28796 Federal Register / Vol. 72, No. 98 / Tuesday, May 22, 2007 / Rules and Regulations 

DEPARTMENT OF LABOR 

Mine Safety and Health Administration 

30 CFR Part 75 

RIN 1219–AB52 

Sealing of Abandoned Areas 

AGENCY: Mine Safety and Health 

Administration (MSHA), Labor. 

ACTION: Emergency temporary standard; 

Notice of public hearings; Notice of 

close of comment period. 

SUMMARY: The Mine Safety and Health 

Administration (MSHA) is issuing an 

emergency temporary standard (ETS) 

under section 101(b) of the Federal 

Mine Safety and Health Act of 1977 in 

response to the grave danger that miners 

face when underground seals separating 

abandoned areas from active workings 

fail. MSHA has concluded from its 

investigations of mine explosions that 

occurred and other recent reports, that 

additional immediate action is 

necessary to protect miners. This ETS 

includes requirements to strengthen the 

design, the construction, the 

maintenance, and the repair of seals, as 

well as requirements for sampling and 

controlling atmospheres behind seals. It 

also increases the level of overpressure 

for new seals, thus implementing the 

requirements of the Mine Improvement 

and New Emergency Response (MINER) 

Act of 2006. 

DATES: This emergency temporary 

standard is effective May 22, 2007. This 

standard must be replaced with a final 

rule within 9 months. MSHA will hold 

public hearings on July 10, 2007, July 

12, 2007, July 17, 2007 and July 19, 

2007 at the locations listed in the Public 

Hearings section below under the 

SUPPLEMENTARY INFORMATION section of 

this document. If individuals or 

organizations wish to make an oral 

presentation for the record, the Mine 

Safety and Health Administration 

(MSHA) is asking that you submit your 

request at least 5 days prior to the 

hearing dates. The comment period will 

close on July 6, 2007. 

ADDRESSES: Comments must be clearly 

identified and may be submitted by any 

of the following methods: 

(1) Federal Rulemaking Portal: http:// 

www.regulations.gov. Follow the 

instructions for submitting comments. 

(2) Electronic mail: zzMSHAComments@dol.gov. Include ‘‘RIN 

1219–AB52’’ in the subject line of the 

message. 

(3) Telefax: (202) 693–9441. Include 

‘‘RIN 1219–AB52’’ in the subject. 

(4) Regular Mail: MSHA, Office of 

Standards, Regulations, and Variances, 

1100 Wilson Blvd., Room 2350, 

Arlington, Virginia 22209–3939. 

(5) Hand Delivery or Courier: MSHA, 

Office of Standards, Regulations, and 

Variances, 1100 Wilson Blvd., Room 

2350, Arlington, Virginia 22209–3939. 

Sign in at the receptionist’s desk on the 

21st floor. 

Docket: Comments can be accessed 

electronically at www.msha.gov under 

the ‘‘Rules and Regs’’ link. MSHA will 

post all comments on the Internet 

without change, including any personal 

information provided. Comments may 

also be reviewed at the Office of 

Standards, Regulations, and Variances, 

1100 Wilson Blvd., Room 2350, 

Arlington, Virginia. 

MSHA maintains a listserve that 

enables subscribers to receive e-mail 

notification when rulemaking 

documents are published in the Federal 

Register. To subscribe to the listserve, 

go to http://www.msha.gov/ 

subscriptions/subscribe.aspx. 

Information Collection Requirements: 

Comments concerning the information 

collection requirements must be clearly 

identified as such and sent to both the 

Office of Management and Budget 

(OMB) and MSHA as follows: 

(1) OMB: All comments must be sent 

by mail addressed to the Office of 

Information and Regulatory Affairs, 

Office of Management and Budget, New 

Executive Office Building, 725 17th 

Street, NW., Washington, DC 20503, 

Attn: Desk Officer for MSHA; and 

(2) MSHA: Comments must be clearly 

identified by RIN 1219–AB46 as 

comments on the information collection 

requirements and transmitted either 

electronically to zzMSHAComments@dol.gov, by facsimile to 

(202) 693–9441, or by regular mail, hand 

delivery, or courier to MSHA, Office of 

Standards, Regulations, and Variances, 

1100 Wilson Blvd., Room 2350, 

Arlington, Virginia 22209–3939. 

Hearings: Locations of the public 

hearings are in the SUPPLEMENTARY

INFORMATION section of this document. 

FOR FURTHER INFORMATION CONTACT: 

Patricia W. Silvey, Director, Office of 

Standards, Regulations, and Variances, 

MSHA, 1100 Wilson Blvd, Room 2350, 

Arlington, Virginia 22209–3939, 

silvey.patricia@dol.gov (e-mail), (202) 

693–9440 (voice), or (202) 693–9441. 

(telefax). 

SUPPLEMENTARY INFORMATION: The 

outline of this ETS is as follows: 

I. Public Hearings 

II. Introduction 

III. Basis for the Emergency Temporary 

Standard 

A. Regulatory Authority 

B. Grave Danger 

IV. Discussion of the Emergency Temporary 

Standard 

A. Background 

B. General Discussion 

C. Section-by-Section Analysis 

V. Executive Order 12866 

A. Population-at-Risk 

B. Benefits 

C. Compliance Costs 

VI. Feasibility 

A. Technological Feasibility 

B. Economic Feasibility 

VII. Regulatory Flexibility Act and Small 

Business Regulatory Enforcement 

Fairness Act (SBREFA) 

A. Definition of a Small Mine 

B. Factual Basis for Certification 

VIII. Paperwork Reduction Act of 1995 

A. Summary 

B. Details 

IX. Other Regulatory Considerations 

X. References 

XI. Emergency Temporary Standard— 

Regulatory text 

I. Public Hearings 

MSHA will hold four public hearings 

on the ETS. The public hearings will 

begin at 9 a.m. and end after the last 

speaker speaks, and in any event not 

later than 5 p.m., on the following dates 

at the locations indicated: 

Date Location Phone 

July 10, 2007 ............. Lakeview Golf Resort and Spa, One Lakeview Drive, Morgantown, WV 26508 ..................................... 800–624–8300 

July 12, 2007 ............. Crowne Plaza Hotel, 1375 South Broadway, Lexington, KY 40504 ........................................................ 859–255–4281 

July 17, 2007 ............. Embassy Suites Denver, 7525 East Hampden Avenue, Denver, CO 80231 .......................................... 303–696–6644 

July 19, 2007 ............. Sheraton Birmingham Hotel, 2101 Richard Arrington Jr. Boulevard North, Birmingham, AL 35203 ...... 205–324–5000 

The hearings will begin with an 

opening statement from MSHA, 

followed by an opportunity for members 

of the public to make oral presentations. 

You do not have to make a written 

request to speak. Speakers will speak in 

the order that they sign in. Any 

unallotted time will be made available 

for persons making same-day requests. 


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Federal Register / Vol. 72, No. 98 / Tuesday, May 22, 2007 / Rules and Regulations 28797 

1MSHA Report of Investigation/Mine Explosion, 

Sago Mine, January 2, 2006 and MSHA Report of 

Investigation/Mine Explosion, Darby Mine Number 

1, May 20, 2006. These reports can be found on 

MSHA’s Web site at: http://www.msha.gov. 

At the discretion of the presiding 

official, the time allocated to speakers 

for their presentation may be limited. 

Speakers and other attendees may also 

present information to the MSHA panel 

for inclusion in the rulemaking record. 

The hearings will be conducted in an 

informal manner. The hearing panel 

may ask questions of speakers. Although 

formal rules of evidence or cross 

examination will not apply, the 

presiding official may exercise 

discretion to ensure the orderly progress 

of the hearing and may exclude 

irrelevant or unduly repetitious material 

and questions. A verbatim transcript of 

the proceedings will be prepared and 

made a part of the rulemaking record. 

Copies of the transcript will be available 

to the public. The transcript will also be 

available on MSHA’s Home Page at 

http://www.msha.gov, under Statutory 

and Regulatory Information. 

MSHA will accept post-hearing 

written comments and other appropriate 

data for the record from any interested 

party, including those not presenting 

oral statements. Written comments will 

be included in the rulemaking record. 

II. Introduction 

This ETS is issued under section 

101(b) of the Federal Mine Safety and 

Health Act of 1977 (Mine Act) as 

amended by the Mine Improvement and 

New Emergency Response Act of 2006 

(MINER Act), 30 U.S.C. 811(b). The ETS 

establishes or revises standards in part 

75—subpart D—Ventilation. These new 

standards strengthen the design, 

construction, maintenance, and repair of 

seals and monitoring and control of 

atmospheres behind seals in order to 

reduce the risk of seal failure and the 

risk of explosions in abandoned areas of 

underground coal mines. 

In accordance with section 101(b)(3) 

of the Mine Act, an Emergency 

Temporary Standard (ETS) serves as 

both a final rule with immediate effect 

and a proposed rule to establish a final 

rule through the notice and comment 

process. Therefore, the final rule may 

differ from an ETS just as any final rule 

may differ from a proposed rule. The 

Mine Act states that the ETS is a 

temporary standard and must be 

superseded by a final rule within nine 

months. The Legislative History of the 

Mine Act reinforces the statutory 

language regarding the ETS serving as a 

proposed rule ‘‘so that all views can be 

carefully considered in connection with 

the issuance of a permanent standard.’’

S. Rept. 181, 95th Cong., 1st Sess. 24 

(1977). 

The preamble discusses specific 

provisions that may be included in the 

final rule and MSHA solicits comments 

on these provisions. 

III. Basis for the Emergency Temporary 

Standard 

A. Regulatory Authority 

Section 101(b) of the Mine Act 

provides that: 

1. The Secretary shall provide, 

without regard to the requirements of 

chapter 5, title 5, United States Code, for 

an emergency temporary mandatory 

health or safety standard to take 

immediate effect upon publication in 

the Federal Register if [s]he determines 

(A) that miners are exposed to grave 

danger from exposure to substances or 

agents determined to be toxic or 

physically harmful, or to other hazards, 

and (B) that such emergency standard is 

necessary to protect miners from such 

danger. 

2. A temporary mandatory health or 

safety standard shall be effective until 

superseded by a mandatory standard 

promulgated in accordance with the 

procedures prescribed in paragraph (3) 

of this subsection. 

3. Upon publication of such standard 

in the Federal Register, the Secretary 

shall commence a proceeding in accord 

with section 101(a) [involving notice 

and comment], and the standards as 

published shall also serve as a proposed 

rule for the proceeding. The Secretary 

shall promulgate a mandatory health or 

safety standard under this paragraph no 

later than nine months after publication 

of the emergency temporary standard as 

provided in paragraph (2). 

An ETS is an extraordinary measure 

provided by the Mine Act to enable 

MSHA ‘‘to react quickly to grave 

dangers that threaten miners before 

those dangers manifest themselves in 

serious or fatal injuries or illnesses.’’ S. 

Rept. 181, 95th Cong., 1st Sess. 23 

(1977). Additionally, ‘‘* * * once the 

Secretary has identified a grave danger 

that threatens miners the Committee 

expects the Secretary to issue an 

emergency temporary standard as 

quickly as possible, not necessarily 

waiting until [she] can investigate how 

well that grave danger is being managed 

or controlled in particular mines.’’

Senate Report at 24. An ETS takes effect 

upon publication in the Federal 

Register, and is a fully enforceable 

standard. 

To assure the comprehensive 

protection of miners, the ETS authority 

applies to all types of grave dangers 

without qualification. The legislative 

history of the Mine Act emphasizes that 

‘‘to exclude any kind of grave danger 

would contradict the basic purpose of 

emergency temporary standards 

protecting miners from grave dangers.’’

S. Rept. 181, 95th Cong., 1st Sess., 24 

(1977). The ETS authority thus covers 

dangers arising from exposure to toxic 

or physically harmful substances or 

agents and to ‘‘other hazards.’’ It applies 

to dangers longstanding or novel, to 

dangers that ‘‘result from conditions 

whose harmful potential has just been 

discovered’’ or to which large numbers 

of miners are ‘‘newly exposed.’’ Id. 

A record of fatalities or serious 

injuries is not necessary before an ETS 

can be issued because ‘‘[d]isasters, 

fatalities, and disabilities are the very 

thing this provision is designed to 

prevent.’’ Id. at 23. At the same time, the 

legislative history of the Mine Act is 

clear that an ETS is not limited to new 

dangers in the mining industry: ‘‘That a 

danger has gone unremedied should not 

be a bar to issuing an emergency 

standard. Indeed, if such is the case the 

need for prompt action is that much 

more pressing.’’ Id. at 24. 

When issuing an ETS, MSHA is ‘‘not 

required to prove the existence of grave 

danger as a matter of record evidence 

prior to taking action.’’ Id. The 

legislative history expressly recognizes 

‘‘the need to act quickly where, in the 

judgment of the Secretary, a grave 

danger to miners exists.’’ Id. The ETS is 

a critical statutory tool that MSHA can 

use to take immediate action to prevent 

the loss of life in the mines. MSHA 

accordingly has employed an ETS 

previously to order ‘‘hands-on’’ training 

for miners in the use of self-contained 

self-rescue (SCSR) devices 52 FR 24373 

(June 30, 1987), to order certain training 

and mine evacuation procedures for 

underground coal mines 67 FR 76658 

(December 12, 2002) and to order new 

accident notification timeframes, 

provide new safety equipment, training 

and drills in mine emergency 

evacuations 71 FR 12252, (March 9, 

2006). 

B. Grave Danger 

Based on MSHA’s accident 

investigation reports of the Sago and 

Darby mine explosions,1 the National 

Institute for Occupational Safety and 

Health’s (NIOSH) reports on explosion 

testing and modeling, MSHA’s in-mine 

seal evaluations, and review of technical 

literature, MSHA has determined that 

new comprehensive standards for seal 

design approval, strength and 

installation approval, construction, 

maintenance and repair, sampling and 

monitoring, training and recordkeeping 


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are necessary to immediately protect 

miners from hazards of sealed areas. 

Underground coal mines are dynamic 

work environments in which the 

working conditions can change rapidly. 

Caved, mined-out areas may contain 

coal dust and accumulated gas which 

can be ignited by rock falls, lightning, 

and in some instances, fires started by 

spontaneous combustion. Seals are used 

to isolate and contain this environment 

of the active workings of the mine. 

Adequate seals are crucial to prevent an 

explosion from propagating to the outby 

side of the seal where miners work or 

travel. Seals must therefore be designed 

to withstand elevated pressures and 

contain explosions by preventing 

potentially explosive or toxic gasses 

from migrating into the active working 

areas of underground coal mines. 

Miners rely on seals to protect them 

from the hazardous and sometimes 

explosive environments within the 

sealed area. 

The existing safety standards for 

construction of solid-concrete block 

seals adopt specific construction 

criteria. Existing requirements 

addressing construction of seals using 

equivalent alternative materials and 

methods were established, as an interim 

measure, in MSHA’s Program 

Information Bulletin No. P06–16, ‘‘Use 

of Alternative Seal Methods and 

Materials Pursuant to 30 CFR 

75.335(a)(2)),’’ issued on July 19, 2006 

(July 2006 PIB). Under the July 2006 

PIB, MSHA increased the strength 

requirements for new alternative seals to 

reliably withstand an overpressure of at 

least 50 pounds per square inch gauge 

(psig) in the conditions in which they 

will be installed as demonstrated by 

well-defined and certified engineering 

designs. An alternative seal design 

could also be approved based on actual 

test results validating the psig. All seal 

construction must be approved by the 

District Manager in the mine’s 

ventilation plan. To be considered for 

approval, mine operators must have a 

professional engineer (PE) who is 

knowledgeable in structural engineering 

to certify seal designs and supporting 

data. In addition, the proposed 

ventilation plan must provide that a 

senior mine management official (such 

as mine manager, superintendent, etc.) 

certify that the construction, 

installation, and materials used were in 

accordance with the mine’s approved 

ventilation plan. Furthermore, the July 

2006 PIB requires an assessment of the 

atmosphere behind existing alternative 

seals to determine the potential for an 

explosion and to assess seal integrity. 

The July 2006 PIB requires the operator 

to take remedial actions which may 

include inerting the sealed atmosphere, 

increasing the capacity of the existing 

seal to withstand at least 50 psig 

overpressure, constructing an additional 

alternative seal having this capacity, or 

constructing a solid-concrete seal. 

Finally, the July 2006 PIB requires that 

high risk seals, (such as if failure could 

adversely affect miners’ safety) and seals 

with a poor performance history will 

require additional actions to better 

protect miners, including periodic 

monitoring of the atmosphere behind 

the seals. 

MSHA determined in the Sago 

accident that even though the seals were 

not constructed as approved in the 

ventilation plan, they still could 

withstand an explosion overpressure of 

21 psi. In the Agency’s root cause 

analysis of the Sago accident, MSHA 

found that: (1) The seals were not 

capable of withstanding the forces 

generated by the explosion; (2) The 

atmosphere in the sealed area was not 

monitored and it contained explosive 

methane/air mixtures; (3) Lightning was 

the most likely ignition source for the 

explosion with the energy transferring 

onto an abandoned pump cable in the 

sealed area and providing an ignition 

source for the explosion. MSHA found 

that the explosive forces generated 

behind the sealed area in the Sago 

accident were at least 93 psi. 

In the Darby accident, MSHA found 

that the seals were improperly 

constructed and had an inadequate 

pressure rating. MSHA also concluded 

that the use of an oxygen acetylene 

cutting torch to cut a metal strap outby 

a seal was the most likely ignition 

source. MSHA further concluded that 

when seals are improperly constructed, 

they present a hazard to miners, even 

when ignition sources are located outby 

the seal. 

When seals are improperly 

constructed and maintained, air may 

leak excessively through the seals, 

which may result in explosive 

conditions inby the seals. The air 

leakage causes increased levels of 

hazardous conditions whereby 

introduction of ignition sources could 

cause an explosion. Air leakage from the 

sealed area to active working areas 

could also contaminate the 

atmospheres, resulting in miners being 

exposed to potential explosions or toxic 

gasses. 

In addition, the ETS requires that 

insulated cables and metallic objects 

through or across seals be removed from 

the area to be sealed, and prohibits 

welding, cutting or soldering with an 

arc or flame within 150 feet of a seal. 

The July 2006 PIB’s interim action has 

serious limitations in that it fails to 

provide comprehensive protection for 

miners from the dangers of explosions 

in sealed areas: it only permits testing 

as one method of demonstrating seal 

strength; it does not address explosion 

forces generated behind a sealed area 

that are greater than 50 psi; it requires 

only a one-time assessment of the 

atmosphere behind the seal rather than 

a sampling plan approved by MSHA as 

required under the ETS; although the 

July 2006 PIB states that periodic 

monitoring of sealed areas may be 

required for high risk seals (such as if 

failure could adversely affect miners’

safety), a periodic monitoring frequency 

was not specified in the July 2006 PIB; 

the July 2006 PIB does not address the 

hazard of welding, cutting, and 

soldering with an arc or flame in close 

proximity to a seal. Therefore, hazards 

in existing sealed areas present a grave 

danger to miners. 

The Secretary has therefore 

determined that miners are exposed to 

grave danger if existing and new seals 

are not properly constructed, 

maintained, monitored, and repaired in 

accordance with this ETS. 

In addition, for the above-stated 

reasons under the Administrative 

Procedure Act (APA), 5 U.S.C. 553(b)(B) 

and (d)(3), MSHA finds good cause 

exists to dispense with notice and 

comment and make the ETS effective 

immediately. To delay the effective date 

of the ETS is contrary to the public 

interest because any delay in the ETS 

effective date further exposes miners to 

grave danger from inadequately 

designed, constructed, maintained, and 

repaired seals. 

IV. Discussion of the Emergency 

Temporary Standard 

A. Background 

In the Federal Coal Mine Health and 

Safety Act of 1969 (Coal Act), the 

predecessor to the existing Mine Act, 

Congress first recognized that mine 

operators must seal abandoned and 

isolated areas of underground coal 

mines for the protection of miners’

safety: 

In the case of mines opened on or after the 

operative date of this title, or in the case of 

areas developed on or after such date in 

mines opened prior to such date, the mining 

system shall be designed, in accordance with 

a plan and revisions thereof approved by the 

Secretary and adopted by the operator, so 

that, as each set of cross entries, room entries, 

or panel entries of the mine are abandoned, 

they can be isolated from active workings of 

the mine with explosion-proof bulkheads. 

Pub. L. 91–173 (Dec. 1969) Section 

303(2)(3)). 

In the conference report filed in the 

House, the statement of the managers on 


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the part of the House stated, regarding 

the requirement that an abandoned area 

of a mine either be ventilated or sealed 

that: 

[t]he determination of which method 

[(ventilated or sealed)] is appropriate and the 

safest at any mine is up to the Secretary or 

[her] inspector to make, after taking into 

consideration the conditions of the mine, 

particularly its history of methane and other 

explosive gases. The objective is that [s]he 

require the means that will provide the 

greatest degree of safety in each case. * * * 

When sealing is required, such sealing shall 

be made in an approved manner so as to 

isolate with explosion-proof bulkheads such 

areas from the active working of the mine. 

Under the conference substitute, paragraph 

(3) of section 303(z) provides that, in the case 

of mines opened on or after the operative 

date of this title, or in the case of areas 

developed on or after such date in mines 

opened prior to such date, the mining system 

shall be designed, in accordance with a plan 

and revisions thereof approved by the 

Secretary and adopted by the operator, so 

that, as each set of cross entries, room entries, 

or panel entries of the mine are abandoned, 

they can be isolated from active workings of 

the mine with explosion-proof bulkheads 

approved by the Secretary or his inspector. 

The managers expect the Secretary to take 

the lead in improving technology in this area 

of controlling methane accumulations in gob 

areas and to improve upon this important 

section 303(z). 

Conf. Rep. No. 91–761, 91Fst Cong. 1st 

Sess., 82 (Dec. 16, 1969) (statement of 

the managers on part of the House) 

(emphasis added). 

The Mine Act interim mandatory 

standards required seals to be ‘‘made in 

an approved manner so as to isolate 

with explosion-proof bulkheads such 

areas from the active workings of the 

mine.’’ 30 U.S.C. 863(z)(2). 

On May 15, 1992, as part of a 

comprehensive revision of its 

regulations for ventilation of 

underground coal mines, MSHA 

published standards for construction of 

seals in § 75.335 of the ventilation 

standards. The standard requires seals 

to be constructed of solid concrete 

blocks at least six inches by eight inches 

by sixteen inches, but allows seals to be 

constructed using alternative methods 

and materials, provided, among other 

things, that the seal is capable of 

withstanding a horizontal static 

pressure of 20 psi. MSHA based this 

threshold on a U.S. Bureau of Mines 

1971 report entitled ‘‘Explosion-Proof 

Bulkheads—Present Practices.’’

A number of manufacturers 

developed materials, such as 

cementitious foams and glass-fiber 

material, which were tested and 

subsequently deemed suitable for use in 

alternative seals and marketed under 

various trade names. MSHA required 

the manufacturers to have full-scale 

seals be subjected to explosion testing at 

NIOSH’s Lake Lynn Experimental Mine 

(Lake Lynn). MSHA then intended for 

mine operators to construct seals as 

constructed and tested at Lake Lynn. 

On January 2, 2006, an explosion at 

the Sago Mine in Upshur County, West 

Virginia caused the death of twelve 

miners. Later that year, on May 20, 

2006, an explosion at the Darby Mine 

No. 1 in Harlan County, Kentucky, 

caused the death of five miners. 

Common to both of these accidents was 

the failure of the seals in the mine. The 

failed seals in both mines were 

constructed with the same approved 

alternative material for a 20 psi seal. 

None of the failed seals were 

constructed in the same manner as they 

were constructed at Lake Lynn. 

Therefore, MSHA issued a moratorium 

on alternative methods and materials for 

construction of new seals (Program 

Information Bulletin (PIB) No. P06–11, 

June 1, 2006, reissued on June 12, 2006 

as PIB No. P06–12.). 

Following these underground coal 

mine disasters in 2006, Congress passed 

and the President signed the MINER 

Act. Section 10 of the MINER Act 

requires that the Secretary issue 

mandatory health and safety standards 

for seals of abandoned areas no later 

than December 15, 2007. It also requires 

the Secretary to revise the current 

standard to increase the 20 psi standard 

for alternative seals. 

Seal failures at the Sago Mine and 

Darby No. 1 Mine in 2006 raised 

awareness of the problems with seal 

construction and the design criterion of 

a 20-psi static horizontal pressure. 

MSHA continued its investigation of 

these and other failures of alternative 

seals, and conducted in-mine 

evaluations of existing alternative seals. 

It also reviewed the history of seals in 

the United States and other countries. 

Presently, most coal producing 

countries have coal mine seal 

requirements that are in excess of a 20- 

psi overpressure. As a result of MSHA’s 

continued investigations and in-mine 

evaluations, MSHA increased the 

strength of alternative seals to 50 psi 

and addressed a number of other issues 

related to the construction and the 

effectiveness of current alternative and 

solid concrete block seals in Program 

Information Bulletin No. P06–16, ‘‘Use 

of Alternative Seal Methods and 

Materials Pursuant to 30 CFR 

75.335(a)(2)),’’ issued on July 19, 2006 

(July 2006 PIB). 

On February 8, 2007, NIOSH issued a 

draft report, ‘‘Explosion Pressure Design 

Criteria for New Seals in U.S. Coal 

Mines’’ (2007 NIOSH Draft Report). The 

draft report states that ‘‘mine seals and 

their related systems such as the 

monitoring, inertization and ventilation 

systems require the highest level of 

engineering and quality assurance. 

Successful implementation of the seal 

design criteria and recommendations in 

this report should reduce the risk of seal 

failure due to explosions in abandoned 

areas of underground coal mines.’’ (2007 

NIOSH Draft Report at 40). In the 

executive summary of the draft report, 

NIOSH makes recommendations for 

formulating seal design criteria. 

B. General Discussion 

Existing § 75.334(a) requires that 

inactive areas of underground coal 

mines be ventilated or sealed. Most 

inactive areas are sealed because of 

ground control, ventilation issues, and 

the long-term costs of maintaining 

ventilation and roof support in inactive 

areas. Seals are also installed to 

withstand overpressures resulting from 

explosions in inactive areas and to 

prevent the potentially explosive 

methane/air mixtures from migrating to 

the working areas. 

A methane/air mixture becomes 

explosive when 5 percent to 15 percent 

methane is present with at least a 12 

percent oxygen concentration. If an 

ignition source is available, then an 

explosion can occur and create high 

overpressures. The homogeneity of the 

methane/air mixture contributes to its 

explosiveness. The homogeneity of the 

methane/air mixture can vary 

depending on the elevation and the 

methane liberation of the sealed area 

and outside factors such as the current 

temperature and barometric pressure. 

The speed of an explosion and the 

physical characteristics of a sealed area 

can increase the force of the explosion 

such that detonations and significant 

pressure piling are possible. 

In order to address mine conditions 

that influence the magnitude of 

overpressures in explosions, seals need 

to be designed and constructed properly 

and then inspected on a periodic basis 

and properly maintained to ensure their 

reliability. The 2007 NIOSH Draft 

Report states as follows: 

NIOSH engineers examined seal design 

criteria and practices used in the U.S., 

Europe and Australia and then classified 

seals into their various applications. Next, 

NIOSH engineers considered various kinds of 

explosive atmospheres that can accumulate 

within sealed areas and used simple gas 

explosion models to estimate worst case 

explosion pressures that could impact seals. 

Three design pressure pulses (pressure-time 

curves) were developed for the dynamic 

structural analysis of new seals under the 

conditions in which those seals may be used: 

unmonitored seals where there is a 


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possibility of methane-air detonation behind 

the seal; Unmonitored seals with little 

likelihood of detonation; and monitored seals 

where the amount of potentially explosive 

methane-air is strictly limited and controlled. 

These design pressure pulses apply to new 

seal design and construction. 

For the first condition, an unmonitored 

seal with the possibility of detonation, the 

recommended design pulse rises to 4.4 MPa 

(640 psi) and then falls to the 800 kPa (120 

psi) constant volume explosion overpressure. 

For unmonitored seals without the 

possibility of detonation, a less severe design 

pulse that simply rises to the 800 kPa (120 

psi) constant volume explosion overpressure, 

but without the initial spike, may be 

employed. For monitored seals, engineers 

can use a 345 kPa (50 psi) design pulse if 

monitoring can assure (1) that the maximum 

length of explosive mix behind a seal does 

not exceed 5 m (15 ft) and (2) that the volume 

of explosive mix does not exceed 40% of the 

total sealed volume. Use of this 345 kPa (50 

psi) design pulse requires monitoring and 

active management of the sealed area 

atmosphere. 

Based on MSHA’s accident 

investigation reports of Sago and Darby 

mine explosions, NIOSH reports on 

explosion testing and modeling, 

MSHA’s in-mine seal evaluations, and 

review of technical literature, MSHA 

identified a number of issues pertinent 

to the construction and efficacy of 

current alternative and solid concrete 

block seals. 

C. Section-by-Section Analysis 

1. Sec. 75.335 Seals Requirements 

The ETS increases seal strength 

requirements for construction of new 

seals and, where necessary, establishes 

new requirements for monitoring and 

inerting atmospheres of sealed areas. 

New § 75.335(a) provides that seals 

constructed in underground coal mines 

after May 22, 2007 must be designed, 

constructed and maintained in 

accordance with MSHA approval of a 

mine operator’s design application and 

installation procedures incorporated in 

the ventilation plan. 

The ETS establishes a three-tiered 

approach for overpressure loading 

criteria applicable to new seals: (1) 50 

psi overpressure; (2) 120 psi 

overpressure; and (3) an overpressure 

greater than 120 psi. For purposes of 

this ETS, MSHA intends that 

overpressure be any pressure exerted by 

the forces of an explosion that is above 

normal atmospheric pressure. In 

developing these overpressure loading 

criteria, MSHA relied upon the 2007 

NIOSH Draft Report, the Agency’s safety 

and health experience with respect to 

seals and underground mining 

conditions and investigations, and 

accepted scientific and engineering 

principles. 

Under the ETS, if a mine operator 

monitors and maintains the atmosphere 

in these areas inert, new § 75.335(a)(1) 

requires a seal design to withstand at 

least 50 psi overpressure. If a mine 

operator does not monitor and maintain 

atmospheres in these areas inert, new 

§ 75.335(a)(2) requires a seal design to 

withstand at least 120 psi overpressure. 

A seal design that will withstand an 

overpressure greater than 120 psi is 

required under new § 75.335(a)(3) when 

the mine operator does not monitor and 

maintain the atmosphere within sealed 

areas inert and when: (1) The 

atmosphere in the area is likely to 

contain homogeneous mixtures of 

methane between 4.5 percent and 17.0 

percent, and oxygen exceeding 17.0 

percent throughout the entire sealed 

area; (2) or pressure piling is likely due 

to opening restrictions near the 

proposed seal area; or (3) other 

conditions are encountered, such as the 

likelihood of a detonation in the 

proposed seal area. Where the 

conditions in § 75.335(a)(3) are likely to 

occur, the mine operator must revise the 

ventilation plan required by existing 

§ 75.370 to address the appropriate seal 

strength. 

The ETS does not require mine 

operators to upgrade seals constructed 

prior to May 22, 2007. However, new 

§ 75.335(b) enhances the protection 

afforded miners under the previous 

standard by requiring, among other 

things, that atmospheres in the sealed 

areas be monitored and inerted. If a 

mine operator does not monitor and 

inert the atmosphere in an existing 

sealed area, the strength of the seals 

must be increased to 120 psi or greater. 

a. Sec. 75.335(a) 

New paragraph (a)(1) requires that 

seals be constructed to withstand 50 psi 

overpressure. However, mine operators 

who construct these seals must monitor 

the atmosphere behind the seals and 

maintain them inert. Mine operators are 

currently required to construct seals that 

will withstand 50 psi overpressure 

under the July 2006 PIB. In addition, the 

July 2006 PIB required mine operators 

to assess atmospheres behind alternative 

seals and take remedial action where 

necessary. The 2007 NIOSH Draft 

Report also recommends a 50 psi 

overpressure for monitored and 

managed atmospheres behind sealed 

areas. Monitoring sealed areas allows 

the mine operator to know the 

composition of potentially hazardous 

gases in sealed areas. Use of a 50 psi 

overpressure seal requires the mine 

operator to maintain an inert 

atmosphere in the sealed area since 

explosions cannot occur within inert 

atmospheres. 

MSHA believes that in mines that 

liberate significant volumes of methane, 

the atmosphere in sealed areas will 

become inert naturally. In mines that 

produce very small volumes of methane, 

the atmosphere in sealed areas may 

never approach explosive methane/air 

mixtures of 5 percent. However, some 

mines may need to actively inert the 

atmosphere in the sealed area. To inert, 

an inert gas such as nitrogen or carbon 

dioxide may be injected into the sealed 

area through boreholes or pipes 

extending through the seals. The gas 

may be obtained from a bulk plant and 

trucked to the mine site and pumped 

into the sealed area through a borehole 

or pipe into the seal. It also may be 

produced at the mine using a nitrogen 

generator, Tomlinson Boiler, or other 

inertization device. This process is 

commonly used in underground coal 

mines in the United States during 

firefighting activities and in other 

countries where spontaneous 

combustion is common. MSHA is 

interested in receiving comments 

regarding: (1) The economic and 

technological feasibility of monitoring 

and inerting sealed atmospheres; and (2) 

methods of inerting sealed atmospheres. 

New paragraph (a)(2) requires 120 psi 

overpressure if the sealed atmosphere is 

not monitored and maintained inert 

except as provided in new paragraph 

(a)(3). This provision allows mine 

operators to install seals that withstand 

120 psi overpressure if they do not 

choose to monitor and inert the sealed 

atmosphere. In MSHA’s experience, the 

overwhelming majority of underground 

coal mine explosions are typically 

deflagrations. A deflagration occurs 

when the flame of an explosion 

propagates through unburned fuel at a 

velocity below the speed of sound. The 

faster the flame travels, the higher the 

pressures become. Maximum pressures 

in a deflagration involving methane or 

coal dust are limited to approximately 

120 psi without the occurrence of 

detonation or significant pressure 

piling. MSHA accident reports during 

the past 30 years do not reference an 

underground coal mine explosion in the 

United States that generated an 

overpressure of greater than 120 psi 

except in the rare instance when 

detonation occurred. 

New paragraph (a)(3) also addresses 

overpressures resulting from pressure 

piling and detonations. Methane is 

explosive between 5 percent and 15 

percent and requires at least 12 percent 

oxygen to ignite. (NIOSH 2006, IC 9486) 

When ignited, an explosion can occur. 

To account for correction factors of 


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methane detection equipment and 

potential contamination of the samples, 

the ETS requires that methane 

concentrations between 4.5 percent and 

17.0 percent shall be used to determine 

an explosive atmosphere. If ignited, 

large volumes of homogeneous 

explosive methane/air mixtures in a 

sealed area can generate high explosion 

overpressures. The homogeneity of 

methane/air mixtures in a sealed area is 

affected by a number of factors such as 

elevation, temperature, methane 

liberation, and barometric pressure. 

Based on Agency experience, MSHA 

anticipates that there will be few mines 

that have homogeneous explosive 

methane/air mixtures throughout the 

entire area to be sealed. Commenters are 

encouraged to submit information, with 

supporting documentation, regarding 

the number of mines that may have 

homogeneous explosive methane/air 

mixtures throughout the entire area to 

be sealed. 

MSHA believes that detonations and 

significant pressure piling may occur 

under certain situations. Detonations in 

underground coal mines are rare. A 

detonation occurs when the flame of an 

explosion propagates through the 

unburned fuel at a velocity exceeding 

the speed of sound (1129 feet per 

second). Pressures resulting from a 

detonation involving methane or coal 

dust can exceed 250 psi. Pressure piling 

occurs when the atmosphere ahead of 

the flame front is compressed prior to 

the arrival of the flame. When the flame 

burns through this compressed mixture, 

an increase in the explosion pressure 

occurs. Thus, if this mixture is 

compressed to 45 psi prior to the flame 

arriving, the resulting explosion 

pressure could exceed 300 psi. Pressure 

piling can occur when the physical 

configuration through which the 

explosion will propagate inhibits the 

flow of gases for pressure equalization, 

such as decreasing the number of 

entries, decreasing the size of the 

entries, or obstructing the entry. 

The ETS does not specify a seal 

strength under paragraph (a)(3). Under 

this provision, the mine operator would 

submit a strength requirement based on 

mine-specific conditions that are likely 

to result in pressure piling or detonation 

in the sealed area. The mine operator 

must first recommend the seal strength 

in the ventilation plan. MSHA expects 

that mine operators will submit a 

thorough engineering analysis 

conducted by a person knowledgeable 

in explosions and explosion 

overpressures, based on the conditions 

in the mine. After the seal strength is 

approved by the District Manager, the 

process in § 73.336 will apply. MSHA 

expects that in these few instances, the 

District Manager and the Office of 

Technical Support will coordinate 

MSHA activities related to the approval 

process. MSHA believes that most mine 

operators who encounter homogenous 

explosive methane/air mixtures and 

pressure piling in the entire sealed area 

will monitor and inert the atmosphere 

in sealed areas. Although the 

recommended maximum seal strength 

in the 2007 NIOSH Draft Report is 640 

psi, MSHA has no empirical or other 

data, at this time, demonstrating that 

mine conditions exist that will 

necessitate seals stronger than 120 psi. 

MSHA requests comments from the 

mining community on the 

appropriateness of the strategy in this 

ETS for addressing seal strength greater 

than 120 psi. 

In the ETS, MSHA considered a 

performance-based approach to the 

strength requirement for seals. However, 

MSHA included specific numbers for 

the strength of seals in the ETS as the 

agency believes this represents a more 

appropriate approach. MSHA 

specifically solicits comments on the 

Agency’s approach to the strength 

requirement for seals. 

MSHA is also interested in receiving 

comments on the appropriateness of the 

three-tiered approach to seal strength in 

the ETS. If commenters believe a 

different regulatory approach should be 

developed for the final rule the Agency 

would like commenters to provide: (1) 

The details for such a strategy, (2) 

rationale for such a strategy; and (3) 

feasibility of using such strategy. The 

Agency particularly seeks the views of 

the mining community regarding 

whether there are other effective 

alternatives to the requirements in the 

ETS with respect to providing the most 

appropriate and protective action for 

miners exposed to hazards of existing 

sealed areas. Commenters should 

provide supporting data, and specific 

alternatives, including information on 

technological and cost implications. 

Most existing seals were constructed 

to withstand a static horizontal pressure 

of 20 psi. MSHA also considered 

requiring mine operators to remove 

existing seals and replace them with 

seals that withstand at least 50 psi. 

Currently, the Agency believes that 

replacing existing seals is impractical, 

and in some instances, may create safety 

hazards. In addition, these existing seals 

must be monitored and the atmospheres 

behind them must be maintained inert. 

The atmosphere inby and outby the 

seals near the roof, ribs, or floor adjacent 

to the seal may contain low oxygen and/ 

or explosive methane/air mixtures that 

are highly hazardous to miners’ safety. 

In addition, the conditions inby the 

seals, such as bad roofs, roof falls, and 

water accumulations, may prevent the 

mine operator from making changes to 

provide adequate ventilation inby the 

seals. MSHA seeks comments on the 

feasibility of including in the final rule 

a requirement that existing seals be 

removed and replaced with a higher 

strength seal. 

Another regulatory option that MSHA 

considered is whether to require mine 

operators to build new seals outby 

existing seals. In some cases, this may 

not be feasible because the seals may 

have been constructed too close to the 

outby corner of the pillar so that there 

is insufficient space to build new seals 

in the same pillar; and there may not be 

an additional open entry outby the 

existing seals allowing for construction 

of new seals. 

MSHA also considered whether to 

require mine operators to reinforce 

existing seals. The Agency is concerned 

with the feasibility of this option and 

whether such a requirement could 

expose miners to greater hazards as 

discussed earlier in this preamble. 

MSHA, however, will continue to 

explore technological advances 

addressing feasible and safe methods to 

reinforce existing seals in underground 

coal mines. Commenters are encouraged 

to submit information and supporting 

data regarding new technologies to 

reinforce seal strength. 

Existing § 75.335(a) included 

minimum specifications for seals 

constructed of solid concrete blocks 

after November 15, 1992. Also, existing 

§ 75.335 (a)(2) allowed mine operators 

to use alternative construction methods 

or materials to construct a seal provided 

the seal could withstand a static 

horizontal pressure of 20 psi 

(subsequently increased to 50 psi in the 

July 2006 PIB). In addition, the method 

of installation and material used had to 

be approved by the District Manager 

under MSHA’s ventilation plan 

procedures in § 75.370 based on a 1971 

report entitled ‘‘Explosion-Proof 

Bulkheads—Present Practices,’’ issued 

by the former U.S. Bureau of Mines. 

According to that report, when a sealed 

atmosphere has adequate incombustible 

material and minimum coal dust 

accumulations, it is doubtful that 

pressures exceeding 20 psi could occur 

very far from the origin of the explosion. 

The primary disadvantage of this level 

of explosion protection is that current 

evidence establishes that explosions of 

coal dust or methane can generate 

explosion pressures of 120 psi, without 

detonation or pressure piling. 

Previous § 75.335(a)(2) also included 

measures to prevent exposed timber 


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seals from quickly failing in a fire or 

other mine emergency. New 

construction of timber seals must meet 

the requirements set forth in this ETS. 

b. Sec. 75.335(b) Sampling and 

Monitoring Requirements 

ETS § 75.335(b) establishes new 

sampling and monitoring requirements 

for sealed areas. This provision requires 

that on the effective date of this ETS, a 

certified person, as defined under 

existing § 75.100, must immediately 

monitor atmospheres in all existing 

sealed areas when seals are outgassing, 

such as when the barometric pressure in 

the sealed area exceeds the pressure on 

the outby side of the sealed area. MSHA 

intends for mine operators to establish 

a baseline analysis over a 14-day 

sampling period, as specified under 

§ 75.335(b)(5)(iii), followed by weekly 

sampling under paragraph (b)(1) of this 

section. While sampling is being 

conducted, mine operators must train 

certified persons in sampling 

procedures and develop a sampling 

protocol to be included in the 

ventilation plan and submitted to the 

District Manager for approval. 

This provision also requires that for 

seals constructed prior to May 22, 2007 

and seals designed for 50 psi 

overpressure according to ETS 

§ 75.335(a)(1), mine operators shall 

develop and follow a protocol to 

monitor methane and oxygen 

concentrations and to maintain an inert 

atmosphere in sealed areas. The 

protocol shall be approved in the 

ventilation plan. The sampling protocol 

must ensure that an inert atmosphere 

behind the seal area is maintained. An 

explosion will not occur in an inert 

atmosphere. The July 2006 PIB and this 

ETS require mine operators to conduct 

an atmospheric assessment behind 

existing alternative seals to determine 

the potential for an explosion and assess 

seal integrity. This ETS requirement 

enhances protection of miners working 

in the active portions of the mine 

adjacent to sealed areas where existing 

seals were installed prior to this ETS. In 

addition, this provision protects the 

miner where 50 psi seals will be 

installed under this rule. MSHA 

recognizes that conditions in mines may 

vary and mine operators can more 

appropriately address their specific 

conditions in the ventilation plan. 

During 2006, MSHA inspected existing 

seals. The inspections revealed that 

some mine operators were not adhering 

to their approved ventilation plan for 

seal installation and construction. The 

ETS emphasizes the importance of 

sampling sealed atmospheres to ensure 

that they remain inert. 

ETS § 75.335(b)(1) requires that a 

trained certified person sample 

atmospheres of sealed areas weekly 

when the barometric pressure is 

decreasing or the seal is outgassing. 

Because the information obtained 

during sampling of a sealed area is 

critical to the safety of miners, the ETS 

requires sampling to be conducted by a 

certified person. At least one sample 

shall be taken at each set of seals. If a 

seal is ingassing, such as when the 

barometric pressure outside the sealed 

area exceeds the pressure on the inby 

side of the sealed area during the 

weekly examinations, the ETS requires 

that a sample shall be collected during 

the next weekly examination to 

determine if the seal will outgas. If the 

seal is ingassing during the second 

consecutive weekly examination, the 

operator shall examine that seal daily 

until the seal is outgassing, unless the 

seal does not outgas. In this 

circumstance, an alternative protocol 

must be developed to effectively 

evaluate the atmosphere in the sealed 

area and submitted to the District 

Manager for approval. Although the ETS 

does not specify the length of time that 

the seal must be examined to determine 

if it will outgas, MSHA intends to 

require mine operators to develop the 

alternative protocol within a reasonable 

timeframe. The District Manager may 

approve different sampling frequencies 

and locations in the ventilation plan or 

approve the use of atmospheric 

monitoring systems in lieu of weekly 

sampling. The mine operator shall 

revise the protocol in the ventilation 

plan if repeated sampling indicates that 

a seal is not likely to outgas. 

MSHA expects that the certified 

person will conduct sampling required 

under the ETS as part of the 

examinations of seals required in 

existing § 75.360 and § 75.364 and base 

the time of these examinations on the 

barometric conditions to the extent 

possible. All seals and the strata around 

them will leak air, resulting in an air 

exchange near the seal during 

barometric changes. MSHA does not 

expect the air leakage to significantly 

impact the atmosphere in a large portion 

of the sealed area, but it may affect the 

atmosphere at a sampling location when 

the seal is ingassing. Therefore, it is 

important that samples be 

representative of the atmospheric 

conditions in the larger portion of the 

sealed area, rather than just the area 

immediately inby the seal. 

The certified person must take at least 

one sample at each set of seals during 

the weekly examination. Each newly 

constructed seal must be equipped with 

two sampling pipes. In accordance with 

the ETS, MSHA expects that most mines 

will need to take only one sample from 

a seal in each set of seals. However, the 

number of seals that need to be sampled 

will be determined from the results of 

the 14-day sampling period specified in 

paragraph (b)(5)(iii) of this section. 

If the seal is ingassing during the 

examination, the certified person must 

attempt to take a sample during the next 

weekly examination. After a second 

attempt is made and the seal is still 

ingassing, attempts must be made daily 

until the seal outgasses. If repeated 

sampling indicates that a seal is not 

likely to outgas, then the mine operator 

must submit an alternative protocol to 

the District Manager. The alternative 

protocol must address a means to 

effectively evaluate the atmosphere in 

the sealed area. The alternate protocol 

may address various means such as: (1) 

The use of a borehole or previously 

installed sampling line to obtain 

samples, (2) pressure balancing of the 

ventilation system to make the seals 

outgas, or (3) the use of inert gas 

injection. 

The District Manager may approve 

different sampling frequencies and 

locations in the ventilation plan. This is 

intended to address those instances 

when the atmosphere in the sealed area 

is unstable, close to the explosive range, 

or subject to other hazardous 

conditions, such as a history of 

spontaneous combustion, which make it 

necessary to sample at a greater 

frequency. However, a less frequent 

sampling strategy may be approved in 

the ventilation plan if the atmosphere in 

the sealed area is stable and not at all 

close to explosive range. For example, 

the oxygen must be significantly below 

10 percent, and methane far less than 3 

percent or far greater than 20 percent. 

Sampling requirements also addresses 

instances when an adequate evaluation 

of the atmosphere in the sealed area 

cannot be obtained with the sampling 

pipes located 15 feet inby the seal and 

into the center of the first connecting 

crosscut inby the seal. In some sealed 

areas, the District Manager may find it 

necessary to require in the ventilation 

plan that samples be obtained at 

additional locations to determine that 

the atmosphere is inert. Additional 

samples may need to be taken at mines 

with sealed areas that are very large, 

have multiple sets of seals, connect with 

another mine, have flooded areas, have 

capped shafts, or in other circumstances 

which may cause samples of the 

atmosphere taken near the seals not to 

be representative of the entire sealed 

area. 

The ETS also allows the use of an 

Atmospheric Monitoring System (AMS) 


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in lieu of a person physically taking 

samples on a weekly basis. The use of 

AMS is discussed more fully under 

paragraph (b)(5)(vi) of this section. 

MSHA believes that the sampling 

strategy in this ETS will yield results 

that reflect a reasonable representation 

of the atmosphere in a sealed area. 

MSHA is requesting comments 

addressing the sampling approach in 

this ETS. The agency is particularly 

interested in comments concerning 

sampling, and the sampling frequency, 

including sampling only when a seal is 

outgassing. The Agency requests 

comments on whether another sampling 

approach is more appropriate for a final 

rule, such as when the seal is ingassing. 

MSHA also requests comments, 

information, and experiences of the 

mining community concerning 

sampling sealed areas. 

Paragraph (b)(2) requires that certified 

persons shall be trained in sampling 

procedures included in the protocol at 

paragraph (b)(5) of this section prior to 

conducting sampling. This requirement 

would ensure that certified persons 

conducting the sampling have the 

training necessary to use the sampling 

devices and knowledge of the sampling 

protocol requirements in the mine’s 

ventilation plan. 

This training shall be conducted by 

persons with knowledge of the 

requirements in paragraph (b)(5) of this 

section. Training may be conducted by 

a variety of people, including a 

manufacturer’s representative, 

ventilation engineer or a certified 

person at the mine. MSHA expects the 

operator to utilize appropriate people to 

conduct the training. 

At a minimum, this training should 

include: 

1. Relevant information in the mine’s 

ventilation plan; 

2. Sampling procedures including 

equipment and methods to be used; 

3. Location of sampling points and 

sampling pipes; 

4. The baseline analysis of oxygen and 

methane concentrations in a sealed area 

over a 14-sampling day period; 

5. Frequency of sampling for each set 

of seals; 

6. Recording procedures required in 

paragraph (b)(6) of this section; 

7. Sampling frequency in the mine’s 

ventilation plan, if an AMS is used; and 

8. General information concerning 

mine gases present in sealed areas. 

Training should include specific 

actions to take in implementing the 

operator’s ‘‘action plan’’ when methane 

concentrations are at one of three 

different ranges and oxygen 

concentrations are 10.0 percent or 

greater. 

MSHA recognizes that the amount of 

time required to train a certified person 

will vary. For this reason, MSHA is not 

specifying a minimum amount of time 

for training, but instead a requirement 

that is performance-oriented. MSHA 

anticipates that mine operators will 

adjust the time required for this training 

based on the complexity of sampling 

procedures, sampling protocol, and 

existing knowledge and skill level of the 

certified person. MSHA also expects 

operators will include ‘‘hands-on’’

training during this session to assure 

that the certified person demonstrates 

the necessary skills and abilities to 

perform the tasks. Hands-on training 

would mean that a certified person 

demonstrates to the trainer the 

necessary skills and abilities to perform 

the testing for oxygen and methane. 

Hands-on training includes practical 

application of the type of sampling 

equipment and the methods to be used 

at the mine. Examples of this type of 

training include calibration of sampling 

equipment, setup of equipment, and 

recognition of the proper functioning of 

equipment. 

All certified persons shall receive 

refresher training annually to ensure 

that they maintain the competence 

necessary to effectively perform the 

requirements in paragraph (b)(5) of this 

section. Annual retraining shall be 

required within 12 months of the person 

receiving initial or annual training. For 

example, a certified person receiving 

initial training in May 2007 is expected 

to complete annual retraining no later 

than the end of May 2008. The month 

that the refresher training is completed 

establishes the anniversary month for 

the next annual retraining. This is 

consistent with other MSHA training 

requirements. 

This ETS also requires mine operators 

to certify the date and content of the 

training provided to the certified 

person. Operators are required to retain 

these certifications for one year from the 

time training was conducted. This 

provision is similar to other certification 

requirements in part 75 in which the 

operator certifies by signature and date 

that training was provided. 

ETS § 75.335(b)(3) states that the 

atmosphere in the sealed area is 

considered inert when any of the 

following conditions occur: 

(1) The oxygen concentration is less 

than 10.0 percent; 

(2) The methane concentration is less 

than 3.0 percent; or 

(3) The methane concentration is 

greater than 20.0 percent. 

This ETS provision is consistent with 

MSHA guidance published in the July 

2006 PIB. The explosive range of 

methane is 5 to 15 percent when the 

oxygen level is 12 percent or more (IC 

9486, 2007 NIOSH Draft Report). To 

allow for the inaccuracy of methane and 

oxygen detection equipment and 

potential contamination of the samples, 

oxygen less than 10.0 percent, methane 

concentration less than 3.0 percent and 

methane concentration greater than 20.0 

percent were used to determine an inert 

atmosphere. 

ETS § 75.335(b)(4) requires that when 

oxygen concentrations are 10.0 percent 

or greater and methane concentrations 

are from 3.0 percent to 20.0 percent in 

a sealed area, the mine operator shall 

take two additional gas samples at one 

hour intervals. If the two additional gas 

samples are from 3.0 percent to 20.0 

percent methane and oxygen is 10.0 

percent or greater, then the mine 

operator shall initiate actions required 

in ETS § 75.335(b)(4)(i) or (ii). The 

ranges for methane and oxygen in this 

paragraph include a margin of safety, 

account for errors in instrumentation or 

sampling methods (NIOSH IC 9486), 

and allow the mine operator to obtain 

confirming samples before 

implementing the actions outlined in 

(b)(4)(i) and (b)(4)(ii). However, because 

the atmosphere in the sealed area is 

critical to the safety of miners, the ETS 

requires that samples be taken at onehour intervals under § 75.335(b)(4). 

Paragraphs (b)(4)(i) and (b)(4)(ii) of 

the ETS require the mine operator to 

implement the action plan specified in 

the protocol or to withdraw all persons 

from the affected area when the 

specified concentrations are 

encountered. Historically, when 

methane levels reached 4.5 percent in 

active areas of mines, miners were 

withdrawn from the areas that were 

dangerous due to high concentrations of 

methane. However, withdrawal of 

miners is not required if, under 

paragraph (b)(4)(i), the operator chooses 

to implement the action plan to address 

the actions to be taken by mine 

operators when the specified 

concentrations in § 75.335(b)(4) are 

reached; these concentrations provide a 

margin of safety. However, the action 

plan must be approved in the mine’s 

ventilation plan and must provide 

protection to miners equivalent to 

withdrawal under paragraph (b)(4)(ii). 

MSHA requests comments on this 

approach and whether it provides 

adequate protection for miners. 

Commenters are encouraged to submit 

specific language, with supporting data 

for MSHA to consider for development 

of a final rule. 

ETS § 75.335(b)(5) establishes the 

elements that must be addressed in a 

mine operator’s sampling protocol and 


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actions to be taken when sampling 

results indicate that the atmosphere 

behind the sealed area is not inert. 

Paragraph (b)(5)(i) requires that the 

mine operator specify sampling 

procedures, including the type of 

equipment and methods to be used by 

the mine operator for the sampling 

program. MSHA believes most mine 

operators will use hand-held methane 

and oxygen detection equipment that 

they currently have at the mine site. 

Other operators may need to purchase 

detectors capable of measuring high 

levels of methane. Although the mine 

operator may collect samples in 

containers to be analyzed by a gas 

chromatograph, the operator must 

specify in the protocol when the sample 

will be analyzed and the procedures 

that will be followed when the sample 

results indicate action levels are 

reached. The methods to be used should 

include the physical connections to the 

sample pipes as well as the length of 

time the detector or pump should be 

operated to collect the sample. The 

length of time will be dependent on the 

length of the sampling pipes. 

ETS § 75.335(b)(5)(ii) requires that the 

mine operator specify in the sampling 

protocol the location of sampling points 

used for the sealed area in a set of seals. 

The sampling points should be 

identified on a mine map, or the 

operator should have a narrative 

description of the location of the 

sampling points that can be readily 

identified on a mine map. 

ETS § 75.335(b)(5)(iii) requires that 

the mine operator specify procedures in 

the protocol to establish a baseline 

analysis of oxygen and methane 

concentrations at each sampling point 

over a 14-day sampling period. For 

existing seals, the mine operator must 

begin this sampling upon the effective 

date of this rule. For newly constructed 

seals, the mine operator must begin this 

sampling upon completion of the seal 

construction. 

The baseline shall be established after 

the atmosphere in the sealed area is 

inert or the trend reaches equilibrium. 

These samples would be taken by 

approved hand-held gas detectors or 

equipment that collects samples in 

containers to be analyzed by gas 

chromatograph. These samples need to 

be collected over a consecutive 14-day 

sampling cycle to establish a baseline 

for a future sampling cycle at each 

sampling point. Samples need only be 

taken when the seals are outgassing 

during the baseline period to ensure 

samples are representative of the larger 

area inby the seals. If the seals are not 

outgassing during any of the days of 

sampling, the baseline sampling period 

needs to be extended until 14 samples 

are taken. Once a baseline is 

established, the seals need to be 

sampled at least weekly. MSHA is 

requesting comments on this sampling 

approach. The agency is particularly 

interested in comments concerning the 

establishment of a baseline, including 

sampling only when a seal is outgassing 

and whether it is appropriate to sample 

the atmosphere in sealed areas during 

ingassing. MSHA also requests 

comments, information, and 

experiences with sampling sealed areas, 

including data, analytical information, 

establishment of equilibrium, and 

trends. 

ETS § 75.335(b)(5)(iv) establishes the 

frequency of sampling at each seal or set 

of seals. Once a baseline is established, 

the seals must be sampled at least 

weekly while the seals are outgassing. 

Weekly examinations under existing 

§ 75.364 cannot exceed a 7-day interval. 

Mine operators may conduct sampling 

required under this ETS in conjunction 

with weekly examinations under 

existing § 75.364. Depending on the 

location and the results of sampling, 

MSHA may require that seals or sets of 

seals be sampled at different sampling 

intervals. Additionally, there may be 

circumstances where seals or sets of 

seals within a single sealed area, have 

a different sampling frequency. 

ETS § 75.335(b)(5)(v) requires that the 

mine operator specify size and 

conditions of the sealed area. Some 

mine-specific conditions inby the sealed 

area may include the type of mining, the 

presence of pillared areas, the average 

mining height, the occurrence of bottom 

mining, any entry restrictions near the 

seals, the size of the sealed area and the 

number of seals in each set of seals. This 

information is important to determine 

the appropriate seal strength. 

ETS § 75.335(b)(5)(vi) requires that 

the protocol address an atmospheric 

monitoring system (AMS) to monitor 

sealed areas, where applicable. MSHA 

may approve use of an AMS to monitor 

methane and oxygen levels and pressure 

differentials across the seals in lieu of a 

person physically taking or collecting 

methane samples. The AMS consists of 

sensors to monitor methane and oxygen 

levels in the sealed area and the 

pressure differential across the seal. 

ETS § 75.335(b)(5)(vii) requires that 

the protocol include an action plan 

addressing hazards presented and 

actions taken when gas samples indicate 

oxygen concentrations of 10.0 percent or 

greater for each of the following ranges 

of methane concentrations: (1) 3.0 

percent or greater but less than 4.5 

percent; (2) 4.5 percent or greater but 

less than 17.0 percent; and (3) 17.0 

percent to 20 percent. MSHA expects 

the action plan to address the risk to 

miners based on the location of seals, 

the locations of escapeways, the size 

and nature of the sealed area, potential 

impact of seal failure on the mine 

ventilation system, and the exposure to 

miners to any potential seal failures. 

MSHA may require additional sampling 

when methane ranges are between 3.0 

and up to 4.5 percent and from over 

17.0 percent to 20 percent, as well as 

possible changes to the ventilation 

system, or the addition of inert gas to 

the sealed area. A methane range 

between 4.5 and 17.0 percent and an 

oxygen level greater than 10 percent 

requires the mine operator to follow the 

action plan set forth in the protocol in 

the ventilation plan or to evacuate 

miners from the affected area of the 

mine. If miners must be withdrawn, the 

only persons who may remain in the 

affected area are those persons referred 

to in section 104(c) of the Mine Act. 

ETS § 75.335(b)(6) requires that the 

certified person promptly record each 

sample result from sealed areas, 

including the location of sampling 

points, and oxygen and methane 

concentrations. The results of oxygen 

and methane samples must be recorded 

as the percentage of oxygen and 

methane measured by the certified 

person. Also, the ETS requires, where 

applicable, that the certified person 

promptly record monitoring results from 

AMS systems. 

If sampling and monitoring results 

indicate the presence of a hazardous 

condition to miners, the certified person 

must record the hazardous condition 

found in accordance with existing 

§ 75.363 (Hazardous conditions; posting, 

correcting and recording). Also 

§ 75.335(b)(6) requires that hazardous 

conditions be corrected immediately or 

the area must be posted. In addition, 

records of hazardous conditions must be 

reviewed and countersigned by the 

mine foreman, or equivalent mine 

official, by the end of the mine 

foreman’s or equivalent mine officials 

next regularly scheduled working shift. 

ETS § 75.335(b)(7) requires that the 

mine operator retain sampling records at 

the mine for at least one year from the 

date of sampling. A one year retention 

period permits the mine operator to 

track trends or changes. The one year 

retention period is consistent with 

existing §§ 75.360 and 75.364. 

c. Sec. 75.335(c) Welding 

ETS § 75.335(c) prohibits the use of 

open flames or arc associated with 

welding, cutting, and soldering 

activities within 150 feet of a seal. 

MSHA intends to apply this 


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requirement to seals when their 

construction has been completed. The 

use of an oxygen acetylene cutting torch 

to cut a metal strap at a seal was the 

most likely ignition source in the Darby 

Mine No. 1 explosion in 2006. Although 

the metal strap should have been 

removed before the seal was 

constructed, the event underscores the 

importance of the potential dangers 

when working near seals, and 

emphasizes the dangers of using open 

flames near a seal. A methane enriched 

atmosphere can leak through the seal or 

surrounding strata into the active area of 

the mine. The methane may accumulate 

and form a methane layer outby the seal. 

If ignited, a flame can propagate into the 

sealed area. The 150-foot limit is 

consistent with an existing requirement 

in § 75.1002(a)(1) that non-permissible 

equipment be excluded within 150 feet 

of pillar workings or longwall faces. In 

determining the 150-foot distance, 

MSHA provides guidance in MSHA’s 

Program Policy Manual (Volume V-Coal 

Mines February 2003, Release V–33) 

which states that the 150-foot distance 

shall be measured by following the 

shortest distance that air can travel 

(tight string distance) through crosscuts, 

entries or other openings. MHSA does 

not believe that this requirement will 

present significant practical or technical 

problems for the underground coal 

mining industry. MSHA is requesting 

comments from the mining community 

on the appropriateness of the ETS 

requirement regarding open flames 

associated with welding, cutting and 

soldering activities within 150 feet of a 

seal and the feasibility of this 

requirement. MSHA suggests that 

commenters provide specific rationale 

in support of their position, and include 

alternatives, if applicable. 

d. Sec. 75.335(d) Sampling Pipes 

ETS § 75.335(d) revises previous 

§ 75.335(b) and requires each newly 

constructed seal to have at least two 

sampling pipes. One sampling pipe 

must extend into the sealed area 

approximately 15 feet as required by 

previous § 75.335(b). This provision of 

the ETS is based upon sampling 

procedures recommended in the 1979 

MSHA study, ‘‘Interpreting the State of 

a Mine Fire.’’ The study shows that in 

sampling situations involving fires 

behind sealed areas, sampling pipes 

should extend at approximately 15 feet 

toward the fire. This distance also 

applied to atmospheric sampling in 

sealed areas for non-fire situations. The 

area directly inby a seal is more likely 

to be affected by ingassing during 

normal barometric changes. 

Under this provision, the second 

sampling pipe must extend into the first 

connecting crosscut inby each seal and 

to the center of the first connecting 

crosscut in the middle of the 

intersection. MSHA has included this 

new provision in the ETS so that the 

operator can obtain a representative 

sample of the sealed area. The Agency 

believes that sampling points within the 

first connecting crosscut will provide a 

more representative sample of the 

sealed area because this atmosphere is 

less likely to be affected by ingassing. 

The District Manager may require more 

than two sampling locations in the 

ventilation plan under § 75.335(b)(1). 

ETS § 75.335(d) requires that each 

sampling pipe be equipped with a shutoff valve and an appropriate fitting for 

taking atmospheric samples behind the 

seals. A tapered fitting, for example, 

may be connected at the tip of the 

sampling pipe to easily accommodate a 

flexible tube attached to a gas analyzer. 

The ETS allows for other types of 

sampling methods that may be used to 

monitor sealed atmospheres. ETS 

§ 75.335(b) allows a mine operator to 

use an atmospheric (gas) monitoring 

system when appropriate. Although 

MSHA no longer requires that sampling 

pipes be installed with the sampling 

end of the pipe to be about 12 inches 

from the roof and in the centerline of 

the entry, the most appropriate 

placement of the sampling end of the 

pipe should be about 12 inches from the 

roof. The ETS affords flexibility to mine 

operators for the placement of the 

sampling end to allow more accurate 

sampling strategies to better protect 

miners. Therefore, the ETS requires that 

the location of sampling points be 

specified in the protocol provided under 

ETS § 75.335(b)(5). MSHA requests 

comments regarding the appropriate 

number and location of sampling pipes 

for a final rule. 

e. Sec. 75.335(e) Water Drainage 

Systems 

ETS § 75.335(e) requires that a 

corrosion-resistant, water drainage 

system be installed in the seal at the 

lowest elevation within the set of seals. 

Water accumulations can affect the 

integrity of seals since they are not 

designed to impound water. Previous 

§ 75.335(c)(2) required each water 

drainage pipe to have a water trap outby 

the seal. MSHA required the water trap 

to prevent the exchange of air through 

the seal and propagation of an 

explosion. New seal designs under the 

ETS, however, must meet performance 

requirements for a drainage system 

which prevents the exchange of air and 

the accumulation and impoundment of 

mine water inby the seals. The ETS also 

allows for use of new and innovative 

designs. MSHA has determined that the 

ETS provision enhances the level of 

protection afforded under the previous 

standard. ETS § 75.336(a)(1)(i) requires 

that drainage system designs be 

approved by MSHA, and ETS 

§ 75.336(b)(3)(iii)(I) requires estimation 

of the volume of water flow in the 

ventilation plan. Depending on the size 

and mine floor elevations of the sealed 

area, it may be necessary for more than 

one seal in a set of seals to contain a 

water drainage pipe. These provisions 

provide flexibility and additional 

oversight by MSHA to help ensure safe 

and effective water drainage systems to 

protect miners from seal failure due to 

water impoundment. The ETS prohibits 

seals from impounding water. 

MSHA requests comments from the 

mining community on the ETS 

requirement for water drainage systems 

for seals, including effective alternatives 

for a final rule. 

2. Sec. 75.336 Seal Design 

Applications and Installation Approval 

The ETS requires that seal design 

applications and installation procedures 

be approved by MSHA prior to 

construction. The ETS approval 

requirements for seals are derived from 

previous § 75.335(a)(2), the July 2006 

PIB, and Procedure Instruction Letter 

(PIL) No. I–06–V–09, ‘‘Procedures for 

Approval of Alternative Seals,’’ issued 

on August 21, 2006 (August 2006 PIL) 

and are consistent with existing 

requirements for approving coal mine 

impoundments in § 77.216–2. Paragraph 

(a) requires that seal design applications 

be submitted to MSHA’s Office of 

Technical Support for approval. Seal 

design applications must conform to the 

provisions provided in paragraph (a)(1) 

or (a)(2) which address seal design and 

installation approval. Once a seal design 

is approved by MSHA, a mine operator 

may use the design in accordance with 

new provisions in paragraph (b) of this 

section and the requirements of existing 

ventilation standards in §§ 75.370, 

75.371, and 75.372, which address the 

submission and approval of the 

ventilation plan. 

Previous §§ 75.335(a), (b), and (c) that 

address design parameters of seals are 

transferred to ETS §§ 75.336 (a) and (b) 

and are revised. These previous 

provisions required mine operators to 

either use a seal constructed of solid 

concrete blocks or seals constructed of 

alternative methods and materials if 

approved in the mine’s ventilation plan. 

Under the new provisions, a 

manufacturer or mine operator may 

submit an application for approval 


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which can include any seal design. Seal 

designs specified in previous § 75.335 

may be submitted to MSHA for 

approval, provided the proposed design 

meets the strength requirements of ETS 

§ 75.335(a). The provisions of ETS 

§ 75.336(a) are derived from the July 

2006 PIB that established criteria to 

guide the District Managers’ approval of 

the use of alternative seals in ventilation 

plans. These provisions are also derived 

from the August 2006 PIL that 

established uniform procedures for 

application of MSHA regulations related 

to review and approval of ventilation 

plans, which include alternative seals 

constructed in underground coal mines 

after July 19, 2006. Installation of seals 

is required to be approved by the 

District Manager in the ventilation plan 

in accordance with ETS § 75.336(b). 

a. Sec. 75.336(a)(1) Engineering Design 

Applications 

ETS § 75.336(a)(1), which is derived 

from the August 2006 PIL, sets forth 

specific requirements that an 

engineering design application must 

include. The requirements in 

paragraphs (a)(1)(i) through (iii) are new 

and are based on sound engineering 

principles. They require that a seal 

design application shall: (1) Address 

design calculations and analyses, (2) 

include certification by a professional 

engineer, and (3) include a Seal Design 

Table. The documentation required 

under this paragraph includes design 

calculations, drawings, and 

specifications. Design calculations are 

required, since they provide the 

technical basis for developing drawings 

and specifications and serve as the 

record of the engineering design. 

Drawings and specifications provide 

detailed information necessary to 

construct seals, technical requirements 

for a seal, and important information 

and guidance to be followed during seal 

construction. 

These ETS requirements are 

consistent with existing approval 

requirements for various mining-related 

products under subchapter B—Testing, 

Evaluation, and Approval of Mining 

Products for permissibility and for 

approval of impoundment designs 

under existing § 77.216. Existing 

approval regulations require applicants 

to submit substantial engineering 

documentation as the basis for approval. 

The engineering documentation 

provides MSHA with evidence that the 

design meets accepted engineering 

practices and principles. 

ETS § 75.336(a)(1)(i) requires each 

engineering design application to 

address essential design parameters. 

This information is required for MSHA 

to make a thorough assessment of the 

design application to ensure that the 

seal design will reliably withstand a 

specific overpressure, and to verify that 

the seal design is certified according to 

ETS § 75.336(a)(1)(ii). MSHA will 

review the application for evidence that 

each of these design parameters is 

sufficiently addressed. 

The design application should show 

the placement of gas sampling pipes 

required under § 75.335(b). Also, the 

application must address a water 

drainage system. The drainage system 

must be corrosion-resistant and should 

not be subject to detrimental 

environmental conditions. The 

dimensions, material type, and 

components of the water drainage 

system should be specified. The 

application should show how the water 

drainage system will prevent both the 

exchange of air and the propagation of 

an explosion through the water drainage 

system. Also, the application should 

show how the water drainage system 

will be able to withstand the applicable 

overpressure in ETS § 75.335(a). 

The design application must address 

air leakage and should specify the 

method and materials used to minimize 

air leakage along the perimeter of each 

seal and through any construction joints 

or cracks that could develop. Consistent 

with previous § 75.335(a)(iv) that 

required that a sealant material should 

have a flame-spread index of 25 or less, 

the mine operator must address the 

flame-spread index. The flame spread 

index is established through recognized 

laboratory testing such as that 

designated by ASTM E162–07, ‘‘Surface 

Flammability of Materials Using a 

Radiant Heat Energy Source’’ or 

equivalent. 

The design application must include 

appropriate information to address fire 

resistance, such as methods and 

materials used to provide at least onehour fire resistance. The fire resistance 

is established through recognized 

laboratory testing. The seal material 

should not fail or allow transfer of 

sufficient heat while being subjected to 

a fire test incorporating an ASTM 

E–119–07 time/temperature heat input, 

or equivalent, for one hour. 

A pressure-time curve provides the 

necessary loading criterion for a seal 

design and must be provided in the seal 

design application. The pressure-time 

curve provides the reflected 

overpressure and constant-volume 

pressure plotted as a function of a 

specific time period. Pressure-time 

curves for the 50-psi and 120-psi seal 

strength requirements of ETS § 75.335(a) 

are provided in the 2007 NIOSH Draft 

Report. Alternative pressure-time curves 

may be used for designs provided the 

pressure-time curves are submitted to 

MSHA’s Office of Technical Support for 

approval. 

The applicant must document the 

entry dimensions for which the seal 

design is applicable and the engineering 

design and analysis. MSHA expects the 

design documentation, the design 

assumptions, references of design 

standards and guidance, material 

properties and relevant test data, 

presumptive geotechnical properties 

and information, geotechnical test data 

used to substantiate presumed 

geotechnical properties, data to address 

the long-term durability of seal 

materials, loading criteria, design 

calculations, and the identification of 

computer software used and the 

computer input and output files with 

the critical design values indicated. The 

design should also address the factors 

used to account for the variability in 

material properties, geologic conditions, 

and the quality of construction. For 

example, the applicant must show that 

an appropriate approach was used to 

derive the geotechnical and material 

design values. The design should also 

show the methodology and the 

procedures used to evaluate all potential 

failure modes of the seal and strata. 

MSHA considers design standards and 

guidance documents as appropriate 

references, such as Army TM 5–1300, 

‘‘Structures to Resist the Effects of 

Accidental Explosions,’’ American 

Concrete Institute ACI 318–05, 

‘‘Building Code Requirements for 

Structural Concrete and Commentary,’’

and American Concrete Institute ACI 

440.2R–02, ‘‘Design and Construction of 

Externally Bonded FRP Systems for 

Strengthening Concrete Structures.’’

Specifications must be provided in 

the seal design application to define the 

performance requirements for 

construction materials and equipment 

used. Test methods and reference to 

industry standards for materials (e.g., 

American Society for Testing and 

Materials) that will be used in seal 

construction must also be included in 

the application. For construction 

materials whose properties and 

performance are not well-researched or 

well-documented, the applicant would 

be required to provide data 

substantiating long-term durability and 

strength. 

Applications must provide 

construction specifications adequately 

addressing the preparation of the site for 

seal construction. For example, 

construction specifications must 

include rock and coal removal 

requirements for the foundation. 

Specifications for foundations must 


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address both the horizontal and vertical 

surfaces of the mine opening. Keys 

formed in rock and coal to increase the 

lateral restraint must be excavated with 

equipment that minimizes fracturing 

and breakout. The applicant must also 

specify the necessary actions to be taken 

to prevent water accumulation in the 

seal construction area since water 

accumulation could affect material 

strength. Necessary storage conditions 

for construction materials, such as 

moisture, heat, or shelf life should be 

specified. Construction specifications 

should also address formwork when a 

seal construction involves cast-in-place 

and pneumatically-applied materials. 

The application must list provisions 

that specify quality control procedures 

for construction and include 

requirements for material sampling and 

testing. Material testing should be 

conducted by personnel certified by 

professional organizations such as the 

American Concrete Institute and by 

Nationally-Recognized Testing 

Laboratories to ensure proper quality 

control testing. 

The seal design should establish the 

maximum allowable convergence a seal 

may undergo without affecting the 

structural integrity of the seal. The 

design should also address other 

physical limitations for a seal, such as 

the time required following construction 

to achieve the specified material 

strength. For example, the time required 

for an explosive atmosphere to develop 

in a sealed area must exceed the time 

required for the seal construction 

material to achieve its specified 

strength. The specified strength of a 

material must take into account 

variability in strength of the material. 

The required material strength ensures 

that the installed material strength of 

the seal exceeds the specified design 

strength. 

The professional engineer designated 

in ETS § 75.336(a)(1)(ii) is responsible 

for the preparation, signing, dating, 

sealing, and issuing of engineering 

documents for the design of a seal. 

Engineering decisions and actions that 

must be made by and must be the 

responsibility of the professional 

engineer are: 

1. The selection or development of 

design standards or methods, and 

materials to be used in seal 

construction; 

2. Development and preparation of 

the structural analyses and design 

computations, drawings, and 

specifications; 

3. The selection or development of 

techniques or methods of testing to be 

used in evaluating materials used either 

during seal construction or following 

completion of seal construction; and 

4. The development of construction 

procedures. 

ETS § 75.336(a)(1)(iii) requires that a 

Seal Design Table that discusses 

characteristics related to mine-specific 

construction be included in the 

application. These characteristics 

include the maximum entry width and 

height for which the specific design is 

applicable, specified strength of the seal 

material, thickness of the seal, and the 

reinforcement and foundation 

anchorage requirements for the seal. The 

mine operator may provide additional 

information in the seal design 

application. 

EXAMPLE CONCRETE SEAL DESIGN TABLE

Entry dimensions (ft) Thickness 

(ft-in) 

Specified unconfined 

compressive strength 

(psi) 

Reinforcement Foundation 

anchorage 

b. Sec. 75.336(a)(2) Full-Scale 

Explosion Test Application 

ETS § 75.336(a)(2) provides 

requirements for seal applications that 

are based on full-scale explosion testing. 

ETS § 75.336(a)(2)(i) requires that 

explosion tests be certified by a 

professional engineer knowledgeable in 

structural engineering that full-scale 

tests were conducted in accordance 

with current, prudent engineering 

practices and the results are applicable 

to an underground coal mine. Current, 

prudent engineering practices should 

include the preparation, signing, dating, 

certifying and issuing of engineering 

documents for the design of a seal. The 

decisions and actions that are the 

responsibility of the professional 

engineer are the same as stated above. 

ETS § 75.336(a)(2)(ii) requires that the 

application include technical 

information related to the methods and 

materials used during a successful fullscale explosion test. The testing should 

include, at a minimum, the following 

blast loadings: (1) The reflected 

overpressure due to the blast wave of a 

methane explosion, and (2) the 

constant-volume pressure due to the 

exothermic reaction of the combustion 

of methane. The overpressures stated in 

ETS § 75.335(a)(1) serve as the 

minimum peak reflected overpressures 

that a seal should be capable of 

withstanding. Ideally, the seal should be 

tested to its predicted ultimate strength 

to determine the actual strength of the 

seal. For example, seals should be tested 

with the face perpendicular to the 

direction of a blast wave and subjected 

to a reflected overpressure, rather than 

a side-on overpressure. The testing 

program must address projectile impact 

on the seals. 

ETS § 75.336(a)(2)(ii) requires the 

applicant to provide technical 

information related to the methods and 

material used to construct and test the 

seals. The properties and laboratory test 

data of the materials are required. The 

laboratory test data should be provided 

by personnel certified by professional 

organizations such as the American 

Concrete Institute and by a NationallyRecognized Testing Laboratory to ensure 

proper quality control testing. MSHA 

intends to substantiate the design values 

used in the analysis and the full-scale 

testing of the seals. 

ETS § 75.336(a)(2)(iii) requires that 

the application include proper 

documentation. Proper documentation 

includes engineering analyses, 

construction drawings and 

specifications, and data that address 

seal material, fire resistance and flamespread index. The applicant must 

establish the materials and materials 

properties required for adequate seal 

construction. Construction 

documentation is required to ensure 

that the seals are properly built and 

reliable, to address air leakage, and to 

verify that the material properties of the 

seal will meet the specified strength 

criteria. 

ETS § 75.336(a)(2)(iv) requires the 

application to include an engineering 

analysis addressing differences between 

actual full-scale test support conditions 

and the range of support conditions that 

could be encountered in an 

underground coal mine. MSHA 

recognizes that the test site may have 

different support conditions than an 

underground coal mine. This 

information must ensure that a tested 


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seal design will reliably function as 

designed in an underground coal mine. 

ETS § 75.336(a)(2)(v) requires a Seal 

Design Table be included in the 

application that discusses 

characteristics related to mine specific 

seal construction. These characteristics 

include the maximum entry width and 

height for which the specific design is 

applicable, specified strength of the seal 

material, thickness of the seal and the 

reinforcement and anchorage 

requirements for the seal. Additional 

information may be provided at the 

discretion of the designer. 

Entry dimensions 

(ft) 

Thickness 

(ft-in) 

Specified unconfined 

compressive strength 

(psi) 

Reinforcement Foundation anchorage 

c. Sec. 75.336(a)(3) 

ETS § 75.336(a)(3) is consistent with 

existing § 77.216(2)(b) and Approval 

Policy 1009, and specifies that MSHA 

will notify the applicant if additional 

information or testing is required. The 

applicant must provide this 

information, arrange for any additional 

or repeat tests related to this additional 

information, and notify the Agency of 

the location, date, and time of such 

tests. 

d. Sec. 75.336(a)(4) 

The applicant, under ETS 

§ 75.336(a)(4), will be notified by MSHA 

in writing, whether the design is 

approved or denied. If the design is not 

approved, MSHA will specify, again in 

writing, the deficiencies of the 

application, or necessary revisions for 

approval. This provision is consistent 

with existing § 77.216–2 and Approval 

Policy 1009. 

e. Sec. 75.336(a)(5) 

ETS § 75.336(a)(5) is consistent with 

existing § 77 .216–3 and requires the 

approval holder to promptly contact 

MSHA’s Office of Technical Support, in 

writing, of all deficiencies, such as 

design or material flaws, when they 

become aware. MSHA’s intent is that 

‘‘promptly’’ means the approval holders 

are expected to contact MSHA as soon 

as they have knowledge that a 

deficiency exists. 

f. Sec. 75.336(b) Mine Specific 

Application; Seal Design Approval in 

the Ventilation Plan 

The ETS requires the mine operator to 

use an approved seal design, provided 

the District Manager approves 

installation of the design in the 

ventilation plan. The requirements in 

this section are consistent with 

Procedure Instruction Letter No. 

I06–V–9 (August 2006) that established 

uniform procedures for application to 

MSHA for approval of alternative seals 

constructed after July 19, 2006. 

ETS § 75.336(b) is new and requires 

that mine operators use an MSHAapproved seal design. The mine 

ventilation plan that addresses the 

installation of seals must be approved 

by the District Manager prior to the 

mine operator initiating seal 

construction in the mine. The Darby and 

Sago mine explosions revealed 

problems with seal construction. 

MSHA’s accident investigation report 

into both explosions states that the seals 

were constructed without mortar 

between the joints. MSHA determined 

that overpressure was a problem in both 

the Sago and Darby accidents. Adequate 

seals are crucial to contain explosions 

and prevent potentially explosive or 

toxic gasses from migrating into the 

active working areas of underground 

coal mines. MSHA is requiring that seal 

installation be approved in the 

ventilation plan to help ensure that 

seals are appropriately installed to 

effectively protect miners. 

Under ETS § 75.336(b), the mine 

operator must use an approved seal 

design provided the installation is 

approved in the ventilation plan. These 

design documents will serve as 

historical references. Seal design 

applications must provide information 

that the seal will withstand the 

appropriate overpressure from an 

explosion in accordance with current, 

prudent engineering practices, design 

codes and guidelines, and the seal 

strength requirements of ETS 

§ 75.335(a). 

ETS § 75.336(b)(1) requires the mine 

operator to retain a copy of the seal 

design approval information for as long 

as the seal is needed to serve the 

purpose for which it was built. MSHA 

intends to review mine operators’ seal 

design approvals at the mine site to 

evaluate and address construction and 

other installation-related issues. 

ETS § 75.336(b)(2) requires the mine 

operator to designate a professional 

engineer to conduct or have oversight of 

seal installation. The professional 

engineer is required to certify that the 

site-specific seal design complies with 

the provisions of paragraph(a) of this 

section. The professional engineer will 

help ensure that proper seal design 

implementation and related analyses are 

performed by qualified personnel and 

ensure seals are constructed according 

to the drawings and specifications. A 

copy of the certification must be 

submitted to the District Manager with 

the information provided in ETS 

§ 75.336(b)(3). The mine operator must 

keep a copy of the certification for as 

long as the seal is needed to serve the 

purpose for which it was built. 

ETS § 75.336(b)(3) lists specific 

information that a mine operator must 

address in the ventilation plan. This 

information will be used by the District 

Manager to evaluate a seal installation 

and determine whether the seal design 

is appropriate for a particular site. 

Paragraph (b)(3)(i) requires that mine 

operators include the MSHA Technical 

Support Approval Number of the seal 

design. Paragraph (b)(3)(ii) requires a 

mine map certified by a professional 

engineer showing the proposed seal 

location and surrounding areas to be 

submitted. 

ETS § 75.336(b)(3)(iii) requires 

specific information about the mine site. 

This information may be included on 

the mine map of the area to be sealed. 

Paragraph (b)(3)(iii)(A) requires that the 

type of seal be included in the 

ventilation plan. The type of seal must 

be identified by the approval number 

provided in (b)(3)(i) of this paragraph. 

ETS § 75.336(b)(3)(iii)(B) requires 

mine operators to include safety 

precautions to be taken before seals 

achieve their specified strength. Safety 

precautions could include withdrawing 

miners a safe distance from the seal 

installation site or actively inerting the 

sealed area. 

ETS § 75.336(b)(3)(iii)(C) requires that 

the mine operator include methods to 

address site-specific conditions that 

may affect the strength and applicability 

of a seal. These conditions could 

include: the mine opening dimensions 

and an estimate of dimension increases 

due to site preparation, such as the 

removal of weak roof, floor strata or 

friable coal; consideration of the local 

geology and mine conditions of the seal 

installation location; and a description 

of the ground conditions, which may 

include anchorage pull-test information. 

Other factors such as variability in 

material properties, geotechnical 


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properties, geologic conditions, and the 

quality of construction should be 

considered to ensure that a seal can 

reliably withstand the overpressures. 

Adverse ground conditions, such as 

convergence, may be unsuitable for 

certain types of seals. These conditions 

should be addressed and resolved by the 

professional engineer. 

ETS § 75.336(b)(3)(iii)(D) requires that 

the mine operator specify construction 

techniques for each type of seal. This 

could include equipment, procedures, 

materials and general mine safety 

information. This information is 

required to help ensure that the seal is 

properly constructed. 

ETS § 75.336(b)(3)(iii)(E) requires the 

mine operator to address seal 

construction site preparation which 

should include localized mine water 

drainage and foundation preparation as 

required in each seal design. The 

foundation refers to the horizontal and 

vertical surfaces of the mine opening. 

Keys or hitches formed in rock and coal 

to increase the lateral restraint should 

be excavated with equipment that 

minimizes the fracturing and breakout 

of strata. Strata with open joints should 

be addressed. 

ETS § 75.336(b)(3)(iii)(F) requires the 

mine operator to include the sequence 

of seal installations. Ventilation controls 

should be managed during seal 

construction until the final seals are 

installed. 

ETS § 75.336(b)(3)(iii)(G) requires the 

mine operator to provide the projected 

completion date of each set of seals. 

Changes in ventilation controls may be 

necessary as seal construction 

progresses and may occur on a daily 

basis. MSHA intends for seals to be 

installed in a timely manner. 

ETS § 75.336(b)(3)(iii)(H) requires the 

mine operator to specify supplemental 

roof support to be installed inby and 

outby each seal. Supplemental support 

provides long-term stability for each 

seal, and it is important that the Agency 

know the type of support used in the 

sealed area. The competency of the 

strata surrounding the seal is critical to 

its long-term stability. 

ETS § 75.336(b)(3)(iii)(I) requires the 

mine operator to provide an estimation 

of the water flow and the dimensions of 

the water drainage system. This 

information will be used by MSHA to 

evaluate whether the water drainage 

system is appropriate since seals must 

not impound water. 

ETS § 75.336(b)(3)(iii)(J) requires the 

mine operator to specify the methods 

used to ventilate the entries outby the 

seals after completion. Ventilation is 

necessary to control methane which 

outgasses from the sealed area. 

Information about the ventilation 

methods will help MSHA assess the 

adequacy of the ventilation plan. 

ETS § 75.336(b)(3)(iii)(K) requires the 

mine operator to specify methods and 

materials used to maintain each type of 

seal. Mine operators should include 

information to address minor repair of 

cracks, spalls, and small air leaks 

through and about the perimeter of each 

seal to control leakage. Roof 

deterioration, roof falls, and sloughing 

of the coal pillars may adversely affect 

the overall strength of a seal by 

compromising the structural integrity of 

the supporting strata. 

ETS § 75.336(b)(3)(iii)(L) requires the 

mine operator to specify methods to 

address shafts and boreholes within the 

sealed area. The mine operator should 

specify how and when each borehole 

will be plugged and each shaft will be 

filled during the sealing process. 

ETS § 75.336(b)(3)(iii)(M) requires the 

mine operator to provide any additional 

information requested by the MSHA 

District Manager for inclusion in the 

ventilation plan. This provision will 

ensure that any new developments in 

technology or any problems related to 

site-specific conditions in sealing may 

be addressed by the mine operator 

through the ventilation plan. 

MSHA requests comments on the 

appropriateness of the ventilation plan 

contents and whether additional 

information should be included. 

Commenters should submit information 

in support of their positions, including 

data related to projected cost and 

technological feasibility. 

3. Sec. 75.337 Construction and Repair 

of Seals 

This ETS includes new provision 

§ 75.337 addressing requirements for: 

preparation of the area to be sealed; 

supervision of seal construction and 

repair; certification that the seal was 

built in accordance with the provisions 

in ETS § 75.336(b); notification to 

MSHA concerning construction 

schedules; and training miners and 

senior mine management officials in the 

construction and repair of seals. Repairs 

addressed by this section are limited to 

non-structural repairs. The scope of 

these repairs is related to general 

maintenance and includes: Excessive air 

leakage through and around seals; repair 

of minor cracks; spalling of seal coating; 

water drainage systems; and sampling 

pipes. This section of the ETS is based 

on MSHA experience with mine 

ventilation plans under existing 

§§ 75.334, 75.370, and 75.371, and 

regarding worked-out areas and areas 

where pillars are being recovered. 

MSHA believes these ETS provisions 

are necessary to adequately protect 

miners’ health and safety. 

a. Sec. 75.337(a) Site Preparation 

ETS § 75.337(a) requires removal of 

insulated cables from the area to be 

sealed and removal of metallic objects 

through or across seals. Paragraph (a)(1) 

requires removal of all insulated cables, 

including hanging, buried, and cables 

within conduit, from the sealed area 

before seals are built. This requirement 

is included in the ETS because a spark 

could be developed if a length of 

insulated cable were inductively 

coupled to an electromagnetic pulse, 

such as those generated by lightning 

strikes. These sparks can ignite an 

explosive methane/air mixture. After 

the SAGO explosion, MSHA contracted 

with Sandia Corporation, the operator of 

Sandia National Laboratories (Sandia), 

to perform modeling and testing to 

determine if it were possible for 

lightning to cause electrical energy to 

enter the Sago Mine and cause an 

explosion. Sandia has preliminarily 

determined that a lightning strike could 

create enough energy in the sealed area 

to ignite methane. 

Typically, as mine operators complete 

mining activities in an area, they 

recover the more valuable cables and 

may only leave behind damaged or 

deteriorated cables. MSHA anticipates 

that the removal of abandoned cables 

will not be a significant burden for mine 

operators and would not adversely 

affect future mining activities. This 

requirement would improve miners’

safety because removal of cables reduces 

the hazard of an explosion caused by an 

electrical discharge. 

MSHA believes that removal of 

insulated cables and metallic objects 

through or across seals is feasible and 

will not involve significant technical or 

practical problems. MSHA solicits 

comments on these measures. 

ETS § 75.337(a)(2) requires metallic 

objects that pass through or across a seal 

to be removed. Gas sampling pipes and 

water drainage systems required by ETS 

§ 75.335(d) and (e), and form ties 

approved in the seal design provided by 

ETS § 75.336 are allowed in the sealed 

area. 

Metallic material can provide a 

conduit for electrical current to enter 

the sealed area and ignite methane/air 

mixtures. It is necessary to limit the use 

of conductors that may pass around or 

across seals. Screen, straps, rails, 

channels, and water pipes are typical 

metallic materials that are required to be 

removed under the ETS. Removal of 

metallic objects through or across seals 

before they are built will reduce the 


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hazard of methane explosions and 

improve miner safety. 

b. Sec. 75.337(b) Supervision of 

Construction and Repair of Seals 

ETS § 75.337(b) requires a certified 

person designated by the mine operator 

to directly supervise the seal 

construction and repair process and 

make appropriate examinations. After 

the Sago Mine and Darby No. 1 Mine 

explosions, MSHA inspected seals in 

underground coal mines across the 

country. The Agency has determined 

that some seals were not built correctly. 

This new provision requires that seal 

construction for all seals built after May 

22, 2007 be directly supervised by a 

certified person. Existing § 75.100 

defines certified person and requires 

that person to obtain certification from 

the Secretary of Labor or the State in 

which the coal mine is located. A 

certified person shall directly supervise 

the construction of each seal throughout 

the construction or repair process. This 

new provision will assure that all 

activities related to seal construction, 

repair, and examination are performed 

safely and in accordance with 

appropriate requirements. ETS § 75.337(b)(1) requires a certified 

person to examine each seal 

construction or repair site prior to 

beginning seal construction or repair to 

ensure that the site conditions are in 

accordance with the approved 

ventilation plan. ETS § 75.337(b)(2) requires a certified 

person to observe the construction or 

repair process during each shift that 

construction or repair take place. This 

provision will help ensure construction 

or repairs of seals conform to the 

approved seal design and site specific 

information provided under § 75.336(b). 

ETS § 75.337(b)(3) requires a certified 

person to perform an examination of 

each seal or repair to verify that the seal 

or repair is complete. The District 

Manager may require that each 

examination include an assessment of 

any supplemental roof support, 

ventilation of the seals, sampling pipes 

and appropriate fittings, and the water 

drainage system as provided in the 

ventilation plan under ETS § 75.336(b). 

ETS § 75.337(b)(4) requires the 

certified person certify each seal 

construction or repair by initialing the 

date and time of their examination to 

verify that the required examinations 

were made. 

ETS § 75.337(b)(5) requires a record 

be made in a book or a log provided for 

that purpose to affirm that the 

examinations were conducted. The 

record shall describe any deficiencies in 

site preparation, such as construction, 

repairs, seal completion, and hazardous 

conditions and any corrections made. 

The record must be made by the 

certified person conducting the 

examination when the examiner arrives 

on the surface at the end of the shift. 

The record shall be countersigned by 

the mine foreman or equivalent mine 

official. Records of the deficiencies and 

the corrective actions provide valuable 

safety information about seal conditions 

and sealed areas in the mine and the 

effectiveness of corrective measures. 

The recordkeeping requirement for 

examination of seals would allow 

MSHA to determine if examinations 

have been conducted, if results are 

valid, and that deficiencies in site 

preparation, construction, repairs, and 

seal completion found were corrected. 

By requiring that a record be 

countersigned, MSHA expects that the 

mine foreman or equivalent mine 

official must review the record before 

countersigning. This provision makes 

certain that a mine foreman or 

equivalent mine official is responsible 

for oversight of seal installation. The 

countersignature shall be made by the 

end of the mine foreman’s or equivalent 

mine official’s next regularly scheduled 

working shift. The records of examinations required 

under ETS § 75.337(b)(5) shall be kept at 

the mine for one year. ETS § 75.338 sets 

out additional seal recordkeeping 

duration requirements. 

c. Sec. 75.337(c) Certification of 

Construction by Senior Mine 

Management 

ETS § 75.337(c) requires that upon 

completion of construction of each seal, 

a senior mine management official, such 

as a mine manager or superintendent, 

certify that the construction, 

installation, and materials used were in 

accordance with the approved mine 

ventilation plan. This requirement 

assures that a senior mine management 

official takes responsibility for making 

sure that seals are constructed in 

accordance with the provisions under 

ETS § 75.336(b). 

d. Sec. 75.337(d) Notification to 

MSHA 

ETS § 75.337(d)(1) requires the mine 

operator to notify the local MSHA field 

office between two and fourteen days 

prior to commencement of seal 

construction. This requirement provides 

MSHA the opportunity to observe seal 

construction. This is particularly critical 

when a mine operator is installing a 

new seal design or the mine liberates 

large amounts of methane. ETS § 75.337(d)(2) requires the mine 

operator to notify the MSHA District 

Manager, in writing, within 5 days of 

completion of each set of approved 

seals. This provision allows the District 

Manager to be informed when all 

construction is completed. This is a 

critical time period during the 

construction of seals. It involves the 

time period during which seals are 

achieving full strength and the 

atmosphere inby the seals may be 

transitioning into or through a 

potentially explosive methane/air 

mixture. MSHA may decide to inspect 

the newly sealed area, or sample the 

atmosphere. 

ETS § 75.337(d)(3) requires the mine 

operator to submit to the MSHA District 

Manager quality control test results 

required in ETS § 75.336. Material test 

results shall be sent to MSHA and must 

include all seal testing and tests of seal 

construction materials. 

e. Sec. 75.337(e) Training 

Failure of a seal may result in 

significant injury, loss of life and/or 

significant economic loss. Based on 

recent explosion investigations, MSHA 

learned that numerous persons involved 

in constructing seals that failed were not 

adequately trained. As a result, 

installation, construction, and repair 

tasks and the level of quality control 

exercised during these activities are 

critical to preventing seal failures and 

protecting miners. 

Under ETS § 75.337(e), the mine 

operator is responsible for providing 

training to miners constructing or 

repairing seals, certified persons 

supervising seal construction, repair, 

and examinations described in (b)(1) of 

this section, and senior mine 

management officials described in 

paragraph (c) of this section. 

The training shall address materials 

and procedures required in the 

approved seal design in the mine’s 

ventilation plan. For example, material 

training could include how to construct 

reinforced concrete, masonry block, 

gunite, and cementitious foam seals. 

Additionally, training shall include 

procedures in tasks such as hitching, 

evacuating weak materials, supporting 

and stabilizing roofs, and installing 

sampling pipes and water drainage 

systems. 

Training under this paragraph is also 

required for persons repairing seals. In 

addition to the training required for 

constructing seals, further training may 

be necessary for repairing a damaged 

seal. This training could include tasks 

such as patching small cracks, sealing 

leaks, and maintaining water drainage 

systems. 

MSHA recognizes that the amount of 

time required for training in 

constructing or repairing seals will vary. 


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For this reason, MSHA is not proposing 

a minimum amount of time for the 

training. MSHA expects mine operators 

to adjust the time for this training based 

on the complexity of the seal design in 

the ventilation plan, construction or 

repair procedures, materials used, and 

existing knowledge and skill levels of 

persons receiving the training. Also, 

changes in the approved seal design or 

approved ventilation plan will require 

retraining. 

This paragraph also requires mine 

operators to certify the date that training 

was provided. Operators are required to 

retain these certifications for one year 

from the time training was conducted. 

This provision is similar to other 

certification requirements in Part 75 

where the operator certifies by signature 

and date that training was provided. 

MSHA requests comments on the 

provisions provided in this section. In 

particular, MSHA requests comments 

concerning the scope and possible 

alternatives to the requirements related 

to site preparation, examinations, and 

notification provisions. 

4. Sec. 75.338 Seals Records 

ETS § 75.338(a) sets out the 

recordkeeping duration required for 

records created under ETS §§ 75.335, 

75.336, and 75.337. For the convenience 

of the mining community, these 

requirements are listed in the table 

entitled ‘‘Table § 75.338(a) Seal 

Recordkeeping Requirements.’’ The 

table lists the record which must be 

kept, the section requiring the record, 

and the required retention time. 

TABLE TO § 75.338(a). SEAL RECORDKEEPING REQUIREMENTS

Record Section reference Retention time 

(1) Protocol to monitor methane and oxygen and maintain an 

inert atmosphere.

75.335(b) .......... Same as ventilation plan requirements. 

(2) Training of certified persons ................................................ 75.335(b)(2) ...... 1 year. 

(3) Gas sampling records .......................................................... 75.335(b)(6) ...... 1 year. 

(4) Approved seal design .......................................................... 75.336(b)(1) ...... As long as the seal is needed to serve the purpose for which 

it is built. 

(5) Certification of provisions of approved seal design is addressed.75.336(b)(2) ...... As long as the seal is needed to serve the purpose for which 

it is built. 

(6) Record of examinations ....................................................... 75.337(b)(5) ...... 1 year. 

(7) Seal construction certification .............................................. 75.337(c) .......... As long as the seal is needed to serve the purpose for which 

it is built. 

(8) Certification of training ......................................................... 75.337(e) .......... 1 year. 

ETS § 75.338(b) applies to seal records 

required to be kept under the ETS, 

except for the certification required 

under ETS § 75.337(b)(4) which must be 

retained at the seal site. Operators must 

retain records at the mine site. The mine 

operator may retain records in a 

computer system elsewhere, provided 

they are immediately accessible from 

the mine site by electronic transmission. 

Records must be secure and not subject 

to alteration. 

ETS § 75.338(c) requires that the 

operator allow access to any record to 

an authorized representative of the 

Secretary of Labor, the Secretary of 

Health and Human Services, the 

authorized representative of miners, or 

other interested parties, upon request. 

Mine operators are to promptly provide 

access to any record listed in the table 

in paragraph (a) of this section. MSHA 

expects that an operator show due 

diligence in providing access to 

required records. Whenever an operator 

ceases to do business, the operator will 

be required to transfer all records 

required to be maintained by this part 

to any successor operator. 

5. Conforming Changes to Other 

Sections in Part 75 

Existing paragraph (ff) of § 75.371 

requires the mine operator to provide a 

description of methods and materials to 

be used to seal worked out areas when 

they are different from those specified 

in paragraph (a)(1) of § 75.335. The 

provisions in existing paragraph (a) of 

§ 75.335 are revised and moved to 

paragraph (b) of § 75.335 and paragraph 

(b)(3) of § 75.336. Therefore, paragraph 

(ff) is revised to reference sampling 

requirements provided by paragraph (b) 

of § 75.335 and ventilation plan 

contents requirements provided by 

paragraph (b)(3) of § 75.336. 

V. Executive Order 12866 

Executive Order (E.O.) 12866 (58 FR 

51735) as amended by E.O. 13258 

(Amending Executive Order 12866 on 

Regulatory Planning and Review (67 FR 

9385)) requires regulatory agencies to 

assess both the costs and benefits of 

regulations. To comply with Executive 

Order 12866, MSHA has prepared a 

Regulatory Economic Analysis (REA) for 

the ETS. The REA contains supporting 

data and explanation for the summary 

materials presented in sections V–IX of 

this preamble, including the covered 

mining industry, costs and benefits, 

feasibility, small business impact, and 

paperwork. The REA is located on 

MSHA’s Web site at http:// 

www.msha.gov/regsinfo.htm. A copy of 

the REA can be obtained from MSHA’s 

Office of Standards, Regulations and 

Variances. MSHA requests comments on 

all the estimates of costs and benefits 

presented in this ETS and in the REA. 

MSHA has determined that the ETS 

would not have an annual effect of $100 

million or more on the economy and, 

therefore, it is not an economically 

‘‘significant regulatory action’’ pursuant 

to Sec. 2(f) of E.O. 12866. 

A. Population-at-Risk 

The ETS applies to all underground 

coal mines in the United States. Based 

on preliminary MSHA data, there were 

670 underground coal mines, employing 

42,667 miners, operating in the U.S. in 

2006. Of these, 372 underground coal 

mines use seals. These 372 mines 

employ 33,684 miners, of which 30,095 

work underground. 

B. Benefits 

To provide a preliminary quantitative 

estimate of benefits, MSHA analyzed the 

explosions in sealed areas that have 

taken place since 1993, and especially 

studied the two accidents in 2006 where 

the seals failed and fatalities occurred: 

the Sago mine explosion, where 12 

miners died, and the Darby No. 1 mine 

explosion, where 5 miners died. It is 

reasonable to assume that if the ETS had 

been in effect, all 17 of these miners’

lives might have been saved. Fourteen 

of these lives might have been saved by 

the 2006 ETS and final rule on 

emergency mine evacuation. However, 

three of the miners that perished in the 

Sago and Darby accidents died 


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immediately from the explosion impact. 

They could not have been saved by the 

emergency mine evacuation rule. For 

purposes of estimating benefits, MSHA 

attributes the saving of three miners’

lives to this ETS and splits the 

remaining 14 lives between this ETS 

and the 2006 emergency mine 

evacuation rule. Hence, MSHA 

attributes the saving of 10 lives to this 

ETS (3 + (14 ÷ 2) = 10). 

MSHA has good data on explosions in 

sealed areas only since 1993. During the 

period 1993–2006 (14 years) there were 

13 explosions in sealed areas. However, 

only 11 of these explosions caused any 

seal damage and thus had the potential 

to cause fatalities or injuries. Only two 

of these 11 explosions actually caused 

fatalities or injuries. A strict division, 

(10 lives)/(14 years), would suggest that 

the ETS will save approximately 0.7 

lives per year if the explosions followed 

approximately the same distribution as 

they did since 1993. 

However, MSHA believes that the risk 

from explosions in sealed areas has been 

increasing during this time period 

because the number of seals has been 

increasing. MSHA did not allow 

alternative seals until 1992. Prior to 

1992, most mines did not seal, but 

instead ventilated. During the period 

from 1993 through 2006, mines went 

through a transition period of shifting 

from ventilation to seals. The current 

risk from explosions in sealed areas is 

therefore higher than the historic risk 

during this transition period. 

MSHA roughly estimates that, on 

average, during that transition period, 

the number of mines using seals was no 

more than 2⁄3 of the number of mines 

that currently use seals. Furthermore, 

the number of seals in mines is 

cumulative. During this period of 

increased seal use, MSHA roughly 

estimates that the average number of 

seals in mines that used seals was no 

more than 2/3 of the number in mines 

that currently use seals. MSHA 

specifically asks for comment on these 

estimates. After adjusting this estimate 

to account for the increased future risk, 

the ETS will save approximately 1.6 

lives per year, since (10⁄14/2⁄3/2⁄3) = 1.6. 

This is MSHA’s best estimate on the 

number of lives saved per year due to 

this rulemaking. 

MSHA also developed a higher risk 

estimate, based primarily on the 

distribution of miners put at risk and 

the characteristics of the explosions 

themselves. MSHA also asks for 

comment on these calculations. 

In the 11 explosions in sealed areas 

with property damage, approximately 

688 miners total were underground at 

the time of the explosions. This is an 

average of 62.5 miners per explosion 

that were put at risk. In the two 

explosions at Sago and Darby only a 

total of 35 miners were underground at 

the time of the explosions, for an 

average risk exposure of 17.5 miners per 

explosion. Fortunately, no explosions in 

sealed areas at larger mines (so far) have 

caused any injuries or fatalities. 

If an explosion with the 

characteristics of the explosions at Sago 

or Darby occurs at a larger mine, many 

more lives potentially could be lost. 

Assuming the risk of fatality from an 

explosion in a sealed area is about the 

same at both large and small mines, and 

the number of potential fatalities is 

proportional to the number of miners 

working underground, during the other 

explosions studied by MSHA, then a 

higher risk estimate of the benefits of 

the ETS is approximately 5.7 lives saved 

per year, since 1.6 x (62.5/17.5) = 5.7. 

MSHA also calculated the cumulative 

risk faced by a miner over a 45 year 

working life. The 372 existing 

underground coal mines that seal 

employ 33,684 miners; of these, 30,095 

work underground. Under MSHA’s best 

estimate, the ETS will save 1.6 lives per 

year, which means that the risk of 

fatality per year per 1,000 miners is 

0.053. Over a 45-year working lifetime, 

the risk of fatality from an explosion in 

a sealed area is 2.4 per 1,000 miners. If 

the ETS will save the higher estimate of 

benefits of 5.7 lives per year, then the 

risk of fatality per year per 1,000 miners 

is 0.191. Over a 45-year working 

lifetime, the risk of fatality from an 

explosion in a sealed area is 8.5 per 

1,000 miners. 

With the provisions of the ETS in 

effect, an explosion is less likely to 

occur behind seals that are being 

actively monitored to maintain an inert 

atmosphere. The provisions of the ETS 

also strengthen seals to better withstand 

explosions, which reduces immediate 

miner injuries and fatalities and gives 

miners more time to react to a situation 

involving an explosion. 

MSHA requests comments on the 

benefit estimates developed above and 

in the REA, as well as on the 

assumptions and data sources that 

MSHA used. 

C. Compliance Costs 

MSHA estimates that the ETS will 

result in total yearly costs for 

underground mine operators and 

contractors of approximately $39.7 

million. Total first year costs will be 

approximately $43.2 million. 

Disaggregated by mine size, yearly costs 

will be $2.6 million for the 83 mine 

operators with fewer than 20 employees; 

$34.7 million for the 279 mine operators 

with 20–500 employees; and $2.4 

million for the 10 mine operators with 

more than 500 employees. Most of the 

compliance cost occurs in the mine size 

category with 20–500 employees 

because 75 percent of the mines that use 

seals are in this category. 

MSHA requests comments on the cost 

estimates developed above and in the 

REA, as well as on the assumptions and 

data sources that MSHA used. 

VI. Feasibility 

MSHA has concluded that the 

requirements of the ETS are 

technologically and economically 

feasible. 

A. Technological Feasibility 

MSHA concludes that the ETS is 

technologically feasible. MSHA based 

its conclusion on an analysis of the 

compliance requirements of the ETS 

provisions for training, sampling, and 

construction and repair. MSHA believes 

compliance with these requirements is 

technologically feasible because the 

materials, equipment, and methods for 

implementing these requirements 

currently exist. However, MSHA will be 

gathering information on seal designs at 

120 psi overpressure and will make this 

information available to the mining 

community. MSHA solicits comments 

on this issue, and on seal designs that 

are greater than 120 psi overpressure. 

B. Economic Feasibility 

MSHA also believes that the ETS is 

economically feasible. The yearly 

compliance cost of the ETS is $39.7 

million which is 0.30 percent of all 

revenues ($39.7 million/$13.1 billion) 

for all underground coal mines. MSHA 

concludes that the ETS is economically 

feasible for these mine operators 

because the total compliance costs are 

well below one percent of the estimated 

revenues for all underground coal 

mines. 

VII. Regulatory Flexibility Act and 

Small Business Regulatory Enforcement 

Fairness Act (SBREFA) 

Pursuant to the Regulatory Flexibility 

Act (RFA) of 1980, as amended by the 

Small Business Regulatory Enforcement 

Fairness Act (SBREFA), MSHA has 

analyzed the impact of the ETS on small 

businesses. Based on that analysis, 

MSHA has notified the Chief Counsel 

for Advocacy, Small Business 

Administration, and made the 

certification under the Regulatory 

Flexibility Act at 5 U.S.C. 605(b) that 

the ETS will not have a significant 

economic impact on a substantial 

number of small entities. The factual 

basis for this certification is presented 


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2U.S. Department of Energy, Energy Information 

Administration, Annual Coal Report 2005, Table 28. 

in full in Chapter V of the REA and in 

summary form below. 

A. Definition of a Small Mine 

Under the RFA, in analyzing the 

impact of the ETS on small entities, 

MSHA must use the Small Business 

Administration (SBA) definition for a 

small entity or, after consultation with 

the SBA Office of Advocacy, establish 

an alternative definition for the mining 

industry by publishing that definition in 

the Federal Register for notice and 

comment. MSHA has not taken such an 

action and hence is required to use the 

SBA definition. The SBA defines a 

small entity in the mining industry as 

an establishment with 500 or fewer 

employees. 

In addition to examining small 

entities as defined by SBA, MSHA has 

also looked at the impact of this ETS on 

underground coal mines with fewer 

than 20 employees, which MSHA and 

the mining community have 

traditionally referred to as ‘‘small 

mines.’’ These small mines differ from 

larger mines not only in the number of 

employees, but also in economies of 

scale in material produced, in the type 

and amount of production equipment, 

and in supply inventory. Therefore, the 

cost of complying with MSHA’s ETS 

and the impact of the ETS on small 

mines will also be different. It is for this 

reason that small mines are of special 

concern to MSHA. 

MSHA concludes that it can certify 

that the ETS will not have a significant 

economic impact on a substantial 

number of small entities that are 

covered by this ETS. The Agency has 

determined that this is the case both for 

mines with fewer than 20 employees 

and for mines with 500 or fewer 

employees. 

B. Factual Basis for Certification 

MSHA initially evaluates the impacts 

on ‘‘small entities’’ by comparing the 

estimated compliance costs of a rule for 

small entities in the sector affected by 

the rule to the estimated revenues for 

the affected sector. When estimated 

compliance costs are less than one 

percent of the estimated revenues, the 

Agency believes it is generally 

appropriate to conclude that there is no 

significant economic impact on a 

substantial number of small entities. 

When estimated compliance costs 

exceed one percent of revenues, MSHA 

investigates whether a further analysis 

is required. 

For underground coal mines, the 

estimated 2006 production was 

7,813,073 tons for mines that had fewer 

than 20 employees and 277,500,019 tons 

for mines that had 500 or fewer 

employees. Using the 2005 price of 

underground coal of $36.42 per ton 2

and total 2006 coal production in tons, 

underground coal revenues are 

estimated to be approximately $285 

million for mines employing fewer than 

20 employees and $10.1 billion for 

mines employing 500 or fewer 

employees. Thus, the yearly cost of the 

ETS for mines that have fewer than 20 

employees is 0.9 percent ($2.6 million/ 

$285 million) of annual revenues, and 

the yearly cost of the ETS for mines that 

have 500 or fewer employees is 0.4 

percent ($0.037 billion/$10.1 billion) of 

annual revenues. Using either MSHA’s 

traditional definition of a small mine 

(one having fewer than 20 employees) or 

SBA’s definition of a small mine (one 

having 500 or fewer employees), the 

yearly costs for underground coal mines 

to comply with the ETS will be less than 

1 percent of their estimated revenues. 

Accordingly, MSHA has certified that 

the ETS will not have a significant 

impact on a substantial number of small 

entities that are covered by the ETS. 

VIII. Paperwork Reduction Act of 1995 

A. Summary 

This ETS contains information 

collection requirements that MSHA 

estimates will result in 82,037 new 

burden hours and approximately $4.7 

million related burden costs to mine 

operators and manufacturers in the first 

year that the ETS is in effect. In the 

second year that the ETS is in effect, 

and for every year thereafter, MSHA 

estimates that mine operators and 

manufacturers will incur 73,006 new 

burden hours and approximately $4.6 

million related burden costs. The 

burden is different in the first year 

because some information collection 

requirements occur only in the first year 

that the ETS is in effect. 

This ETS contains information 

collection requirements in the following 

sections: § 75.335 seal requirements; 

§ 75.336 seal design applications and 

installation approval; and § 75.337 

construction and repair. 

For a detailed explanation of how the 

burden hours and related costs were 

determined, see Chapter VII of the 

Regulatory Economic Analysis (REA) 

associated with this ETS. The REA is 

located on MSHA’s Web site at http:// 

www.msha.gov/REGSINFO.HTM. A 

print copy of the REA can be obtained 

from the Office of Standards, 

Regulations, and Variances at MSHA. 

B. Details 

The information collection package 

has been submitted to the Office of 

Management and Budget (OMB) for 

review under 44 U.S.C. § 3504(h) of the 

Paperwork Reduction Act of 1995, as 

amended. A copy of the information 

collection package can be obtained from 

the Department of Labor by email 

request to king.darrin@dol.gov or by 

phone request at (202) 693–4129. 

Comments on the provisions in the 

information collection requirements 

should be sent to both the Office of 

Information and Regulatory Affairs of 

OMB and to MSHA. Comments sent to 

OMB should be sent to the Attention of 

the Desk Officer for the Mine Safety and 

Health Administration. Comments sent 

to MSHA should be sent to the Office of 

Standards, Regulations, and Variances. 

Addresses for both offices can be found 

in the Addresses section of this 

preamble. Respondents are not required 

to respond to any collection of 

information unless it displays a current 

valid OMB control number. MSHA will 

publish a notice in the Federal Register 

announcing when OMB has approved 

the new information collection 

requirements. 

IX. Other Regulatory Considerations 

A. The Unfunded Mandates Reform Act 

of 1995 

MSHA has reviewed the ETS under 

the Unfunded Mandates Reform Act of 

1995 (2 U.S.C. 1501 et seq). MSHA has 

determined that this ETS does not 

include any federal mandate that may 

result in increased expenditures by 

State, local, or tribal governments; nor 

will it increase private sector 

expenditures by more than $100 million 

in any one year or significantly or 

uniquely affect small governments. 

Accordingly, the Unfunded Mandates 

Reform Act of 1995 (2 U.S.C. 1501 et 

seq.) requires no further agency action 

or analysis. 

B. Executive Order 13132: Federalism 

This ETS does not have ‘‘federalism 

implications’’ because it will not ‘‘have 

substantial direct effects on the States, 

on the relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government.’’ Accordingly, 

under E.O. 13132, no further Agency 

action or analysis is required. 


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C. The Treasury and General 

Government Appropriations Act of 

1999: Assessment of Federal 

Regulations and Policies on Families 

Section 654 of the Treasury and 

General Government Appropriations 

Act of 1999 (5 U.S.C. 601 note) requires 

agencies to assess the impact of Agency 

action on family well-being. MSHA has 

determined that this ETS will have no 

effect on family stability or safety, 

marital commitment, parental rights and 

authority, or income or poverty of 

families and children. This ETS impacts 

only the underground coal mine 

industry. Accordingly, MSHA certifies 

that this ETS would not impact family 

well-being. 

D. Executive Order 12630: Government 

Actions and Interference With 

Constitutionally Protected Property 

Rights 

This ETS does not implement a policy 

with takings implications. Accordingly, 

under E.O. 12630, no further Agency 

action or analysis is required. 

E. Executive Order 12988: Civil Justice 

Reform 

This ETS was written to provide a 

clear legal standard for affected conduct 

and was carefully reviewed to eliminate 

drafting errors and ambiguities, so as to 

minimize litigation and undue burden 

on the Federal court system. 

Accordingly, this ETS will meet the 

applicable standards provided in 

section 3 of E.O. 12988, Civil Justice 

Reform. 

F. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

This ETS will have no adverse impact 

on children. Accordingly, under E.O. 

13045, no further Agency action or 

analysis is required. 

G. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

This ETS does not have ‘‘tribal 

implications’’ because it will not ‘‘have 

substantial direct effects on one or more 

Indian tribes, on the relationship 

between the Federal government and 

Indian tribes, or on the distribution of 

power and responsibilities between the 

Federal government and Indian tribes.’’

Accordingly, under E.O. 13175, no 

further Agency action or analysis is 

required. 

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

Executive Order 13211 requires 

agencies to publish a statement of 

energy effects when a rule has a 

significant energy action that adversely 

affects energy supply, distribution or 

use. MSHA has reviewed this ETS for its 

energy effects because the ETS applies 

to the underground mining sector. 

Because this ETS will result in yearly 

costs of approximately $39.7 million to 

the underground coal mining industry, 

relative to annual revenues of $13.1 

billion in 2006, MSHA has concluded 

that it is not a significant energy action 

because it is not likely to have a 

significant adverse effect on the supply, 

distribution, or use of energy. 

Accordingly, under this analysis, no 

further Agency action or analysis is 

required. 

X. References 

ACI 318–05, ‘‘Building Code Requirements 

for Structural Concrete and 

Commentary,’’ American Concrete 

Institute. 

ACI 440.2R–02, ‘‘Design and Construction of 

Externally Bonded FRP Systems for 

Strengthening Concrete Structures,’’

American Concrete Institute. 

Army TM 5–1300, Navy NAVFAC P0397, Air 

Force AFR 88–22, Departments of the 

Army, the Navy, and the Air Force, 

‘‘Structures to Resist the Effects of 

Accidental Explosions,’’ November 1990. 

ASTM E119–07, ‘‘Standard Test Methods for 

Fire Tests of Building Construction and 

Materials,’’ ASTM International. 

ASTM E162–06, ‘‘Surface Flammability of 

Materials Using a Radiant Heat Energy 

Source,’’ ASTM International. 

Department of Labor, Mine Safety and Health 

Administration, Final Rule, 

Underground Coal Mine Ventilation 

Standards, May 15, 1992. 

Kissell, Fred N., ‘‘Handbook for Methane 

Control in Mining,’’ Information Circular 

9486. National Institute of Occupational 

Safety and Health, U.S. Dept. of Health 

and Human Services, 2006. 

Mitchell, Donald W., ‘‘Explosion-Proof 

Bulkheads—Present Practices,’’ Report of 

Investigations No. 7581, U.S. Dept. of the 

Interior, Bureau of Mines, 1971. 

Mitchell, Donald W., Burns, Frank A., 

‘‘Interpreting the State of a Mine Fire,’’

Investigational Report No. 1103, U.S. 

Department of Labor, Mine Safety and 

Health Administration, 1979. 

MSHA. Report of Investigation/Mine 

Explosion, Sago Mine, January 2, 2006. 

MSHA. Report of Investigation/Mine 

Explosion, Darby Mine No. 1, May 20, 

2006. 

MSHA. Program Information Bulletin No. 

P06–11, ‘‘Moratorium on Future Use of 

Alternative Seal Methods and Materials 

Pursuant to 30 CFR 75.335 and 

Assessment of Existing Sealed Areas in 

Underground Bituminous Coal Mines,’’

June 1, 2006. 

MSHA. Program Information Bulletin No. 

P06–12, ‘‘Reissued Moratorium on 

Future Use of Alternative Seal Methods 

and Materials Pursuant to 30 CFR 75.335 

and Assessment of Existing Sealed Areas 

in Underground Bituminous Coal 

Mines,’’ June 12, 2006. 

MSHA. Program Information Bulletin No. 

P06–16, ‘‘Use of Alternative Seal 

Methods and Materials Pursuant to 30 

CFR 75.335(a)(2),’’ July 19, 2006. 

MSHA. Procedure Instruction Letter No. I06–

V–9, ‘‘Procedures for Approval of 

Alternative Seals,’’ August 21, 2006. 

MSHA. Program Policy Manual, Volume V–

Coal Mines, Release V–33, February 

2003. 

MSHA, Approval and Certification Center, 

Application Cancellation Policy, CDS 

No. APOL1009, Revised February 27, 

2004. 

Zipf, R. K., Sapko, M. J., Brune, J. F., 

‘‘Explosion Pressure Design Criteria for 

New Seals in U.S. Coal Mines, Draft 

Report,’’ National Institute of 

Occupational Safety and Health, U.S. 

Dept. of Health and Human Services, 

February 8, 2007. 

XI. Emergency Temporary Standard— 

Regulatory Text 

List of Subjects in 30 CFR Part 75 

Mine safety and health, Underground 

coal mines, Reporting and 

recordkeeping, Ventilation. 

Dated: May 17, 2007. 

Richard E. Stickler, 

Assistant Secretary for Mine Safety and 

Health. 

■ Chapter I of Title 30, part 75 of the 

Code of Federal Regulations is amended 

as follows: 

PART 75—SAFETY STANDARDS FOR 

UNDERGROUND COAL MINES 

■ 1. The authority citation for part 75 

continues to read as follows: 

Authority: 30 U.S.C. 811, 863. 

■ 2. Revise § 75.335 to read as follows: 

§ 75.335 Seal requirements. 

Seals shall be designed, constructed, 

and maintained to protect miners from 

hazards related to sealed areas. Seal 

designs and the installation of each seal 

shall be approved in accordance with 

§ 75.336. 

(a) Seal strength requirements. Seals 

constructed on or after May 22, 2007 

shall be designed, constructed, and 

maintained to withstand—

(1) 50 psi overpressure when the 

atmosphere in the sealed area is 

monitored and maintained inert in 

accordance with paragraph (b) of this 

section; 

(2) 120 psi overpressure if the 

atmosphere is not monitored, and is not 


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maintained inert, and the conditions in 

paragraphs (a)(3)(i) through (iii) of this 

section are not present; or 

(3) An overpressure greater than 120 

psi if the atmosphere is not monitored 

and is not maintained inert and; 

(i) The atmosphere in the area to be 

sealed is likely to contain homogeneous 

mixtures of methane between 4.5 

percent and 17.0 percent and oxygen 

exceeding 17.0 percent throughout the 

entire area; 

(ii) Pressure piling is likely due to 

opening restrictions near the proposed 

seal area; or 

(iii) Other conditions are encountered, 

such as the likelihood of a detonation in 

the proposed seal area. 

(iv) Where the conditions in 

paragraphs (a)(3)(i), (ii), or (iii) of this 

section are encountered, the operator 

must revise the ventilation plan to be 

submitted to the District Manager to 

address the potential hazards. The plan 

shall include seal strength sufficient to 

address the conditions. 

(b) Sampling and monitoring 

requirements. Effective May 22, 2007, a 

certified person as defined in § 75.100 

shall monitor atmospheres of sealed 

areas. For seals constructed prior to May 

22, 2007 and for seals designed for 50 

psi overpressure, mine operators shall 

develop and follow a protocol to 

monitor methane and oxygen 

concentrations, and to maintain an inert 

atmosphere in the sealed area. The 

protocol shall be approved in the 

ventilation plan. 

(1) A certified person shall sample 

atmospheres of sealed areas weekly 

when the barometric pressure is 

decreasing or the seal is outgassing. At 

least one sample shall be taken at each 

set of seals. If a seal is ingassing during 

the weekly examination, a sample shall 

be collected during the next weekly 

examination. If the seal is ingassing 

during the second consecutive weekly 

examination, the operator shall examine 

that seal daily until the seal is 

outgassing, unless the seal does not 

outgas. In this case, an alternative plan 

needs to be developed and submitted to 

the District Manager. The District 

Manager may approve different 

sampling frequencies and locations in 

the ventilation plan, or approve the use 

of atmospheric monitoring systems in 

lieu of weekly sampling. The mine 

operator shall revise the protocol, if 

repeated sampling indicates that a seal 

is not likely to outgas. 

(2) Certified persons conducting 

sampling shall be trained in the 

sampling procedures included in the 

protocol, as provided by paragraph 

(b)(5) of this section, before they 

conduct sampling, and annually 

thereafter. The mine operator must 

certify the date and content of training 

provided certified persons and retain 

each certification for one year. 

(3) The atmosphere shall be 

considered inert when—

(i) The oxygen concentration is less 

than 10.0 percent; 

(ii) The methane concentration is less 

than 3.0 percent; or 

(iii) The methane concentration is 

greater than 20.0 percent. 

(4) When oxygen concentrations are 

10.0 percent or greater and methane 

concentrations are from 3.0 percent to 

20.0 percent in a sealed area, the mine 

operator shall take two additional gas 

samples at one-hour intervals. If the two 

additional gas samples are from 3.0 

percent to 20.0 percent and oxygen is 

10.0 percent or greater—

(i) The mine operator shall implement 

the action plan in the protocol; or 

(ii) Persons shall be withdrawn from 

the affected area, except those persons 

referred to in section 104(c) of the Act. 

(5) The protocol shall address—

(i) Sampling procedures, including 

equipment and methods to be used; 

(ii) Location of sampling points; 

(iii) Procedures to establish a baseline 

analysis of oxygen and methane 

concentrations at each sampling point 

over a 14-day sampling period. The 

baseline shall be established after the 

atmosphere in the sealed area becomes 

inert or the trend reaches equilibrium; 

(iv) Frequency of sampling; 

(v) Size and conditions of the sealed 

area; and 

(vi) Use of atmospheric monitoring 

systems, where applicable; 

(vii) The protocol shall include an 

action plan that addresses the hazards 

presented and actions taken when gas 

samples indicate oxygen concentrations 

of 10.0 percent or greater for each of the 

following ranges of methane 

concentrations—

(A) 3.0 percent or greater but less than 

4.5 percent; and 

(B) 4.5 percent or greater but less than 

17.0 percent; and 

(C) 17.0 percent to 20 percent. 

(6) The certified person shall 

promptly record each sampling result, 

including the location of the sampling 

points, and oxygen and methane 

concentrations. The results of oxygen 

and methane samples shall be recorded 

as the percentage of oxygen and 

methane measured by the certified 

person and any hazardous condition 

found, in accordance with § 75.363. 

(7) The mine operator shall retain 

sampling records at the mine for at least 

one year from the date of sampling. 

(c) Welding, cutting, and soldering 

with an arc or flame are prohibited 

within 150 feet of a seal. 

(d) For seals constructed after May 22, 

2007, at least two sampling pipes shall 

be installed in each seal. One pipe shall 

extend approximately 15 feet into the 

sealed area and another shall extend 

into the center of the first connecting 

crosscut inby the seal. Each sampling 

pipe shall be equipped with a shut-off 

valve and appropriate fittings for taking 

gas samples. 

(e) For each set of seals constructed 

after May 22, 2007, the seal at the lowest 

elevation shall have a corrosionresistant water drainage system. Seals 

shall not impound water. 

■ 3. Add § 75.336 to read as follows: 

§ 75.336 Seal design applications and 

installation approval. 

(a) Seal design applications from seal 

manufacturers or mine operators shall 

be in accordance with paragraphs (a)(1) 

or (a)(2) of this section and submitted 

for approval to MSHA’s Office of 

Technical Support, Pittsburgh Safety 

and Health Technology Center, P.O. Box 

18233, Cochrans Mill Road, Pittsburgh, 

PA 15236. 

(1) An engineering design application 

shall: 

(i) Address gas sampling pipes, water 

drainage systems, air leakage, fire 

resistance, flame spread index, pressuretime curve, entry size, engineering 

design and analysis, material properties, 

construction specifications, quality 

control, design references, and other 

information related to seal construction; 

(ii) Be certified by a professional 

engineer that the design of the seal is in 

accordance with current, prudent 

engineering practices; and 

(iii) Include a Seal Design Table that 

discusses characteristics related to 

mine-specific seal construction. 

(2) Each application based on fullscale explosion tests shall address the 

following requirements to ensure that a 

seal can reliably withstand the 

overpressures provided by § 75.335: 

(i) Certification by a professional 

engineer knowledgeable in structural 

engineering that the testing was done in 

accordance with current, prudent 

engineering practices and its 

applicability in a coal mine; 

(ii) Technical information related to 

the methods and materials; 

(iii) Proper documentation; 

(iv) An engineering analysis to 

address differences between the seal 

support during test conditions and the 

range of conditions in a coal mine; and 

(v) The application shall include a 

Seal Design Table that discusses 

characteristics related to mine specific 

seal construction. 

(3) MSHA will notify the applicant if 

additional information or testing is 


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required. The applicant must provide 

this information, arrange any additional 

or repeat tests, and notify MSHA of the 

location, date, and time of the test(s). 

(4) MSHA will notify the applicant, in 

writing, whether the design is approved 

or denied. If the design is not approved, 

MSHA will specify, in writing, the 

deficiencies of the application, or 

necessary revisions. 

(5) Once the seal design is approved, 

the approval holder must promptly 

notify MSHA, in writing, of all 

deficiencies of which they become 

aware. 

(b) The mine operator shall use an 

approved seal design provided its 

installation is approved in the 

ventilation plan. The mine operator 

shall—

(1) Retain the seal design approval 

information for as long as the seal is 

needed to serve the purpose for which 

it was built. 

(2) Designate a professional engineer 

to conduct or have oversight of seal 

installation and certify that the 

provisions in the approved seal design 

specified in paragraph (a) of this section 

have been addressed. A copy of the 

certification shall be submitted to the 

District Manager with the information 

provided in § 75.336(b)(3) and a copy of 

the certification shall be retained for as 

long as the seal is needed to serve the 

purpose for which it was built. 

(3) Provide information for approval 

in the ventilation plan—

(i) The MSHA Technical Support 

Approval Number; 

(ii) The mine map of the area to be 

sealed and proposed seal locations. This 

portion of the mine map shall be 

certified by a professional engineer; 

(iii) Specific mine site information, 

including’

(A) Type of seal; 

(B) Safety precautions taken prior to 

seal achieving full design strength; 

(C) Methods to address site specific 

conditions that may affect the strength 

and applicability of the seal; 

(D) The construction techniques; 

(E) Site preparation; 

(F) Sequence of seal installations; 

(G) Projected date of completion of 

each set of seals; 

(H) Supplemental roof support inby 

and outby each seal; 

(I) Water flow estimation and 

dimensions of the water drainage 

system through the seals; 

(J) Methods to ventilate the outby face 

of seals once completed; 

(K) Methods and materials used to 

maintain each type of seal; 

(L) Methods to address shafts and 

boreholes in the sealed area; and 

(M) Additional information required 

by the District Manager. 

■ 4. Add § 75.337 to read as follows: 

§ 75.337 Construction and repair of seals. 

(a) Prior to sealing, the mine operator 

shall—

(1) Remove insulated cables from the 

area to be sealed when constructing 

seals; and 

(2) Remove metallic objects through 

or across seals, except water pipes, gas 

sampling pipes, and form ties approved 

in the seal design. 

(b) A certified person designated by 

the mine operator shall directly 

supervise seal construction and repair 

and—

(1) Examine each seal site 

immediately prior to construction or 

repair to ensure that the site is in 

accordance with the approved 

ventilation plan; 

(2) Examine each seal under 

construction or repair during each shift 

to ensure that the seal is being 

constructed or repaired in accordance 

with the approved ventilation plan; 

(3) Examine each seal upon 

completion of construction or repair to 

ensure that construction or repair is in 

accordance with the approved 

ventilation plan; 

(4) Certify by initials, date, and time 

that the examinations were made; and 

(5) Make a record of the examination 

at the completion of any shift during 

which an examination was conducted. 

The record shall include each 

deficiency and the corrective action 

taken. The record shall be countersigned 

by the mine foreman or equivalent mine 

official by the end of the mine foreman’s 

or equivalent mine official’s next 

regularly scheduled working shift. The 

record shall be kept at the mine for one 

year. 

(c) Upon completion of construction 

of each seal, a senior mine management 

official, such as a mine manager or 

superintendent, shall certify that the 

construction, installation, and materials 

used were in accordance with the 

approved ventilation plan. The mine 

operator shall retain the certification for 

as long as the seal is needed to serve the 

purpose for which it was built. 

(d) The mine operator shall—

(1) Notify the local MSHA field office 

between two and fourteen days prior to 

commencement of seal construction; 

(2) Notify the District Manager, in 

writing, within five days of completion 

of a set of seals; and 

(3) Submit a copy of quality control 

results to the District Manager for seal 

material properties specified by 

§ 75.336. 

(e) Miners constructing or repairing 

seals, certified persons under paragraph 

(b) of this section, and senior mine 

management officials under paragraph 

(c) of this section shall be trained prior 

to constructing or repairing a seal. The 

training shall address materials and 

procedures in the approved seal design 

and ventilation plan. The mine operator 

must certify the date of training 

provided each miner, certified person, 

and senior mine management official 

and retain each certification for one 

year. 

■ 5. Add § 75.338 to read as follows: 

§ 75.338 Seals records. 

(a) The table entitled ‘‘Seal 

Recordkeeping Requirements’’ lists the 

records the operator must maintain 

pursuant to §§ 75.335, 75.336, and 

75.337, and the duration for which 

particular records need to be retained. 

TABLE TO § 75.338(a).—SEAL RECORDKEEPING REQUIREMENTS

Record Section 

reference Retention time 

(1) Protocol to monitor methane and oxygen and maintain an 

inert atmosphere..

75.335(b) .......... Same as ventilation plan requirements. 

(2) Training of certified persons ................................................ 75.335(b)(2) ...... 1 year. 

(3) Gas sampling records .......................................................... 75.335(b)(6) ...... 1 year. 

(4) Approved seal design .......................................................... 75.336(b)(1) ...... As long as the seal is needed to serve the purpose for which 

it is built. 

(5) Certification of provisions of approved seal design is addressed.75.336(b)(2) ...... As long as the seal is needed to serve the purpose for which 

it is built. 

(6) Record of examinations ....................................................... 75.337(b)(5) ...... 1 year. 

(7) Seal construction certification .............................................. 75.337(c) .......... As long as the seal is needed to serve the purpose for which 

it is built. 


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TABLE TO § 75.338(a).—SEAL RECORDKEEPING REQUIREMENTS—Continued 

Record Section 

reference Retention time 

(8) Certification of training ......................................................... 75.337(e) .......... 1 year. 

(b) Records required by §§ 75.335, 

75.336, and 75.337 shall be retained at 

a surface location at the mine in a 

secure book that is not susceptible to 

alteration. The records may be retained 

electronically in a computer system that 

is secure and not susceptible to 

alterations, if the mine operator can 

immediately access the record from the 

mine site. 

(c) Upon request from an authorized 

representative of the Secretary of Labor, 

the Secretary of Health and Human 

Services, or from the authorized 

representative of miners, mine operators 

must promptly provide access to any 

record listed in the table in this section. 

(d) Whenever an operator ceases to do 

business, that operator must transfer all 

records required to be maintained by 

this part, or a copy thereof, to any 

successor operator who must maintain 

them for the required period. 

■ 6. Amend § 75.371 by revising 

paragraph (ff) to read as follows: 

§ 75.371 Mine ventilation plan; contents. 

* * * * * 

(ff) The sampling protocol as provided 

by § 75.335(b) and seal installation 

requirements provided by § 75.336(b)(3). 

* * * * * 

[FR Doc. 07–2535 Filed 5–17–07; 3:11 pm] 

BILLING CODE 4510–43–P 


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