Sealing of Abandoned Areas, 21182-21209 [08-1152]

Agencies

• DEPARTMENT OF LABOR
• Mine Safety and Health Administration

[Federal Register Volume 73, Number 76 (Friday, April 18, 2008)]
[Rules and Regulations]
[Pages 21182-21209]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 08-1152]



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Part III





Department of Labor





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Mine Safety and Health Administration



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30 CFR Part 75



Sealing of Abandoned Areas; Final Rule

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

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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.

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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 Sec.  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 methane-air 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 in-mine 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 Sec.  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 Sec.  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 Sec.  
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 Sec.  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 Sec.  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 Sec.  75.335(a)(3)(i) through (iii) of this section 
are not present. Final Sec.  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 Sec.  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 Sec.  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 Sec.  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-by-
case 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 Sec.  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 pressure-
time 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 Sec. Sec.  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.

[[Page 21186]]

[GRAPHIC] [TIFF OMITTED] TR18AP08.009

[GRAPHIC] [TIFF OMITTED] TR18AP08.010

    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 Sec. Sec.  75.335(a)(1)(i) and (a)(2)(i) provide specific 
pressure-time 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 Sec. Sec.  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.

[[Page 21187]]

[GRAPHIC] [TIFF OMITTED] TR18AP08.011

[GRAPHIC] [TIFF OMITTED] TR18AP08.012

    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 small-volume 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

[[Page 21188]]

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 Sec.  75.335(b) renumbers and revises ETS Sec.  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 Sec.  75.335(b)(1), like the ETS, sets forth specific 
requirements for an engineering design application. Under final Sec.  
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 Sec.  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 Sec.  75.335(b)(1)(iii) revises ETS Sec.  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

[[Page 21189]]

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 Sec.  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 Sec.  75.335(b)(2)(i), like ETS Sec.  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 Sec.  75.335(b)(2)(ii), like ETS Sec.  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 Sec.  75.335(b)(2)(iii) requires that the application include 
supporting documentation. This clarifies ETS Sec.  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 flame-spread 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 Sec.  75.335(b)(2)(iv), like ETS Sec.  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 Sec.  75.335(b)(2)(v) revises ETS Sec.  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 Sec.  75.335(b)(3), like ETS Sec.  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 Sec.  75.335(b)(4), like ETS Sec.  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 Sec.  75.335(b)(5), like ETS Sec.  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 Sec.  75.335(c), like ETS Sec.  75.336(b), requires that the 
installation of the approved seal design be approved in the ventilation 
plan.
    Final Sec.  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 Sec.  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 Sec.  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

[[Page 21190]]

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 Sec.  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 Sec.  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 Sec.  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 Sec.  75.335(c)(3)(ii) revises ETS Sec.  
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 Sec.  
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 Sec.  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 Sec.  75.1201 which permits a professional land surveyor 
to certify the mine map.
    Final Sec.  75.335(c)(3)(iv), like the ETS, requires that mine 
operators submit specific mine site information in the ventilation 
plan. Final Sec.  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 Sec.  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 Sec.  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 site-specific conditions that may affect the 
strength and applicability of the seal, including set-back distances. 
The set-back 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 
set-back 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,

[[Page 21191]]

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 Sec.  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 Sec.  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 Sec.  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 Sec.  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 Sec.  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 Sec.  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 Sec.  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 Sec.  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 Sec.  75.335(c)(3)(iv)(L) is derived from ETS Sec.  
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 Sec.  
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 Sec.  75.335(c)(3)(iv)(M) renumbers and clarifies ETS Sec.  
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 Sec.  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 Sec.  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 Sec.  75.336, derived from ETS Sec.  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 Sec.  75.336(b); requirements for sampling 
pipes are discussed in final Sec.  75.337(g). Requirements for welding, 
cutting and soldering are discussed in final Sec.  75.337(f); 
requirements for water drainage systems are discussed in final Sec.  
75.337(h); and requirements for training of certified persons 
conducting sampling are discussed in final Sec.  75.338(a).
    Section 75.336(a) of the final rule retains the requirement in ETS 
Sec.  75.335(b) for a certified person, as defined under existing Sec.  
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 Sec.  
75.338(a) and are unchanged from the ETS.
    Final Sec. Sec.  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 Sec.  75.336(a)(2) is derived from ETS Sec. Sec.  
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 Sec.  75.337(g) provides 
appropriat