternative cable protection options. 

Arthur D Little. inc 
A. GBJECTLVE 

Fires and ~xplosions in underground mines car: be life-threatening 

emergencies. 3uring such emsrgencies, reliable coisi~~unication links 

could play vital roles in saving iives and in c~mbating the spread of 

the emergency condition. However, under such conditions, co~nunication 

licks may becone disabled at the wry time at which they need to be used 

for alerting others of the emzrgency and for coordinating energency 

res?cnse activities. 

The objective of this project was tcl perform a prelinin~ry study to 

determine whether or not it is desirable or practical to bury the 

comunication cabLe in underground mines in order to protect it fro2 the 

effects of fires and explosions. . 

The cveral.1 c'c j ect ive of this preliminary study was eccomplished by 

~ssessing: 

a the need for protecting the conmunication cable from the 

hostile environmental effects of fires and explosions, 

a and t considerations that affect the practical 

inplenentaiion of cable burial. 

To assess the need for burying the comunication cable, we examized 

a number of issues concerning the 1Fkel:ihood of cable involveme~zt in a 

mine fire or ac explosion, the extent of cable involvenent, the 

likelihood of Loss of commcnication to endangered micere due to cable 

dsnage, and the ccnsequenc2s of such loss of comuilication in tsrms of 

~Cded risk to the micers. 
We conlucteci dfsccssions with Bureau of !,lines zechnical staff, 

?.lining Safety and Sealth Ahinis trztion (M5I-W) personnel ard inhs try 

specialists, associated ~ith the physics of nine fires zlnd explosions, 

wieh mine disaster fighti~g, rzscze, aid Lnves~igatFon activities, and 

with nix operations. In addition, we exanined published reports on 

alne fires and explosio~s. As a rzsult, we obtained verbal acd written 

irrformation on the various coirm~i-ikcation needs, statistics on fire arid 

e:cplosion accidents in mining, quantitative descriptions of physical 

conditions measured during controlled fire and explosion experiments, 

and practical cable installation ccnsiderations. However, we found that 

no one had exanined and reported on involvement of the comunicatiorr 

cable. Accordi~gly, it became important to the outcome of this study 

that we review detailed MSHA accident reports for selected major fires 

and 2xplosions to assess the nzture and severity of cable involvenent, 

and the potential benefits obtainable from burial. Although the 

obtzining and reviewing of k~y accident repcrts caused scme delays and 

reallocations of project efforts, these activities proved to be vital to 

the findings of this initial study. 

The available informatioc was, by and large, widely disper~ed, 

incomplete, and not in a form lending itself to ready and specific 

application to the buried cable prablem. It became evident that the 

effort required to evaluate this information in detail would be 

significantly greater tha~ origznally allocated to this study. 

Therefore, as a result of budgetary limitations, the U.S. Bursau of 

Mines aad Arthur D. Little, Inc. agreed to capture the main results of 

this initial study in the forn of a stlmnary data report instead of a 

fcrmal final report. This report summarizes our main findings, 

conclusions and recomendations. They are based ofi preliminary 

evaluations of the assembled data and the application of professional 

judgment. The statistical, physical and operaticnal dzta evaluated 

during the study are summarized in four Appendices. 

,4rthur D Little, Inc. 
C. FINDINGS 

1. Examination of the general statistical accident daza fdr nice 

firss and sxplosiocs revealed tha: e o-~er~ll i;uii'b~r a:' zccidents 

involving injury or death appeared LO be somewhat linited co;ns.%red to 

everall c~sualties in underground nines. The zverag~ nu~ber of deaths 

per yeir from pine fires is relati- sly .law arid remaining steady, whiie 

the average number of injuries per year frcrc mine fires is low and 

decreasing. F3r an eight year period in the 1970's, tha average numbers 

for fires are z;proxirnately 5 injuries and 2 deaths per year. The nuniber 

of injuries and deaths per year from cine explosions in the 1970's. 

averaged over the sane eight year period,, is aboct 3 to 5 times that for 

fires, respectively. However, the number of yearly inj?lries due to 

explosions has decreased by a factor of about 5 since the early 1970's. 

For the same eight year period, the average number of 10 deaths per year 

from explosions is the result of averaging a few high death toll 

explosions with many low death toll incidents (see tippecdix I). 

2. Sased cn a mre detailed revia;? of detailed accident data, we 

were able to Identify the nost important accident scenzrios for xine 

fires and explosions to be examined with regard to the nature of 

communication cable involvexcent and the cable's potential utility for 

saving lives. Eiectrically-initiated fires, both on working sections 

ar,d those associatzd with vehicular movements along the electric rail 

hauiageways, were found to be the most :important sources of najor mine 

fires. Spark induced methane ignitions in the imediste face areas of 

working sectiocs were found to be the most important causes of major 

nine explosions (see Appendix I). 

3. In the d2tailed examix?ation of the scenarios a~d the xine 

accident rsports, we found no specifically-reported need for cable 

burial. Furthermore, benefits to be derived from such burial appeared 

to Se quite limited and constrzined to specific scenarios. For mine 

Arthur. D Little, Inc. 
fires, it appears that the nost i~porta:nt scexarlo is a aajor fire along 

a nair. haul.ageway. Such a fire could endenger many alnzrs Iscated inb;~ 

the fire. Fcr mine explosioas, it was more difficult to identify a k27 

benefiting scenario. 12 each case, the potmtial bezefits to be gained 

from cable burial stili appear, at first glance, 20 be quite limited, 

especially in view of the pot~ntial problems associated with cable 

burial and the presence of alternative scll~tions for cable protection 

(see Appendices I1 and IIIj. 

4. The practical problems can be grouped into two major 

categories: one associated with its utilization on working sections, and 

:he second with its utiiization on haulageways. On sections, the 

greatest hazard will be to miners in the immediate face area, where it 

is inpractical to exte~d a buried cable for up to 15 days after mining, 

because of ground movenent problems during this 15 day period. 

Furthermore, pager phone communicatf oils up to the face becone acedemic 

for methzne explosions in which everyone in the area can bc killed 

immediately. It is also of questionable utility for fires, because che 

overriding need is for direct face-to-face personal comunication 

between the miners on the section shortly after the fire is discoversd. 

Along the main haulageways, burial becomes a bit more attractive because 

of the permanence of these main travel routes. However, buried cable 

must function over long periods in the face of water, acidity and ground 

movement, pernaps for the life of ths haulzgeway. Therefore, burial 

will require more expensive and difficclt instaliation and maintenance 

prccedures in the forrn of trenching equipaent, types of cable and 

splices, troubleshooting, and repair. t2n the positive side, a buried 

cable installation would be less suscept:ible to roof falls and other 

nechanical accidents in haulageways. Finally, although a survivable 

buried cable could be available for use by rescue and recovery teams, 

questions remain as to whether long stending concerns ab~ut s2arking 

3azards at the exposed pager phones would in fact still prahibit use of 

the phone system by such teams (see Appendix IV). 

Arthur DLfi$dnc 
c( 

. I2 view of tk practical problens associaced wi?h burial, and 

the spgarsntsurvi-<al of ccriiunicatior?, cables for significant t irnes i~ 

many mfze fires and explssion zccidents, we belie-ce that several 

alternative solutions to cabie burial may przvide sufficiznt protection 

in most accldent situations. These potential alternative solutions 

i~clude : 

m cable loop-back through parallel tunne1s 01: other passages, 

m repositioning of the cable away from the immediate roof area, 

where fires tend to spread more rapidly, to a more favorable 

side wall (rib) location in the tunnel, 

use of a heavier duty or better insulated ccmmunication cable, 

or 

perhaps even covering the cablie on the floor of the tunnel 

instead of burying it. 

Although each of these nethods admittedly provides less absolute 

protection under the most extreme accident circunstances, each also 

requires less drastic departures from present mine practices. Finally, 

the needs of rescue and recovery teams will probably be best satisfied 

by nev medium frequency pcrtable radio equipment recently developed 

under Bureau of ?lines sponsorship (see Appendix IV). 

D. CONCLUSIONS 

Although cable burial should improve the long-term availability of 

pager phone co~municat~ons during mine fire and explosiorr emergencies, 

this may rot necessarily lead to corresponding benefits in the form of 

fewer injuries and fatalities during these emergencies. This initial 

study, which Lacluded a review of detziied accidsnt reports of past 

e~ergenzies, has revealed: 

Arthur D Little, inc 
B that cables did survive 1032 maugh to pernit comuaicaticns 

with endang2red niners iz sonz majcr emergencies, 

a no cases where deaths or injuries wers reported as being 

directly attributed to failxre of the communication cable, 

no czses wher2 we could easiiy infer that lives were in fact 

lost as a result of cable failure, and 

some fire cases where deaths could be attributed to inadequate 

familiarity with emergency warning and response procedures, 

and to inadequate emergency breathing devices. 

In summary, we have found that burial of the comunication cable is - not' 

generally needed, although cable burial can conceivably be useful in a 

specific scenario, such as a aajcr haulageway fire. 

The overall desirability (need) /practicality (feasibility) of cable 

burial must be regarded at this time as highly questioneble, both 

because of its benefit limitations to special scenarios, and its 

practical operational shortcomings. This questionability becomes 

particularly appareRt where alternative cable protection options, 

offering somewhat lower pratection but also less dramatic actions, are 

available for consideration. Furthermore, it also appears that improved 

emergency response procedures and emergency breathing devices could have 

a bearing on the number of potential fatalities from mine fires. 

Arhr D Little, JIIC 
In view of our firrdings and co~clu.sions in this preliniriary study, 

we aake the following rec~~endations: 

a Befare requiring any najor ckLangzs ir, cable instaliation and 

protection practice in undergrougd rrines, 

-- identify and defFne specific scenarios where some for-a of 

cable protection could be beneficial, 

-- perform cost/benefit analyses for various cabie protection 

and miner protection alternatives, and 

-- document the favorsbie and practical aiternatives, if 

any, in guideline form. 

a Evaluate the need for more effective enezgency rzspszlse 

training. 

Arthur 1) Little, Inc. 
APPENDIX I 

GENERAL MINE ACCIDENT STATISTICS 

A major objective of this study was to assess the need for burying 

the communication cable to protect it from the hostile environmental 

effects of fires and explosions. This need will depend on a number of 

factors such as the frequency of occurrence of fires and explosions in 

mines, the degree of involvement of the cable, the likelihood of losing 

the communication capability, and its impact on the endangered miners. 

This appendix presents summary information and data related 

primarily to the first of these factors. To identify statistics and 

general trends on coal mine fires and explosions, we reviewed the 

literature and talked with knowledgeable MSIiA staff. 

A. FREQUENCY OF COAL MINE FIRES 

We searched the literature and f~und that the Allen Corporation 

(Orlando, Florida) was conducting a detailed study of coal mine fires, 

under the sponsorship of the Bureau of Mines (Denver Federal Center). 

The Allen Corporation study consists of developing an annotated 

bibliography for over 1200 coal fires covering the period from 1950 to 

1977. (Explosions were excluded unless initiated by these fires.) Data 

were collected from MSHA fire reports, periodicals and interviews of 

nine safety directors. The data were categorized into reportable fires 

(at least one-half hour duration or injury), non-reportable fires and 

opinion data. (The latter two were based on the interviews.) 

The data were analyzed by time trends, state, ignition source, 

burning substance, location, equipment, detection, duration, injuries, 

fatalities and successful extinguishins agents. A qualitative ranking 

Arthur D Little, Inc. 
of the importance of these factors is given in Table 1-1 for underground 

mine fires involving injuries and fatalities. The study concluded that 

the overwhelming majority of fires are of electrical origin. 

Underground fires occur mostly- outby the face, at the working face and 

along haulageways. A number of recomme!ndatioils were made, none of which 

called for improving the communication c~ables. 

The number of fires in each year is plotted in Figure 1-1 for the 

period of 1950 to 1977, along with the corresponding number of tons of 

coal produced. There is a noticeable upward trend in the number of 

fires in the 19501s, followed by a downward trend in the late 19601s, 

and a leveling-off in the 1970's. However, coal production was fairly 

constant over this period, so that the number of fires per million short 

tons of coal-mined per year followed the same trend as the number of 

fires, and ranged from approximately 0.2 to 0.03 fires per nillion short 

tons per year. 

The frequency distribution of various casualty levels is given in 

Table 1-2 covering both injuries and deaths. The results are given for 

two time periods: 1970-1977 and 1953--1977. This separation of time 

periods is made because the number of fires are generally lower in the 

1970's as indicated in Figure 1-1. Table 1-2 also gives the total 

number of fires during these periods and their breakdown in terms of 

with or without casualties. 

Note that the number of fires resulting in a casualty is a small 

fraction of the total number of fires: about 7 to 8% for injuries and 3 

to 4% for deaths. The estinated arithmetic average numbers of 

casualties per year from fires for these periods are: 5 to 9 for injuries 

and about 2 to 3 for deaths. These numbers provide an upper bound on the 

potential benefits to mine fire casualties to be gained by improving the 

availability of the mine pager phone coimunication sys tern through cable 

burial. The actual benefits are likely to be lower since improved 

communications may have little or no effects on some of these casualties. 

Arthur D Little, Inc. 
TABLE 1-1 

MAJOR ALLEN CORP. STUDY RESUT,TS FOR 

UNDERGROUND COAL MINES 

Note: Items in descending order of s:ignificance in each box of matrix. 

Category 

Ignition 

Source 

Burning 

Substance 

Ref: Allen Corp. of America "An Annotated Bibliograplly of Coal Mine Fire Reports, 

Vol I, Final. Report, BoM Contract J0275008, 15 Feb. 1979. 

Reportable Fires 

Incident Descriptions 

Overall 

Electrical, 

Spontaneous, 

Weld ing 

Non-Report

Incident Descriptions 

Eqii i-pmen t 

Involved 

Wiring 

'Insulation, 

Coa 1, 

Rubber 

Overall 

Electrical, 

Fr ic t ion 

Welding 

Equipment 

Belt, 

Cutter, 

Locomotive 

Injury 

El ectrical, 

Weld ing 

Conveyor 

Belt, 

Shuttle 

Car, 

S~ccn ,/ ~rgm I L -... 

-- 

1,oca t ion Outby Face, Outby Face, 

Working Haulageway 

Face, 

Haulageway - 

- -- 

Fatal 

Electrical 

--- 

Wiring 

Insulation, 

Coal 

. 

Outby Face, 

Working 

Face 

. 

Successful Water, 

Extinguish- Dry Chemical, 

i11g Agent ~ock ~~1st 

Portable 

Extinguisher, 

Water, Power 

Disconnect 

Main Haul - 

ageway, 

Haulagcway 

-- 
Q Number of Fires 

Tons Produced 

Year 

1952 Law 1969 Law 

Source: Allen Corp. Final Report, Vol. I, 15 Feb. 1979 

Figure 1-1 

Trends Over Time for Occurence of Underground Fires 

Arthur D Little Jnc 
Arthur D Little, Inc 
B. FREQUENCY OF SEVERE COAL MINE EXPLOSIONS 

We also searched the literature for infornation on coal mine 

explosions. We found an old report covering a detailed review of all * 

incidents between 1910-1958. More recent similar studies were being 

conducted by George Price of MSHA and John Nagy (formerly of MSHA). 

These reports were due to be complet~ed after the completion of this 

study. Accordingly, we obtained some general results through telephone 

conversations and a meeting with George Price and Edward Kawenski of 

MSHA, Bruceton, PA. These results are summarized below: 

Methane ignitions are very common in mines--about 100 

ignitions per year. They occur near the face due to the 

friction generated when continuous mining machines hit a hard 

surface such as sandstone. Most of these "ignitions" cause no 

damage, due to the limited availability of nethane or coal 

dust. On the other hand, a few develop into devastating 

explosions. It is noteworthy that an explosion involving 

nethane alone is not likely to ignite the coal seam, while 

that involving coal dust may ignite it. (This is generally 

true for Pittsburgh seam coal.) 

2. In the period of 1959-1979, there were 918 underground 

casualty-involving explosions, leading to 353 deaths and 453 

injuries. Of these explosions, 16 were major ones involving 

294 deaths. In 1970-1979, there were 10 explosions causing 79 

deaths. The date, location and number of casualties for each 

of these major explosions are given in Appendix 11. 

* 11 Humphrey, H. B., Historical Summary of Coal Mine Explosions in the 

United States," 1810-1958, Bureau of Mines Eulletin 580, 1960. 

Arthur D Littie, Inc. 
3. The explosions involving injuries in 1970-1979 are very 

numerous. However, the total number of injurieslyear has been 

decreasing as shown below: 

Year Total Number of Injuries/Year 

1970 29 

1971 12 

1972 28 

1973 3 

1974 5 

1975 6 

1976 9 

1977 6 

1978 6 

1979 9 

1980 (incomplete) 5 

- 

Total 118 

4. The accident investigation reports on these explosions are not 

likely to have any informatior1 on the conditions of the cable 

after the explosion. Howeve:r, there seems to be agreement 

between Price, Kawenski and Nagy that the cables will generally 

not survive in the explosion a.rea. They are likely to be torn 

loose and burned. This was based on both judgment and some 

recollection of specific fires, 

5. Nagy reported that some 20 years ago they used to bury cables 

during fire tests in the experimental mine at PXSRC. They 

found it easier to bury the cables in the nine rib than the 

mine floor because the former: is much softer. They used a 

Arthur D Little, Inc. 
cutting machine to cut a 6-inch wide and 6-inch deep slot in 

the rib. This was done very frequently but was not documented 

to the best of Nagy's knowledge. (In an operating mine 

environment, burial in the rib becomes impractical because of 

the presence of crosscut tunnels.) 

C. COMPARISON WITH OTHER MINE ACCIDESTS 

The data presented above is summarized below to compare the risk of 

fatalities from fire and explosions over the following periods. 

1970-77 1970--79 1970-78 

Fires Explosions All Accidents 

Fatalities 15 79 ~1000 

Injuries 43 113 - 

We also give the corresponding values for all accidents in underground 

mines. Note that, on the average, fires and explosions cocstitute a 

small percentage of the total number of accident casualties. Figure 

1-2 prepared by G. Price of MSHA presents the mine fatality data in 

summary bar graph form for the 21 year period from 1958 to 1978. It 

illustrates the general decline in overall mining fatalities, and the 

reduced contributions made in the 1970's by fires and explosions on the 

average. However, it also indicates th'at the number of fatalities from 

fires and explosions can still become significant in any particular year 

as a result of a few severe incidents. 

In view of these trends, it became necessary to examine in detail 

MSHA accident reports for major fires and explosions to assess the 

degree to which cable burial might improve miner survival rates. 

Appendix I1 provides summary information and data from this review. 

Arthur D Little, Inc. 

APFENDIX I1 

MSHA ACCIDENT REPORTS FOR MINE FIRES KXD EXPLOSIONS 

A. NEED FOR MINE ACCIDENT REPORT REVIEW 

The miner casualty numbers presented in Appendix I provide an upper 

bound on the casualties that could potentially be reduced by a survivable 

communications system. The actual benefits will of course be lower, 

since some or all of the casualties may remain unaffected by 

communications links. This, together with the decreasing frequency of 

occurrence of fires and explosions involving casualties, made it 

important to examine detailed MSHA accident reports describing the 

circumstances and outcomes of selected key fires and explosions in which 

casualties did occur. Such a review could help identify the role and 

utility, if any, of the communication cable in affecting outcomes in 

terms of lives saved or lost. 

MSHA mine accident reports are published in more limited quantities 

than other government documents, and they are not stored in a central 

repository. They are generally kept at various MSHA district offices, 

and not always in districts where the accidents occurred. In addition, 

there are two locations where special collections of certain accident 

reports have been accumulated; namely mine fire accident reports at the 

Allen Corporation in Orlando, Florida, and mine expiosion reports at the 

MSHA office in Bruceton, PA. To obtain printed copies of the reports, 

it becane necessary to contact the MSH-4 Office of Public Information in 

Washington, and to follow up with a formal letter request to that 

off ice. 

Thirty-three accident reports covering selected coal mine fires and 

explosions and netal/non-metal nine fires from the period 1970 to 1979 

were requested. The requested list of reports is shom in Table 11-1, 

Arthur D Little, Inc. 
LIST OF SELECTED >IINE FIE ANT) EXPLOSION ACCIBENTS 

KEQUESTEZI FXOM MSHA OFFICE OF PUBLIC INFORMATION 

DATE OF ACCIDENT MINE NANE 

Coal Mine Fires 

Coal Mine Ex~losions 

Metal/Non-Metal Mine Fires 

Olga Mine 

Itrnann Nc. 3 

Nemacolin Nine 

l3lacksville No. 1 

Pyro Mine No. 2 

Jane No. 1 and 2 

Powhatan No. 6 

No. 3 Mine(Itmann Goal Go.) 

Franklin High-wall Mine 

MIXE LOCATION 

Coalwood, W.Virginia 

Itaann, W. Virginia 

Nemacolin, Pennsylvania 

Blacksville, V. Virginia 

Sullivan, Kencucky 

Elderton, Pannsylvania 

Beallsville, Ohio 

Itmann, W. Virginia 

New Athens, Ohio 

Compass No. 3 Dola, W. Virginia 

Homer City Homer City, Pennsylvania 

Pyro No. 2 Sullivan, Kentucky 

No. 15 and 16 Hurricane Creek, Kentucky 

(Finley Coal Co.) 

Itrnann No. 3 Itrnann, W. Virginia 

No. 4 Vansant, Virginia 

Scotia(B1ue Diamond Coal Co.) Kentucky 

Scot ia Kentucky 

Mulga Mulga, Alabama 

No. 2 St. Charles, Virginia 

Lakeshore 

Star Mine 

Sunshine 

Lisbon 

Lakeshore 

Sherwood 

Pilot Knob 

Buick Mine & Mill Facility 

Cabin Creek 

Alchem Trona 

Eagle 

U.S. Engergy Corp. 

Project 74 

Belle Isle (Cargill, Inc.) 

Cassagrande,Arizona 

Burke, Idaho 

Kellogg, Idaho 

LaSal, Utah 

Cassagrande, Arizona 

Ircn River, Michigan 

Pilot Knob, Missouri 

Ross, Missouri 

Mayesville, Kentucky 

GreenRiver, Wyoming 

Gilman, Colorado 

Caycee, Wyomiag 

Calumet, Lousiana 

v'~e~or ts received 

Arthur D Lit tie, Inc. 
Check narks on the table inciicate which reports were eventually received. 

Reports on the metal and non-metal mine accidents were obtained in about 

one month. The coal mine accident reports took about three months to 

arrive. 

B. VISITS FOR EXAPIINATIOK OF ACCIDENT REPORTS 

To expedite the accident information review znd analysis process, we 

visited the Allen Corporation in Orlando, Florida. The visit was made to 

get a timely preview of the environmental and operational conditions 

surrounding serious mine fire accidents. The visit was made by R. Lagace 

and A. Efoussa of Arthur D. Little, Inc., who met with R. Baker and C. 

Duncan of the Allen Corporation. Twenty-two coal mine fire reports and 

five metal/non-metal fire reports dating back to 1952 were selected and 

examined in detail. 

Reading the reports on-site at an early date gave us the advantage 

of quickly obtaining several llsnapshotsll of the actual conditions and 

outcomes related to cable and miner :survival for these accidents. 

Summary information and impressions for (each mine accident examined were 

recorded on a dictating machine, and accompanied where necessary by 

brief notes and sketches, for later transcription and analysis. 

Our examination of the fire accident reports convinced us that the 

fire dynamics in relationship to the loc~ation of the cable and miners, 

and the operational dynamics of the miners and supervisors directly and 

indirectly involved with the fire, may be even more important than 

naximum physical stresses that could be imposed on communication 

cables. For example, in some cases the communication cable was not 

involved and not a factor in the emergency events, while in others it 

survived beyond the time that it was needed, and was used to 

communicate with endangered miners. For many of the reports it was 

somewhat tedious and difficult to extract information on cable 

Arthur D Little. Inc. 
involvement and damage, because accident inspection teans have not been 

particularly concerned with the comunicaticn cables. 

We also expedited the review and analysis process for tne l1Sffi 

mine explosion accident reports by visiting the MSHA office in 

Bruceton, PA. This visit was made by R. Lagace and A. Moussa of Arthur 

D. Little, Inc., who met with E. Kawenski, G. Price, and R. Reynolds of 

MSHA. Fifteen major mine explosion reports dating back to 1959 were 

selected from their files. As in the case of the fire reports, the 

review process was somewhat difficult and tedious, and included the 

dictation of summary information and impressions, accompanied by brief 

sketches and notes, for later transcription and analysis. 

The review difficulties are due to the need to extract in a short 

time period, information related to cabie survival and its potential 

impact on miner survival, from reports t:hat vary in style and content, 

and are typically not concerned with damage to cables. Not 

withstanding these difficulties, the review and analysis of the MSHA 

fire and explosion accident reports were successful and of critical 

importance to this buried cable study. 

C. PRELIMINARY mALYSIS OF MSHA ACCIDENT REPORTS 

Tables 11-2, 11-3, and 11-4 list the MSHA accident reports 

reviewed by Arthur D. Little, Inc. for coal mine fires, metal and 

nonmetal nine fires, and mine explosions, respectively. The tables 

also indicate those reports for which summaries were dictated durinz 

the review process. Nearly all the reports reviewed were selected from 

the files of the Allen Corporation and MSHA Bruceton during the preview 

visits of R. Lagace and A. Moussa. Most of the reports requested from 

the MSHA Office of Public Information arrived too late in the project 

to Ee fully utilized. 

Arthur D Little. Inc 
TABLE 11-2 

LIST OF MSHA ACCIDENT REPORTS OF 

MAJOR 6 PIINOR UNDERGROUND COAL MINE FIRES 

REVIEWED BY ARTHUR D. IdITTIJE, INC. 

(Tablulated information excerpted f ronl All en Corp. , Final. Report, Vol. 

Mine Name 

Date and Company Location Fire Description Fatalities In 

12/13/52 No. 3 Elkhorn Evanston , Fire caused by friction 4 

Mine Pond Creek Kentucky of belt drive pulleys 

Pocahontas turning against a stall-ed 

belt. Area was sealed. 

5/06 154 Pursglove No. Pursglove, Fire occurred when roof 

15 Christopher W. Virginia fall pulled trolley wire 

Coal Co, on rail igniting coal 

and clothing on men. Area 

sealed. 

8/04/55 Vesta No. 5 Vestaburg, 

Jones 6 1,aughlin Pennsylvania 

Steel Corp, 

10/05/57 Crescent Mine Central City, 

Nashvil.le Coal, Kentucky 

Fi re of undetermined 

origin occurred on 

locomotive. Possibly 

main resistor overheated. 

Water, rock dust, and 

power used to extinguisll 

the fire. 

Fire caused by fall of roof 0 

which shorted light line 

and ignited timber. Water, 

rock dust, and powder 

applied to extil~guisll fire. 
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TABLE 11-2 (Cont inued) 

Mine Name 

Date and Company Location Fire I)escri.pti.on Fatalities In 

-- 

4/14/64 ZeiglerNo. 3 Zeigler , Fire caused by short 1 

Bell & Zoller Illinois circuit in locomotive 

ignited it and timbers. 

Water and rock dust applied. 

7/24/65 Arkwriglit No. 1 Mona, Fire was caused by pliase to 2 

Christopher Coal W. Virginia phase fault. Seals erected. 

Co . 

10116165 MarsNo. 2 Wilsonburg, Fire caused by sllort on 

Clinchf ield Coal W. Virginia miner ignited hydraulic 

fluid, coal, and rubber. 

Water and C02 put fire 

out. 

11/13/65 No. 3 Mine Leivasy , Fire of undetermined origin 0 

Dean Coa.1 Co. W. Virginia discovered by shaft portal. 

Water and rock dust applied 

to burning timber and coals 

and belt. 

12/28/65 Nemacolin Mine Nemacolin, 

Buckeye Coal Co. Pennsylvania 

5/02/66 Keystone No. 1 Keystone, 

Eastern Asso- W. Vi.rgi11i.a 

ociated Coal 

Corp . 

Fire caused by short circuit 1 

in trolly pole cable which 

ignited'cable, trolly pole, 

and cab of locomotive. 

Powder applied. 

Fire caused by short in pump 0 

power cables ignited same. 

Fire self-extingui.shlng . 
Mine Name 

Date and Company 1,ocation Fire Description Fatalities Ia

7/21/66 Forge Slope Newport Township Fire caused by sparks from 0 

Glen Nan Coal Pennsylvania torch ignited timbers and 

Co . plank liners at top of air 

shaft . 

12/12/68 No. 8-B Mine Saunders , Fire caused by short circuit 3 

Buffalo Mining W. Virginia in splice on blet power cable 

Co . and belt, hydraulic fluid, 

coal, dust, l~oses , and wooden 

crib ignited. Rock dust and 

extinguishers applied. 

3/26 171 Nemacolin Mine Nemacolin, 

Buckeye Coal Co. Pennsylvania 

N 

u3 

7/22/72 BlacksvilleNo. lBlacksville, 

Consolidation W. Virginia 

Coal 

7/11/73 Powhatan No. 6 Beallsvillc, 

Nacco Mining Co. Ohio 

b 

2 3' 8/3.1./74 Jane Nos. l & 2 Elderton, 

5 Kocl~ester & Pennsylvania 

.D Pit tsburgll Coal 

r Co . c*r 

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=3' 

0 

Troll-ey wire fell and 3 

contacted grounding 

clamp on rail which ignited 

coal. Water and nitrogen 

applied to extinguish fire. 

Fire occurred when miner 9 

contacted trolley wires 

igniting insulation, 

llydraulic fluid, and coal. 

mine was sealed. 

Fire caused by short circuit 0 

in trolley wire ignited insulation, coal, and hose on 

compressor. Powder extinguished 

the fire. 

Fire caused when trolley wire 1 

contacted levelins bar on 

bolter and arc ignited insulation, hydraulic fluid, 

and clothing. Powder applied 

to fire. 
TABLE 11-2 (Continued) 

Mine Name 

Date and Company Locat ion Fire lYcscription Fatalities Ii

10/03/77 Franklin High- New Athens, Fire caused when ram 0 

wall. Mine Ohio car ran over charging 

Consolidated cable while bat tcry 

Coal being charged and cable 

ignited. Powder 

extinguished the fire. 
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.Arthur D Little, Inc. 
Arthur D Lit t ie, Jnc 
The following criteria were used to decide which MSHA fire and 

explosion accident reports would be selected for review. 

o Fires that resulted in fatalities or several injuries, and 

occurred in a location that could involve a communication 

cable. Of particular concern were fires of an electrical 

origin, since communi.cation cables are generally in the 

vicinity of electrical cables, especially along main and 

section haulageways. 

o Major explosions that involved five or more fatalities since 

these are classified as mine disasters. 

More fires than explosions were examined because explosions tend to 

occur more frequently on sections, and mainly in the face areas where 

comunication cables are not usually located. 

Tables 11-5 and 11-6 present the results of our preliminary review 

and analysis of the fire and explosion accident reports, respectively. 

They represent our initial attempts, within the constraints of this 

project, to characterize the dynamics of the physical and cperational 

events of mine fires and explosions, and the potential impacts on the 

role of mine communication cable survival in reducing miner fatalities 

and injuries. To our knowledge, Tables 11-5 and 11-6 are the first 

tine that such characteristics have been tabulated in this manner for a 

large number of mine fires and explosions. It should also be noted 

that the various factors we studied and tabulated were not intended to 

be comprehensive, but to illustrate various key indicators and trends 

of significance to this initial assessment of the feasibility and 

utility of cable burial. 

Arthur D Little, Inc 
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Arthur D Little, Inc 

cf Times Survival 
Although the detailed informatior1 summarized in Tables 11-5 and 

11-6 is preliminary and incomplete, several trends and characteristics 

can be detected and some important ccnclusions can be drawn. For 

example, consider the question: Would cable burial have improved the 

casualty outcomes for the reviewed mine fire and explosion accidents? 

For many cases, the answer was a cle4ar "No." In no cases, was the 

answer a clear "~es". In few cases, the answer was uncertain and most 

of these were for haulageway fires. Thus, more detailed analyses of 

these reports are required to resolve the issue. 

A second finding relates to the utility of cable survival, through 

burial, during mine methane and/or coal dust explosions. In such cases 

it appears that cable survival is a moot point. Namely, the miners in 

the area cf the explosion are almost invariably killed, if not 

instantly, within a few minutes, leaving no one alive to use any 

survivable communication system. The reports also indicate that if the 

explosion is due to methane ignition on.ly, the cables appear to survive 

even in the explosion area. On the other hand, a violent coal dust 

explosion is highly destructive to everyone and everything, including 

cables, in the explosion area and beyond. However, beyond the working 

section containing the explosion, the cables appear to survive, thereby 

allowing communications to continue im the unaffected parts of the 

mine. 

A third observation is related to likely survival times, for the 

miners exposed to the dangers. For serious fires, the survival tines 

have been mainly on the order of minutes to a couple of hours, and 

typically much shorter than the durat:ions of the fires. For major 

explosions, the survival times have been mainly seconds to a few 

minutes for miners in the explosion area. Furthermore, in two major 

mine fires, miners were found dead wearing their self-rescuers, an 

indication that the CO-type, self rescuers apparently did not provide 

Arthur D Little. Inc. 
adequate protection against deadly cornbustion products. For some of 

the other fires, more detailed investigations of the accident reports 

are required to resolve uncertainties regarding the utilization and 

effectiveness of the self-rsscuers during the fire. The new MSHA 

regulation requiring the use of emergency breathing devices that supply 

oxygen to the miners is aimed at providing adequate protection to 

miners exposed to all hazardous atmospheres during mine emergencies. 

A fourth observation is that in several mine fires, deaths and 

injuries occurred because of inadequate emergency responses by 

supervisory personnel or the miners themselves. These include a 

variety of actions, such as delays in notifying miners inby the fire of 

the dangers, inappropriate advice to inby miners, and returning to 

dangerous areas to retrieve equipment:. Inprovements in this area 

should be possible through the establishment of practical emergency 

procedures and associated training and drills. 

Several other important findings and conclusions concerning mine 

fires and explosions could be obtained from a more comprehensive 

analysis of the accident reports and the factors tabulated in Tables 

11-5 and 11-6. More comprehensive analyses are not required for this 

initial study, but the Bureau of Mines may want to consider the 

applicability of such analyses to its post disaster or environmental 

monitoring programs. 

A final observation is included here concerning fires in coal 

mines that leave a layer of highly volatile roof coal to prevent roof 

shale exposure and spalling, a common practice in the Pittsburgh seam. 

It appears that once ignited, the roof coel continues to burn and the 

fire spreads rapidly along the roof. Furthermore, it appears that the 

burning of the thin layer (6" to 10") of roof coal could allow the fire 

to spread into adjacent entries by passing right over the thin cinder 

Arthur D Little, Inc. 
block barriers erected in crosscuts. This of course would defeat the 

effectiveness of the barrier as a restraint to fire propagation and the 

containment of noxious fumes. Theref~:re, it may be possible to avoid 

this problem in a simple manner during ths construction of new 

barriers; namely, by taking dom the 6" to 12" of roof coal at the 

barrier, and installing cinder blocks up to the roof material above the 

coal. This hypothesis on the spread of fires over barriers by means of 

the roof coal, and its potential solution, should be practical to check 

by straightforward experiments in a fire gallery. 

Arthur D Little, Inc. 
SUf43fARIES OF FOUR SELECTED MINE FIRES XND EXPLOSIONS 

This Appendix presents sumaries of four mine fires and explosions 

selected to illustrate the represe!ntative types of physical and 

operational dynamics that affect the survivability of endangered miners 

and communication cables. 

Arthur D Little, Inc. 
A, SUliE,IARY OF NAJOR HAULAGEWAY FIRE 

BLACHSVILLE NO. 1 COAL 31:INE FIRE ON 7/22/72 

This was an electrically initiated fire 'which resulted in nine (9) 

fatalities and no injuries. The B1acks:ville fire is a good example of a 

track haulageway fire involving a trolley wire, The fire rapidly got 

out of control and generated large quantities of smoke and toxic 

combustion products that were carried by the ventilation system to men 

working on sections inby the fire, The fatalities occurred because of 

inadvertent delays in the sounding of the alarm (escape) instructions 

after the initiation of the fire. This extended delay prevented the 

successful egress from the mine of the men working on sections inby the 

fire because of the rapid spread of the fire and combustion products to 

the escape routes taken by these men. 

The fire started during the movement of a continuous mining machine 

along the haulageway on a Saturday maintenance shift when the machine 

boom came into contact with the trolley wire, causing a flash fire 

around 7:30 pn (T start). Fire fighting with local extinguishers began 

immediately, but was ineffective, Trolley wire voltage was not 

disconnected for several minutes after fire initiation. Initial 

communication with the dispatcher was attempted almost immediately after 

fire initiation via the towing locomotive's trolley carrier phone. No 

reply was received. 

Five to ten minutes iater (T report-1) the dispatcher was informed 

of the fire from a nearby pager phone, and of the need for additional 

help. It was not until 8:OOpn, about half an hour after fire 

initiation, that the dispatcher was told by pager phone to inform the 

miners in the inby A-2 section to expect smoke on the A-2 section, and 

to remain near the pager phone (T report-2). No information was relaysd 

as to location of the fire or direction from which the smoke was coming. 

Arthur D Little, Inc 
At approximately 8: 15, the man on A-2 section informed (T report-3) the 

dispatcher of the worsening smoke situation, and at that time (T 

alarm-1) was told by the dispatcher to leavz the mine. However, the 

dispatcher did not give the man on A-2 any details concerning the fire, 

nor did he ask the miner of his intended direction of travel out of the 

mine. 

At approximately this same time (T report-4), a vehicle operator on 

inby Section A-3 informed the dispatcher of loss of trolley wire power. 

At about 8:30 pm (T alarm-2), the foreman called A-3 section from the 

pager phone outby the fire to ask if miners on A-3 had detected smoke. 

Upon reply that no smoke was detected, they were told to assemble all 

the men with their self rescuers, and to leave the mine immediately by 

way of the returns escapeway. All miners still at the fire location 

exited the mine at about 8:45 pm because the fire went out of control. 

The reasonable conclusion of the investigating team was that the 

work crews in the inby Sections A-2 and A-3 would have escaped to safe 

areas through established escapeways if they had received timely and 

adequate instructions to evacuate. However, the time the men were told 

to leave, the fire had burned to the point where the integrity of the 

escapeway system may have been destroyed, thereby trapping the miners 

from Sections A-2 and A-3. 

The rapid spread of the fire was caused by two factors. The first 

was the high percentage of volatile mat:ter in the Pittsburgh coal seam. 

The volatility ratio was -46 as compared to .12 which is considered 

high. The second was the 6 to 10 inches of coal left on the roof to 

support the unconsolidated carbonaceous shale above the coal. This top 

coal burns very rapidly, and was a major factor in the rapid advance of 

the fire into surrounding areas such as adjacent entries and escapeways. 

This coal was ignited by the burning lubricants and hydraulic fluids on 

the mining machine, which were ignited by coming into contact with the 

trolley wire. 

Arthur D Little, Inc. 
A key observation from the standpoint of coramunication cable 

survival for this mine was the fact that the pager phone system 

integrity was maintained at least one hour after the start of the fire; 

right up u~ltil the general alarm and escape command was given to all 

miners inby the fire location. From t'he report text, without the aid of 

a map, we deduced that the pager ph0n.e line was installed on the wide 

side of the track haulageway, as is a common practice in mines. 

Therefore, the cable survived in the haulageway in which the fire 

occurred and developed during this period. The investigative report 

gave no other indication that further communications were attempted 

either to or from the miners in sect:ions A-2 and A-3 after they were 

given the alarm to evacuate. The miners from Section A-3 were found 

dead with their self rescuers on in the No. 8 heading return air 

escapeway between Sections A-2 and A-3 along 3-North main inby the fire. 

The miners from A-2 section were found dead along the A-2 section 

beltway nearly halfway out of the section. 

The miners located directly inby the machine who were involved in 

the machine movement and fire fighting escaped from the inby area, when 

threatened by extensive smoke, by using a crosscut to a parallel entry 

to pass around the fire to the outby side of the machine. Heavy roof 

involvement of the fire occurred, resulting in roof collapse by Monday. 

The fire started on the Saturday evening maintenance shift, and all 

people were evacuated for the last time on Monday just after an 

explosion around 2 pm. The mine was eventually sealed. 

In summary: 

o The following key times were determined: 

T start is known (at approximate 7:30 pm) 

T detection = T start 

Arthur D Littie, Inc. 
T report01 about 5-10 minutes after T detect (to dispatcher) 

T report-2 about 30 minutes after T detect (to dispatcher 

and Section A-2) 

T report03 about 45 minutes after T detect (to dispatcher from 

Section A-2) 

T alarm-1 about 45 minutes after T detect (to A-2 from 

dispatcher) 

T report-4 about 45 minutes after T detect (to dispatcher from 

A-3) 

T alarm-2 about 1 hour after T detect (to A-3 from foreman) 

T evacuate about 1-1/4 hour after T detect (fire fighting 

o The pager phone line survived in the fire haulageway up to, 

and for an unknown time after, the time (1 hour after T start) 

which all the miners inby the fire were told to leave the 

mine. 

o The roof coal was heavily invsolved in the fire and was perhaps 

the region of the greatest concentration and spreading of the 

fire. 

o Miners working in the sectiorls inby, the fire would probably 

have been saved if an alarm to evacuate the inby areas had 

been given soon after report of the fire. Effective emergency 

response procedures need to be adopted by coal miners, and 

mine personnel need to be properly trained and drilled in 

these procedures. 

Arthur D Little, inc. 
B. SUMMARY OF EWOR SECTION FIRE 

NEMACOLIN COAL NINE 'FIRE ON 3/26/71 

This was an electrically initiated fire which resulted in three (3) 

fatalities and no injuries. The fire occurred in a development section 

on 118 '~ains Straight', and required that the miners on two threatened 

sections be given an alarm to escape. The sections included the one in 

which the fire occurred, and the adjacent section called 118 'Mains 

Left' perpendicular to 'Mains Straight.' 

The fire started unnoticed within 2-112 hours of start of the 

morning shift, in a section track entry containing an air compressor. 

This entry was 2 entries away from a track entry with loaded cars, and 

3, 4, and 5 entries from miners operating roof bolting equipment and 

operating a continuous miner. Detection of the fire nay have taken 

long, perhaps as long as 2-112 hours or as short as 114 to 112 hour. 

However, once discovered, its presence was reported to the dispatcher 

via the pager phone at the junction of 'Mains Straight' and 'Mains Left' 

within minutes. 

The dispatcher was informed of the fire, was requested to send 

additional help, and was told to inform workers in the adjacent 'Mains 

 eft ' section to leave the mine (which they did safely). DC power was 

cut off to the fire area via two trolley wire cut-out switches within 

minutes of the discovery by the section foreman. Workers in the section 

with the fire were also informed and directed to exit the section within 

minutes of fire discovery; with the exception of a roving mason, whose 

location in the section was unknown. (He was later found dead in an 

entry on the opposite side of the fire from the rest of the men.) This 

on-section alarm was made by voice and personal contact with each 

individual. 

Arthur D Little, Inc. 
None of the three fatalities were caused by failure to use, or 

non-performance of, the pager phone com~unication system in existence at 

this time. However, if an emergency warning system utilizizg a howler 

siren-type alarm incorporated in the pager phone system had been 

installed, even the roving mason night have been alerted and possibly 

saved. The second fatality occurred because one of the roof bolt 

operators, once safe, returned to his machine to retrieve his flame 

safety lamp before escaping. He never returned. The third fatality, by 

drowning, occurred several days later during flooding and sealing 

operations. 

The clue leading to fire discover:^ at this mine was loss of air 

pressure by the roof bolt stopeing macihine located three entries away 

from the air compressor. Once smoke was subsequently discovered in the 

number 2 entry by the stoper operator, the effects of the fire, 

particularly in terms of smoke (initially yellow in this case) and other 

combustion productions, spread rapid1:y through the section. This 

created a very hazardous situation requiring the evacuation of all 

section personnel before ascertaining the final location of the mason. 

Though there seems to be some questions as to the exact cause of 

the fire, it appears that the principal factor was the replacement of a 

200 amp fuse on a trailing cable nipped to the dc trolley wire with a 

300 amp fuse. This apparently led to the deterioration of the trailing 

cable to the compressor, and to the electrical failure of this cable and 

the mechanical/electrical failure of a trolley wire support near the nip 

point. These failures occurred during the morning shift. The 200 amp 

fuse had been replaced by a 300 amp fuse on the midnight shift of the 

previous day by another stoper operator. 

The following key investigative 0b:servations were made regarding 

the nature of the fire and the survivz.bility of trailing cables and 

power cables within the number 2 entry in which the fire started. 

Arthur D Little, Inc 
First, it was found that the fire was mostly concentrated along, or 

confined to, the roof areas of the entry, and had commenced between the 

nip point and the compressor. Burning was also indicated along the 

roof, and in some loaded coai cars, in the number 4 entry, and in the 

crosscuts between entries 3 and 4. Machinery and equipment in the fire 

entries did not reveal any signs of being on fire, another indication of 

the fire's confinement to the roof coal in the entries. This is further 

supported by the fact that sections of trailing cable and power cables 

suspended from the roof were destroyed by the heat and flame, while 

sections of cables on or near the mine floor showed no evidence of heat 

or flame. Evidence also indicated that control cables on a car spotter, 

presumably in entry 4, developed a short circuit due to the destruction 

of the cable insulation by flame and heat. 

A final observation of importance is concerned with the hydraulic 

hoses on the compressor. The sides of the hoses facing the fire were 

charred and blistered, while the sides of the hoses facing away from the 

fire showed no evidence of charing or blistering. Similarly, sections 

of the hoses shielded from the fire by parts of the compressor were not 

damaged. We believe that the charing and blistering in these cases were 

caused by radiative transfer and not by contact with the flames. 

In summary: 

o The following key times were determined: 

T start of fire is unknown, 

T fire detection is uncertain (maybe as short as 1/4 to 

1/2 hour, to as long as 2--1/2 hours after T start), 

T fire report to dispatcher was within about 10 minutes cf 

initial detection, 

T alarm to men was within about 5 minutes of T report. 

Arthur D Little, Inc. 
o The pager phone cable extending outby the 118 'Mains Left' and 

'Mains Straight' junction phone survived up to and beyond the 

tine (about 15-30 minutes after fire detection) when the 

miners left both threatened siections of the mine. Phone cable 

located close to the source of the fire on 'Mains Straight' 

section eventually burned, time unknown. 

o The fire was prinarily confirled to (at least for some time), 

and spread by, the roof coal in the entries involved. 

o A general alarm howler system might have saved at most one 

person. 

Arthur D Little, Inc 
C. SUMMARY OF MAJOR SECTION EXPLOSION 

FINLEY NO. 15 MTD 16 C0,4L MINES EXPLOSION ON 12/30/70 

This was a coal dust explosion which killed 38 of the 39 men who 

were underground at the time. No. 15 and 16 are drift mines side by 

side, together forming a "T", each mine consisting cf approximately 1/2 

of a vertically bisected "T". The explosion was initiated in mine No. 

16, at a boom hole being blasted for a load point on the left side of 

the top leg of the "T". The investigation showed 14 of the 17 men in 

mine No. 16 were killed instantly by the explosion, while 3 others may 

have moved a short distance of at most 100 feet from their work site 

before dying, presumably from asphyxiation or carbon monoxide poisoning. 

Nineteen out of the 21 men in mine No. 15 were apparently killed 

instantly by the explosion, while the other two may have moved a short 

distance of about 140 feet before dying, presumably from asphyxiation or 

carbon monoxide poisoning, shortly after the explosion. The lone 

survivor was located at the portal of th~e belt entry of the No. 15 drift 

mine. He was injured only slightly by the explosive force and debris 

coming from the mine. 

Both blast and flame fronts occurred during this explosion. The 

primary damage was caused by the force of the blast. The forces 

involved from the explosion were substantial, blowing out a large number 

of concrete stoppings throughout the mine. The explosion forces 

extended throughout the whole mine workings and out the portals, while 

the flame front extended over approximately 80% of the mine workings. 

The top of "T" was about 1,750 feet long while the base of the "T" was 

abcut 2,000 feet long at this mine. Although not stated, it appears 

that the force of the blast would have ruptured or severed nearby 

communication cables in light' of the substantial destruction observed by 

the investigating team. However, even if the communication cables did 

survive, the severity of the coal dust e:rplosion was such that no miners 

survived to use them. 

53 Arthur D Little, Jnc. pppppp - 
Self-rescuers were not carried by the nien, however, 21 NSA one-hour 

self-rescuers were stored in a metal container in No. 16 mine. There 

were no self-rescuers stored in mine No. 15, but 16 of them were stored 

in a trailer on the surface. Investigation showed nore than 60 concrete 

block stoppings were completely or partially blown out, equipment moved, 

belt-conveyor structures damaged, and explosion doors blown open. 

The conclusion of the investigating team was that the explosion 

occurred when coal dust was thrown into suspension and ignited during 

the blasting of roof rock for a loading point (boom hole). Excessive 

accumulations of coal dust, and inadequate applications of rock dust, in 

parts of No. 15 and 16 mines permitted the explosion to propagate 

throughout both mines. The geometric configuration of the mines also 

allowed the forces to expand rapidly from the point of origin, and to 

become less intense while traveling toward the surface. Rock dust 

applications in the main entries assisted in damping the explosion as it 

traveled toward the surface. Evidence indicated that the flame front 

spread to within 23 pillars of the mouth of the drift mine, but 

extensive burning did not occur after the explosion. 

In summary, this was a violent coal dust explosion that extended 

throughout this relatively small dri.ft mine. Although not stated, we 

assume thzt the excessive forces would have destroyed communication 

cables in the vicinity of the explcsion. Furthermore, if the 

communication cables had survived, the force of the blast was such that 

the instantaneous and near-instantaneous deaths of all miners would have 

prevented the use of such communication cables after this type of severe 

explosion. The lone survivor was located at the mine portal, and thus 

did not need to communicate via the mine pager phone cable. 

Arthur D Little, Inc. 
D. SUMNARY OF A MINOR SECTION EXPLOSION 

SILTIX COAL MINE EXPLOSION ON 7/23/66 

This was a methane gas explosion that claimed the lives of seven 

out of the eight men working on a development section at the end of 

2-Left Mains of the Siltix mine. The layout of this part of the nine 

can be visualized as a crucifix-shaped cross formed by 2-Left Mains, and 

the 6-Left and 6-Right working sectiorls perpendicular to 2-Lef t Mains, 

with the 2-Left Mains development section forming the top part of the 

cross. 

The flames extended about 700 feet beyond the explosion igniticn 

source in 2-Left Mains section, down to the beginning of the junction 

between 2-Left Mains and the 6-Left and 6-Right sections. The explosion 

forces extended to about 1700 feet beyond the ignition source, but were 

greatly attenuated after reaching the junction of the 6-Left and 6-Right 

sections. All evidence indicated that the explosion was a relatively 

weak methane gas explosion. Coal dust entered into the explosion's 

propagation only to a minor degree. The explosion was caused by 

ignition of a body of methane by an electrical spark from a shuttle car 

trailing cable during the morning of a normal day shift. Men working on 

both 6-Left and 6-Right sections communicated with the mine 

superintendent who was located at the underground motor pit, via the 

mine pager phone line which remained intact during and after the 

explosion. A miner shoveling coal onto the belt at the junction of 

2-Left Mains and 6-Left section was blown over by the blast and tossed 

about 60 feet. Upon recovery, he moved to the 6-Left junction pager 

phone and also notified the mine superintendent of the occurrence. 

Miners on 6-Left section felt an unusually strong blast of wind, 

and saw dust suspended in the air afterwards. The mine foreman, who was 

on the 6-Left section, instructed the 6-Left section foreman to 

assemble his men at the section phone while he attempted to learn what 

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had happened. Once assercbled at the phone, communication was 

established via pager phone with the cline sqerintendent, who asked the 

section foreman tc ascertain what happened. The section foreman walked 

outby the phone about 1000 feet, returned after he noted nothing 

unusual, and recalled the superintendent. The superintendent informed 

the section foreman of the explosion i11 2-Left Mains, and instructed him 

to take his crew out of the mine by the 6-Left fresh air entry. These 

men encountered smoke approximately 1000 feet outby the phone, and 

switched over to a return airway, where they also encountered smoke upon 

reaching the No. 1 entry of 2-Left Mains. Their escape being blocked, 

they returned to a suitable place in No. 2 entry of 6-Left section, and 

constructed a barricade in a crosscut. Eleven men entered the barricade, 

where they remained until they were rescued in good condition 

approximately 45 minutes later. 

The section foreman and 10 men wo.rking on 6-Right section were not 

affected by the explosion. This crew was instructed from the surface by 

pager phone to deenergize their equipment and come to the surface, which 

they did. They arrived at the surface! without incident shortly before 

the miners in 6-Left section barricaded themselves. 

Only one miner survived on thme section where the explosion 

occurred. The four men nearest to the explosion were badly burned and 

died quickly. The lone survivor, a shuttle car operator, was found by 

the rescue team about 200 feet from the explosion lying on the ground 

behind his shuttle car. After the initial blast and flames, the section 

did not burn very much, which accounts in part for the miner's fortunate 

survival. However, in spite of his survival, he was in no condition to 

utilize the section's pager phone comunications, if it had also 

survived (unknown). 

56 Arthur D Little,Inc. 
As the superintendent proceeded towards 2-Left Mains after being 

informed of the explosion, he encountzred smoke and dust about 500 feet 

inbv the mouth of the 2-Left Hains. This smoke and dust became extremely 

dense as he approached the affected sections. Therefore, the chief 

electrician was sent to the mouth of ?-Left Mains to deenergize all 

power circuits. The superintendent and other miners then advanced to 

the 6-Right junction, and continued to reestablish the ventilation 

on their way to the affected sections. The last body of the victims was 

found around 5 p.m. the day of the explosion, and all bodies and members 

of the recovery crew were removed from the nine by 6:15 p.m. 

In summary, this was primarily a weak methane gas explosion caused 

by electrical sparks together with bad ventilation which resulted in a 

gas build up in the face area. The main forces and flame effects were 

essentially confined to the section. Pager phone cables outside the 

section were not destroyed, thereby allowing comunications to and from 

adjacent sections 6-Lef t and 6-Right by mine supervisory personnel. 

These communications allowed the men in those sections to be alerted and 

instructed to leave the mine shortly after the explosion. No mention 

was made of the survivability of communications within the section where 

the explosion occurred. 

This is an example of an explosion which kills or incapacitates all 

miners on the section where it occurs;, but whose destructive effects 

remain essentially confined to that section. Thus, miners and 

communication equipment outside the section may not be threatened, at 

least initially, and are able to function in a way that permits effective 

alert and escape activities. However, survivability of the communication 

facilities within the explosion section becomes moot in cases such as 

these when no miners are alive or able to use them. 

Arthur D Little, Inc 
APPENDIX LV 

METHODOLOGY FOR CALCULATING CABLE BURIAL DEPTHS 

FOR ADVERSE ENVI:ROXf!IENTS 

The practical feasibility of cable burial depends to a large extent 

on the burial depth required to protect the cable from the adverse 

physical environment of fire and explosions. In the early phase of this 

study, we outlined a methodology for determining this burial depth as a 

function of the physical environmental conditions in the tunnel. 

During the course of the study, however, we found that the survival 

time over which the cable must function was nct defined, and had to be 

estimated from a detailed review of 'historical mine accident reports. 

Secondly, it became increasingly evident: that the overall need for cable 

burial was questionable. Accordingly, it was necessary to direct more 

of the effort towards assessing the specific needs, if any, for cable 

burial or for some less dramatic form of cable protection. 

This appendix summarizes the approach or methodology we formulated 

for defining cable burial depths to achieve various degrees of 

survivability under different environrn.enta1 stress conditions. This 

methodology can be used and integrated into a detailed cost/benefit 

analysis that the Bureau of Mines may wish to undertake in the future 

concerning cable protection. 

A. APPROACH 

The methodology is discussed for the case of thermal stress from a 

fire. It can also be applied to different types of stress from an 

explosion and from normal operating environments. 

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In fires, the heat output builds up to a maximum value and then 

decreases as the fire burns out. Some of this heat is transferred to 

the mine floor and is transmitted through it to a buried cable. As the 

cable insulation is heated, it may u~dergo physical and chemical changes 

depending mainly on the temperature reached. The burial depth, at which 

the cable will remain functional, can be detemined as follows: 

First, one can characterize the themal exposure expected from 

various types of fires that may occur i.n mines. For each fire, this can 

be represented as a constant heat flux level imposed over a given 

duration. The magnitude of the heat flux can be obtained from the 

experiments conducted by PRC, and its duration from review of MSZiA 

accident data. Note that each fire type may be associated with a range 

of heat fluxes and exposure durations. This is illustrated in Figure 

IV-1, where we indicate qualitatively the regicn where each fire type 

may be plotted. The indicated fire categories, which are described in 

the following section, were obtained from PRC mine fire investigators. 

Second, one can characterize the thermal endurance response of the 

cable to these thermal exposures, for various burial depths or other 

means of protection. This is portrayed qualitatively by three curves 

for three burial depths in Figure IV-1. Each curve gives the maximum 

exposure duration that can be withstood without cable functional damage, 

for a given heat flux impinging on the mine floor. These curves can be 

obtained by a heat conduction analysis through the mine floor material 

to the cable, along with a criterion for functional damage of the cable 

insulation. This criterion nay be the melting of the insulation, or 

some other manifestation of the thermal aging process. The primary 

thermal aging mechanism is oxidation for most materials used in mi~e 

communication cables. 

Arthur D Littk inc 
Arthur 132 Little, Inc 
Third, by comparing the thermal exposure and the cable endurance, 

one can determine the minimum burial depth required for each fire type. 

Note that a feasibility index (such as cost) can be attached to each 

burial depth curve. Furthermore, a probability estimate may be 

associated with each fire type or heat flux--duration level. This could 

be obtai~ed from review of detailed accident data. Thus, cost and 

benefit could be traded off using Figure IV-I or some modification 

thereof. 

B. PHYSICAL CHARACTERIZATION OF FIRES AND EXPLOSIONS 

We had a number of discussions with the staff of the Bureau of 

Mines associated with mine fire and explosion physics. These 

discussions identified the major categories or types of mine 

fires/explosions for which experimental data have been obtained. 

o A gob fire involving a heap of mixed coal, wood and other 

materials, formed by roof colltapse. 

o A shaft fire involving the wood structure of an air shaft. 

o A tunnel fire involving the coal. 

o A crib fire involving the wood cribs which support the roof. 

o A methane explosion. 

o A coal dust explosion. 

The Figure IV-1 sketch provides a qualitative comparison of the fire 

categories with respect to the relative ranges of expected flux levels 

and time durations. 

Arthur D Little, Inc. 
We collected and reviewed various reports describing comprehensive 

experimental investigations at the Bureau of Mines for these 

fires/explosions (Ref. 1-9). In these investigations, the heat flux 

from the fires has been measured or estimated. A heat flux value that 

is often quoted for a tunnel fire that is well developed is 2 cal/cm 2 

2 (80 kW/m ), a severe thermal environment. For explosion tests utilizing 

natural gas (mainly methane or natural gas/coal dust mixtures, unsteady 

deflagration was observed. The maximum static pressure and wind speed 

reached in these tests were approximately 20 psi and 800 fps, 

respectively. This could subject the cables to a severe mechanical 

stress. 

The frequency distribution of the duration of actual mine fires is * 

shown in Table IV-1 obtained from data in the Allen Corporation study. 

Note that approximately 65 to 70% of the fires last 4 hours or less. In 

recent years only about 20% lasted more than 24 hours. This gives some 

reference points for the required duration of cable survival (if survival 

is needed). In reality, the required cable survival time depends more on 

whether, and how long, affected miners are endangered. Thus, it can be 

significantly different from the values in Table IV-1. Finally, duration 

of the pressure pulse in an explosion is on the order of a second, and 

the need for cable survival also depends on the presence of surviving 

miners in the vicinity of the exp1os:ion. Therefore, more realistic 

information on the need for cable survivi3l and the corresponding survival 

durations had to be obtained by analyzing the emergency activities and 

fire and explosion dynamics described in MSHA accident reports (see 

Appendix 11). 

C. THERMAL PROPERTIES OF CABLES 

The thermal endurance of communication cables depends on the 

thermal zging of the cable insulation materials. Many cables used in 

* 

Op.cit, Appendix I. 

Arthur D Little, IRC. 
m a 49 3 . 'a* H cn C C 

d 30 

0 .?I 2$ h k 'u 3 I: 0-0 

m m b 

m CO r-l rl hl rl 

Arthur D Little Inc 
mines are constructed of ~aterials that are prone to aging by oxidation 

at elevated temperatures. These materials include cellulose, rubber, 

polyvinyl chloride, polyvinyl acetai, acrylic resins, and polyamides. 

The IEEE has established a thermal classification system for 

insulating materials that is shown in Table IV-2. The class assignments 

are based on the results of thermal aging tests. The temperature for 

each class indicates the operating temperature limit for which the 

material will achieve an expected lifetime. As the temperature rises 

above this value, the cable lifetime will generally be shortened 

according to the logarithmic re1ationshi.p: 

Log L = A + B/T 

where 

L = life in hours 

T = absolute temperature in OK 

A, B are constants. 

Mine communication cables are likely to fall into classes 0, A and 

B, with Class A (105°C) probably being the most representative. Saums 

and Pendleton (Ref. 10) indicate that the average life of a Class A 

insulating material, with a 20,000 hour lifetime at 105"C, will decrease 

to about 100 hours at 200°C and 10 hours at 250°C. The figure shows 

that the life of even the highest rated Class C materials (> 250°C) 

plummet to about 10 hours at temperatures around 350°C. 

This brief discussion on the thermal response of cable insulation 

has been included to indicate an approach and resources for defining 

criteria for cable functional failure that can be applied in the 

methodology described in Section A of this Appendix. 

Arthur D Little, Inc. 
TABLE IV--2 

IEEE THEFW CLASSIFICATION SYSTEM 

Class 

Class 0 

Class A 

Class B 

Class F 

Class H 

* 

Class 200 

** 

Class 200 

Class C 

Tem~erature O C A~~licable Materials 

90 Uninpregnated celluiose 

Polyvinyl acetal, polyurethane, 

impregnated cellulose, polyamide 

Epoxy, polyester glass (styrene type) 

phe~olic glass 

Tereplhthalate polyester, modified 

silic.one 

Silicone, silicone glass, silicone 

rubber, ester-imide, cyanurated 

terephthalate polyester 

Amide-imide overcoated ester-imide, 

amide-imide overcoated polyester 

Amide-imide, polyimide, hightemperzture polyzmide fibers? 

Polytetrafluoroethylene, glass, 

ceraaics 

Source: Saums, H. L. and Pendleton, W.W., ateri rials for Electrical 

Insulating and Dielectric Functions, Hayden Book Co., N.J., 

1973. 

* 

U.S. Navy-designated as Class K. ** 

Industry-designated as Class 11. i 

DuPont ' s Nomex 

65 Arthur D Little, Inc. 
. OPERATIONAL CONSIDERATIONS 

Our interviews with several government and industry mining personnel 

revealed some practical operational considerations that are briefly 

summarized below. The objective is a survivable communication link for 

emergency connunications with endangered and/or trapped miners and with 

mine rescue/recovery teams, in post disaster environments. An important 

parallel objective, of course, is its availability and practicality for 

daily operational communications. 

In practice, it was felt that two to three hour cable survival times 

for communicating with endangered/trapped miners in fire and explosion 

environments would meet most needs. This . is not inconsistent with most 

of the preliminary estimates of miner survival time tabulated in Appendix 

11. As suggested in Appendix I1 and the body of this report, additional 

protection is not generally needed, and burial may not be the most 

practical way to obtain whatever short-term protection may be needed. 

For extended duration communications among the rescue/recovery tean 

members and between these and the surface, a system that is not totally 

dependent on the mine pager phone system appears to be the most 

realistic. Recent Bureau of Mines spclnsored developments in portable 

medium frequency radio communications may provide the best equipment for 

meeting the needs of mine rescue/recovery teams. This possibility should 

be investigated. 

To satisfy daily operational needs, the pager phone communication 

link must have a high availabili.ty, practical maintainability, and 

reasonable installation and operating .Life time costs. Communication 

cable burial will cause some increases in installation costs, depending 

on burial depth, quality of cable needed, and floor material, and some 

changes in maintenance costs. Since 60-70% of the nining operations in 

Appalachia are smaller than 70,000 tons per year, any csble protection 

guidelines dramatically different from current mine practice should be 

checked for their economic impact on such mines. 

Arthur D Little, Inc. 
The following paragraphs present some summary considerations of the 

effects of cable burial on both the cable and the mine tunnel. The MSPA 

Roof Control and Geotechnical Serv:ices groups provided us with 

information on mine roof novement and nine opening stability of interest 

to cable burial. 

They are not sure if a trench in the middle of an entry would 

adversely effect roof control stabilitly. They tend to think that a 

shallow trench on the order of 18 to 20 inches would probably have no 

major effect. It could, however, initiate bottom movement by relieving 

certain counter-balancing lateral forces which surround the mine opening. 

There would be three types of movements which would effect the cable: 

offsets, vertical thrust vaulting, and squeezing. They feel that the 

actual degree of movement would be very unpredictable and that there is a 

strong need for additional study before any buried mine communication 

systems are considered feasible. Apparlently, 10% of the coal mines in 

the United States have minimal bottom movenent, 10% have excessive bottom 

movement, and 80% have bottom m~venent present, but its magnitude is 

undefined and needs to be further studied. 

MSHA staff also provided infornation that shows roof movement is 

very active ten to fifteen days after the opening is made. There is an 

exponential time/movement relationship within the first week of mining. 

These movements are very localized and suggests that cable stretchability 

will not be an important design factor. In their opinion, the further 

the communication system lags behind at the initial development, the more 

stable the environment will be and the less likely that the cable will be 

severed or pinched. Using the typica:L figure of 100 feet of face 

advancement per week, this could prevent cable burial within up to about 

4-6 crosscuts. This creates some serious problems with regard to the 

objective of communicating with miners trapped in face areas, and raises 

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questions such as: Kould a buried mine communication cable be of any use 

to workers operating in a face area 100 to 250 feet from the lzst cable 

terminal post? Would a communication line from the last permanent 

terminal post to the working area be any more reliable than a simple 

two-wire phone system typically in existence in most mines? Even if the 

cable is buried, will the unburied phone survive? There is also the 

problem of keeping the cable at the face. How will the cable be extended 

to the working area during advance mining without using numerous splices? 

The complexity of the splices and the need for secure watertight 

connections could have a severe impact on the reliability of the system. 

The importance of keeping the cable back from the face area was 

illustrated by analytical data shown by the roof control people. One 

question arises as to whether the roof's movement is a rough 

approximation to movements in the floor. At the present time, no one has 

taken the time to drill bore holes into the floor to study its movement, 

to see if there is a correlation between floor and roof movement. Based 

on the distribution of forces, one mig:ht roughly assume that the same 

timelmovement relationships exist in the floor. If so, this suggests a 

need to lag cable burial by ten to fifteen days (200 to 300 ft) behind 

the active face area. 

We also obtained coments on a nunber of issues concerning potential 

movements in the roof and floor as a result of the trenching activity. 

One could expect minimal impact with regard to mine opening stability if 

the trench is less than 24 inches deep, but crushing of the cables should 

be expected to occur during the life of the phonz system. The 

possibility was also pointed out that existing fracture fault systems 

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might be activated locally by trenching, and that additional research is 

needed to evaluate this possibility. Thus additional work should focr?s 

oc ths time distance relationship between the face, time of mining, and 

the resulting adjustments in the rcof, the rib and the floor. 

In summary, there nay be major problems associated with advancing 

buried cable to the face area where the men will probably be when an 

explosion occurs. If roof movement is a close approxination to what can 

be expected for the floor, movements can be expected for tsn to fifteen 

days after a face is mined. Using an average face advance of 100 feet 

per week, there is a major question as to whether the phone system will 

be available at the face where it might be needed in an emergency. 

Splicing, to keep the system moving with the mine advsnce, will almost 

certainly result in decreased system reliability. The potential problem 

of reactivating local and regional fault systems which cross through the 

mine opening needs additional research to evaluate this possibility. 

Arthur DLittle,Inc. 
Chaiken, Robert, F., et al, "Modei Coal Tunnel Fires in Ventilation 

 low," Washington, D.C. : U.S. Department of the I~terior, 1979, RI 

8355. 

Bwang, Charles C., "Effect of Duct Fire on the Ventilation Air 

Velocity," Washington, D.C.: U.S. Department of the Interior, 1978, 

RI 8311. 

Johnson, A. L., et al, "~nfrared Spectrai Radiances and Expiosion 

Properties of Inhibited Methane-Air Flames, Washingtor~, D.C.: U.S 

Department of the Interior, 1977, RI 8246. 

Kuchta, J. M., et. al, "Criteria of Incipient Combustion in Coal 

tlines," Reprinted from the Fifteenth Symposium (International) on 

Combustion, Tokyo, Japan, 25-31, 1974, Pennsylvania: The 

Combustion Institute, 1974. 

Lee, Calvin, K., et al, "Interaction Between Duct Fires and 

Ventilation Flow: An Experimental Study,'' Combustior, Science and m ~echnology, 20: 59-72, 1979. 

Nagy, John, et al, "Controllicg Mine Fires with High Expansion 

Foam, Washington, D.C.: U.S. Depa-rtment of the Interior, 1960, RI 

5632. 

Nagy, John, et al, "Tests on Control of Coal-Mine Fires in the 

Experimental Coal Mine, Washington., D.C.: U.S. Department of the 

Interior, 1950, RI 4685. 

Richmond, J. K., et al, "~ffect of Rock Dust of Explosibility of 

Coal Dust, Washington, D.C.: U.S. Department of the Interior, 1975, 

RI 8066. 

Sapko, M. J., et al., "Flame and Pressure Development of 

Large-Scale CH -Air-N Explosions:, Buoyancy Effects and Venting 

Requirements," bashing$on, D. C. : U. S. Department of the Interior, 

1976, RI 8176. 

Saums, H. L. and Pendleton, W. W., "~aterials for Electrical 

Insulating and Dielectric Functions," Hayden Book Co., N. J., 1973, 

Figure 4.1. 

Arthur D Little Inc. 
LIST OF PEOPLE COlVTACTED 

Visited 

Joseph Kuchta, BoM-PRC 

Kenneth Richmond, BoM-PRC 

David Burgess, BoF1-PRC 

Robert Chaiken, BoM-PRC 

Richard Reynolds, MSHA - Bruceton 

William Debovic, MSHA - Brucetoln 

George Karabin, MSHA - Bruceton 

Kevin Wu, MSHA - Bruceton 

Edward Kawenski, MSHA - Brucetoln 

George Price, MSHA - Bruceton 

Robert Baker, Allen Corp. 

Christopher Duncan, Allen Corp. 

John Burr, Lee Engineering Div., Consol Coal 

Telephoned 

Claude Reich, MSHA - PTSC 

John Nagy, MSHA Retired 

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