21182 Federal Register / Vol. 73, No. 76 / Friday, April 18, 2008 / 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: Final rule. 

SUMMARY: This final rule revises 

MSHA’s Emergency Temporary 

Standard (ETS) and addresses sealing 

abandoned areas in underground coal 

mines. The final rule includes 

requirements for seal strength, 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. It also 

addresses the level of overpressure for 

new seals. 

EFFECTIVE DATE: This final rule is 

effective April 18, 2008. 

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 the final rule is as 

follows: 

I. Background 

II. Discussion of the Final Rule 

III. Section-by-Section Analysis 

IV. Executive Order 12866 

A. Mine Sector Affected 

B. Benefits 

C. Compliance Costs 

V. Feasibility 

A. Technological Feasibility 

B. Economic Feasibility 

VI. Regulatory Flexibility Act and Small 

Business Regulatory Enforcement 

Fairness Act 

A. Definition of Small Mine 

B. Factual Basis for Certification 

VII. Paperwork Reduction Act of 1995 

A. Summary 

B. Details 

VIII. Other Regulatory Considerations 

A. The Unfunded Mandates Reform Act of 

1995 

B. The Treasury and General Government 

Appropriations Act of 1999: Assessment 

of Federal Regulations and Policies on 

Families 

C. Executive Order 12630: Government 

Actions and Interference With 

Constitutionally Protected Property 

Rights 

D. Executive Order 12988: Civil Justice 

Reform 

E. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

F. Executive Order 13132: Federalism 

G. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. Executive Order 13272: Proper 

Consideration of Small Entities in 

Agency Rulemaking 

IX. References 

I. 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 isolate abandoned areas 

of underground coal mines from active 

workings 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. Law 91–173 (Dec. 1969) Section 

303(2)(3). 

In the conference report filed in the 

House, the statement of the managers on 

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, 91st 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 standards 

for ventilation of underground coal 

mines, MSHA published standards for 

construction of seals in § 75.335 of the 

ventilation standards (57 FR 20868). 

The standard required seals to be 

constructed of solid concrete blocks at 

least six inches by eight inches by 

sixteen inches, but allowed seals to be 

constructed using alternative methods 

and materials, provided, among other 

things, that the seal was 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 

the National Institute for Occupational 

Safety and Health (NIOSH) 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, reissued on June 21, 

2006 as PIB No. PO6–14). 


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Following these underground coal 

mine disasters in 2006, Congress passed 

and the President signed the MINER 

Act. Section 10 of the MINER Act 

requires the Secretary of Labor to 

finalize mandatory health and safety 

standards relating to the sealing of 

abandoned areas in underground coal 

mines, and to increase the 20 psi 

standard. 

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 

existing 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 made recommendations for 

formulating seal design criteria. 

On May 22, 2007, MSHA published 

an Emergency Temporary Standard; 

notice of public hearings; and notice of 

close of comment period (72 FR 28796). 

The comment period, scheduled to close 

on July 6, 2007, was extended to August 

17, 2007 (72 FR 34609) and four public 

hearings were held. The hearings were 

held on July 10, 2007, in Morgantown, 

West Virginia; on July 12, 2007, in 

Lexington, Kentucky; on July 17, 2007, 

in Denver, Colorado; and on July 19, 

2007, in Birmingham, Alabama. 

On August 14, 2007, MSHA extended 

the comment period to September 17, 

2007, (72 FR 45358) to allow 

commenters additional time to review 

recently posted documents on MSHA’s 

Web site and a recently published report 

from NIOSH entitled ‘‘Explosion 

Pressure Design Criteria for New Seals 

in U.S. Coal Mines,’’ NIOSH Publication 

No. 2007–144, July 2007, IC–9500 (2007 

NIOSH Final Report). With one 

exception, the final version of this 

report was little changed from the draft 

version of this report that was 

referenced in the ETS. The final report 

includes a new section 3.3, 

Homogeneous Methane-Air Mixtures in 

Sealed-Area Atmospheres. This new 

section discusses methane layering in 

sealed areas and asserts that gaseous 

diffusion will result in a relatively 

homogeneous mixture within a matter 

of days after sealing. Other minor 

changes are related to rounding to 

metric units (sample pipes should 

extend 16 feet (5 meters) into the sealed 

area) and the inclusion of recent NIOSH 

research on methane flammability that 

lists the flammability range of methaneair mixtures at sea level as 5.0 percent 

to 16.0 percent methane. 

On December 7, 2007, MSHA posted 

on the Agency’s Web site the U.S. Army 

Corps of Engineer’s Draft Report ‘‘CFD 

[Computational Fluid Dynamics] Study 

and Structural Analysis of the Sago 

Mine Accident’’ (USACE’s Draft Report). 

The Agency placed the Report in the 

rulemaking record for the ETS on 

Sealing of Abandoned Areas. The 

Report summarizes the preliminary 

results of a study performed by the 

USACE under contract (MSHA NO IA–

AR 600012) for MSHA’s Technical 

Support Directorate (Technical 

Support). The USACE conducted 

research from August 2006 to April 

2007. The USACE provided a draft of 

the Report of their findings to Technical 

Support in May of 2007. The Report 

details the USACE’s efforts to 

mathematically model the methane 

explosion at the Sago Mine and 

potentially establish the seal 

overpressures. 

On December 19, 2007, MSHA 

published a notice (72 FR 71791) to 

reopen the comment period; announce 

availability of the USACE’s Draft Report; 

schedule a public hearing; and 

announce the close of the comment 

period. A public hearing was held in 

Arlington, Virginia on January 15, 2008 

and the comment period closed on 

January 18, 2008. 

In developing this final rule, MSHA 

considered the investigation reports of 

the Sago and Darby mine explosions, 

implementation and enforcement 

experience under the ETS, MSHA’s inmine seal evaluations and review of 

technical literature, the 2007 NIOSH 

Draft and Final Reports on explosion 

testing and modeling, the USACE’s Draft 

Report, accident reports, research 

studies, public comments, hearing 

transcripts and supporting 

documentation from all segments of the 

mining community. 

II. Discussion of the Final Rule 

This final rule assures that miners can 

rely on seals to protect them from the 

hazardous and sometimes explosive 

environments within sealed areas. This 

final rule includes requirements for seal 

strengths; design applications and 

installation; sampling and monitoring of 

sealed atmospheres; construction and 

repair of seals, training for persons 

conducting sampling and persons 

constructing or repairing seals, and 

recordkeeping to 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 this environment from the 

active workings of the mine. Seals are 

also installed to withstand 

overpressures resulting from explosions 

in abandoned areas and to prevent the 

potentially explosive methane/air 

mixtures from migrating to the working 

areas. Overpressure is the pressure 

above the background atmospheric 

pressure. For example, air pressure in a 

car tire is measured with a pressure 

gauge as 30 psi, which is an 

overpressure. The absolute pressure of 

the air inside the tire is 44.7 psi which 

is 14.7 psi or one atmosphere higher. 

Explosion pressures are normally 

expressed as an overpressure beyond 

standard atmospheric pressure. 

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 

overpressures. The homogeneity of the 

methane/air mixture contributes to the 

magnitude of the explosion. 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 

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 may be possible. 

Pressure piling is the development of 

pressure in excess of normal 

atmospheric pressures as a result of the 

velocity-related compression of the 

gases in front of the flame. Pressure 

piling results from the rapid 

acceleration of the front of the flame. 

This acceleration process may be 

increased by cross-sectional restrictions, 

obstructions and other irregularities in 

the path of the flame. If the air flow 

ahead of the front of the flame is 

sufficiently turbulent, the flame speed 

may increase and transition from 

deflagration to detonation. A detonation 

occurs when the flame of an explosion 

propagates through the unburned fuel at 


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a velocity exceeding the speed of sound. 

A deflagration occurs when the flame of 

an explosion propagates through 

unburned fuel at a velocity below the 

speed of sound. 

This final rule addresses seal strength 

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. It also 

addresses the level of overpressure for 

new seals. This final rule will protect 

miners from hazards of sealed areas. 

III. Section-by-Section Analysis 

A. Section 75.335 Seal Strengths, 

Design Applications, and Installation 

The final rule addresses the 

requirements for seal strengths, design 

applications, and seal installation. 

1. Section 75.335(a) Seal Strengths 

Final § 75.335(a) requires that seals 

constructed in underground coal mines 

after October 20, 2008 be designed, 

constructed and maintained in 

accordance with the provisions of this 

final rule. 

Final § 75.335(a)(1)(i), like the ETS, 

requires that seals withstand at least 50- 

psi overpressure when the atmosphere 

in the sealed area is monitored and 

maintained inert. Final § 75.335(a)(1)(i) 

adds new requirements that these seals 

be designed using a pressure-time curve 

with an instantaneous overpressure of at 

least 50 psi, and that the minimum 

overpressure must be maintained for at 

least four seconds and then released 

instantaneously. 

Final § 75.335(a)(1)(ii) addresses new 

requirements that seals constructed to 

separate the active longwall panel from 

the longwall panel previously mined be 

designed using a pressure-time curve 

with a rate of pressure rise of at least 50 

psi in 0.1 second, and that a minimum 

overpressure of at least 50 psi be 

maintained. 

Final § 75.335(a)(2)(i) revises the ETS 

and requires that seals withstand 

overpressures of at least 120 psi if the 

atmosphere in the sealed area is not 

monitored, is not maintained inert, and 

the conditions in final § 75.335(a)(3)(i) 

through (iii) of this section are not 

present. Final § 75.335(a)(2)(i) also adds 

new requirements that these seals be 

designed using a pressure-time curve 

with an instantaneous overpressure of at 

least 120 psi, and that a minimum 

overpressure of 120 psi be maintained 

for at least four seconds and then 

released instantaneously. 

Final § 75.335(a)(2)(ii) adds new 

requirements that seals constructed to 

separate the active longwall panel from 

the longwall panel previously mined be 

designed using a pressure-time curve 

with a rate of pressure rise of 120 psi in 

0.25 second, and that a minimum 

overpressure of 120 psi be maintained. 

Final § 75.335(a)(3) is essentially 

unchanged from the ETS. It requires 

seals to withstand overpressures greater 

than 120 psi if the atmosphere in the 

sealed area is not monitored and is not 

maintained inert, and either (i) the 

atmosphere in the sealed 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 area; or 

(ii) pressure piling could result in 

overpressures greater than 120 psi in the 

area to be sealed; or (iii) other 

conditions are encountered, such as the 

likelihood of a detonation in the area to 

be sealed. 

Final § 75.335(a)(3)(iv) retains the ETS 

requirement that when homogenous 

explosive atmospheres, pressure piling 

or the likelihood of a detonation exists, 

the mine operator must revise the 

ventilation plan to address the potential 

hazards. In addition, the operator must 

conduct an analysis of the mining 

conditions and revise the plan to 

include seal strengths sufficient to 

address these conditions. 

MSHA received many comments in 

response to its request on the 

appropriateness of the three-tiered 

approach to seal strength in the ETS. 

One commenter stated that the strength 

requirements in the first and second tier 

are arbitrary. Other commenters 

objected to the fixed seal strengths and 

requested that either a case-by-case 

determination or a risk analysis be made 

to determine which seal strength is 

needed. One commenter suggested that 

a two-tiered approach is adequate and 

that a third tier is not needed. A 

commenter stated that the 120-psi value 

proposed in the ETS is sufficient for 

design purposes and that the 120-psi 

load prescribed by the ETS is the 

highest design criterion for seals among 

all the coal producing countries. 

Another commenter stated that an 

explosion with a force greater than 120 

psi could not occur in an underground 

coal mine. Other commenters, however, 

stated that greater than 120-psi 

explosion pressures can occur in sealed 

areas. Some commenters suggested that 

a 640-psi seal, as recommended by 

NIOSH, should be included in the 

standard. One commenter on the 

USACE’s Draft Report stated that MSHA 

should consider a provision in the final 

rule that would assure that seals are 

explosion-proof. 

The Agency believes that a risk based 

analysis to determine seal strengths on 

a case-by-case basis rather than the 

tiered approach is not appropriate for 

several reasons. In the ETS, the Agency 

requested comments on alternatives to 

the seal strength requirements in the 

ETS, including supporting data, 

feasibility, and costs. MSHA did not 

receive any specific information, 

relative to alternatives requested, that 

would support a risk-based analysis on 

a case-by-case basis in this final rule. 

The rulemaking record contains little 

information supporting a case for risk 

analysis or costs and feasibility of such 

an approach. Commenters did not 

address how risk analysis on a case-bycase basis would impact the final rule 

and miner safety. Since the rulemaking 

record does not support this alternative 

approach to determine seal strengths, 

MSHA has not included it in this final 

rule. 

The strength requirements for final 

§ 75.335(a) are based on MSHA’s 

investigation of the explosion at the 

Sago mine and the 2007 NIOSH Final 

Report. NIOSH discovered through 

research testing and modeling that a 50- 

psi peak overpressure could occur in a 

limited-volume, unconfined situation. 

Small, unconfined pockets of gases in 

an explosive concentration could 

always exist in a sealed area. If any of 

these pockets were ignited, a 50-psi 

pressure pulse could be generated. 

In addition, NIOSH stated that a 120- 

psi peak pressure could occur in a 

limited, confined-volume situation. 

According to NIOSH, in such a 

situation, even if the overall 

concentration of explosive gases in the 

gob is well above the explosive 

concentration, explosive concentrations 

could be present in some areas. NIOSH 

further stated that if an explosive mix of 

methane and oxygen is ignited in this 

situation, an explosion could generate a 

peak explosion pressure of 120-psi. 

Based on the 2007 NIOSH Final Report 

and the Agency’s data and experience, 

this final rule retains the second tier of 

the ETS. 

Unlike NIOSH’s design curves for 50- 

psi and 120-psi overpressures, NIOSH 

did not recommend a static 

approximation to the 640-psi pressuretime curve because ‘‘Additional studies 

are required * * *.’’ (2007 NIOSH Final 

Report at pg. 61). Although the NIOSH 

640-psi pressure-time curve could be 

used to design seals, in this case a 

dynamic analysis would have to be 

conducted by the professional engineer. 

MSHA considered NIOSH’s 640-psi seal 

design. However, a prescriptive specific 

dynamic load factor based on the 640- 

psi design was not determined and 


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requires further studies as stated in the 

2007 NIOSH Final Report. As stated in 

the ETS, ‘‘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.’’ One 

commenter on the USACE’s draft report 

questioned this statement. MSHA stated 

in a Memorandum from its Office of 

Technical Support that ‘‘these 

comparisons [between the USACE 

Report and known conditions after the 

Sago Mine explosion] again brought the 

practical applicability of results of the 

study into question.’’ The Memorandum 

further states that: ‘‘Technical Support 

decided not to publish the study 

because the critical information 

necessary to develop an accurate 

simulation was not available, and 

therefore, any results could not be relied 

upon for decision-making. Much of the 

data provided to the USACE for the 

three simulations described in the draft 

report was speculative * * *’’

Based on the Agency’s available 

information and data, MSHA could not 

specifically recommend a 640-psi 

strength requirement. The final rule 

retains the third tier of the ETS and 

requires a seal stronger than 120 psi if 

certain conditions are encountered. 

Under the final rule, mine operators 

must perform a risk analysis and 

evaluate the atmosphere of the area to 

be sealed and determine when higher 

pressure seals should be used and at 

what strength. The seal design must be 

approved at the appropriate strength for 

the specific conditions to be 

encountered. 

Most commenters expressed concern 

that under the ETS, it is virtually 

impossible to determine when the 

conditions requiring a seal greater than 

120 psi are present. MSHA has 

structured the final rule to 

accommodate pressures greater than 120 

psi in recognition of the fact that 

explosion pressures may exceed this 

limit under certain conditions. These 

conditions would be a concern only in 

sealed areas that are not monitored and 

not maintained inert. The final rule 

requires seal strengths greater than 120 

psi if seals are constructed around areas 

that are not monitored and are not inert, 

and one of the following three 

conditions occurs: (1) A homogeneous 

explosive atmosphere exists, (2) 

pressure piling could result in pressures 

exceeding 120 psi, or (3) detonation is 

likely. 

MSHA expects that mine operators 

will sample an appropriate number of 

locations within the sealed area during 

the period when seals are reaching their 

design strength to address whether a 

homogeneous explosive atmosphere 

exists. These samples could be taken at 

various locations, including through 

seals constructed around the sealed area 

and possibly through boreholes or shafts 

within the sealed area. When these seals 

reach design strength of 120 psi, 

sampling is no longer required. If the 

methane concentration stabilizes 

between 4.5 percent and 17 percent and 

the oxygen concentration remains above 

17 percent in all samples, then the 

atmosphere is considered homogeneous 

throughout the sealed area, and seal 

strengths must be designed to an 

adequate level above 120 psi, as 

determined by the professional 

engineer, which will provide adequate 

protection for miners underground. 

MSHA realizes that the seals 

surrounding the sealed area must be in 

place prior to sampling. 

MSHA expects that mine operators 

will evaluate the physical 

characteristics of the underground 

workings near all seals surrounding the 

sealed area to address whether pressure 

piling can occur to a degree that causes 

explosion overpressures to exceed 120 

psi. Overpressures that occurred during 

the 2006 explosion at the Sago Mine 

increased in magnitude due to a severe 

change in the physical characteristics of 

the underground workings near the 

seals. The seals at the Sago Mine were 

constructed to a height of approximately 

7 feet. The workings in the sealed area 

had been previously second mined to a 

height of nearly 20 feet in some 

locations near the seals. As the 

explosion propagated toward the seals, 

pressure piling occurred and caused 

excessive pressure at the location of the 

seals. These factors must be considered 

by the mine operator to determine if a 

situation exists that will cause pressure 

piling, resulting in pressures above 120 

psi. If this situation exists, then seal 

strengths must be designed to an 

adequate level above 120 psi, as 

determined by the professional 

engineer. 

MSHA expects that mine operators 

will fully evaluate potential ignition 

sources, potential methane 

concentrations, and potential oxygen 

concentrations in the sealed areas to 

determine if detonation could occur. 

Mine operators should consider whether 

a high energy ignition source exists in 

the sealed area, whether extensive 

volumes of homogeneous mixtures of 

explosive methane concentrations may 

exist, and whether sufficient oxygen 

may be present in the sealed area. 

MSHA received several comments on 

the USACE’s Draft Report. The report 

details the USACE’s efforts to 

mathematically model the methane 

explosion at the Sago Mine and 

potentially establish the seal 

overpressures. The report recommended 

that additional research was needed to 

refine the models in order to better 

predict an explosion pattern. 

Commenters stated that 

computational fluid dynamics modeling 

could be used effectively to compare the 

effect of different variables on 

explosions, but that this type of 

modeling cannot accurately predict 

conditions. According to one 

commenter, their data collection and 

analysis of an actual gob composition is 

highly non-homogeneous, and the 

chance of methane gas detonation in a 

coal mine is almost zero. Therefore, this 

commenter stated that the 120-psi 

criterion in the ETS is adequate. 

Final §§ 75.335(a)(1)(i) and (a)(2)(i) 

include requirements that seal designs 

must resist explosions of specific 

duration and intensity. The duration 

and intensity is characterized in 

pressure-time curves. A pressure-time 

curve gives engineers a mechanism to 

perform a dynamic analysis or to derive 

a dynamic load factor that they can use 

in a static analysis of a design. The 

pressure-time curves in Figures 1 and 2 

yield a dynamic load factor (DLF) of 2.0, 

which is the theoretical maximum 

(Structures to Resist the Effects of 

Accidental Explosions, Department of 

the Army, Report TM 5–1300, 

November 1990) (1990 Department of 

the Army Report). Holding the applied 

pressure for at least four seconds assures 

that a seal could be loaded elastically at 

a DLF of 2.0 (1990 Department of the 

Army Report). The instantaneous 

release of the overpressure load after at 

least four seconds gives engineers a 

criterion to address the rebound effect 

that would occur in the seal after the 

explosive force was removed. Under 

this final rule, a professional engineer 

could submit, for MSHA approval, a 

unique design that is able to withstand 

the prescribed design criteria. 

Figures 1 and 2 are the 50-psi and 

120-psi pressure-time curves to be used 

for seal design. 


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Several commenters requested a more 

prescriptive design standard identifying 

minimum overpressures. MSHA 

believes that a more prescriptive 

standard would eliminate ambiguity 

and result in greater protection of 

miners. In response to these comments 

and for clarity, final §§ 75.335(a)(1)(i) 

and (a)(2)(i) provide specific pressuretime curves for certain seal designs. 

Some commenters requested that they 

be allowed to use seals constructed to 

separate the active longwall panel from 

the longwall panel previously mined. 

These commenters stated that such seals 

protect miners from explosions and help 

control spontaneous combustion, which 

has historically been a problem in the 

western U.S. mines. MSHA’s 

enforcement policy under the ETS is 

consistent with the prescriptive design 

requirements in final §§ 75.335(a)(1)(ii) 

and (a)(2)(ii) for these types of seals. 

These provisions allow seals to be 

designed using pressure-time curves 

that characterize an explosion having 

pressure venting and slower pressure 

rise times. Such pressure-time curves 

are published in the 2007 NIOSH Final 

Report. 

Both NIOSH 50-psi and 120-psi 

pressure-time curves for these seals 

yield a dynamic load factor of 1.0. The 

caved roof gob adjacent to seals used to 

separate the active longwall panel from 

the longwall panel previously mined 

minimizes run-up distances, which may 

otherwise be long enough to generate 

steeper rise times on either pressure 

pulse. Thus, both pressure-time curves 

enable engineers to analyze these seal 

designs based upon a dynamic analysis 

or a static, uniform pressure, which is 

equal to the peak overpressure in the 

applicable pressure-time curve. Figures 

3 and 4 are the 50-psi and 120-psi 

pressure-time curves that can be used 

for the design of seals that separate the 

active longwall panel from the longwall 

panel previously mined. 


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Several commenters asked that 

explosion wave mitigation procedures 

be allowed in lieu of seal designs to 

withstand overpressures greater than 

120-psi. Based on MSHA’s knowledge 

and experience, if a seal is to withstand 

overpressures at the design seal 

strength, then wave mitigation methods 

may not provide effective protection. 

Most wave mitigation techniques are 

designed for a one-time use, after which 

they do not offer any quantifiable 

resistance to explosion overpressure. 

While wave mitigation methods are not 

discouraged by MSHA, wave mitigation 

alone cannot be used to meet the 

requirements of the standard. 

Several commenters inquired about a 

safety factor in the seal designs. Some 

commenters believed that the seal 

design requirement in the ETS included 

a safety factor of two. Like the ETS, this 

final rule does not require a safety factor 

in any seal designs. As mentioned 

above, for static-equivalent seal designs 

using either of the two prescribed 

pressure-time curves having an 

instantaneous rise, a Dynamic Load 

Factor (DLF) of 2 would be applied to 

the peak overpressure. The DLF is 

multiplied by the peak overpressure for 

a static-equivalent overpressure for 

which the seal should be designed to 

resist. For example, a 120-psi seal 

designed with a static-equivalent 

procedure would have to withstand a 

design static overpressure of 240 psi. 

The two prescribed pressure-time 

curves that are permitted for use with 

seals constructed to separate the active 

longwall panel from the longwall panel 

previously mined have a DLF of 1. A 

DLF is not a factor of safety. It is a ratio 

used to equate a dynamic load with a 

static load for design purposes. 

Professional engineers are expected to 

incorporate load factors in their designs, 

in addition to the DLF, in accordance 

with current prudent structural 

engineering practices. 

Many commenters questioned why 

Mitchell-Barrett seal designs were not 

permitted under the ETS. Some 

commenters stated that Mitchell-Barrett 

seals were tested by NIOSH and that 

they are capable of holding a static load 

over 95 psi. This maximum 95 psi 

overpressure was generated in a smallvolume chamber behind the tested seal 

and was not generated by an explosion 

pressure wave traveling down a mine 

opening at the Lake Lynn Experimental 

Mine, as seals had been tested 

previously. NIOSH attempted to 

establish equivalency of a small-volume 

chamber to the full-scale explosion 

tests. NIOSH did not establish 

equivalency between the two types of 

tests. Also, the pressure-time curve in 

this final rule for 50-psi seals 

incorporates a DLF of 2 and results in 

a static equivalent load of 100 psi. This 

static equivalent load is greater than the 

95 psi static load that NIOSH measured. 

Mitchell-Barrett seals that were tested 


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by NIOSH would not be permitted 

under this final rule for 50-psi seals 

requiring a DLF of 2.0. 

One commenter stated that the ETS 

would cause existing seals in three 

mines operated by the mine operator to 

be replaced with 50-psi rated seals and 

that replacement of the existing seals 

would be costly. The final rule does not 

require replacement of existing seals; 

rather, for existing seals, it requires 

operators to monitor methane and 

oxygen concentration levels and to 

maintain an inert atmosphere in the 

sealed area. 

Another commenter stated that the 

turnkey costs for seals used in the 

company’s mines ranged from $12,000 

to $25,000 and stated that MSHA had 

severely understated costs. However, 

the Agency’s cost estimates are 

weighted averages of the costs for 

various types of seals. MSHA’s 

estimated turnkey costs range from 

approximately $7,370 to $25,000 for 50 

psi seals and $11,330 to $38,550 for 120 

psi seals. The commenter’s costs come 

within the range of seal costs MSHA 

used to develop its cost estimates. 

2. Section 75.335(b) Seal Design 

Applications 

Final § 75.335(b) renumbers and 

revises ETS § 75.336(a). It requires that 

seal design applications be based on 

either engineering design applications 

or full-scale explosion tests. The final 

rule permits the applicant to use other 

equivalent means of physical testing in 

lieu of full-scale explosion tests. The 

final rule also requires that seal design 

applications from seal manufacturers or 

mine operators be 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. 

Final § 75.335(b)(1), like the ETS, sets 

forth specific requirements for an 

engineering design application. Under 

final § 75.335(b)(1)(i), an engineering 

design application must address the 

following: Gas sampling pipes, water 

drainage systems, methods to reduce air 

leakage, pressure-time curve, fire 

resistance characteristics, flame spread 

index, entry size, engineering design 

and analysis, elasticity of design, 

material properties, construction 

specifications, quality control, design 

references, and other information 

related to seal construction. 

Section 75.335(b)(1)(i) has been 

revised to include elasticity of design in 

the engineering design application. 

MSHA has included this requirement in 

the final rule for clarity. It is based on 

the 2007 NIOSH Final Report and on 

MSHA’s experience with seal design 

approvals under the ETS. NIOSH notes 

in the 2007 NIOSH Final Report that 

repeated pressure waves will likely 

impact the seal structure. Applications 

for seals designed for overpressures of 

120 psi or greater must address 

elasticity in their design in order to 

withstand repeated, independent 

overpressures. This is consistent with 

current prudent engineering practices 

and with MSHA’s seal approval process 

under the ETS. Addressing elasticity in 

seal design does not require a higher 

seal strength than that under the ETS. 

The final rule is consistent with 

MSHA’s approved seal designs under 

the ETS. This final rule retains the other 

requirements of the ETS. 

Final § 75.335(b)(1)(ii), like the ETS, 

requires that an engineering design 

application be certified by a 

professional engineer that the design of 

the seal is in accordance with current, 

prudent engineering practices. In 

addition, it clarifies the ETS 

requirement and specifies that the 

professional engineer certify that the 

seal design is applicable to conditions 

in an underground coal mine. In the 

ETS, MSHA discussed the engineering 

decisions and actions that must be made 

by and must be the responsibility of the 

professional engineer. Those included 

(1) the selection or development of 

design standards or methods, and 

materials to be used in seal 

construction; (2) the 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. This final rule clarifies 

MSHA’s intent that a seal design must 

reliably function given a set of specific 

conditions in an underground coal 

mine, and that a professional engineer 

must certify that the seal design is 

applicable to conditions in an 

underground coal mine. 

Several commenters stated that 

professional engineers who are required 

to comply with the engineering design 

application requirements in the ETS 

could lose complete dominion and 

control over the design of a seal. A 

commenter stated that West Virginia 

state law requires a professional 

engineer to maintain complete direction 

and control over all specifications, 

reports, drawings, plans, design 

information, and calculations to be 

certified. Commenters raised an issue 

concerning a seal designed by MSHA 

but requiring certification by a 

professional engineer. Under the ETS, 

this particular seal approval required a 

separate review and certification by a 

professional engineer before it could be 

used. However, the professional 

engineer may also use that particular 

design as basis for a new seal design and 

submit it to MSHA for approval. 

A commenter stated that the design of 

mine seals for use in West Virginia is 

engineering work and requires that it be 

done by a registered West Virginia 

professional engineer. MSHA accepts 

the certification of a professional 

engineer from any state and allows that 

certification to be used in other states. 

Each state is responsible for enforcing 

its rules and regulations. 

Another commenter stated that 

because field conditions change the 

professional engineer must be allowed 

to make the necessary field changes to 

meet those conditions in order to 

protect the public safety. MSHA 

acknowledges that some field 

conditions may change but because of 

the importance and complexity of the 

seal designs, the final rule does not 

permit field changes. Like the ETS, the 

final rule allows the mine operator to 

make revisions to the original approved 

design by submitting those changes that 

are certified by a professional engineer 

to MSHA’s office of Technical Support 

for approval. 

Final § 75.335(b)(1)(iii) revises ETS 

§ 75.336(a)(1)(iii) and requires that an 

engineering design application include 

a summary of the installation 

procedures related to seal construction. 

Based on MSHA’s field experience 

under the ETS, the requirement for a 

summary of installation procedures is 

more appropriate than that in the ETS 

for specific information to be included 

in a Seal Design Table. Under the final 

rule, the summary should include all of 

the information necessary to construct a 

seal including quality control and other 

necessary information. 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 a certified 

laboratory and by qualified personnel. 

The certification for the laboratory must 

be from a professional organization such 

as the International Organization for 

Standardization (ISO) and the personnel 

must be able to demonstrate 

qualifications to ensure proper quality 

control testing. MSHA’s experiences 

under the ETS reveal that some 

information included in the seal design 

application is proprietary. Although this 

information is required to be submitted 

to Technical Support for evaluation of 


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the design, it is not necessary to include 

it in the ventilation plan for approval by 

the District Manager. The requirement 

for the summary information will 

eliminate the need to disseminate any 

proprietary information. It will provide 

the District Manager with information 

needed to approve the seal design in the 

ventilation plan. 

Final § 75.335(b)(2) requires that seal 

design applications can be based on 

full-scale explosion tests or equivalent 

means of physical testing. During 

discussions with MSHA on alternatives 

to full-scale testing, NIOSH indicated 

that equivalent testing conditions can be 

represented in suitable hydrostatic test 

chambers similar to those at the NIOSH 

Lake Lynn Experimental mine. MSHA 

believes that an equivalent means of 

physical testing, that has at least the 

same level of confidence as full-scale 

explosion testing, is an acceptable 

means of compliance and the Agency 

has included it in the final rule. 

Final § 75.335(b)(2)(i), like ETS 

§ 75.336(a)(2)(i), requires certification by 

a professional engineer that the testing 

was done in accordance with current, 

prudent engineering practices for 

construction in a coal mine. This final 

rule deletes the requirement in the ETS 

that the professional engineer be 

knowledgable in structural engineering. 

MSHA deleted this requirement because 

there is no certification available to 

assure that a professional engineer is 

knowledgable in structural engineering. 

MSHA’s experience with seal design 

approvals under the ETS reveals that the 

Professional Engineers who successfully 

submit seal designs are knowledgable in 

structural engineering. MSHA received 

one comment on this provision which 

recommended the words ‘‘knowledgable 

in structural engineering’’ be removed. 

Final § 75.335(b)(2)(ii), like 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. MSHA 

received no comments on this 

provision. 

Final § 75.335(b)(2)(iii) requires that 

the application include supporting 

documentation. This clarifies ETS 

§ 75.336(a)(2)(iii) that required proper 

documentation. The term ‘‘supporting’’

more accurately describes the type of 

documentation required. This 

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 material 

properties required for adequate seal 

construction. Construction 

documentation is required to assure 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. 

MSHA received no comments on this 

provision. 

Final § 75.335(b)(2)(iv), like ETS 

§ 75.336(a)(2)(iv), requires the 

application to include an engineering 

analysis addressing differences between 

the seal support during test conditions 

and the range of test conditions in a coal 

mine. MSHA received no comments on 

this provision. 

Final § 75.335(b)(2)(v) revises ETS 

§ 75.336(a)(2)(v) and requires that a 

summary of the installation procedures 

be included in the application. This 

requires that applicants submit more 

appropriate information in the form of 

a summary of installation procedures 

rather than specific information 

included in a Seal Design Table as 

required by the ETS. This summary 

should include the installation 

procedures related to mine specific seal 

construction. For example, it would 

include the maximum entry width and 

height for which the specific design is 

applicable, the specified strength of the 

seal material, the thickness of the seal, 

and the reinforcement and anchorage 

requirements for the seal. Additional 

information may be provided at the 

discretion of the Professional Engineer. 

MSHA received no comments on this 

provision. 

Final § 75.335(b)(3), like ETS 

§ 75.336(a)(3), provides that MSHA will 

notify the applicant if additional 

information or testing is required. It also 

requires the applicant to provide this 

information, arrange any additional or 

repeat tests, and provide prior 

notification to MSHA of the location, 

date, and time of such tests. MSHA 

received no comments on this 

provision. 

Final § 75.335(b)(4), like ETS 

§ 75.336(a)(4), provides that MSHA will 

notify the applicant, in writing, whether 

the design is approved or denied. It also 

provides that if the design is denied, 

MSHA will specify, in writing, the 

deficiencies of the application, or 

necessary revisions. MSHA received no 

comments on this provision. 

Final § 75.335(b)(5), like ETS 

§ 75.336(a)(5), requires that once the 

seal design is approved, the approval 

holder must promptly notify MSHA, in 

writing, of all deficiencies of which they 

become aware. MSHA received no 

comments on this provision. 

3. Section 75.335(c) Seal installation 

approval 

Final § 75.335(c), like ETS § 75.336(b), 

requires that the installation of the 

approved seal design be approved in the 

ventilation plan. 

Final § 75.335(c)(1), like the ETS, 

requires the mine operator to retain the 

seal design approval and installation 

information for as long as the seal is 

needed to serve the purpose for which 

it was built. One commenter stated the 

requirement to retain approval and 

installation information for an indefinite 

period places an onerous burden on 

both the professional engineer and the 

mine operator, and suggested that the 

final rule include a definite duration for 

retaining this information. Based on 

MSHA’s experience under the ETS, the 

requirement for approval and 

installation information provides a 

reliable reference should any problems 

occur during the service life of the seal. 

This provides valuable information as to 

how the seal was constructed and 

identifies the person responsible for 

certifying that the provisions in the 

approved seal design were addressed. In 

some instances, this information may 

enable persons to question individuals 

responsible for designing and 

constructing the seal to gain an insight 

as to the circumstances surrounding the 

construction and identify any problems 

that may have been encountered during 

the construction. Accordingly, this 

provision remains unchanged from the 

ETS. 

Final § 75.335(c)(2), like the ETS, 

requires that the mine operator 

designate a professional engineer to 

conduct or have oversight of seal 

installation and certify that the 

provisions in the approved seal design 

specified in this section have been 

addressed and are applicable to the 

conditions in the mine. This final rule 

also requires that a copy of the 

certification be submitted to the District 

Manager with the information provided 

in final § 75.335(c)(3) and that a copy of 

the certification be retained for as long 

as the seal is needed to serve the 

purpose for which it was built. 

One commenter supported this 

provision and stated that creating 

accountability in the construction 

process is a critical component if MSHA 

is to assure that coal operators take very 

seriously their obligation to provide a 

safe workplace with properly designed 

and constructed seals. 

Several commenters opposed this 

provision. They stated that the 

requirement to conduct or have 

oversight of seal installation should be 

deleted because it would be expensive, 

difficult because there are many 

variables in the construction process, 

and unnecessary because a mine 

operator must also certify construction. 

Some commenters stated that a 


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professional engineer’s function is the 

design of a seal, not oversight of the 

construction. Several commenters stated 

that the provision would require a 

professional engineer to be on site prior 

to, during, and following construction of 

every seal to insure that all parameters 

are met and that would be unnecessary. 

Under the final rule, MSHA does not 

intend that the professional engineer 

take part in the construction process or 

be at the seal installation site during the 

entire construction process. MSHA 

stated its intent with respect to this 

requirement at the public hearings. 

MSHA’s existing enforcement policy 

states that the professional engineer 

must inspect the set of seals during 

construction as part of the oversight and 

certification required by ETS 

§ 75.336(b)(2). To accomplish this 

oversight, MSHA would expect the 

professional engineer to: (1) Verify that 

the seal application is suitable for the 

specific conditions, (2) confirm that the 

site preparation is adequate, (3) confirm 

that the workforce is adequately trained 

to properly build the seals, (4) verify 

that the correct materials and 

procedures are being used to construct 

the seal, and (5) confirm that adequate 

quality controls are in place and are 

being followed. The professional 

engineer however, does not have to be 

onsite the entire time that seals are 

being built. 

Based on the Agency’s knowledge and 

experience, MSHA has determined that 

the oversight by the professional 

engineer, who would be most familiar 

with the seal design, will help assure 

that appropriate seal design 

implementation and related analyses are 

performed properly. In addition, it will 

assure that seals are constructed 

according to the drawings and 

specifications of a professional engineer. 

Final § 75.335(c)(3), like the ETS, lists 

specific information that a mine 

operator must address in the ventilation 

plan. The 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. 

Final § 75.335(c)(3)(i), like the ETS, 

requires that mine operators include the 

MSHA Technical Support Approval 

Number of the seal design in the 

ventilation plan. MSHA did not receive 

any comments on this section. This final 

rule is unchanged from the ETS. 

Final § 75.335(c)(3)(ii) revises ETS 

§ 75.336(b)(3)(iii)(D). It requires a 

summary of the installation procedures 

for approval to be included in the 

ventilation plan. This final rule is 

derived from the ETS requirement that 

the mine operator specify construction 

techniques for each type of seal. It 

revises the ETS requirement to be 

consistent with the language in final 

§ 75.335(b)(1)(iii). The information 

required in this final rule, however, is 

essentially the same as that required in 

the ETS. Examples of information 

required by this provision include: 

Maximum entry width and height for 

which the design is applicable; 

specified strength of the seal; 

construction steps; and reinforcement 

and foundation anchorage requirements. 

In addition, when frame work is used, 

information should specify frame work 

size, spacing and materials used, a 

description of how the frame work is 

erected, size of other material used, 

such as concrete block size, wood 

products used and spacing, and, if 

needed, an anchorage table for rebar 

showing lengths, hole size, and other 

material used with the rebar. If hitching 

is required, information should specify 

hitching location, width and depth, 

calibration of equipment where 

required, sequence of pouring materials 

and thickness, sequence and type of roof 

support used, surface preparation, a 

description of the material pouring 

techniques and how cold joints may or 

may not be permitted, set back 

distances, a diagram of the water 

drainage system and air sampling 

installation, methods for preventing 

water retention during the curing 

process, rockdust removal from rib at 

the seal site, thickness of the seal, and 

other additional information in the seal 

design application. 

Final § 75.335(c)(3)(iii) revises the 

ETS. It requires that mine operators 

provide, in the ventilation plan, a mine 

map of the area to be sealed and 

proposed seal locations that include the 

deepest points of penetration prior to 

sealing. This final rule revises the ETS 

by requiring that locations include the 

deepest points of penetration prior to 

sealing. This provision will help assure 

that the area was surveyed, a map of the 

area to be sealed was completed and the 

map was submitted by the mine 

operator. In addition, this final rule 

requires that the mine map be certified 

by a professional engineer or a 

professional land surveyor. It revises the 

ETS by including a professional land 

surveyor to certify the mine map to be 

consistent with existing § 75.1201 

which permits a professional land 

surveyor to certify the mine map. 

Final § 75.335(c)(3)(iv), like the ETS, 

requires that mine operators submit 

specific mine site information in the 

ventilation plan. Final 

§ 75.335(c)(3)(iv)(A) requires that the 

type of seal be included in the 

ventilation plan. MSHA did not receive 

any comments on this provision. 

Final § 75.335(c)(3)(iv)(B), like the 

ETS, requires mine operators to include 

information in the ventilation plan on 

the safety precautions taken prior to 

seals achieving design strength. Some 

commenters stated that this provision 

should require withdrawal of miners. 

According to commenters, this would be 

consistent with NIOSH’s 

recommendation that miners be 

withdrawn from the affected area until 

seals reach design strength and the 

atmosphere in the sealed areas reaches 

an inert status. Other comments stated 

that withdrawal is not necessary 

because the sealed areas contain no 

likely ignition source, and if an inert 

atmosphere is present, uncured seals do 

not present an imminent danger as there 

is no explosion potential. In addition, 

some of these commenters stated that 

withdrawal of miners during seal curing 

time, which could be up to 28 days, 

would be too costly. 

Based on MSHA’s knowledge and 

experience under the ETS, miners could 

be exposed to the dangers of an 

explosion prior to seals achieving their 

design strength. Accordingly, MSHA 

believes that safety precautions need to 

be taken prior to seals achieving design 

strength. Safety precautions could 

include withdrawing miners from the 

entire mine or other area approved by 

the District Manager. They could also 

include the use of seals that reach their 

design strength in considerably less 

time than 28 days. In addition, the mine 

operator could inert the atmosphere 

prior to or during seal installation. If an 

inert atmosphere is present behind seals 

that have not reached their design 

strength, miners would not need to be 

withdrawn from the affected area. This 

provision remains unchanged from the 

ETS. 

Final § 75.335(c)(3)(iv)(C) revises the 

ETS. It requires that the mine operator 

provide information in the ventilation 

plan on methods used to address sitespecific conditions that may affect the 

strength and applicability of the seal, 

including set-back distances. The setback distance, which is the distance 

from the corner of a pillar block to a 

seal, is critical to the long term stability 

and protection of a seal. Although the 

ETS did not specifically address setback distances, many professional 

engineers included this concept in their 

design applications. 

Based on MSHA’s experience under 

the ETS, professional engineers 

designing seals have listed a minimum 

set-back distance of 10 feet when 

applying for a seal design approval in 

most instances. MSHA believes, 


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however, that set-back distances need to 

be addressed on a mine-by-mine basis. 

Some coal is softer or harder than 

others; and the overburden varies, 

which has an effect on the stability of 

the coal seam pillar. This means that 

some coal pillars will remain more or 

less stable than others over a long 

period of time. It is also possible to 

artificially reinforce the stability of less 

stable coal pillars, for example, by 

injecting materials into the pillars. 

Therefore, MSHA is including a 

requirement that the set-back distance of 

a seal be addressed in the mine 

ventilation plan during the seal plan 

approval process. 

Final § 75.335(c)(3)(iv)(D), like the 

ETS, requires the mine operator to 

submit information in the ventilation 

plan on site preparation. MSHA did not 

receive any comments on this provision. 

Final § 75.335(c)(3)(iv)(E), like the 

ETS, requires the mine operator to 

include information on the sequence of 

seal installations in the ventilation plan. 

MSHA did not receive any comments on 

this provision. 

Final § 75.335(c)(3)(iv)(F), like the 

ETS, requires that the mine operator 

provide information in the ventilation 

plan on the projected date of completion 

of each set of seals. MSHA did not 

receive any comments on this provision. 

Final § 75.335(c)(3)(iv)(G), like the 

ETS, requires the mine operator to 

provide information in the ventilation 

plan on the supplemental roof support 

inby and outby each seal. MSHA did not 

receive any comments on this provision. 

Final § 75.335(c)(3)(iv)(H), like the 

ETS, requires the mine operator to 

provide information in the ventilation 

plan on the water flow estimation and 

dimensions of the water drainage 

system through the seals. MSHA did not 

receive any comments on this provision. 

Final § 75.335(c)(3)(iv)(I), like the 

ETS, requires that the mine operator 

provide information in the ventilation 

plan on the methods used to ventilate 

the outby face of seals once completed. 

MSHA did not receive any comments on 

this provision. 

Final § 75.335(c)(3)(iv)(J), like the 

ETS, requires the mine operator to 

provide information in the ventilation 

plan on the methods and materials used 

to maintain each type of seal. MSHA did 

not receive any comments on this 

provision. 

Final § 75.335(c)(3)(iv)(K), like the 

ETS, requires the mine operator to 

provide information in the ventilation 

plan on methods used to address shafts 

and boreholes in the sealed area. MSHA 

did not receive any comments on this 

provision. 

Final § 75.335(c)(3)(iv)(L) is derived 

from ETS § 75.335(a)(3)(iv). This final 

rule requires the mine operator to 

provide information in the ventilation 

plan on an assessment of potential for 

overpressures greater than 120 psi in the 

sealed area. ETS § 75.335(a)(3)(iv) 

required the mine operator to revise the 

ventilation plan when conditions that 

would necessitate a seal greater than 

120 psi are encountered. This final rule 

is consistent with the ETS. It includes 

this provision to assure that the mine 

operator evaluates the area to be sealed 

and addresses the need for seals greater 

than 120 psi. 

Final § 75.335(c)(3)(iv)(M) renumbers 

and clarifies ETS § 75.335(b)(5)(ii). It 

requires mine operators to provide 

information in the ventilation plan on 

additional sampling locations. This final 

rule is consistent with ETS 

§ 75.335(b)(5)(ii), which required the 

location of sampling points to be 

included in the mine operator’s action 

plan. Under this final rule, additional 

sampling locations could include 

sampling through boreholes and capped 

shafts with vent pipes. 

Final § 75.335(c)(3)(iv)(N), like the 

ETS, requires the mine operator to 

provide, in the ventilation plan, any 

additional information required by the 

District Manager. This final rule will 

help assure 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 did 

not receive any comments on this 

provision. 

B. Section 75.336 Sampling and 

Monitoring Requirements 

Final § 75.336, derived from ETS 

§ 75.335(b), revises and renumbers 

sampling and monitoring requirements 

for sealed atmospheres. In the final rule, 

the terms ‘‘sampling’’ and ‘‘monitoring’’

are used interchangeably. The final rule 

deletes the requirement in the ETS for 

mine operators using seals designed to 

withstand less than 120 psi to develop 

and follow a protocol to monitor 

methane and oxygen concentrations in 

sealed atmospheres. The ETS required 

that the protocol be approved by the 

District Manager in the ventilation plan. 

Requirements to maintain and restore an 

inert atmosphere in the sealed area are 

discussed in final § 75.336(b); 

requirements for sampling pipes are 

discussed in final § 75.337(g). 

Requirements for welding, cutting and 

soldering are discussed in final 

§ 75.337(f); requirements for water 

drainage systems are discussed in final 

§ 75.337(h); and requirements for 

training of certified persons conducting 

sampling are discussed in final 

§ 75.338(a). 

Section 75.336(a) of the final rule 

retains the requirement in ETS 

§ 75.335(b) for a certified person, as 

defined under existing § 75.100, to 

monitor sealed atmospheres for methane 

and oxygen concentrations. Unlike the 

ETS, the final rule requires sealed 

atmospheres to be monitored through 

each sampling pipe and approved 

sampling location whether seals are 

ingassing or outgassing. Training 

requirements for certified persons are 

addressed in final § 75.338(a) and are 

unchanged from the ETS. 

Final §§ 75.336(a)(1)(i) through (iii) 

address ETS requirements for sampling 

frequencies, including initial sampling 

periods and sampling on a continuing 

basis. Atmospheres with seals less than 

120 psi constructed prior to October 20, 

2008, and atmospheres with seals of less 

than 120 psi constructed after October 

20, 2008 must be sampled through each 

sampling pipe and approved location at 

least every 24 hours. Under the final 

rule, the operator may request that the 

District Manager approve different 

frequencies and locations in the 

ventilation plan. Under the final rule, 

seals of 120 psi or greater must be 

monitored until they reach their design 

strength. After they reach their design 

strength, the final rule does not require 

the atmosphere in these sealed areas to 

be monitored and maintained inert. 

Final § 75.336(a)(2) is derived from 

ETS §§ 75.335(b)(1) and (b)(5) and 

requires the mine operator to evaluate 

the atmosphere in the sealed area to 

determine whether sampling through 

required sampling pipes under final 

§ 75.337(g) provides appropriate 

sampling locations. The final rule 

specifies the conditions under which 

the evaluation must be conducted. 

When the evaluation results indicate the 

need for additional sampling locations, 

the mine operator must establish 

additional sampling locations and 

include them in the ventilation plan for 

approval by the District Manager. 

Final § 75.336(a)(3) requires mine 

operators with an approved ventilation 

plan addressing spontaneous 

combustion under existing § 75.334(f) to 

monitor sealed atmospheres in 

accordance with the plan. 

Final § 75.336(a)(4) is derived from 

ETS § 75.335(b)(5)(vi) and allows the 

District Manager to approve the use of 

a continuous monitoring system in lieu 

of monitoring provisions in the final 

rule. 

Final § 75.336(b)(1), like ETS 

§ 75.335(b)(3), defines an inert 

atmosphere as one in which the oxygen 

concentration is less than 10 percent, or 


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the methane concentration is less than 

3.0 percent or greater than 20.0 percent. 

Final § 75.336(b)(2) addresses corrective 

action necessary if the atmosphere is not 

inert. It requires that when a sealed 

atmosphere with less than 120-psi seals 

is not inert, the mine operator must take 

immediate action to reestablish an inert 

atmosphere and monitor the sealed 

atmosphere every 24 hours until it is 

restored to an inert status. 

Final § 75.336(c) revises and clarifies 

ETS § 75.335(b)(4) and specifies when 

persons must be withdrawn from the 

mine due to a hazardous atmosphere in 

the sealed area. 

Final § 75.336(d) clarifies existing 

MSHA policy that allows the operator to 

request that the District Manager 

approve in the ventilation plan a 

different oxygen concentration if the 

atmosphere in the sealed area contains 

carbon dioxide. It also addresses sealed 

areas where inert gas has been injected, 

and sampling methods and equipment. 

Final §§ 75.336(e)(1) and (e)(2) are the 

same as ETS §§ 75.335(b)(6) and (b)(7) 

and include requirements for recording 

sampling results and any hazardous 

condition found in accordance with 

existing § 75.363. 

1. Section 75.336(a) 

Section 75.336(a) retains the 

requirement in ETS § 75.335(b) for a 

certified person, pursuant to § 75.100, to 

monitor sealed atmospheres. The final 

rule continues to require the certified 

person to monitor the sealed area for 

methane and oxygen concentrations. 

Under the final rule, unlike the ETS, 

sealed atmospheres must be monitored 

whether seals are ingassing or 

outgassing. Mine operators must also 

determine the direction of air leakage 

during monitoring which will indicate 

whether seals are ingassing or 

outgassing. Seals outgas when the 

pressure in the sealed area exceeds the 

pressure on the outby side of the sealed 

area. Seals ingas when the pressure 

outby the sealed area exceeds the 

pressure in the sealed area. 

ETS § 75.335(b)(1) required mine 

operators to sample sealed atmospheres 

only when seals were outgassing. MSHA 

requested comments regarding: its 

sampling approach; sampling frequency; 

sampling only when a seal is outgassing; 

whether a different sampling approach 

would be more appropriate for the final 

rule, such as when seals are ingassing; 

and information and experiences of the 

mining community concerning 

sampling sealed areas. 

Commenters’ views were divided 

regarding appropriate conditions for 

monitoring seals, especially on the issue 

of outgassing and/or ingassing. MSHA 

received comments in support of the 

ETS strategy of requiring monitoring 

when seals were outgassing, while some 

other comments supported monitoring 

whether outgassing or ingassing. Several 

commenters suggested that sampling 

only during outgassing is inadequate to 

protect miners, since a greater concern 

exists when a seal is ingassing and adds 

oxygen to a fuel-rich environment in the 

sealed area. One commenter stated that 

ingassing creates zones of explosive 

methane-air mixtures and is more 

dangerous than when the seals are 

outgassing. A number of other 

commenters stated that sampling inby 

an ingassing seal or a seal that is in 

barometric pressure transition is a 

recipe for inaccurate sampling, and 

MSHA should not require sampling 

during ingassing. Finally, one 

commenter who supported sampling 

when seals are outgassing recommended 

that balance chambers could reduce 

incidences of barometric pressure 

changes exceeding the ventilating 

pressure produced by main mine fans 

causing seals to ingas. According to this 

commenter, the sealed atmosphere 

continues to change at least at the 

perimeter of the sealed area, and in 

some parts of the country, this change 

occurs on a daily or even more frequent 

basis. This commenter also suggested 

that MSHA provide incentives for mine 

operators such as allowing them to use 

lower-strength seals than required in the 

ETS. According to the commenter, these 

incentives should include allowing 

lower strength seals where balance 

chambers are used. MSHA 

acknowledges that a number of sealed 

atmospheres fluctuate from outgassing 

to ingassing on a frequent basis. MSHA 

believes that the sampling strategy 

under the final rule, based on ingassing 

or outgassing, would remove the need 

for balance chambers. 

The Agency has reviewed the 

comments, hearing transcripts, data and 

other information contained in the 

rulemaking record regarding sampling 

and monitoring. MSHA also reviewed 

the Agency’s enforcement history and 

field experience with implementation 

under the ETS. The Agency believes 

that sealed atmospheres should be 

monitored whether outgassing or 

ingassing. Since promulgation of the 

ETS, some operators have experienced 

significant delays in monitoring sealed 

areas, especially during the 14-day 

baseline period and while seals are 

reaching their design strength. The 

preamble to the ETS stated: 

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 

outgases. 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. (72 FR at 28802) 

At the time of promulgation of the 

ETS, MSHA did not envision that the 

sampling and monitoring procedure 

would result in the significant delays 

that have been experienced in the 

mining industry. MSHA inspectors also 

experienced delays in monitoring sealed 

atmospheres because of having to wait 

for seals to outgas before a sample could 

be taken. Also, limiting monitoring to 

outgassing affected the operators’ ability 

to promptly implement the ETS 

monitoring requirements for 

determining whether the sealed 

atmosphere had reached the explosive 

range. After a review of the rulemaking 

record, the Agency does not believe that 

the record evidence supports limiting 

monitoring sealed areas to when seals 

are outgassing. In response to comments 

and in light of its own experience, the 

Agency has revised the monitoring 

requirement in this final rule to require 

mine operators to monitor sealed 

atmospheres whether seals are 

outgassing or ingassing. MSHA expects 

the final rule provisions to resolve many 

existing problems with monitoring 

sealed areas and to enhance safety and 

health of underground coal miners. 

Final §§ 75.336(a)(1) requires 

monitoring through each sampling pipe 

and at each approved sampling location. 

Under § 75.336(a)(1)(i), mine operators 

must sample atmospheres with seals of 

120 psi or greater until the design 

strength is reached, after which time 

they may cease sampling. Initial 

sampling for all newly-constructed seals 

is necessary to protect miners if an 

explosive atmosphere forms behind 

seals before they reach their design 

strength. 

Under § 75.336(a)(1)(ii) of this final 

rule, like the ETS, the mine operator 

must monitor for methane and oxygen 

and maintain an inert atmosphere in the 

sealed area when using seals less than 

120 psi constructed prior to the date of 

this final rule. Final § 75.336(a)(1)(iii) 

requires that atmospheres with seals of 

less than 120 psi constructed after the 

date of this final rule must be monitored 

and the atmosphere must be maintained 

inert. 

Final §§ 75.336(a)(1)(ii) and (iii) allow 

the operator to request that the District 

Manager approve different sampling 

locations and frequencies in the 

ventilation plan provided at least one 

sample is taken at each set of seals at 

least every 7 days. Under final 


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§ 75.335(a)(1)(iii) for less than 120 psi 

seals constructed after April 18, 2008, 

the District Manager cannot approve 

different sampling locations and 

frequencies in the ventilation plan until 

after a minimum of 14 days and after 

seals have reached design strength. 

MSHA will consider pertinent 

information supplied by the mine 

operator, such as the results of the 14- 

day sampling period and any other 

previous sampling results, in an 

operators’’ request to change sampling 

locations and frequencies. The 7-day 

interval is the same as the ETS 

monitoring frequency and is consistent 

with weekly examinations required in 

existing § 75.364. MSHA believes the 

sealed atmosphere must be sampled at 

least every 7 days in the event seal 

leakage, strata fracturing, roof 

convergence or another problem has 

developed and is affecting the sealed 

atmosphere. Under the final rule, MSHA 

emphasizes that mine operators must 

monitor sealed atmospheres at a 

frequency of every 24 hours unless the 

District Manager approves a different 

frequency in the ventilation plan. For 

newly constructed seals of less than 120 

psi, the final rule requires a 14-day 

sampling period before the District 

Manager may approve different 

sampling locations and frequencies. The 

final rule deletes ETS § 75.335(b)(5)(iii) 

which required mine operators to 

specify procedures in the sampling 

protocol to establish a baseline analysis 

of oxygen and methane concentrations 

at each sampling point over a 14-day 

sampling period to be approved in the 

ventilation plan. In the final rule, in 

response to commenters and for clarity, 

MSHA has included specific parameters 

for sampling sealed atmospheres. As 

such, there is no need for a sampling 

protocol. 

Several commenters said that the 

atmosphere behind all seals should be 

monitored and maintained inert. One 

commenter stated that sealed areas 

cannot be adequately monitored or 

maintained inert; therefore, all seals 

must be designed to withstand an 

explosion. Another commenter stated 

that monitoring is inadequate to protect 

miners and that it provides a false sense 

of security. MSHA believes that 

monitoring sealed areas informs the 

mine operator of the presence of 

potentially hazardous gases in sealed 

areas. Under the final rule, use of seals 

designed for less than 120-psi 

overpressure 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 which liberate 

significant volumes of methane, the 

atmosphere in sealed areas may become 

inert naturally. In mines that produce 

very small volumes of methane, the 

atmosphere in sealed areas may never 

become explosive. However, some 

mines may need to use other means to 

inert the atmosphere in the sealed area, 

such as injecting inert gas or pressure 

balancing of the ventilation system; or 

injecting material into the strata 

surrounding the seals to reduce leakage. 

These methods could inert the 

atmosphere in the sealed area. Other 

mines may need to construct new seals 

that are 120 psi or greater in front of all 

existing seals. MSHA’s existing 

standards at § 75.334(a)(1) and (a)(2) 

require that worked-out areas be sealed 

or ventilated. 

Commenters stated that the ETS 

sampling and monitoring requirements 

were confusing. A number of 

commenters criticized the need for 

District Manager approval of the 

sampling protocol. Several commenters 

said that there was no scientific basis for 

the monitoring, while others said that 

the final seal regulation should be more 

prescriptive. Several commenters 

criticized MSHA’s weekly sampling 

intervals as being too lengthy to protect 

the miners. One commenter said that 

their data showed sealed areas never 

reach equilibrium and that barometric 

pressure changes continue to affect the 

sealed atmosphere. Commenters stated 

that when a sealed area has reached a 

stable atmospheric composition, weekly 

sampling is unnecessary. 

MSHA continues to believe that 

weekly samples are necessary to protect 

miners’’ safety and health. Barometric 

pressure changes, ventilation changes, 

water accumulations, methane 

liberation, subsidence, cracked strata 

near seals, and other changes may 

render a previously inert atmosphere 

explosive. Periodic monitoring is 

necessary to detect these potentially 

hazardous conditions in the sealed area. 

The final rule, like the ETS, requires 

periodic sampling. 

Final § 75.336(a)(2) clarifies MSHA’s 

intent under ETS § 75.335(b) for the 

mine operator to have responsibility for 

evaluating the atmosphere in the sealed 

area to determine whether sampling 

through seal sampling pipes, in 

accordance with final § 75.337(g), will 

provide an appropriate sample of the 

sealed atmosphere. Appropriate 

sampling must be capable of reliably 

detecting significant accumulations of 

explosive methane in the sealed area. 

MSHA specifies in the final rule when 

the mine operator must conduct the 

evaluation which includes: the planning 

phase for sealing the area; immediately 

after the minimum 14-day required 

sampling; when the mine ventilation 

system is reconfigured; if changes in the 

mine occur that could adversely affect 

the sealed area; or if the District 

Manager requests an evaluation. When 

the results of the evaluations indicate 

the need for additional sampling 

locations, the mine operator must 

provide the additional locations and 

have them approved in the ventilation 

plan. The District Manager may require 

additional sampling locations and 

frequencies in the ventilation plan. 

The mine operator shall evaluate the 

sealed area using the sampling results 

from the minimum 14-day required 

sampling and any other relevant 

information available to confirm that the 

initial evaluation is valid. A mine 

ventilation system reconfiguration may 

affect the direction of air leakage 

through seals and consequently alter the 

interpretation of sampling results in 

order to determine the inert status of the 

sealed atmosphere. The composition of 

the sealed atmosphere can be affected 

by changes in air currents, water 

accumulations, convergence, cracks in 

the strata leading to the surface, and the 

rate and/or location of methane 

liberation. These changes may affect the 

distribution of methane and oxygen 

concentration throughout the sealed 

area. The District Manager may request 

an evaluation based on other factors as 

appropriate. 

Many variables affect the atmospheric 

composition of the sealed area, 

including size, methane liberation, 

leakage, ventilation pressures, and 

barometric changes. Mine operators 

must analyze each sealed area when 

determining appropriate sampling 

locations and frequencies. If the mine 

operator’s analysis indicates that 

sampling through seal sampling pipes 

does not render an appropriate 

evaluation of the sealed atmosphere, the 

mine operator must establish additional 

sampling locations and specify them in 

the ventilation plan for the District 

Manager’s approval. 

Under the final rule, the District 

Manager may require additional 

sampling locations and sampling 

frequencies in the mine ventilation plan 

such as when MSHA sampling results 

differ from the operator’s sampling 

results, or the District Manager’s review 

of the mine operator’s data indicates the 

atmosphere in the sealed area is not 

being adequately evaluated. In the ETS, 

the Agency expressed its intent that 

under ETS § 75.335(b), mine operators 

had to evaluate the sealed atmosphere to 

determine whether additional sampling 

locations were necessary. 


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In the ETS, MSHA also emphasized 

that all seals and the strata around them 

leak, resulting in an air exchange near 

the seal during barometric pressure 

changes. Seals may leak air into a 

methane-rich sealed atmosphere that 

can result in explosive methane 

concentrations. Due to this, MSHA 

stressed in the ETS the significance of 

obtaining appropriate samples of 

atmospheric conditions in the larger 

portion of the sealed area as opposed to 

the smaller area immediately inby the 

seal. 

Some commenters objected to the 

requirement in ETS § 75.335(b) for the 

mine operators to obtain a 

representative sample solely through 

sampling pipes. MSHA acknowledges 

the limitations of the ETS sampling 

method for large sealed areas. While 

sampling a limited number of times or 

at a reduced frequency may result in an 

effective evaluation of the sealed area, 

additional sampling locations can be 

necessary to determine if a sealed 

atmosphere is inert. For instance, a 

sealed atmosphere may have one set of 

seals ingassing fresh air from the mine 

while another set of seals is outgassing 

high concentrations of methane. A 

transition zone exists where the 

atmosphere experiences an explosive 

range of methane between the two sets 

of seals. Thus, final § 75.336(a)(2) 

addresses the mine operator’s 

responsibility to include adequate 

sampling locations and frequencies in 

the ventilation plan. 

Several commenters stated that it is 

impractical to drill boreholes from the 

surface due to cost implications, surface 

topography, or land ownership. 

Although MSHA recognizes that there 

may be situations in which it may be 

impractical to drill boreholes from the 

surface, the Agency is aware that 

directional drilling from the surface or 

from within the mine is commonly 

practiced in the mining industry and 

may be used when topographic or land 

ownership problems are encountered. It 

is common practice in the mining 

industry to remove all persons from the 

affected area when the borehole 

approaches an unexamined or 

unventilated area. Other commenters 

supported a requirement for drilled 

boreholes to adequately monitor large or 

unusual sealed areas. 

A commenter suggested that it is 

unreasonable for MSHA to assume that 

localized samples, regardless of the 

technique, establish the inert status of 

the sealed area. MSHA believes that 

sampling through seals, supplemented 

with additional sampling locations, 

where necessary, provides a safe and 

feasible method of ascertaining 

atmospheric conditions in the sealed 

area. Final § 75.336(a)(2) provides that 

the District Manager can require 

additional sampling locations, such as 

boreholes, and frequencies in a mine 

operator’s ventilation plan. 

One commenter expressed that it is 

not a significant hazard when a large 

sealed area in a mine has explosive 

mixtures when sampled through pipes, 

because coalbed methane production 

wells located above the sealed area 

produce almost pure methane (greater 

than the upper explosive limit). MSHA 

believes that methane extracted from the 

gob vent borehole primarily comes from 

the strata above the active coal mine. 

(Mucho, T.P., W.P. Diamond, F. Garcia, 

J.D. Byars and S.L. Cario, Implications 

of Recent NIOSH Tracer Gas Studies on 

Bleeder and Gob Gas Ventilation 

Design, The Society of Mining Engineers 

Annual Meeting, 2000). MSHA 

determined that boreholes used to 

sample sealed areas must be connected 

to the open entries within the sealed 

area. Degasification boreholes typically 

stop about 30 to 40 feet above the coal 

seam and do not extend into the sealed 

area and will not provide an accurate 

sample of the sealed atmosphere. 

Some commenters recommended a 

risk analysis of sealed areas rather than 

monitoring. As appropriate, mine 

operators may include an analysis of the 

risks in the sealed area in their 

evaluation of the sealed area for 

MSHA’s consideration. An evaluation 

under final § 75.336(a)(2) may include 

size of the sealed area, frequency of 

sampling, likelihood of spontaneous 

combustion, depth of the mine, and the 

patterns of methane liberation. 

However, the Agency concludes that the 

rulemaking record does not support a 

requirement of a risk analysis in lieu of 

monitoring. Monitoring of the sealed 

atmosphere in areas where seals less 

than 120 psi are used, and until the 

design strength is reached for seals of 

120 psi or greater, provides optimum 

safety for miners because of the 

unforeseen changes that can occur 

within the sealed area. 

Final § 75.336(a)(3) requires mine 

operators with an approved ventilation 

plan addressing spontaneous 

combustion under existing § 75.334(f) to 

sample the sealed area as specified in 

the approved ventilation plan. Section 

75.334(f) addresses mines with a 

demonstrated history of spontaneous 

combustion and those located in coal 

seams determined to be susceptible to 

spontaneous combustion. It requires 

that the approved mine ventilation plan 

for these mines specify the measures 

that will be used to detect methane, 

carbon monoxide, and oxygen 

concentrations during and after pillar 

recovery, and in worked-out areas 

where no pillars have been recovered; 

the actions that will be taken to protect 

miners from the hazards of spontaneous 

combustion; and the methods that will 

be used to control spontaneous 

combustion, accumulations of methaneair mixtures, other gases, dusts, and 

fumes in the worked-out area. Sampling 

and maintaining an inert atmosphere are 

critical in sealed areas in coal mines 

that are subject to spontaneous 

combustion of the coal seam due to this 

inherent ignition source. 

Several commenters stated that 

MSHA should continue to require mine 

operators to control spontaneous 

combustion in sealed areas through 

compliance with § 75.334(f). These 

commenters stated that the sampling 

requirements of a spontaneous 

combustion plan should be more 

comprehensive than the requirements of 

§ 75.336 to safely manage the 

combustion potential. MSHA allows the 

spontaneous combustion monitoring 

requirements in the approved 

ventilation plan to be used in lieu of the 

monitoring requirements of this section 

which is more protective for miners. 

Final § 75.336(a)(4), derived from ETS 

§ 75.335(b)(5)(vi), allows the District 

Manager to approve the use of a 

continuous monitoring system in lieu of 

the monitoring provisions in this 

section. A continuous monitoring 

system may include bundles of 

sampling tubes that sample a frequency 

of every few hours and monitor at 

numerous sampling locations in the 

sealed area. MSHA standards addressing 

atmospheric monitoring systems are in 

existing § 75.351 and are applicable to 

belt air courses, primary escapeways, 

return air splits, and electrical 

installations. These standards do not 

address monitoring in sealed areas. The 

final rule broadens the scope and 

applicability of the ETS requirement in 

that it addresses continuous monitoring 

systems rather than atmospheric 

monitoring systems. Since promulgation 

of the ETS, MSHA does not believe that 

all of the provisions of § 75.351, 

atmospheric monitoring systems, are 

applicable to monitoring sealed 

atmospheres. 

One commenter stated that MSHA did 

not adequately address continuous gas 

monitoring systems in the ETS. The 

final rule allows for use of these 

monitoring systems. Several 

commenters expressed that current 

atmospheric monitoring sensors could 

not be used in sealed areas due to 

calibration and maintenance 

requirements. The final rule deletes 


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reference to atmospheric monitoring 

systems. 

Mine operators using continuous 

monitoring systems to monitor sealed 

atmospheres must submit a revised 

ventilation plan to the District Manager. 

The District Manager will review the 

revised plan to assure that the 

continuous monitoring system will 

perform effectively. In making a 

decision to approve this system, MSHA 

expects the mine operator to address 

calibration, recordkeeping, oversight of 

the continuous monitoring system, 

maintenance features of the monitoring 

system and sampling locations. 

2. Section 75.336(b) 

Final §§ 75.336(b)(1) and 75.336(b)(2) 

address inert atmospheres in sealed 

areas. Section 75.336(b)(1), unchanged 

from ETS § 75.335(b)(3), defines an inert 

atmosphere as one in which the oxygen 

concentration is less than 10.0 percent; 

the methane concentration is less than 

3.0 percent; or the methane 

concentration is greater than 20.0 

percent. MSHA has included a margin 

of safety in the definition of an inert 

atmosphere so that mine operators can 

address potential explosion hazards 

before having to withdraw miners. As 

the Agency stated in the ETS, the 

explosive range of methane is 5 to 15 

percent when the oxygen level is 12 

percent or more (2007 NIOSH Draft 

Report) which are the traditional values 

used in the coal mining industry. 

According to the 2007 NIOSH Draft 

Report, methane is explosive in air 

when the concentration ranges from 5 

percent to 15 percent by volume. As in 

the ETS, to allow for the inaccuracy of 

methane and oxygen detection 

equipment and potential contamination 

of samples, oxygen less than 10.0 

percent, methane concentration less 

than 3.0 percent and methane 

concentration greater than 20.0 percent 

are used to determine an inert 

atmosphere. 

For atmospheres behind seals with 

design strengths less than 120-psi, final 

§ 75.336(b)(2) requires the mine operator 

to take immediate action to restore the 

sealed atmosphere to an inert condition. 

Mine operators also must sample sealed 

atmospheres at least every 24 hours. In 

addition, MSHA requires withdrawal of 

miners when methane is between 4.5 

and 17 percent and oxygen is 10 percent 

or greater. 

Some commenters stated that until 

seals ‘‘cure’’ all sealed atmospheres 

must be inert, including seals of 120 psi 

or greater, or miners must be withdrawn 

from the mine. A critical time period for 

seals is immediately after construction 

prior to seals reaching their design 

strength. Miners must be protected from 

the hazard of an explosive atmosphere 

behind seals prior to seals reaching their 

design strength. Under the final rule, 

hazardous conditions are controlled by 

frequently monitoring and maintaining 

an inert atmosphere or withdrawing 

miners from the mine. Under MSHA’s 

final rule, mine operators must monitor 

and maintain an inert atmosphere 

behind all newly-constructed seals. 

After 120-psi seals or greater reach their 

design strength, they are not required to 

be monitored under § 75.336. MSHA 

noted in the ETS that its accident 

history covering mines in the United 

States does not include documentation 

of an explosion in an underground mine 

that has generated an overpressure 

greater than 120 psi. One commenter 

addressing the final draft U.S. Army 

Corps of Engineers report stated that the 

chance of having a methane gas 

detonation in a coal mine is almost zero 

and further stated that with using actual 

gob compositions the constant volume 

explosion loads were found to not 

exceed 100 psi. Based on the Agency’s 

experience under the ETS and other 

record evidence, the final rule does not 

require seals with a design strength of 

120 psi or greater to be monitored after 

they reach their design strength. 

Several commenters stated that 

MSHA’s definition of an inert 

atmosphere in the ETS was overly 

conservative and recommended the 

generally accepted definition of a nonexplosive atmosphere of oxygen less 

than 12.0 percent, and methane less 

than 5.0 percent or greater than 15.0 

percent. A commenter suggested an 

expanded explosion risk buffer zone 

based on a Queensland, Australia 

underground coal mining standard. 

Commenters also stated that MSHA 

should take a tiered approach to address 

varying levels of methane and oxygen in 

the sealed area. Some of these 

commenters used the term ‘‘explosive 

buffer zone’’ when addressing broader 

gas concentrations to incorporate a 

margin of safety into the definition of 

inert and protocol requirements in ETS 

§§ 75.335(b)(4) and 75.335(b)(5). The 

ETS required an action plan for which 

mine operators were required to address 

hazards presented and actions to be 

taken when gas samples indicated that 

oxygen was 10.0 percent or greater and 

methane concentrations were 3.0 

percent or greater but less than 4.5 

percent; 4.5 percent or greater but less 

than 17.0 percent; and 17.0 percent to 

20.0 percent. Several commenters said 

that no buffer zones are necessary if a 

gas chromatograph is used to analyze 

the samples. MSHA believes that 

chromatographic analyses are more 

accurate than handheld instruments. 

MSHA also believes that handheld 

detectors can be an adequate sampling 

method to determine the methane and 

oxygen concentration at a sample 

location. The definition of an inert 

atmosphere in the final rule includes a 

margin of safety to account for sampling 

less than the entire sealed area and 

time-related changes in the sealed 

atmosphere. 

A number of commenters said that 

explosive atmospheres that periodically 

develop when the barometric pressure is 

rising or the seals are ingassing are not 

hazardous. The effects of ingassing 

depend on several factors including the 

duration and magnitude of the pressure 

differential across seals, leakage rates, 

and the typical methane concentration 

for the sealed area. Therefore, MSHA 

believes that hazards may exist when 

the seals are ingassing and the final rule 

is structured to address such hazards. 

Commenters objected to the ETS 

requirement for a 14-day baseline 

sampling period or questioned its 

benefit. MSHA considered these 

comments, but the final rule retains a 

14-day initial sampling requirement for 

seals less than 120 psi constructed after 

April 18, 2008. MSHA believes that 

monitoring of the sealed area during the 

initial 14-day period provides optimum 

safety for miners because of the 

unforeseen changes that can occur 

within the sealed area. For newly 

constructed seals, the final rule is 

structured so that mine operators can 

establish the appropriate number of 

sampling locations. Several commenters 

expressed concern with the alternative 

ventilation plan requirements for seals 

that only ingas or rarely outgas. MSHA 

has reexamined this issue and believes 

that monitoring and maintaining an 

inert atmosphere is protective only 

when the sealed area is inert at all 

times. The final rule requires mine 

operators to establish and maintain an 

inert atmosphere behind seals less than 

120 psi. 

Some other commenters stated that all 

sealed atmospheres must be monitored 

and maintained inert. Another 

commenter said monitoring is not the 

answer and that MSHA must require 

stronger seals. The final rule is 

structured so that the mine operator can 

address unique characteristics of sealed 

areas through either monitoring and 

maintaining an inert atmosphere or 

using seals designed to address the 

potential overpressures which may 

develop in the sealed area. 

Another commenter stated that MSHA 

should require gas concentrations in the 

sealed area to be maintained sufficiently 


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outside the explosive range to prevent 

any excursions into the explosive zone 

during normal changes in barometric 

pressure. Finally, a commenter 

suggested that one way to reduce the 

possibility that a detonation may occur 

in the sealed area is to keep the methane 

air behind the seal far from the 

explosive range so that changes in 

pressure conditions due to foreseeable 

events are not possible. This commenter 

also stated that methane concentration 

greater than 50 percent could assure that 

the methane range in the sealed area 

will not fall within the 5 to 15 percent 

explosive range. In addition, this 

commenter stated that the ETS required 

more frequent monitoring for specified 

ranges of gases, but the provision does 

not provide a margin of safety that 

would prevent swings into the explosive 

range for foreseeable events such as 

weather, will not prevent detonations, 

and sampling, regardless of the 

technique, will not confirm an inert 

status of the sealed area. 

The Agency’s definition of an inert 

atmosphere incorporates a margin of 

safety which accounts for sampling less 

than the entire sealed area and timerelated changes in the sealed 

atmosphere. MSHA believes that the 

increased sampling frequencies required 

by the final rule along with the 

definition of inert and the requirements 

for withdrawal of miners will provide 

appropriate and necessary protection of 

miners. 

3. Section 75.336(c) 

Final § 75.336(c) revises and clarifies 

ETS §§ 75.335(b)(4) and (b)(5) and 

addresses requirements for potentially 

explosive atmospheres in sealed areas 

with less than 120-psi seals. Final 

§ 75.336(c) requires that when a sample 

is taken from the sealed atmosphere 

with seals of less than 120 psi and the 

sample indicates that the oxygen 

concentration is 10 percent or greater 

and methane is between 4.5 percent and 

17 percent, the mine operator must 

immediately take an additional sample 

and then immediately notify MSHA. In 

addition, final § 75.336(c) requires that 

when the additional sample indicates 

that the oxygen concentration is 10 

percent or greater and methane is 

between 4.5 percent and 17 percent, 

persons must be withdrawn from the 

affected area which is the entire mine or 

other affected area identified by the 

operator and approved by the District 

Manager in the ventilation plan, except 

those persons referred to in § 104(c) of 

the Act. Under this final rule, the 

operator may identify areas in the 

ventilation plan to be approved by the 

District Manager where persons may be 

exempted from withdrawal. The 

operator’s request must address the 

following factors regarding the location 

of seals in relation to: (1) Areas where 

persons work and travel in the mine; (2) 

escapeways and potential for damage to 

the escapeways; and (3) ventilation 

systems and controls in areas where 

persons work or travel and where 

ventilation is used for escapeways. The 

District Manager, in making a 

determination concerning the area 

where persons may be exempted from 

withdrawal, would take these factors 

into consideration. The operator’s 

request shall also address the gas 

concentration of other sampling 

locations in the sealed area and other 

required information. 

Final § 75.336(c) clarifies when 

miners may reenter the mine and 

requires the mine operator to have an 

approved and revised ventilation plan 

specifying the actions to be taken by the 

mine operator to protect miners. 

MSHA requested comments on the 

ETS action plan approach to potentially 

explosive sealed atmospheres and 

whether that approach provides 

adequate protection for miners. Several 

commenters stated that persons should 

not be withdrawn merely due to 

explosive samples in the sealed area and 

that other factors such as the size of the 

sealed area, roof and weather 

conditions, or the volume of non-inert 

atmosphere should be considered. 

Several commenters wanted MSHA to 

consider the possibility of defining 

safety zones around seals. Other 

commenters said that miners should 

unconditionally be evacuated from the 

mine when any sealed atmosphere is in 

the explosive range. Several 

commenters questioned whether an 

action plan could provide protection to 

miners which would be equivalent to 

withdrawal. One commenter suggested 

that rather than withdrawing miners, a 

‘‘safety zone,’’ or a specific distance, 

should be established around seals with 

explosive atmospheres. A commenter 

stated that keeping miners underground 

with a sealed atmosphere within the 

explosive range is an unacceptable risk 

due to the enormous potential for a 

catastrophe if a seal fails. 

Some action plans approved under 

the ETS require the withdrawal of 

miners from the entire mine. MSHA 

now believes that some large mines with 

multiple fans, multiple shafts, multiple 

portals, or multiple escapeways may not 

require evacuation of the entire mine to 

protect miners from the hazards 

presented by an explosion in a sealed 

area. Accordingly, this final rule allows 

an operator to identify areas in the 

ventilation plan to be approved by the 

District Manager where persons may be 

exempted from withdrawal. The 

operator’s request must address the 

factors in this provision of the final rule. 

For example, in a large mine, the 

District Manager may approve an area 

where persons may be exempted from 

withdrawal if: (1) The area where 

persons work or travel is remote from 

the sealed area; (2) the area is on 

separate air splits that would not be 

contaminated from the gaseous products 

of an explosion; and (3) those areas are 

served by escapeways that would not be 

impacted by an explosion. 

One commenter said that MSHA 

district offices do not have the resources 

to properly evaluate proposed action 

plans required by the ETS and the rule 

should provide specificity about the 

actions required to be taken by mine 

operators. Action plans are not required 

in the final rule. MSHA has replaced 

action plans with specific actions to be 

taken under certain circumstances. 

Several commenters said that 

withdrawal should only be required 

when oxygen levels in the sealed area 

exceeded 12 percent because this is the 

minimum oxygen level that will sustain 

an explosion at normal atmospheric 

pressure. Another commenter said that 

introduction of oxygen caused the 

formation of an explosive atmosphere. 

Other commenters said that the 

explosive gas range is too broad. 

Another commenter said the 

Queensland Australia regulation 

specifies, for continuous monitoring, the 

maximum oxygen concentration should 

be 8 percent and the methane 

concentration should be less than 2.5 

percent or greater than 22 percent. 

Several commenters said that 

withdrawal should only be required 

when the atmosphere in sealed area is 

in the explosive range of methane which 

they defined as 5 percent to 15 percent. 

A commenter recommended using 

mapping software to generate isopach 

maps of methane concentration 

throughout the sealed area in order to 

determine potentially explosive zones. 

MSHA does not believe that isopach 

mapping software, based on arbitrary 

mathematical interpolations, will 

accurately represent the complex 

methane liberation, diffusion and 

convection processes in the sealed area 

in combination with leakage through or 

around seals to predict explosive zones 

with any degree of reliability. 

In the ETS, MSHA referenced the 

2007 NIOSH Draft Report which stated 

that the explosive range is 5 to 15 

percent when the oxygen level is 12 

percent or more. NIOSH, in its Final 

Report, stated that methane is explosive 

in air when the concentration ranges 


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from 5 percent to 16 percent by volume. 

The NIOSH Final Report stated: ‘‘A 

desirable sealed area atmosphere, from 

a safety perspective is fuel-rich and 

oxygen-low, which is * * * less than 

10% oxygen.’’ The final rule continues 

to account for the inaccuracies of 

sampling and monitoring equipment, 

and for potential contamination of the 

gas sample. The final rule retains the 

methane range of 4.5 percent to 17.0 

percent with oxygen 10 percent or 

greater for withdrawal of miners as 

specified in the ETS. This range of 

methane concentration is slightly 

broader than the explosive range 

specified by NIOSH (2007 NIOSH Draft 

Report and ‘‘Handbook for Methane 

Control in Mining,’’ Information 

Circular 9486, 2006 (2006 NIOSH IC 

9486), and ‘‘Flammability of Methane, 

Propane, and Hydrogen Gases,’’

Cashdollar (2000). The slightly broader 

range of methane includes a safety 

measure to help assure the mine 

operator has time to safely evacuate the 

mine. MSHA has considered these 

comments and continues to accept the 

methane in air mixtures provided by 

NIOSH as the most appropriate basis for 

the final rule. The levels in the final rule 

are the same as those provided in the 

ETS. 

The ETS allowed mine operators to 

take three samples at one hour intervals 

before requiring evacuation of the mine. 

Several commenters objected to this 

provision. A commenter suggested that 

three consecutive samples be taken at 24 

hour intervals to allow the sealed area 

to react to changes in the barometer. 

MSHA believes that it is neither 

appropriate nor protective of miners’

safety to allow them to remain 

underground two additional hours 

before a mine operator confirms a 

hazardous sealed atmosphere. The final 

rule requires that a second sample be 

taken immediately and that MSHA be 

immediately notified regardless of the 

results of the second sample. 

4. Section 75.336(d) 

For sealed areas with a demonstrated 

history of carbon dioxide or where inert 

gas has been injected, final § 75.336(d) 

allows the mine operator to use an 

alternative method to determine if a 

particular atmosphere is inert as defined 

in § 75.336(b)(1). This provision also 

allows the mine operator to use an 

alternative method to determine when 

to withdraw miners as provided in 

§ 75.336(c). The mine operator shall 

address the specific levels of methane, 

carbon dioxide, nitrogen and oxygen in 

the ventilation plan; the sampling 

methods and equipment used; and the 

methods to evaluate these 

concentrations underground at the seals. 

Some commenters requested MSHA 

to consider carbon dioxide 

concentrations when making a 

determination for inert and explosive 

atmospheres, because it is slightly more 

effective at preventing an explosion 

than nitrogen in normal air. A 

commenter stated that it is unrealistic to 

ignore the effects of carbon dioxide on 

methane explosibility and that MSHA 

must let mine operators use both the 

Coward flammability triangle and 

Zabetakis nose curve to assess whether 

a sealed atmosphere is explosive. 

Commenters also requested that MSHA 

consider excess nitrogen concentrations 

when determining the sealed 

atmosphere. 

A methane explosion requires the 

presence of sufficient amounts of 

methane and oxygen. The presence of 

carbon dioxide and excess nitrogen 

affects the concentrations of oxygen and 

methane needed for an explosion to 

occur. The two most common gases 

used for purposes of maintaining a 

sealed area inert are nitrogen and carbon 

dioxide. Both gases may be obtained as 

cryogenic liquids transported to the 

mine site on tanker trucks. Nitrogen 

may also be extracted from compressed 

air using filter technology and carbon 

dioxide may be produced as the exhaust 

gas from combustion processes 

(Tomlinson boiler, diesel engine or jet 

engine). Both the ETS and final rule 

implicitly consider nitrogen as an inert 

gas. Fresh air contains 78% nitrogen 

and nitrogen is typically the most 

prevalent gas in sealed atmospheres. If 

additional nitrogen is injected in a 

sealed atmosphere, it helps move the 

gas mixture toward an inert status 

merely by diluting and rendering 

harmless the methane and oxygen 

levels. Carbon dioxide is slightly more 

effective at producing an inert 

atmosphere than nitrogen. 

This final rule allows mine operators 

to use carbon dioxide and nitrogen 

levels to determine how to manage the 

sealed atmosphere. If the mine operator 

chooses an alternative method to 

determine if the sealed atmosphere is 

inert, the operator must specify the 

types of instruments that will be used to 

measure the gas levels and how these 

more complicated evaluations will be 

performed at the seal. Because of the 

critical nature of these measurements 

and determinations, the use of gas 

chromatographs and computers located 

on the surface is not practical except 

where continuous monitoring systems 

are used. This surface analytical 

equipment cannot be used since this 

final rule requires that a second sample 

be taken and analyzed immediately after 

any near explosive gas concentrations 

are identified. 

Although the Zabetakis nose curve or 

the Coward flammability triangle is 

designed to show whether a methane 

mixture is explosive after inert gas is 

added, the nose curve or flammability 

triangle is not intended for the purpose 

of establishing an inert atmosphere 

under this final rule or the explosibility 

range contained in the final rule. 

The concentration of gases for 

methane in the nose curve and 

flammability triangle ranges from 

approximately 5% to 15%. The nose 

curve and flammability triangle were 

not designed to account for the methane 

ranges specified in the final rule of 4.5% 

to 17% where a safety factor is used. In 

addition, the use of the R-Ratio, or ratio 

of methane to total combustibles, to 

compensate for the safety factor is not 

appropriate. The alternative gas 

concentrations of methane, carbon 

dioxide, nitrogen and oxygen must be 

based on sound scientific principles. 

For example, operators may consider 

the Bureau of Mines Bulletin 503 

(Coward, H.F. and G.W. Jones, ‘‘Limits 

of Flammability of Gases and Vapors,’’

Bulletin 503, U.S. Dept. of the Interior, 

Bureau of Mines, 1952). The alternative 

gas concentrations must provide the 

same levels of protection to the miners 

as the gas concentrations specified in 

§ 75.336(b) and (c) of this final rule. 

MSHA intends that samples of gas 

concentrations be analyzed promptly. 

At present, handheld detectors are 

available to measure carbon dioxide, 

methane and oxygen. The operator shall 

address several related issues in the 

ventilation plan including handheld 

equipment and methods to take these 

measurements underground and 

methods to make the calculations 

necessary to evaluate the gas 

concentrations at the seal. The operator 

should also include methods to ensure 

the reliability of the sampling 

equipment, the training of the certified 

persons who must take these samples 

and perform these calculations, a system 

to validate these determinations and the 

expanded recordkeeping requirements 

(additional gas concentrations). 

5. Section 75.336(e) 

Final § 75.336(e), like ETS 

§ 75.335(b)(6) and (b)(7), requires that 

the mine operator promptly record 

sampling results and that these records 

be maintained at the mine for at least 

one year. MSHA received no comments 

on this provision. 


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C. Section 75.337 Construction and 

repair of seals 

Final § 75.337 is derived from the ETS 

requirements on construction and repair 

of seals. 

1. Section 75.337(a) 

Final § 75.337(a) clarifies the ETS and 

requires mine operators to maintain and 

repair seals to protect miners from 

hazards of sealed areas. MSHA is 

including this provision in this final 

rule in response to comments 

concerning seal repairs. This final rule 

addresses non-structural repairs only. 

Non-structural repairs are those that are 

related to general maintenance and 

include: excessive air leakage through 

and around seals; repair of minor 

cracks; spalling of seal coating; water 

drainage systems; and sampling pipes. 

One commenter expressed concern that 

seals may become inaccessible, 

deteriorate, weaken, and be impossible 

to repair. This section does not apply to 

seals that require structural repairs. 

MSHA will continue to require that 

seals in need of structural repairs be 

replaced since they would no longer 

serve their necessary function. Seals, 

with the exception of seals used to 

separate the active longwall panel from 

the panel previously mined that are 

inby the longwall face, must be 

maintained accessible or be replaced. 

2. Section 75.337(b) 

Final § 75.337(b) renumbers 

§ 75.337(a) of the ETS, and specifies 

requirements that a mine operator must 

follow prior to sealing. 

Under final § 75.337(b)(1), mine 

operators must remove insulated cables 

from the area to be sealed. Final 

§ 75.337(b)(1) clarifies the ETS and 

requires that mine operators remove 

batteries and other potential electric 

ignition sources from the area to be 

sealed. Because an electric arc can occur 

if a length of insulated cable were 

inductively coupled to an 

electromagnetic pulse such as a 

lightning strike, this final rule reduces 

the hazard of an explosion caused by an 

electric discharge. 

Several commenters stated that the 

removal of insulated cables is 

unnecessary, infeasible, unrealistic and 

can be unsafe. One commenter 

suggested that grounding the ends of a 

cable may safeguard cables that cannot 

be removed. Other commenters stated 

that as mine operators complete mining 

activities in an area, they recover the 

more useful cables and may only leave 

behind damaged or deteriorated cables. 

Another commenter stated that there 

can be miles of cables to pumps or 

electric installations that must continue 

to run to within days or hours of final 

sealing, and that it would be impossible 

to remove these cables prior to sealing. 

One commenter suggested that cable 

removal would be unnecessary if seals 

are constructed to withstand explosive 

forces. One commenter suggested that 

the final rule include a provision for 

removing batteries from the area to be 

sealed. 

To reduce the hazard of an explosion 

from an electric discharge, and to assure 

miners’ safety, MSHA believes that it is 

necessary to remove cables, batteries, 

and other potential ignition sources 

prior to sealing unless it is not safe to 

do so. Other potential ignition sources 

include motors, transformers and 

electromagnetic devices. Potential 

electric ignition sources that may 

expose miners to dangerous conditions, 

such as those that are buried under a 

roof fall, would not have to be removed. 

Based on MSHA’s knowledge and 

experience, if one end of an insulated 

cable is grounded and one is not, a 

potential ignition source remains. Also, 

a potential ignition source remains even 

if both ends of a cable are grounded 

because the condition of the conductors 

within the cable would not be known. 

Based on MSHA testing, cable cannot 

generally be considered safe by 

grounding either one or both ends. 

The final rule includes a clarifying 

change that if ignition sources cannot be 

safely removed from the area to be 

sealed, seals must be constructed to at 

least 120 psi. NIOSH indicated in their 

2007 NIOSH Final Seal Report that a 50 

psi peak overpressure could occur in a 

limited-volume, unconfined situation. 

Leaving a potential ignition source, such 

as a cable, in the sealed area could 

increase the probability that larger 

pockets of gas, which may be 

undetected through sampling, could be 

ignited, resulting in an explosion. An 

explosion in a larger area could result in 

overpressures greater than 50 psi. 

Therefore, the final rule provides 

appropriate protection for miners if 

ignition sources cannot be safely 

removed from the area to be sealed. The 

installation of at least 120 psi seals 

would provide protection for miners 

and prevent the explosion in the sealed 

area from propagating to the active 

workings of the mine. 

Final § 75.337(b)(2), like the ETS, 

requires removal of metallic objects that 

pass through or across seals. Screens, 

straps, rails, and channels are examples 

of the types of metallic objects that are 

required to be removed under this final 

rule. In addition, this final rule does not 

include the exception in the ETS for 

metal sampling pipes, water drainage 

pipes, and form ties. Removal of 

metallic objects before seals are built 

reduces the hazard of methane 

explosions and improves miner safety. 

Several commenters suggested that 

metal sampling pipes, water drainage 

pipes, and form ties need not be 

removed because nonmetallic materials 

can be used as alternatives. MSHA 

agrees. Alternative nonmetallic 

materials exist and can be used for gas 

sampling pipes, water drainage systems, 

and form ties. The use of these 

alternative materials will reduce 

methane explosion hazards and enhance 

miner safety. 

Several commenters stated that 

removal of metallic roof support is 

hazardous. One commenter noted that 

an accident occurred during removal of 

wire mesh at a seal location. Based on 

MSHA’s experience, removal of metallic 

roof support can be accomplished safely 

so long as appropriate precautions are 

taken. Under the final rule, the best 

option would be for an operator to plan 

the location of the seals and the roof 

supports, such as cribs and non-metallic 

mesh, to be used in the area to be 

sealed. 

One commenter requested 

clarification of the hazards associated 

with metallic roof mesh or mats that are 

grounded. Based on MSHA’s 

experience, metallic roof mesh or mats 

are not always adequately grounded. In 

addition, metallic roof mesh or mats are 

potential conductive paths into the 

sealed area and need to be removed. 

One commenter stated that MSHA 

should not require removal of degassing, inerting, or pre-sealing 

ventilation pipes that may be needed to 

effectively control the gob atmosphere. 

Based on MSHA’s experience, these 

metallic objects can provide a conduit 

for electric current to enter the sealed 

area and ignite methane/air mixtures. 

Removal of these objects before seals are 

built reduces the hazard of methane 

explosions and improves miner safety. 

Therefore, in response to its request for 

comments in the ETS on information 

concerning the removal of metallic 

objects, the final rule requires removal 

of metallic objects through or across 

seals. 

Final § 75.337(b)(3) is new. It requires 

mine operators to breach or remove all 

stoppings in the first crosscut inby the 

seals immediately prior to sealing the 

area. This procedure is a recognized 

common practice in the coal mining 

industry. 

One commenter stated that 

monitoring could easily provide a false 

sense of security. Another commenter 

said that sampling behind one seal in a 

set would not be able to detect a pocket 


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of explosive gas that may exist. In 

response to commenters’’ concerns, the 

final rule includes the requirement to 

remove or breach the stopping in the 

first connecting crosscuts inby seal 

locations. Under MSHA’s experience, 

breaching or removing stoppings allows 

the same atmosphere to exist 

immediately inby each seal as exists 

throughout the sealed area. Ventilation 

stoppings in the first connecting 

crosscut inby the seal locations are used 

to maintain ventilation, through the area 

to be sealed, during seal construction. 

These stoppings should not be breached 

or removed until immediately prior to 

installing the final seal. The timing of 

the breaching or removing of stoppings 

is critical and should be addressed in 

the mine ventilation plan under 

§ 75.335(c)(3)(iv)(N). 

3. Section 75.337(c) 

Final § 75.337(c), renumbers ETS 

§ 75.337(b), and requires a certified 

person designated by the mine operator 

to directly supervise seal construction 

and repair. Existing § 75.100 defines a 

certified person as one certified by the 

Secretary of Labor or the State in which 

the coal mine is located. Following 

explosions at the Sago and Darby mines 

in 2006, MSHA inspected seals in 

underground coal mines across the 

country and concluded that some seals 

were not correctly built. The 

supervision requirement will help 

assure that seal construction and repair 

are performed correctly. 

Under final § 75.337(c)(1), the 

certified person must examine each seal 

site immediately prior to construction or 

repair to assure that the site is in 

accordance with the approved 

ventilation plan. Under final 

§ 75.337(c)(2), the certified person must 

examine each seal under construction or 

repair during each shift to assure that 

the seal is being constructed or repaired 

in accordance with the approved 

ventilation plan. Under final 

§ 75.337(c)(3), the certified person must 

examine each seal upon completion of 

construction or repair to assure that 

construction or repair is in accordance 

with the approved ventilation plan. 

Some commenters objected to these 

provisions stating that it was 

unnecessary and burdensome for the 

certified person to supervise the entire 

construction process. They stated that 

trained qualified persons should be 

permitted to repair or construct seals in 

accordance with the approved plan and 

that the certified person can then 

conduct an examination to assure the 

plan was followed. Other commenters, 

however, supported a requirement for a 

certified person to be on site during 

each step of seal construction. 

MSHA believes that a certified person 

needs to be in the vicinity of the seal 

site to address problems and questions 

during seal construction or repair. 

Under the final rule, MSHA does not 

intend that a certified person 

continuously observe construction or 

repair of all seals in a set. The certified 

person should be available at each seal 

site during the shift to assure proper 

construction or repair. 

Some commenters expressed concern 

regarding potential conflicts created by 

requiring that certain tasks be 

performed, under the ETS, by both 

professional engineers and certified 

persons. Based on MSHA’s experience 

under the ETS, the Agency has not 

encountered any potential conflicts and 

does not believe any are likely to arise. 

The role of the professional engineer to 

have oversight of seal installation is 

more fully discussed in § 75.335(c). 

Final § 75.337(c)(4), like the ETS, 

requires that the certified person certify 

by initials, date, and time that the 

examinations were made. MSHA did 

not receive any comments on this 

provision. 

Final § 75.337(c)(5), like the ETS, 

requires that the certified person make 

a record of the examination at the 

completion of any shift during which an 

examination was conducted, and 

include each deficiency and the 

corrective action taken. The record must 

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, and the record must be 

kept at the mine for one year. This 

recordkeeping requirement allows 

MSHA and other persons to determine 

that examinations have been conducted, 

that results are valid, and that 

deficiencies in site preparation, 

construction and repairs were found 

and corrected. In addition, the record 

must identify seal completion dates. 

One commenter stated that 

countersigning simply identifies the 

person to blame in the event of an 

accident or seal failure. Another 

commenter stated that countersigning 

was unnecessary. Historically, the 

countersigning requirement has been an 

integral part of MSHA’s enforcement of 

coal mining standards. It is consistent 

with other recordkeeping requirements 

in 30 CFR part 75; such as §§ 75.360 

(pre-shift examination) and 75.361 

(supplemental examination), 75.362 (onshift examination), 75.363 (hazardous 

conditions), and 75.364 (weekly 

examination). The countersignature 

must be made by the end of the mine 

foreman’s or equivalent mine official’s 

next regularly scheduled working shift. 

If the mine foreman or equivalent mine 

official is absent, the person acting in 

that position would review and 

countersign the record. Based on 

MSHA’s experience under the ETS, this 

provision assures that a mine foreman 

or equivalent mine official is 

responsible for seal installation. 

4. Section 75.337(d) 

Final § 75.337(d) renumbers 

§ 75.337(c) of the ETS, and 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. It also 

requires the mine operator to retain the 

certification for as long as the seal is 

needed to serve the purpose for which 

it was built. 

Some commenters stated that this 

certification was unnecessarily 

duplicative of the certification required 

by the certified person during 

construction and repair and the 

certification required by the 

professional engineer during the plan 

approval process. Some commenters 

stated that the certification requirement 

by a senior mine official is unreasonable 

and redundant because the official may 

not have expertise to make certification; 

the official may not have knowledge 

unless present during construction; a 

professional engineer is required to have 

‘‘oversight’’; the certified person directly 

supervises construction and makes a 

record of the exam; and the mine 

foreman countersigns the certified 

person’s record. Other commenters 

suggested modification of the ETS 

requirement to either allow a senior 

mine official to rely on reports from the 

professional engineer and certified 

person, or to allow a senior mine 

management official to countersign the 

official seal record book. 

Based on MSHA’s experience 

regarding methane explosions in sealed 

areas and MSHA’s experience regarding 

the same certification requirements 

under the ETS, the Agency believes that 

some amount of redundancy is 

necessary in the review of these critical 

seal construction tasks; this provides an 

added margin of safety for miners. 

Certifications by certified persons, and 

senior mine management officials 

protect miners by helping assure that 

the seal is correctly designed and 

constructed. 


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5. Section 75.337(e) 

Final § 75.337(e) renumbers 

§ 75.337(d) of the ETS, and remains 

essentially unchanged. Final 

§ 75.337(e)(1) requires the mine operator 

to notify the District Manager between 

two and fourteen days prior to 

commencement of seal construction. 

This final rule revises the ETS 

requirement to notify the MSHA local 

field office. 

One commenter supported the 

notification requirement stating that it is 

necessary so that MSHA can oversee 

seal construction. This commenter 

recommended that an MSHA inspector 

be present at least part of the time 

during seal construction. 

One commenter opposed the 

notification requirement. This 

commenter stated that it is inefficient to 

require contacting MSHA since an 

MSHA inspector is at the mine over 150 

days during the year. In the final rule, 

MSHA has retained the notification 

requirement because the Agency 

believes that it is necessary and it is also 

responsive to comments. 

This requirement gives MSHA the 

opportunity to observe seal construction 

and to help assure that the construction, 

installation and materials were in 

accordance with the ventilation plan 

approved by MSHA. The requirement to 

notify the District Manager establishes 

consistency with other MSHA 

notification requirements. Like other 

notification provisions, the District 

Manager either contacts the appropriate 

field office or inspectors from the 

District Office may make the inspection. 

Final § 75.337(e)(2), like the ETS, 

requires the mine operator to notify the 

MSHA District Manager, in writing, 

within five days of completion of each 

set of seals and provide a copy of the 

certification required in § 75.337(d) of 

this section. The purpose of this 

provision is to give the District Manager 

notice of completed seal construction. 

The period immediately following 

construction of the seal is the time 

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. During this critical 

time period, the District Manager may 

decide to inspect the seals or sample the 

sealed area. 

Final § 75.337(e)(3), like the ETS, 

requires the mine operator to submit a 

copy of quality control test results for 

seal material properties specified in 

§ 75.335 to the District Manager. To 

clarify the performance required, the 

final rule includes a requirement that 

the test results be submitted within 30 

days of completion of the tests. The 

final rule, like the ETS, requires that test 

results include all tests of seal 

construction materials. Some 

commenters expressed concern over a 

specified time requirement for the 

submission of quality control tests 

results because some results are often 

not available for weeks after the tests are 

completed. Sampling must be continued 

on a 24-hour basis for all seals until 

MSHA receives the test results and 

determines that they are adequate. 

Based on MSHA’s experience under the 

ETS, MSHA believes that a 30-day 

period will provide sufficient time to 

obtain results and assures that test 

results are submitted promptly. MSHA 

has not experienced any problems with 

this timeframe under the ETS. 

6. Section 75.337(f) 

Final § 75.337(f) renumbers 

§ 75.335(c) of the ETS, and like the ETS, 

prohibits welding, cutting, and 

soldering with an arc or flame within 

150 feet of a seal. This final rule revises 

the ETS by allowing this work within 

150 feet of a seal unless it is not safe to 

do so. The operator may request that the 

District Manager approve a different 

location in the ventilation plan. The 

purpose of this provision is to protect 

miners from the hazards of open flames 

near seals. A methane enriched 

atmosphere can leak through the seal, 

accumulate out by the seal, and if 

ignited, the flame can propagate into the 

sealed area causing an explosion. 

The 150-foot limit in the final rule is 

consistent with an existing MSHA 

requirement in § 75.1002(a) that nonpermissible equipment be excluded 

within 150 feet of pillar workings or 

longwall faces. To measure the 150 feet, 

MSHA recommends that mine operators 

use the longstanding industry practice 

of following the shortest distance that 

air can travel (tight string distance) 

through crosscuts, entries or other 

openings (MSHA Program Policy 

Manual, Volume V, Subpart J (February 

2003)). 

In response to MSHA’s request for 

comments, some commenters supported 

and others opposed the provision. 

Commenters who supported the 

provision stated that the protection was 

necessary to prevent another explosion 

like the one that occurred at the Darby 

Mine. Commenters who opposed the 

provision stated that it was too 

restrictive and unenforceable under 

current mining conditions. Some of 

these commenters stated that the 

provision could significantly interrupt 

mining operations where the next entry 

from the seal contains a pre-existing 

belt, belt-drive, shop area, travelway, or 

track. In addition, some commenters 

requested that MSHA consider that 

some belt drives in underground coal 

mines have separate splits of large 

quantities of air, and that compliance 

flexibility should be included in the 

final rule to accommodate different 

mining conditions. 

In response to comments and based 

on MSHA’s experience under the ETS, 

MSHA has revised the ETS. An operator 

may request that the District Manager 

approve in the ventilation plan welding, 

cutting, and soldering with an arc or 

flame within 150 feet of a seal. The 

operator’s request must address 

methods the mine operator will use to 

continuously monitor atmospheric 

conditions in the sealed area during 

welding or burning; the airflow 

conditions in and around the work area; 

the rock dust and water application 

methods; the availability of fire 

extinguishers on hand; the procedures 

to maintain safe conditions, and other 

relevant factors. MSHA believes that 

welding, cutting and soldering with an 

arc or flame near a sealed area may be 

allowed depending upon mining 

conditions at the mine, and that 

determination should be made by the 

District Manager on a case-by-case basis. 

7. Section 75.337(g) 

Final § 75.337(g) renumbers and 

revises § 75.335(d) of the ETS. Final 

§ 75.337(g)(1) requires one non-metallic 

sampling pipe in each seal that extends 

into the center of the first connecting 

crosscut inby the seal. The final rule 

requires that if an open crosscut does 

not exist, the sampling pipe shall extend 

into the center of the length of the open 

entry inby the seal. The requirement 

that only non-metallic materials be used 

for sampling pipes is consistent with 

other provisions of this final rule that 

require the removal of metallic objects 

through or across seals. 

MSHA received many comments 

regarding the ETS requirements on the 

locations and number of sampling 

pipes. Many commenters questioned the 

requirement of two sampling pipes in 

each seal. They stated that it is doubtful 

that two sampling pipes in each seal 

will provide much additional 

information and they could result in 

conflicting and confusing information. 

In addition, several commenters 

disagreed with the need for a sampling 

pipe in each seal. Some commenters 

questioned whether a representative 

sample could be obtained by using a 

sampling pipe through a seal. Several 

commenters suggested putting a 

sampling pipe at the high and low 

points of the seals. One commenter 

stated that the location and number of 


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sampling pipes should be based on the 

mining conditions. 

MSHA reviewed sampling data 

collected under the ETS 14-day baseline 

requirement and other sampling data, 

including that associated with the 

Agency’s citations and withdrawal 

orders. Based on this review, MSHA 

believes that one sampling pipe 

provides adequate information and that 

two sampling pipes in each seal are not 

necessary and could result in conflicting 

and confusing information. In addition, 

the Agency’s evaluation of its sampling 

data from the 15-foot pipe found 

significant variation of methane 

concentrations at different seals in the 

set and between sets of seals for the 

same sealed area. MSHA attributes this 

to different ventilation pressures at the 

various seals and differences in leakage 

characteristics through the ribs and 

strata surrounding the seals (cracks, 

joints, etc), depending on the location of 

the seals. MSHA believes that sampling 

points with a longer pipe located 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. 

In addition, this sampling location is 

less susceptible to swings in oxygen 

levels associated with changes in 

barometric pressure. Based on 

comments, data, and Agency 

experience, MSHA has revised the ETS 

to remove the requirement that a 

sampling pipe extend 15 feet into the 

sealed area. 

One commenter stated that gob 

isolation seals are installed in crosscuts 

immediately behind the longwall face 

and, therefore, it would be impossible to 

meet the requirements to extend one 

tube into the center of the first 

connecting crosscut inby the seal as that 

intersection will no longer exist once 

the longwall mines pass the crosscut 

where the seal is to be installed. In 

addition, this commenter stated that 

installing sampling pipes near the 

intersection is not practical as crosscut 

conditions often quickly deteriorate on 

the gob side of the seal. Under 

circumstances where gob isolation seals 

will have no connecting crosscut inby 

the seal, or under similar circumstances, 

the sampling pipe must be extended to 

the center of the expected open space to 

obtain a sample that is representative of 

the gas in the sealed area. In addition, 

under circumstances where crosscut 

conditions may deteriorate, sampling 

pipes should be located so that they are 

subjected to the least amount of 

deterioration. Even if some pipes 

deteriorate, it is unlikely that all pipes 

will deteriorate at every sampling 

location. In addition, under this final 

rule, the District Manager may require 

additional sampling locations in the 

ventilation plan under § 75.336. 

Final § 75.337(g)(2) retains the ETS 

requirement that each sampling pipe be 

equipped with a shut-off valve and 

appropriate fittings for taking gas 

samples. MSHA received no comments 

on this provision. 

Final § 75.337(g)(3) is new. It requires 

the sampling pipes to be labeled to 

indicate the location of the sampling 

points when more than one sampling 

pipe is required under § 75.337(g)(4). 

Final § 75.337(g)(4) is derived from 

and is consistent with existing MSHA 

enforcement policy under the ETS. If a 

new seal is constructed to replace or 

reinforce an existing seal with a 

sampling pipe, final § 75.337(g)(4) 

requires the sampling pipe in the 

existing seal to be extended through the 

new seal. It also requires that an 

additional sampling pipe be installed 

through each new seal to sample the 

area between seals, as specified in the 

approved ventilation plan. Final 

§ 75.337(g)(4) is consistent with existing 

MSHA policy that addresses 

requirements for placement of the 

sampling pipe when a new seal is 

constructed outby an existing seal to 

replace or reinforce an existing seal. 

Final § 75.337(g)(4) was added to 

clarify requirements gained as a result of 

MSHA’s experience under the ETS 

concerning construction of new seals 

immediately outby existing seals that 

had been either damaged, or had had 

significant structural defects. In 

addition, some operators of mines with 

potentially explosive atmospheres 

decided to construct new 120-psi seals 

outby existing seals under the ETS. 

Under these circumstances, MSHA 

found that if a new seal is constructed 

as an extension or reinforcement of an 

existing seal, there may be no additional 

sealed area to sample. In addition, most 

existing seals have only one sampling 

pipe per set of seals and some sets of 

seals that predate MSHA’s 1992 

ventilation standards may have no 

sampling pipes. 

If the new seals are close to the 

existing seals, an explosion in the area 

inby the old seals could damage the new 

seals. By maintaining the area inert 

between the new seals and the old seals, 

the possibility of an explosion between 

the seals effectively is eliminated. 

MSHA considered requiring the mine 

operator to drill holes through existing 

seals to install sampling pipes. MSHA 

rejected this approach due to the 

possibility of sparking or frictional 

ignition associated with drilling. 

The final rule requires that sampling 

pipes in existing seals be extended 

through the new seals to permit the 

sampling of the atmosphere inby the 

existing seals. If there is a space 

between the new seals and the existing 

seals, this area will need to be sampled 

and maintained inert and will require a 

sample pipe through each new seal. If 

the space between the seals does not 

include a connecting crosscut, the new 

sampling pipe must be extended to the 

center of the open space. 

8. Section 75.337(h) 

Final § 75.337(h) renumbers and 

revises § 75.335(e) of the ETS. It requires 

that for each set of seals, the seal at the 

lowest elevation shall have a corrosion 

resistant, non-metallic water drainage 

system. In addition, seals must not 

impound water or slurry, and water or 

slurry cannot be allowed to accumulate 

within the sealed area to any depth that 

can adversely affect a seal. 

This final rule revises the ETS 

requirement by allowing only nonmetallic materials to be used for a 

drainage system. This requirement is 

consistent with other provisions of this 

final rule regarding the removal of 

metallic objects through or across seals. 

MSHA experience shows that 

alternatives to metallic materials are 

readily available for use in drainage 

systems. 

In response to MSHA’s request, 

several commenters stated that the ETS 

requirement that a seal not impound 

water is vague, that it is impossible to 

guarantee that there will be no water at 

a seal, and that there will always be 

some minimal amount of standing water 

in some mines. Seals should not be 

designed to impound water other than 

to a minimal depth, such as the height 

of the water trap. Based on MSHA’s 

experience, drainage systems can be 

designed to prevent the accumulation 

and impoundment of mine water inby 

the seals. The actual size and number of 

pipes used in a drainage system should 

be based on the anticipated maximum 

flow rate at the seal location. In addition 

to being corrosion resistant and made of 

non-metallic material, drainage pipes 

must have strength properties consistent 

with the design strength of the seal, and 

the drainage system must have blast 

resistance equivalent to that of the seal. 

If the seal design does not allow any 

impoundment of water, the drainage 

system design could incorporate a water 

diversion or pumping system. For 

example, a low weir or catchment could 

be constructed across the entry inby the 

seal to trap sediment and debris that 

may impede drainage and prevent water 

from adversely affecting the seal. These 

provisions addressing water drainage 

systems and impoundment of water or 


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slurry accommodate varied mining 

conditions and assure safe and effective 

workplaces for miners. 

D. Section 75.338 Training 

Final § 75.338 addresses training for 

sampling and seal construction. This 

final rule consolidates the training 

requirements of ETS §§ 75.335(b)(2) and 

75.337(e) into this new section. The 

final rule changes the retention period 

for training certifications from one year 

to two years from the date of training. 

This change is made to be consistent 

with existing MSHA training standards 

at part 48. It provides that mine 

operators maintain training records 

under the final rule for the same period 

as existing training records. Consistent 

with the burden cost in MSHA’s 

information collection package for part 

48, under OMB Control Number 1219–

0009, the Agency determined that 

increasing the retention period from one 

year to two would not affect operator 

costs. 

1. Section 75.338(a) 

Final § 75.338(a), like the ETS, 

requires that certified persons 

conducting sampling be trained in the 

use of appropriate sampling equipment, 

procedures, location of sampling points, 

frequency of sampling, size and 

condition of the sealed area, and the use 

of continuous monitoring systems, if 

applicable, before they conduct 

sampling, and annually thereafter. The 

final rule also requires the mine 

operator to certify the date of training 

and retain each certification for two 

years, instead of one year under the 

ETS. This provision is similar to other 

certification requirements in 30 CFR 

part 75. 

2. Section 75.338(b) 

Final § 75.338(b), like the ETS, 

requires the mine operator to provide 

training to miners constructing or 

repairing seals, designated certified 

persons, and designated senior mine 

management officials. This training 

must be conducted prior to constructing 

or repairing a seal and annually 

thereafter. The final rule also requires 

the mine operator to certify the date of 

training provided each miner, certified 

person, and senior mine management 

official, and retain each certification for 

two years. 

One commenter stated that the record 

showing certification of training for 

miners doing the construction of seals is 

required to be kept for only one year. If 

there is a seal failure outside of that 

time period, those records are no longer 

available during the investigation 

process. The commenter recommended 

that the certification be kept for as long 

as the seal is satisfying the purpose for 

which it was built. 

This final rule revises the ETS by 

requiring operators to retain training 

certifications for two years from the date 

of training. This change is consistent 

with existing § 48.9 (records of training) 

which requires training certificates be 

kept at the mine site for two years. 

Training certifications need not be kept 

longer than two years because the final 

rule requires annual training for miners 

constructing or repairing seals. Annual 

training assures that miners are capable 

of repairing seals when necessary and 

therefore, the training certification 

would be up-to-date. 

Several commenters requested 

clarification as to whether the training 

provisions are included in part 48 

training. Training required by the final 

rule should not be included in part 48 

training, although the mine operator 

may choose to conduct the training at 

the same time. However, even though 

the ventilation plan review is required 

as part of the eight-hour annual 

refresher training, additional time must 

be allotted since the training is required 

by this section, not part 48. 

The final rule does not require a 

minimum amount of time for training. 

MSHA expects mine operators to 

determine the time necessary for this 

training based on the complexity of the 

seal design in the ventilation plan, 

construction or repair procedures, 

materials used, and knowledge and skill 

levels of persons receiving training. In 

addition, changes in the approved seal 

design or approved ventilation plan will 

necessitate that persons be retrained. 

E. Section 75.339 Seals records 

Final § 75.339, like ETS § 75.338, 

addresses seals records. 

1. Section 75.339(a) 

Final § 75.339(a) lists the records a 

mine operator is required to maintain 

and the retention time for those records. 

2. Section 75.339(b) 

Final § 75.339(b), like the ETS, 

requires that records be retained at a 

surface location at the mine in a secure 

book that is not susceptible to alteration. 

The final rule allows records to be 

retained electronically in a computer 

system that is secure and not 

susceptible to alteration, if the mine 

operator can immediately access the 

record from the mine site. 

One commenter stated that after seal 

construction is completed and quality 

control test results have been provided 

to MSHA, the operator should be 

permitted to retain seal construction 

certification records at a central 

location. Because electronic storage of 

records is a practical and reliable 

method of records storage, the final rule 

allows records to be stored 

electronically, provided that the records 

are secure and not susceptible to 

alteration. 

3. Section 75.339(c) 

Final § 75.339(c) of the final rule 

remains unchanged from the ETS. It 

requires that, upon request from an 

authorized representative of the 

Secretary of Labor or 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. 

4. Section 75.339(d) 

Final § 75.339(d), like the ETS, 

requires that 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. In addition, in response to 

comments, this final rule revises the 

ETS to require an operator who transfers 

control of the mine to another entity to 

transfer all records to that successor 

entity. Having access to records will 

allow MSHA and the new mine operator 

to determine if seals were designed, 

constructed, and repaired as approved 

and maintained to assure their 

reliability. 

F. Section 75.371 Conforming Changes 

to Other Sections of Part 75 

Final § 75.371(ff) requires the mine 

operator to provide in the ventilation 

plan the information provided in the 

sampling requirements in § 75.336 and 

the seal installation requirements in 

§ 75.335. The sampling requirements in 

ETS § 75.335(b) are revised and moved 

to final § 75.336. The installation 

requirements provided by ETS 

§ 75.336(b)(3) are revised and moved to 

final § 75.335. Therefore, this provision 

is revised to conform to the new section 

numbers. 

IV. Executive Order 12866 

Executive Order (E.O.) 12866, as 

amended by E.O.13258 (Amending 

Executive Order 12866 on Regulatory 

Planning and Review), requires that 

regulatory agencies assess both the costs 

and benefits of regulations. To comply 

with E.O.12866, MSHA has prepared a 

Regulatory Economic Analysis (REA) for 

the final rule. The REA contains 

supporting data and explanation for the 

summary materials presented in this 


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preamble, including the covered mining 

industry, costs and benefits, feasibility, 

small business impacts, 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 

at the address in the ADDRESSES section 

of this preamble. 

Executive Order 12866 requires that 

regulatory agencies assess both the costs 

and benefits of significant regulatory 

actions. Under the Executive Order, a 

‘‘significant regulatory action’’ is one 

meeting any of a number of specified 

conditions, including the following: 

Having an annual effect on the economy 

of $100 million or more, creating a 

serious inconsistency or interfering with 

an action of another, materially altering 

the budgetary impact of entitlements or 

the rights of entitlement recipients, or 

raising novel legal or policy issues. 

Based on the REA, MSHA has 

determined that the final rule does not 

have an annual effect of $100 million or 

more on the economy. Therefore, it is 

not an economically ‘‘significant 

regulatory action’’ under section 3(f) of 

E.O. 12866. MSHA, however, has 

determined that the final rule is a 

‘‘significant action’’ under Executive 

Order 12866 because it raises novel 

legal or policy issues. 

A. Mine Sector Affected 

The final rule applies to all 

underground coal mines in the United 

States. Based on MSHA data as of 

February 5, 2008, there were 624 

underground coal mines, employing 

42,207 miners, operating in the U.S. in 

2007. Based on an MSHA survey 

conducted in November 2006, 372 

underground coal mines have seals. In 

2007, these mines employed 32,412 

miners, of which 28,009 worked 

underground. 

B. Benefits 

To provide a quantitative estimate of 

the benefits of this final rule, MSHA 

analyzed the explosions in sealed areas 

that have taken place since 1993 

including the two accidents in 2006 

where the seals failed and fatalities 

occurred. At the Sago Mine, 12 miners 

died, and at the Darby Mine, 5 miners 

died. If this final rule had been in effect, 

these lives might not have been lost. 

For purposes of estimating benefits for 

this final rule, MSHA attributes the 

potential saving of the 5 miners’ lives 

from the Darby Mine accident to this 

final rule. MSHA also attributes the 

potential saving of half of the miners’

lives from the Sago Mine accident. 

(MSHA attributes the remaining miners’

lives from the Sago Mine accident to 

MSHA’s 2006 emergency mine 

evacuation rule.) The total potential 

saving is 11 lives attributed to this final 

rule. 

One commenter stated that under the 

ETS, MSHA should not have included 

as a benefit potential lives saved from 

the Sago and Darby Mine accidents. 

This commenter stated that the design 

of the seals used at both the Sago and 

Darby Mines was not established as the 

cause of the deaths, that MSHA’s 

accident reports focus on construction 

deficiencies of seals at both mines, and 

that the Darby Mine explosion resulted 

from miners attempting to cut a metal 

strap on the inby and outby side of a 

previously constructed seal. Based on 

MSHA’s experience under the ETS, 

MSHA believes that the lives lost at the 

Sago and Darby Mine accidents might 

have been saved had this final rule been 

in effect. This final rule, like the ETS, 

addresses the design, construction, and 

maintenance of seals, and training of 

persons involved in seal construction 

and repair. The final rule requires 

insulated cables be removed from the 

area to be sealed, unless it is not safe to 

do so. In addition, this final rule does 

not permit welding, cutting, and 

soldering with an arc or flame within 

150 feet of a seal unless such work is 

approved by the District Manager in the 

ventilation plan. 

MSHA has data on explosions that 

occurred in sealed areas. From 1993 

through 2006, there were 13 explosions 

in sealed areas. Of the 13 explosions, 11 

caused seal damage and had the 

potential to cause fatalities or injuries, 

and two caused fatalities or injuries. If 

the explosions followed approximately 

the same distribution as they did since 

1993, MSHA estimates that this final 

rule would save approximately one life 

per year. 

Based on the Agency’s knowledge and 

experience, MSHA determined that the 

risk from explosions in sealed areas was 

increasing from 1993 through 2006 

because the number of seals being 

installed was increasing during that 

period. After adjusting this estimate to 

account for the increased risk during the 

period, this final rule will save 

approximately 2 lives per year. The 

estimate that the final rule will save 

approximately 2 lives per year is based 

on an increased risk of an explosion 

during 1993–2006 because the number 

of seals in mines increased and the 

number of mines with seals increased. 

This is MSHA’s best estimate of the 

number of lives saved per year due to 

the final rule. 

MSHA also developed a higher risk 

estimate based on the distribution of 

miners at risk and the characteristics of 

the explosions. If an explosion with the 

characteristics of the explosions at Sago 

or Darby Mines were to occur at a large 

mine, many lives potentially could be 

lost. Assuming that the risk of fatality 

from an explosion in a sealed area does 

not vary with the size of the mine, and 

that the number of potential fatalities is 

proportional to the number of miners 

working underground, MSHA estimates 

that approximately 6 lives will be saved 

per year under this final rule. 

MSHA also calculated the cumulative 

risk over a 45-year working life of a 

miner. If, under MSHA’s best estimate, 

this final rule saves approximately 2 

lives per year, the risk of fatality from 

an explosion in a sealed area is 

approximately 3 per 1,000 miners over 

a 45-year working lifetime. If the final 

rule saves 6 lives per year under 

MSHA’s higher estimate, the reduction 

in the lifetime risk of a fatality from an 

explosion in a sealed area is 

approximately 9 per 1,000 miners over 

a 45-year working lifetime. 

Under this final rule, an explosion is 

less likely to occur where the 

atmosphere behind seals is monitored 

and maintained inert. This final rule 

also requires stronger seals to better 

withstand explosions. The stronger seals 

will reduce miner injuries and fatalities 

should an explosion occur. 

C. Compliance Costs 

MSHA estimates that the final rule 

will result in total yearly costs for 

underground coal mine operators of 

approximately $45.4 million. Total first 

year costs are estimated to be 

approximately $46.4 million. 

Disaggregated by mine size for mines 

that use seals, yearly costs are $2.8 

million for the 83 mine operators with 

fewer than 20 employees; $37.8 million 

for the 279 mine operators with 20–500 

employees; and $4.8 million for the 10 

mine operators with more than 500 

employees. Most of the compliance 

costs occur in the mine size category 

with 20–500 employees because 75 

percent of the mines that use seals are 

in this category. 

V. Feasibility 

MSHA has concluded that the 

requirements of the final rule are 

technologically and economically 

feasible. For atmospheres behind seals 

where the atmosphere will not inert 

naturally, operators may choose any of 

the following alternatives for inerting 

the atmosphere: (1) Injecting inert gas; 

or (2) pressure balance of the ventilation 

system; or (3) injecting material into the 

strata surrounding the seals to reduce 

leakage. Other mines may choose to 


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construct new seals that are 120 psi or 

greater in front of all existing seals in 

the sealed area. 

A. Technological Feasibility 

MSHA concludes that the final rule is 

technologically feasible. This 

conclusion is based on the requirements 

of the final rule for training, sampling, 

construction and repair. Compliance 

with these requirements is 

technologically feasible because the 

materials, equipment, and methods for 

implementing these requirements 

currently exist. In addition, this 

feasibility determination is supported 

by MSHA’s approval of several seal 

designs at overpressures of 50 psi and 

120 psi. 

B. Economic Feasibility 

The yearly compliance cost of the 

final rule is $45.4 million, which is 0.3 

percent of all revenue for all 

underground coal mines. MSHA 

concludes that the final rule is 

economically feasible because the total 

yearly compliance cost is well below 

one percent of the estimated annual 

revenue for all underground coal mines. 

VI. Regulatory Flexibility Act and 

Small Business Regulatory Enforcement 

Fairness Act 

Pursuant to the Regulatory Flexibility 

Act (RFA) of 1980, as amended by the 

Small Business Regulatory Enforcement 

Fairness Act (SBREFA), MSHA analyzed 

the impact of the final rule on small 

businesses. Based on that analysis, 

MSHA notified the Chief Counsel for 

Advocacy, Small Business 

Administration, and certified under the 

Regulatory Flexibility Act at 5 U.S.C. 

605(b) that the final rule does not have 

a significant economic impact on a 

substantial number of small entities. 

The factual basis for this certification is 

in Chapter V of the REA, and is 

summarized below. 

A. Definition of a Small Mine 

Under the RFA, in analyzing the 

impact of the final rule on small 

entities, MSHA must either 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 

uses the SBA definition. The SBA 

defines a small entity in the mining 

industry as an establishment with 500 

or fewer employees. MSHA concludes 

that it can certify that the final rule does 

not have a significant economic impact 

on a substantial number of small 

entities, those mines with 500 or fewer 

employees. 

B. Factual Basis for Certification 

MSHA initially evaluates the impacts 

on ‘‘small entities’’ by comparing the 

estimated compliance cost of a rule for 

small entities in the sector affected by 

the rule to the estimated revenue for the 

affected sector. When the estimated 

compliance cost is less than one percent 

of the estimated revenue, the Agency 

concludes that the rule does not have a 

significant economic impact on a 

substantial number of small entities. 

When the estimated compliance costs 

exceeds one percent of revenue, MSHA 

determines whether a further analysis is 

required. 

For underground coal mines, the 

estimated 2007 production was 

277,830,429 tons for mines that had 500 

or fewer employees. Using a 2007 price 

of underground coal of $40.37 per ton 

and total 2007 underground coal 

production in tons, underground coal 

revenue is estimated to be 

approximately $11.2 billion for mines 

employing 500 or fewer employees. 

Thus, the yearly cost of the final rule for 

mines that have 500 or fewer employees 

is 0.36 percent of annual revenue. Using 

SBA’s definition of a small mine (one 

having 500 or fewer employees), the 

yearly cost for underground coal mines 

to comply with the final rule is less than 

1 percent of estimated annual revenue. 

Accordingly, MSHA has certified that 

the final rule does not have a significant 

impact on a substantial number of small 

entities. 

VII. Paperwork Reduction Act of 1995 

A. Summary 

The information collection 

requirements contained in the final rule 

are listed by the Office of Management 

and Budget (OMB) under control 

numbers 1219–0142 and 1219–0088. 

The final rule contains information 

collection requirements that MSHA 

estimates will result in 33,560 burden 

hours and approximately $2.36 million 

related burden costs to mine operators 

and seal manufacturers. This final rule 

contains information collection 

requirements in the following sections: 

§ 75.335 seal requirements, strengths, 

design applications, and installation; 

§ 75.336 sampling and monitoring 

requirements; § 75.337 construction and 

repair of seals; and § 75.338 training. 

A detailed explanation of the burden 

hours and related costs are in the 

Paperwork Reduction Act section of the 

Regulatory Economic Analysis (REA) for 

the final rule. 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 MSHA’s Office of Standards, 

Regulations, and Variances. 

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 e-mail 

request to king.darrin@dol.gov or by 

phone request at (202) 693–4129. 

The information collection package 

for the ETS, which also served as the 

proposal for this final rule, was 

approved by OMB under control 

numbers 1219–0142, for Sealing of 

Abandoned Areas; and 1219–0088, for 

Ventilation Plans, Tests, and 

Examinations in Underground Coal 

Mines. MSHA estimated that the 

information collection requirements in 

the ETS would result in 82,037 annual 

burden hours and approximately $4.7 

million in related annual burden costs. 

MSHA has reduced these estimates in 

the final rule to 33,553 annual burden 

hours and approximately $2.36 million 

related annual burden costs. MSHA’s 

estimated reduction in burden hours is 

due to: (1) The removal of 

approximately 41,600 hours of sampling 

time that was inadvertently included 

with recordkeeping time and counted as 

paperwork; (2) the removal of 

approximately 900 hours of time to 

prepare for training that was 

inadvertently included as paperwork; 

(3) the removal of approximately 3,000 

hours of paperwork associated with the 

deleted requirement for a sampling 

protocol and action plan; and (4) 

approximately 3,000 hours of 

paperwork due to various other changes 

in the final rule. 

Several commenters raised concerns 

regarding the ETS requirement that 

multiple persons must certify that seal 

construction was done correctly. These 

comments are addressed in earlier 

sections of this preamble. 

VIII. Other Regulatory Considerations 

A. The Unfunded Mandates Reform Act 

of 1995 

MSHA has reviewed the final rule 

under the Unfunded Mandates Reform 

Act of 1995 (2 U.S.C. 1501 et seq). 

MSHA has determined that the final 

rule 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 


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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. 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 the final rule has no 

effect on family stability or safety, 

marital commitment, parental rights and 

authority, or income or poverty of 

families and children. Accordingly, 

MSHA certifies that the final rule does 

not impact family well-being. 

C. Executive Order 12630: Government 

Actions and Interference With 

Constitutionally Protected Property 

Rights 

The final rule does not implement a 

policy with takings implications. 

Accordingly, under E.O. 12630, no 

further Agency action or analysis is 

required. 

D. Executive Order 12988: Civil Justice 

Reform 

The final rule 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, the final rule 

meets the applicable standards provided 

in section 3 of E.O. 12988, Civil Justice 

Reform. 

E. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

The final rule has no adverse impact 

on children. Accordingly, under E.O. 

13045, no further Agency action or 

analysis is required. 

F. Executive Order 13132: Federalism 

The final rule does not have 

‘‘federalism implications’’ because it 

does 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. 

G. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

The final rule 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 the final rule 

for its energy effects because the final 

rule applies to the underground mining 

sector. Because this final rule will result 

in yearly costs of approximately $45.4 

million to the underground coal mining 

industry, relative to annual revenues of 

$14.1 billion in 2007, 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. 

I. Executive Order 13272: Proper 

Consideration of Small Entities in 

Agency Rulemaking 

MSHA has thoroughly reviewed the 

final rule to assess and take appropriate 

account of its potential impact on small 

businesses, small governmental 

jurisdictions, and small organizations. 

MSHA has determined and certified that 

the final rule will not have a significant 

economic impact on a substantial 

number of small entities. 

IX. 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. 

Coward, H.F. and G.W. Jones, ‘‘Limits of 

Flammability of Gases and Vapors,’’

Bulletin 503, U.S. Dept. of the Interior, 

Bureau of Mines, 1952. 

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. 

P06–14, ‘‘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 21, 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. 

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

Information Circular–9500, ‘‘Explosion 

Pressure Design Criteria for New Seals in 

U.S. Coal Mines,’’ National Institute of 

Occupational Safety and Health, U.S. Dept. 

of Health and Human Services, July 2007. 


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21206 Federal Register / Vol. 73, No. 76 / Friday, April 18, 2008 / Rules and Regulations 

List of Subjects in 30 CFR Part 75 

Mine safety and health, Reporting and 

recordkeeping requirements, 

Underground coal mines, Ventilation. 

Dated: April 14, 2008. 

Richard E. Stickler, 

Acting 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—MANDATORY SAFETY 

STANDARDS—UNDERGROUND COAL 

MINES 

■ 1. The authority citation for part 75 

continues to read as follows: 

Authority: 30 U.S.C. 811. 

■ 2. Revise § 75.335 to read as follows: 

§ 75.335 Seal strengths, design 

applications, and installation. 

(a) Seal strengths. Seals constructed 

on or after October 20, 2008 shall be 

designed, constructed, and maintained 

to withstand—

(1)(i) At least 50-psi overpressure 

when the atmosphere in the sealed area 

is monitored and maintained inert and 

designed using a pressure-time curve 

with an instantaneous overpressure of at 

least 50 psi. A minimum overpressure of 

at least 50 psi shall be maintained for at 

least four seconds then released 

instantaneously. 

(ii) Seals constructed to separate the 

active longwall panel from the longwall 

panel previously mined shall be 

designed using a pressure-time curve 

with a rate of pressure rise of at least 50 

psi in 0.1 second. A minimum 

overpressure of at least 50 psi shall be 

maintained; or 

(2)(i) Overpressures of at least 120 psi 

if the atmosphere in the sealed area is 

not monitored, is not maintained inert, 

the conditions in paragraphs (a)(3)(i) 

through (iii) of this section are not 

present, and the seal is designed using 

a pressure-time curve with an 

instantaneous overpressure of at least 

120 psi. A minimum overpressure of 

120 psi shall be maintained for at least 

four seconds then released 

instantaneously. 

(ii) Seals constructed to separate the 

active longwall panel from the longwall 

panel previously mined shall be 

designed using a pressure-time curve 

with a rate of pressure rise of 120 psi in 

0.25 second. A minimum overpressure 

of 120 psi shall be maintained; or 

(3) Overpressures greater than 120 psi 

if the atmosphere in the sealed area is 

not monitored and is not maintained 

inert, and 

(i) The atmosphere in the sealed 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 area; 

(ii) Pressure piling could result in 

overpressures greater than 120 psi in the 

area to be sealed; or 

(iii) Other conditions are encountered, 

such as the likelihood of a detonation in 

the area to be sealed. 

(iv) Where the conditions in 

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

section are encountered, the mine 

operator shall revise the ventilation plan 

to address the potential hazards. The 

plan shall include seal strengths 

sufficient to address such conditions. 

(b) Seal design applications. Seal 

design applications from seal 

manufacturers or mine operators shall 

be in accordance with paragraphs (b)(1) 

or (b)(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, methods to reduce air 

leakage, pressure-time curve, fire 

resistance characteristics, flame spread 

index, entry size, engineering design 

and analysis, elasticity of design, 

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 is applicable 

to conditions in an underground coal 

mine; and 

(iii) Include a summary of the 

installation procedures related to seal 

construction; or 

(2) Each application based on fullscale explosion tests or equivalent 

means of physical testing shall address 

the following requirements to ensure 

that a seal can reliably meet the seal 

strength requirements: 

(i) Certification by a professional 

engineer that the testing was done in 

accordance with current, prudent 

engineering practices for construction in 

a coal mine; 

(ii) Technical information related to 

the methods and materials; 

(iii) Supporting 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) A summary of the installation 

procedures related to seal construction. 

(3) MSHA will notify the applicant if 

additional information or testing is 

required. The applicant shall provide 

this information, arrange any additional 

or repeat tests, and provide prior 

notification to MSHA of the location, 

date, and time of such test(s). 

(4) MSHA will notify the applicant, in 

writing, whether the design is approved 

or denied. If the design is denied, 

MSHA will specify, in writing, the 

deficiencies of the application, or 

necessary revisions. 

(5) Once the seal design is approved, 

the approval holder shall promptly 

notify MSHA, in writing, of all 

deficiencies of which they become 

aware. 

(c) Seal installation approval. The 

installation of the approved seal design 

shall be subject to approval in the 

ventilation plan. The mine operator 

shall—

(1) Retain the seal design approval 

and installation 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 this section have been 

addressed and are applicable to 

conditions at the mine. A copy of the 

certification shall be submitted to the 

District Manager with the information 

provided in paragraph (c)(3) of this 

section 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 the following information 

for approval in the ventilation plan—

(i) The MSHA Technical Support 

Approval Number; 

(ii) A summary of the installation 

procedures; 

(iii) The mine map of the area to be 

sealed and proposed seal locations that 

include the deepest points of 

penetration prior to sealing. The mine 

map shall be certified by a professional 

engineer or a professional land 

surveyor. 

(iv) Specific mine site information, 

including—

(A) Type of seal; 

(B) Safety precautions taken prior to 

seal achieving design strength; 

(C) Methods to address site-specific 

conditions that may affect the strength 

and applicability of the seal including 

set-back distances; 

(D) Site preparation; 

(E) Sequence of seal installations; 

(F) Projected date of completion of 

each set of seals; 


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(G) Supplemental roof support inby 

and outby each seal; 

(H) Water flow estimation and 

dimensions of the water drainage 

system through the seals; 

(I) Methods to ventilate the outby face 

of seals once completed; 

(J) Methods and materials used to 

maintain each type of seal; 

(K) Methods to address shafts and 

boreholes in the sealed area; 

(L) Assessment of potential for 

overpressures greater than 120 psi in 

sealed area; 

(M) Additional sampling locations; 

and 

(N) Additional information required 

by the District Manager. 

■ 3. Revise § 75.336 to read as follows: 

§ 75.336 Sampling and monitoring 

requirements. 

(a) A certified person as defined in 

§ 75.100 shall monitor atmospheres of 

sealed areas. Sealed areas shall be 

monitored, whether ingassing or 

outgassing, for methane and oxygen 

concentrations and the direction of 

leakage. 

(1) Each sampling pipe and approved 

sampling location shall be sampled at 

least every 24 hours. 

(i) Atmospheres with seals of 120 psi 

or greater shall be sampled until the 

design strength is reached for every seal 

used to seal the area. 

(ii) Atmospheres with seals less than 

120 psi constructed before October 20, 

2008 shall be monitored for methane 

and oxygen concentrations and 

maintained inert. The operator may 

request that the District Manager 

approve different sampling locations 

and frequencies in the ventilation plan, 

provided at least one sample is taken at 

each set of seals at least every 7 days. 

(iii) Atmospheres with seals less than 

120 psi constructed after October 20, 

2008 shall be monitored for methane 

and oxygen concentrations and 

maintained inert. The operator may 

request that the District Manager 

approve different sampling locations 

and frequencies in the ventilation plan 

after a minimum of 14 days and after the 

seal design strength is reached, 

provided at least one sample is taken at 

each set of seals at least every 7 days. 

(2) The mine operator shall evaluate 

the atmosphere in the sealed area to 

determine whether sampling through 

the sampling pipes in seals and 

approved locations provides appropriate 

sampling locations of the sealed area. 

The mine operator shall make the 

evaluation immediately after the 

minimum 14-day required sampling, if 

the mine ventilation system is 

reconfigured, if changes occur that 

adversely affect the sealed area, or if the 

District Manager requests an evaluation. 

When the results of the evaluations 

indicate the need for additional 

sampling locations, the mine operator 

shall provide the additional locations 

and have them approved in the 

ventilation plan. The District Manager 

may require additional sampling 

locations and frequencies in the 

ventilation plan. 

(3) Mine operators with an approved 

ventilation plan addressing spontaneous 

combustion pursuant to § 75.334(f) shall 

sample the sealed atmosphere in 

accordance with the ventilation plan. 

(4) The District Manager may approve 

in the ventilation plan the use of a 

continuous monitoring system in lieu of 

monitoring provisions in this section. 

(b)(1) Except as provided in 

§ 75.335(d), the atmosphere in the 

sealed area is considered inert when the 

oxygen concentration is less than 10.0 

percent or the methane concentration is 

less than 3.0 percent or greater than 20.0 

percent. 

(2) Immediate action shall be taken by 

the mine operator to restore an inert 

sealed atmosphere behind seals with 

strengths less than 120 psi. Until the 

atmosphere in the sealed area is restored 

to an inert condition, the sealed 

atmosphere shall be monitored at each 

sampling pipe and approved location at 

least once every 24 hours. 

(c) Except as provided in § 75.335(d), 

when a sample is taken from the sealed 

atmosphere with seals of less than 120 

psi and the sample indicates that the 

oxygen concentration is 10 percent or 

greater and methane is between 4.5 

percent and 17 percent, the mine 

operator shall immediately take an 

additional sample and then immediately 

notify the District Manager. When the 

additional sample indicates that the 

oxygen concentration is 10 percent or 

greater and methane is between 4.5 

percent and 17 percent, persons shall be 

withdrawn from the affected area which 

is the entire mine or other affected area 

identified by the operator and approved 

by the District Manager in the 

ventilation plan, except those persons 

referred to in § 104(c) of the Act. The 

operator may identify areas in the 

ventilation plan to be approved by the 

District Manager where persons may be 

exempted from withdrawal. The 

operator’s request shall address the 

location of seals in relation to: Areas 

where persons work and travel in the 

mine; escapeways and potential for 

damage to the escapeways; and 

ventilation systems and controls in 

areas where persons work or travel and 

where ventilation is used for 

escapeways. The operator’s request shall 

also address the gas concentration of 

other sampling locations in the sealed 

area and other required information. 

Before miners reenter the mine, the 

mine operator shall have a ventilation 

plan revision approved by the District 

Manager specifying the actions to be 

taken. 

(d) In sealed areas with a 

demonstrated history of carbon dioxide 

or sealed areas where inert gases have 

been injected, the operator may request 

that the District Manager approve in the 

ventilation plan an alternative method 

to determine if the sealed atmosphere is 

inert and when miners have to be 

withdrawn. The mine operator shall 

address in the ventilation plan the 

specific levels of methane, carbon 

dioxide, nitrogen and oxygen; the 

sampling methods and equipment used; 

and the methods to evaluate these 

concentrations underground at the seal. 

(e) Recordkeeping. (1) The certified 

person shall promptly record each 

sampling result including the location 

of the sampling points, whether 

ingassing or outgassing, 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. 

(2) The mine operator shall retain 

sampling records at the mine for at least 

one year from the date of the sampling. 

■ 4. Revise § 75.337 to read as follows: 

§ 75.337 Construction and repair of seals. 

(a) The mine operator shall maintain 

and repair seals to protect miners from 

hazards of sealed areas. 

(b) Prior to sealing, the mine operator 

shall—

(1) Remove insulated cables, batteries, 

and other potential electric ignition 

sources from the area to be sealed when 

constructing seals, unless it is not safe 

to do so. If ignition sources cannot 

safely be removed, seals must be 

constructed to at least 120 psi; 

(2) Remove metallic objects through 

or across seals; and 

(3) Breach or remove all stoppings in 

the first crosscut inby the seals 

immediately prior to sealing the area. 

(c) 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 


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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. 

(d) 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. 

(e) The mine operator shall—

(1) Notify the District Manager 

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 provide a copy of 

the certification required in paragraph 

(d) of this section; and 

(3) Submit a copy of quality control 

results to the District Manager for seal 

material properties specified by § 75.335 

within 30 days of completion of quality 

control tests. 

(f) Welding, cutting, and soldering. 

Welding, cutting, and soldering with an 

arc or flame are prohibited within 150 

feet of a seal. An operator may request 

a different location in the ventilation 

plan to be approved by the District 

Manager. The operator’s request must 

address methods the mine operator will 

use to continuously monitor 

atmospheric conditions in the sealed 

area during welding or burning; the 

airflow conditions in and around the 

work area; the rock dust and water 

application methods; the availability of 

fire extinguishers on hand; the 

procedures to maintain safe conditions, 

and other relevant factors. 

(g) Sampling pipes. (1) For seals 

constructed after April 18, 2008, one 

non-metallic sampling pipe shall be 

installed in each seal that shall extend 

into the center of the first connecting 

crosscut inby the seal. If an open 

crosscut does not exist, the sampling 

pipe shall extend one-half of the 

distance of the open entry inby the seal. 

(2) Each sampling pipe shall be 

equipped with a shut-off valve and 

appropriate fittings for taking gas 

samples. 

(3) The sampling pipes shall be 

labeled to indicate the location of the 

sampling point when more than one 

sampling pipe is installed through a 

seal. 

(4) If a new seal is constructed to 

replace or reinforce an existing seal with 

a sampling pipe, the sampling pipe in 

the existing seal shall extend through 

the new seal. An additional sampling 

pipe shall be installed through each new 

seal to sample the area between seals, as 

specified in the approved ventilation 

plan. 

(h) Water drainage system. For each 

set of seals constructed after April 18, 

2008, the seal at the lowest elevation 

shall have a corrosion-resistant, nonmetallic water drainage system. Seals 

shall not impound water or slurry. 

Water or slurry shall not accumulate 

within the sealed area to any depth that 

can adversely affect a seal. 

■ 5. Revise § 75.338 to read as follows: 

§ 75.338 Training. 

(a) Certified persons conducting 

sampling shall be trained in the use of 

appropriate sampling equipment, 

procedures, location of sampling points, 

frequency of sampling, size and 

condition of the sealed area, and the use 

of continuous monitoring systems if 

applicable before they conduct 

sampling, and annually thereafter. The 

mine operator shall certify the date of 

training provided to certified persons 

and retain each certification for two 

years. 

(b) Miners constructing or repairing 

seals, designated certified persons, and 

senior mine management officials shall 

be trained prior to constructing or 

repairing a seal and annually thereafter. 

The training shall address materials and 

procedures in the approved seal design 

and ventilation plan. The mine operator 

shall certify the date of training 

provided each miner, certified person, 

and senior mine management official 

and retain each certification for two 

years. 

■ 6. Add § 75.339 to read as follows: 

§ 75.339 Seals records. 

(a) The table entitled ‘‘Seal 

Recordkeeping Requirements’’ lists 

records the operator shall maintain and 

the retention period for each record. 

TABLE—§ 75.339(a) SEAL RECORDKEEPING REQUIREMENTS

Record Section reference Retention time 

(1) Approved seal design ................................................. 75.335(c)(1) ........................ As long as the seal is needed to serve the purpose for 

which it is built. 

(2) Certification of Provisions of Approved Seal Design 

is Addressed.

75.335(c)(2) ........................ As long as the seal is needed to serve the purpose for 

which it is built. 

(3) Gas sampling records ................................................. 75.336(e)(2) ........................ 1 year. 

(4) Record of examinations .............................................. 75.337(c)(5) ........................ 1 year. 

(5) Certification of seal construction, installation, and 

materials.

75.337(d) ............................ As long as the seal is needed to serve the purpose for 

which it is built. 

(6) Certification of Training for Persons that Sample ....... 75.338(a) ............................ 2 years. 

(7) Certification of Training for Persons that Perform 

Seal Construction and Repair.

75.338(b) ............................ 2 years. 

(b) Records required by §§ 75.335, 

75.336, 75.337 and 75.338 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 alteration, 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 

shall promptly provide access to any 

record listed in the table in this section. 


pwalker on PROD1PC71 with RULES_2
Federal Register / Vol. 73, No. 76 / Friday, April 18, 2008 / Rules and Regulations 21209 

(d) Whenever an operator ceases to do 

business or transfers control of the mine 

to another entity, that operator shall 

transfer all records required to be 

maintained by this part, or a copy 

thereof, to any successor operator who 

shall maintain them for the required 

period. 

■ 7. Amend § 75.371 by revising 

paragraph (ff) to read as follows: 

§ 75.371 Mine ventilation plan; contents. 

* * * * * 

(ff) Seal installation requirements 

provided by § 75.335 and the sampling 

provisions provided by § 75.336. 

* * * * * 

[FR Doc. 08–1152 Filed 4–16–08; 2:14 pm] 

BILLING CODE 4510–43–P 


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