Refuge Alternatives for Underground Coal Mines

DEPARTMENT OF LABOR

Mine Safety and Health Administration

30 CFR Parts 7 and 75

RIN 1219-AB58

Refuge Alternatives for Underground Coal Mines

AGENCY:

Mine Safety and Health Administration, Labor.

ACTION:

Final rule.

SUMMARY:

The final rule establishes the Mine Safety and Health Administration's (MSHA) requirements for refuge alternatives in underground coal mines and the training of miners in their use. It includes testing and approval requirements. The final rule implements section 13 of the Mine Improvement and New Emergency Response (MINER) Act of 2006. Consistent with the MINER Act, it includes MSHA's response to the National Institute for Occupational Safety and Health (NIOSH) Report on Refuge Alternatives.

DATES:

Effective Date:

The final rule is effective on March 2, 2009.

The incorporation by reference of certain publications listed in the rule is approved by the Director of the Federal Register as of March 2, 2009.

Compliance Dates

1. § 7.503—For any approval consideration by MSHA in the first year, an application for approval of a refuge alternative or component shall be submitted no later than April 30, 2009.

2. § 75.1502(c)(3), (c)(4)(vi), (c)(8), and (c)(10) through (12)—For mines with refuge alternatives in the mine on the effective date of the rule (60 days after date of publication), the operator shall submit a revised program of instruction to the appropriate District Manager for approval by April 30, 2009, and conduct initial mine emergency evacuation training and drills on the refuge alternatives and components, under § 75.1504(b)(3)(ii), (b)(4)(ii), and (b)(6) through (10), within 30 days of program approval. For mines with no refuge alternatives in the mine on the effective date of the rule March 2, 2009, the operator shall submit a revised program of instruction to the appropriate District Manager for approval within 30 days of receipt of the refuge alternatives or components, and conduct initial mine emergency evacuation training and drills on the refuge alternatives and components, under § 75.1504(b)(3)(ii), (b)(4)(ii), and (b)(6) through (9), within 30 days of program approval.

3. § 75.1504(c)(3)—For mines with refuge alternatives in the mine on the effective date of the rule March 2, 2009, the operator shall complete the initial annual expectations training on the refuge alternatives and components no later than December 31, 2009. For mines with no refuge alternatives in the mine on the effective date of the rule March 2, 2009, the operator shall complete the initial annual expectations training on the refuge alternatives and components no later than December 31, 2009, or within 60 days of receipt.

FOR FURTHER INFORMATION CONTACT:

Patricia W. Silvey at

silvey.patricia@dol.gov

(E-mail), 202-693-9440 (Voice), or 202-693-9441 (Fax).

SUPPLEMENTARY INFORMATION:

The outline of the final rule is as follows:

I. Introduction

A. Statutory and Rulemaking Background

B. Discussion of the Hazard

C. Timeline for Implementation of the Final Rule

II. Section-by-Section Analysis

A. Part 7 Approvals

B. Part 75 Safety Standards

III. Regulatory Economic Analysis

A. Executive Order 12866

B. Population at Risk

C. Costs

D. Benefits

IV. Feasibility

A. Technological Feasibility

B. Economic Feasibility

V. Regulatory Flexibility Act and Small Business Regulatory Enforcement Fairness Act

A. Definition of a Small Mine

B. Factual Basis for Certification

VI. Paperwork Reduction Act of 1995

VII. 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. Introduction

This final rule is MSHA's response to the National Institute for Occupational Safety and Health (NIOSH) Report on Refuge Alternatives consistent with section 13 of the Mine Improvement and New Emergency Response (MINER) Act of 2006. The final rule requires that mine operators include refuge alternatives in the Emergency Response Plan (ERP) required by section 2 of the MINER Act. MSHA's objective, consistent with the MINER Act, is to improve the safety of mines and mining. This final rule improves mine operators' preparedness for mine emergencies and requires refuge alternatives underground to protect persons trapped when a life-threatening event occurs that makes escape impossible. Refuge alternatives also can be used to assist trapped miners in escaping from the mine after initial escape becomes impossible.

MSHA developed this final rule based on Agency data and experience, NIOSH recommendations, research on available and developing technology, state regulations, and comments and testimony from the mining community. The final rule includes requirements for—

• Testing and approval of refuge alternatives and components of refuge alternatives;

• Assuring that refuge alternatives are readily available, capable of sustaining trapped miners for 96 hours, and maintained in operating condition; and

• Training miners to locate, deploy and use, maintain, and transport refuge alternatives.

A. Statutory and Rulemaking Background

Section 2 of the MINER Act requires underground coal mine operators to develop and adopt a written Emergency Response Plan (ERP), which must be approved by MSHA. The ERP provides for the evacuation of all individuals endangered by an emergency and the maintenance of individuals trapped underground. All ERPs must provide for emergency supplies of breathable air for individuals trapped underground sufficient to maintain them for a sustained period of time.

MSHA issued Program Policy Letter (PPL) No. P06-V-10 (October 24, 2006) to implement section 2 of the MINER Act. The PPL provides guidance to mine operators for developing ERPs and to MSHA District Managers for approving ERPs. MSHA issued Program Information Bulletin (PIB) No. P07-03 (February 8, 2007) to provide additional guidance to be used in conjunction with the PPL. The PIB includes options for the quantity of breathable air that would be sufficient to maintain persons for a sustained period of time.

Section 13 of the MINER Act provides that NIOSH conduct research on refuge alternatives and submit a report on the results of the research to the Secretary of Labor. NIOSH issued its report in January 2008.

Section 13 of the MINER Act also provides that the Secretary of Labor—

* * * provide a response to the Committee on Health, Education, Labor, and Pensions of the Senate and the Committee on Education and the Workforce of the House of Representatives containing a description of the actions, if any, that the Secretary intends to take based upon the [NIOSH] report, including proposed regulatory changes and the reasons for such actions.

MSHA reviewed NIOSH's report and determined that refuge alternatives are practical and, when integrated into the mine's comprehensive escape and rescue plans, will increase the chance for survival for persons trapped in underground coal mines.

MSHA published the proposed rule for refuge alternatives on June 16, 2008 (73 FR 34140). MSHA held four public hearings on the proposed rule. The hearings were held on July 29 in Salt Lake City, UT; on July 31 in Charleston, WV; on August 5 in Lexington, KY; and on August 7 in Birmingham, AL. The comment period closed on August 18, 2008.

B. Discussion of the Hazard

In developing the final rule, MSHA reviewed a number of underground coal mine accident reports and evaluated its accident and injury data from 1900 through 2006. During that period, 264 miners, who were alive after a mine accident, died later during rescue or escape. MSHA has estimated that recent MSHA standards could have saved the lives of 43 of these miners. Thus, for purposes of estimating benefits, this final rule could potentially have saved the lives of 221 miners over the 107 year period. If refuge alternatives had been available, MSHA estimates that the range of lives saved would have been between a low of 25 percent and a high of 75 percent. Using these estimates, the final rule potentially could save an average of from one to three lives every two years.

The preamble to the proposed rule discussed a number of accidents that reflect typical emergency conditions, hazards, and issues in underground coal mines. The explosions at the Sago Mine on January 2, 2006, and the Darby Mine No. 1 on May 20, 2006, which are especially relevant to this rulemaking, are summarized below.

The explosion at the Sago Mine killed one miner instantly and destroyed seals and filled portions of the mine with toxic levels of carbon monoxide. The remaining 12 miners barricaded themselves on the section when their attempts to evacuate were unsuccessful. The barricade was constructed in an area with high concentrations of carbon monoxide. Eleven miners died before they could be rescued. One miner was rescued, but was severely injured.

The force of the explosion at the Darby Mine No. 1 killed two miners. Four other miners encountered thick smoke and donned their SCSRs while attempting to evacuate. The miners eventually became separated and three died from carbon monoxide poisoning.

C. Timeline for Implementation of the Final Rule

MSHA is providing delayed compliance dates for some sections to give mine operators and applicants the time needed to comply with the stated requirements.

1. By April 30, 2009, an application for approval of a refuge alternative or component must be submitted for first year approval consideration by MSHA in accordance with § 7.503. MSHA expects that first year approvals will be completed by December 31, 2009.

2. By April 30, 2009, mine operators must submit a revised program of instruction to the appropriate District Manager for approval in accordance with § 75.1502. The operator must conduct initial mine emergency evacuation training and drills on refuge alternatives and components, under § 75.1504(b)(3)(ii), (b)(4)(ii), and (b)(6) through (10), within 30 days of program approval.

If the refuge alternatives necessary for the training are not yet available, MSHA will accept, as good faith evidence of compliance with the final rule, a valid, bona fide, written purchase order with a firm delivery date for the refuge alternatives. The mine operator must submit a revised program of instruction to the appropriate District Manager for approval in accordance with § 75.1502 within 30 days of receipt of the refuge alternatives. The operator must conduct initial mine emergency evacuation training and drills on refuge alternatives and components, under § 75.1504(b)(3)(ii), (b)(4)(ii), and (b)(6) through (10), within 30 days of program approval.

3. By December 31, 2009, mine operators must complete the initial annual expectations training on the refuge alternatives and components required by § 75.1504(c). However, if the refuge alternatives or components necessary for the training are not yet available, MSHA will accept, as good faith evidence of compliance with the final rule, a valid, bona fide, written purchase order with a firm delivery date for the refuge alternatives and components. The mine operator must complete the initial annual expectations training on the refuge alternatives and components no later than December 31, 2009 or within 60 days of receipt.

II. Section-by-Section Analysis

In developing this final rule, MSHA relied on the NIOSH report on refuge alternatives; research studies on various refuge alternatives; accident investigation reports, especially those for the 2006 Sago and Darby mine explosions; as well as public comments, hearing transcripts, and supporting documentation from all segments of the mining community, including States that already require refuge alternatives.

A. Part 7 Approvals

The approval requirements for refuge alternatives are set out in 30 CFR Part 7—Testing by Applicant or Third-Party. The final rule provides approval criteria, allows alternatives for satisfying the requirements, and promotes the development of new technology. It provides requirements for a complete self-contained refuge alternative and the following components:

• Structural, which creates an isolated atmosphere and contains the other integrated components.

• Breathable air, which includes the means to supply safe concentrations of oxygen.

• Air-monitoring, which provides occupants of the refuge alternative with devices to measure the concentrations of oxygen, carbon dioxide, carbon monoxide, methane, and other harmful gases, as applicable; and

• Harmful gas removal, which provides for removal of harmful gases from the refuge alternative.

Refuge alternatives also must include provisions for communications, lighting, sanitation, food, water, and first aid. These provisions must be approved in the ERP.

MSHA has a 20-year history of administering the part 7 approval program, which has reduced product testing costs and improved approval efficiency. Under the final rule, new subpart L of part 7 requires that an applicant or a third-party must test the refuge alternative or component according to the final rule. The applicant, usually a manufacturer, provides the required information and test results to MSHA to demonstrate that the refuge alternative or component meets the applicable technical requirements and test criteria. MSHA will issue an approval for a refuge

alternative or one of its components based on the Agency's evaluation of the information and test results submitted with the approval application. The MSHA approval under part 7 assures operators and miners that the refuge alternative can be used safely and effectively in underground coal mines and that the components can be used safely with each other.

The existing general provisions of subpart A of part 7 (§§ 7.1 through 7.10) apply to the testing and approval of refuge alternatives. Existing § 7.3(f) addresses the certification statement and requires that each application for original approval, subsequent approval, or extension of approval of a product shall include a certification by the applicant that the product meets the design portion of the technical requirements, as specified in the appropriate subpart, and that the applicant will perform the quality assurance functions specified in § 7.7. Consistent with the existing requirement, the applicant must provide a certification for refuge alternatives and components.

In addition, existing § 7.8 addresses post-approval product audits and requires that, on request, the approval-holder make a product available to MSHA for audit at no cost to MSHA, but no more than once a year except for cause. Consistent with the existing requirement, the approval-holder must provide a refuge alternative or component to MSHA for audit.

Section 7.501 Purpose and Scope

Final § 7.501, like the proposal, provides that subpart L establishes requirements for MSHA approval of refuge alternatives and components for use in underground coal mines. It states that the purpose of approved refuge alternatives is to provide a life-sustaining environment for persons trapped underground when escape is impossible. Refuge alternatives also can be used to facilitate escape by sustaining trapped miners until they receive communications regarding escape options or until rescuers arrive.

MSHA considers refuge alternatives as a last resort to protect persons who are unable to escape from an underground coal mine in the event of an emergency. NIOSH stated, in its report on refuge alternatives, that—

* * * the potential of refuge alternatives to save lives will only be realized to the extent that mine operators develop comprehensive escape and rescue plans that incorporate refuge alternatives.

Several commenters expressed concern that refuge alternatives have not been proven effective in an actual mine and that human subject testing is necessary for proper functioning and durability of the units. Some commenters requested that MSHA defer promulgating a final rule until human subject testing is completed. Commenters also questioned the use of models and calculations in lieu of human subject testing. However, other commenters stated that human subject testing is not necessary nor is it the best proof of viability. One commenter stated that “there is enough data available to properly simulate the metabolic heat and breathing of humans without necessarily subjecting humans to the risks of a manned test” and that “[t]his is not to say that some manned testing may not be valuable to validate portions [of] the test protocol and for training development.”

The requirements of the final rule are extrapolated from existing Federal and State requirements and from published reports from the U.S. Bureau of Mines and NIOSH. In addition, in developing the final rule, MSHA consulted with experts and other knowledgeable professionals, and evaluated the comments and testimony on the proposal. Based on MSHA's knowledge and experience, the Agency believes that the results of human subject testing, which may be appropriate at some later date, are not necessary for the final rule. Accordingly, the requirements of the final rule are not based on human subject testing.

MSHA continues to work with NIOSH on new technology requirements in the MINER Act. MSHA is aware that NIOSH is developing a protocol and seeking approval for human subject testing. If approved, the results of this human subject testing will not be available prior to the effective date of the final rule. The Agency will consider the results of such testing for future rulemaking, if warranted.

MSHA has analyzed various design specifications of manufactured refuge alternatives and has developed approval requirements that manufacturers must follow. Except as otherwise provided in the rule, mine operators are permitted to use only refuge alternatives and components for which the design specifications have been approved by MSHA. MSHA recognizes that, under the Mine Act, States generally may enact laws or prescribe by regulation additional refuge alternative requirements to the extent they are more stringent than MSHA's standards. Such laws and regulations are limited by principles of conflict preemption to requiring specific refuge alternatives that have been approved by MSHA, and cannot under any circumstances require the use of a refuge alternative that has not been approved. Moreover, it is MSHA's intent that its approval of specifications for a refuge alternative preempts private tort litigation questioning the propriety of those specifications. MSHA weighed various trade-offs in setting requirements for approved refuge alternatives and components, such as those involved in arriving at space and volume requirements and strength requirements. Refuge alternatives and components cannot be altered once approved without seeking potentially time-consuming approval for modifications. Tort suits deeming approved designs insufficient could introduce state-by-state uncertainty to national manufacturers, thereby threatening the steady commercial supply of refuge alternatives and components and potentially leaving miners unprotected.

Section 7.502 Definitions

Final § 7.502, like the proposal, establishes a number of definitions because refuge alternatives represent a relatively new technology for underground coal mines and the terminology may not be widely understood.

One commenter requested that a definition of “component” and “examinable” be included. MSHA does not believe that the Agency needs to define the term “component” because several sections in the final rule identify the four types of components—structural, breathable air, air-monitoring, and harmful gas removal—and their specific requirements. The final rule also clarifies examinations and inspections for structural components.

Apparent Temperature

The final rule clarifies the proposal, and defines apparent temperature as the measure of relative discomfort due to the combined effects of air movement, heat, and humidity on the human body. The final rule clarifies MSHA's intent that the term is used to measure relative discomfort. When no air movement is present, the apparent temperature equals the heat index. As heat and humidity increase, the amount of evaporation of sweat from the body decreases. MSHA received a comment that the Agency should specify the method for determining apparent temperature as part of the definition. The Agency has not specified the method in the definition, which is unchanged; however, the apparent temperature is addressed in the final rule under § 7.504(b).

Breathable Oxygen

The final rule, like the proposal, defines breathable oxygen as oxygen that is at least 99 percent pure with no harmful contaminants. Some commenters suggested that MSHA provide performance-based approval criteria to promote innovative new technology, and that the proposal was unnecessarily restrictive. The final rule, like the proposal, includes necessary parameters for oxygen purity.

One commenter suggested that the final rule include a definition of breathable air. MSHA issued a Program Information Bulletin on Breathable Air (PIB P07-03), which addressed the recommended standards for breathable air as identified by the American National Standards Institute (ANSI)/Compressed Gas Association (CGA) Commodity Specifications for Grade D Breathable Compressed Air. Accordingly, the final rule does not define breathable air.

Flash Fire

The final rule, like the proposal, defines flash fire as a fire that rapidly spreads through a diffuse fuel, such as airborne coal dust or methane, without producing damaging pressure. MSHA notes that a flash fire may occur in an environment, such as an underground coal mine, where fuel and air become mixed in adequate concentrations to combust. In an underground coal mine, a flash fire can be a rapidly moving flame front from a combustion explosion. In its report, NIOSH recommended that the fire resistance for refuge alternatives be 300 °F for 3 seconds. NIOSH based its recommendation on NFPA 2113-2007, the National Fire Protection Association's “Standard on Selection, Care, Use, and Maintenance of Flame-Resistant Garments for Protection of Industrial Personnel Against Flash Fire,” but advised that additional investigation is warranted.

A flash fire is defined by NFPA 2113 as “a fire that spreads rapidly through a diffuse fuel, such as dust, gas, or vapors of an ignitable liquid, without the production of damaging pressure.” NFPA 2113 also includes a longer explanation of flash fire in the Annex A.3.3.16. This explanation addresses flame temperatures for diffused fuel flash fires ranging from 1,000° to 1,900 °F. A commenter requested that MSHA clarify the definition of flash fire by adding that a flash fire is not an ongoing fire. MSHA has explained heat transfer and duration and believes the definition given is adequate. The final rule is unchanged.

Noncombustible Material

The final rule, like the proposal, defines noncombustible material as material, such as concrete or steel, that will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat. MSHA received one comment requesting modification of the proposed definition to include tent deployment information. MSHA has addressed this comment elsewhere in this preamble under final § 7.505(a)(6) and believes that the proposed definition is adequate. The final rule is unchanged.

Overpressure

The final rule, like the proposal, defines overpressure as the highest pressure over the background atmospheric pressure that could result from an explosion, which includes the impact of the pressure wave on an object. MSHA notes that explosion pressures are normally expressed as an overpressure beyond standard atmospheric pressure. Standard atmospheric pressure is 14.7 pounds per square inch (psi) (one atmosphere) at sea level. 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. One commenter supported and no commenters opposed the proposal.

Refuge Alternative

The final rule, like the proposal, defines refuge alternative as a protected, secure space with an isolated atmosphere and integrated components that create a life-sustaining environment for persons trapped in an underground coal mine.

One commenter requested that the proposed definition be modified to emphasize the importance of protecting persons from toxic gases entering the space prior to occupancy and to allow the use of an individual breathable air supply. Under the final rule, refuge alternatives must have an isolated atmosphere and life-sustaining environment. Another commenter requested that the term be defined with more clarity. MSHA believes that the definition as stated provides sufficient detail and concludes that no change to the final rule is necessary.

Section 7.503 Application Requirements

Final § 7.503(a), like the proposal, requires that an application include information to assure that MSHA can determine if a refuge alternative or component meets the technical requirements for approval, functions as intended, and is safe for use in an underground coal mine.

Final paragraph (a)(1), like the proposal, requires that the application contain the refuge alternative's or component's make and model number, if applicable. This provision assists MSHA in identifying specific units or parts from different companies.

One commenter requested that the final rule allow approval of design criteria rather than approval of specific models. MSHA has considered the implications of making this change, such as auditing critical characteristics and integration of components, and determined that no change to the rule is necessary.

Final paragraph (a)(2)(i), like the proposal, requires that the application list the refuge alternative's or component's parts, and include the MSHA approval number for electric-powered equipment. With the approval number, MSHA would be able to verify that electric-powered equipment is either approved as permissible or, with respect to certain equipment such as air-monitoring equipment or gas detectors, is approved as intrinsically safe. MSHA received no comments on this provision.

Final paragraph (a)(2)(ii), like the proposal, requires that the list of a refuge alternative's or component's parts in the application include each component's or part's in-mine shelf life, service life, and recommended replacement schedule. Comments concerning shelf life, service life, and replacement schedule are addressed elsewhere in this preamble under final §§ 7.508(c)(4) and 75.1506(a)(3).

Final paragraph (a)(2)(iii) clarifies the proposal and requires that the application list the refuge alternative's or component's parts that include materials, which have a potential to ignite, used in each component or part with their MSHA approval number. The proposal would have required that the application list the materials used in each component or part with their MSHA approval number or statement that the materials are noncombustible. One commenter stated that not all materials used in refuge alternatives or components can be noncombustible. Another commenter requested clarification of noncombustible materials and MSHA approved electrical components. The final rule clarifies that the MSHA approval number must be included for materials that have a potential to ignite. This provision helps assure that materials are safe for use in an underground coal mine. The hazardous nature of an underground coal mine requires that

sources of ignition be eliminated. The confined space of an underground coal mine necessitates that materials be designed so that they will not contribute to a fire or give off harmful gases when exposed to heat.

Final paragraph (a)(2)(iv) was not in the proposed rule. It requires that the application list the refuge alternative's or component's parts that include a statement that the component or part is compatible with other components; and upon replacement, is equivalent to the original component or part.

Commenters expressed concern regarding the reliability of refuge alternatives that consist of multiple separate components. Some commenters opposed mixing different models of breathable air components because miners might get confused during an emergency and be placed at greater risk.

This new provision is responsive to comments and clarifies MSHA's intent to assure that components or parts that are approved must be interchangeable or must integrate with the other components or parts in the refuge alternative so that the refuge alternative will continue to operate as intended. Under the final rule, if the component or part is a replacement, it must be equivalent to the original component or part. The component or part must be designed for the capacity of the refuge alternative for which it is intended.

Final paragraph (a)(3) is substantively the same as the proposal. It requires that the application specify the capacity and duration (the number of persons it is designed to maintain and for how long) of the refuge alternative or component. For example, the application must include a specific length of time that the refuge alternative or component could support a specified number of persons. This information is necessary so that MSHA can appropriately evaluate the performance of the refuge alternative or component and determine if it meets the requirement that it sustain persons for 96 hours. The final rule includes a non-substantive change. It does not include the “per-person per-day” measurement. Comments on capacity and duration and shift changeover are discussed elsewhere in this preamble under final § 75.1506(b)(2).

Final paragraph (a)(4), like the proposal, requires that the application specify the length, width, and height of the space required for storage of each component. The Agency needs this information for components approved separately to assure that the refuge alternative will have enough usable space for occupants when all components are stored. MSHA did not receive comments on this provision.

Final § 7.503(b), like the proposal, requires that the application provide additional specific information. Final paragraph (b)(1) requires that the application specify a description of the breathable air component, including drawings, air-supply sources, piping, regulators, and controls. This information establishes that the component is included and is in its proper location. MSHA received no comments on the proposed requirement.

Final paragraph (b)(2) requires that the application specify the maximum volume of the refuge alternative, excluding the airlock; the dimensions of floor space and volume provided for each person using the refuge alternative; and the floor space and volume of the airlock. This information assures that there is adequate usable space for occupants when all components, parts, equipment, and material are shown in drawings under paragraph (b)(6) in their respective place.

One commenter stated that the phrase in the preamble “in their respective place” implied that the rule required defined locations for specific items. The final rule clarifies that the application specify the dimensions of floor space and volume for each person to assure that the space and volume provided for persons is usable and not reserved for storage.

Another commenter questioned why the airlock in a unit is excluded from the space calculations. In response to comments, final §§ 7.505(a)(1) and 75.1506(b)(1) clarify that the airlock may be included in the space and volume of the refuge alternative if waste is disposed outside the unit. Therefore, final § 7.503(b)(2) replaces the term “interior dimensions” of the airlock with “floor space and volume” of the airlock which must be included in the application.

Final paragraph (b)(3), like the proposal, requires that the application specify the maximum positive pressures in the interior space and airlock and a description of the means used to limit or control the positive pressure. This information allows MSHA to determine whether the atmospheric pressure in the refuge alternative will maintain good air, without being excessive, as persons enter and pass through the airlock. Excessive pressure could create adverse physiological effects on persons. MSHA did not receive comments on this provision. The final rule includes a non-substantive change. MSHA deleted the term “allowable.”

Final paragraph (b)(4), like the proposal, requires that the application specify the maximum allowable apparent temperature of the interior space and the airlock and the means to control the apparent temperature. MSHA will use this information to evaluate the approval of the refuge alternative. MSHA did not receive comments on this provision. Comments concerning the apparent temperature inside the refuge alternative are discussed elsewhere in this preamble under § 7.504(b)(1).

Paragraph (b)(5) is new and provides further clarification of the Agency's intent with respect to controlling internal apparent temperature. This provision requires that applicants specify in the application the maximum mine air temperature under which the refuge alternative is designed to operate when the unit is fully occupied.

This provision is added in response to commenters' concerns regarding the effect that the mine temperature has on the internal apparent temperature in the refuge alternative. Commenters stated that the temperature outside of the unit must be taken into consideration because of heat transfer. This provision corresponds to the requirement in § 75.1507(a)(12) that the Emergency Response Plan (ERP) include the maximum mine air temperature at each of the locations where refuge alternatives are to be placed.

Final paragraph (b)(6) is redesignated from proposed paragraph (b)(5). Like the proposal, it requires that each application include drawings that show the features of each component and contain sufficient information to document compliance with the technical requirements. MSHA's intent is that the drawings of each component should illustrate the internal configuration of the refuge alternative. Drawings should include the dimensions and layout of the refuge alternative components, controls, and materials necessary for proper operation. This information provides a basis for MSHA approval of the refuge alternative. MSHA did not receive comments on this provision.

Final paragraph (b)(7) is redesignated from proposed paragraph (b)(6) and has been changed from the proposal. It requires that the applicant provide a manual rather than a training manual that contains sufficient detail for each refuge alternative or component addressing in-mine transportation, operation, and maintenance of the unit.

Commenters generally supported the proposal. However, one commenter expressed concern that the manuals not be used as a substitute for miner training because the manufacturer's manual may be too detailed and complicated. Another commenter requested that training materials include

detailed information on turning off devices between readings to conserve battery life and adjusting oxygen flow. Another commenter stated the manual should be written in a manner that includes individual mine specific information such as SCSR caches, communication and tracking, and life lines.

MSHA recognizes that, in general, manufacturers provide information necessary for safe and effective use of their products. Consistent with this general practice, the final rule requires the applicant to provide a manual which contains detailed information on in-mine transportation, operation, and maintenance of the refuge alternative. The manual would be used by MSHA to evaluate and approve the refuge alternative. The final rule clarifies MSHA's intent that the manual be used by operators to develop training material required under § 75.1502(c), concerning mine emergency evacuation program of instruction; § 75.1504(b), concerning quarterly training; § 75.1504(c), concerning annual expectations training; and § 75.1508 concerning training on examinations, maintenance, or repairs.

Final paragraph (b)(8) is redesignated from proposed paragraph (b)(7) and has been changed from the proposal. It clarifies that the applicant must provide a summary of procedures for deploying refuge alternatives. MSHA will use this information to evaluate the approval and the operator may use this information to develop instructions for persons in the deployment of refuge alternatives. This provision changes the proposed requirement that the applicant provide a summary of procedures for “constructing” refuge alternatives because prefabricated units do not require construction, and the structural components of units consisting of 15 psi stoppings constructed prior to an event do not require approval under part 7.

Final paragraph (b)(9), redesignated from proposed paragraph (b)(8) and the same as the proposal, requires that the application include a summary of the procedures for using the refuge alternative. This information will be used by MSHA to evaluate the approval and by operators to develop instructions for persons using refuge alternatives. MSHA did not receive comments on this provision.

Final paragraph (b)(10), redesignated from proposed paragraph (b)(9) and the same as the proposal, requires that the application specify the results of inspections, evaluations, calculations, and tests conducted under this subpart. MSHA will use this information to evaluate the effectiveness and compatibility of refuge alternative components. For example, the application must contain the calculation of the rate oxygen is delivered on a per person basis and the results of tests, including calculations, of the carbon dioxide removal (scrubbing) to demonstrate that the refuge alternative will maintain a safe atmosphere for 96 hours. Without having these calculations readily available, the Agency would have difficulty independently verifying that the test results are satisfactory. MSHA did not receive comments on this provision.

Final § 7.503(c), like the proposal, requires that the application for approval of the air-monitoring component provide specific information. This information is necessary for the applicant or third party to make an effective evaluation of the component and to provide a basis for MSHA approval of the air-monitoring component.

Final paragraph (c)(1), like the proposal, requires that the application specify the operating range, type of sensor, gases measured, and any environmental limitations including the cross-sensitivity to other gases, of each detector or device in the air-monitoring component. The Agency believes that this information is essential for MSHA to determine that persons inside the refuge alternative will be aware of the concentrations of carbon dioxide, carbon monoxide, and methane, inside and outside the refuge alternative, including the airlock. In addition, this will assure that oxygen concentrations can be monitored simultaneously. MSHA did not receive comments on this provision.

Final paragraph (c)(2), like the proposal, requires that the application include the procedures for operation of the individual devices so that they function as necessary to test gas concentrations over a 96-hour period. Manufacturers must properly design the system to control gas concentrations inside the refuge alternative. This provision will assist MSHA's evaluation of the air-monitoring component.

One commenter stated that “few if any monitors exist that will operate for 96 hours continuously.” The commenter stated that provisions must be made for recharging or changing batteries and that instrument manufacturers should provide “options for extending the operational life of their devices in a potentially explosive atmosphere.” In the proposal, MSHA did not state that air monitoring instruments or devices were intended to operate continuously. This issue is discussed elsewhere in this preamble under § 7.507 concerning air monitoring components. The Agency anticipates that refuge alternative manufacturers will work with monitoring instrument manufacturers to satisfy the requirements of this provision. The final rule is the same as the proposal, except for an editorial change for clarity.

Final paragraph (c)(3), like the proposal, requires that the application include procedures for monitoring and maintaining breathable air in the airlock, before and after purging. Monitoring and maintaining breathable air in the airlock is necessary to remove contaminants and minimize contamination inside the refuge alternative as miners pass through the airlock into the interior space. MSHA did not receive comments on this provision.

Final paragraph (c)(4), like the proposal, requires that the application include instructions for determining the quality of the atmosphere in the airlock and refuge alternative interior and a means to maintain breathable air in the airlock. Determining the quality of the air and maintaining breathable air are necessary to sustain trapped miners. MSHA did not receive comments on this provision.

Final § 7.503(d)(1) and (2), like the proposal, require that the application for approval of the harmful gas removal component specify the volume of breathable air available for removing harmful gas both at start-up and while persons enter through the airlock; and the maximum volume of each gas that the component is designed to remove on a per-person per-hour basis. Information on harmful gas removal is essential for MSHA to determine the ability of the refuge alternative to sustain occupants for 96 hours. These final provisions also provide information on the removal of carbon dioxide that is exhaled by the occupants and the removal of other harmful gases.

One commenter stated that this provision is not practical and should be removed. Another commenter recommended that the requirement be performance-based. MSHA does not agree since the Agency needs this information to evaluate the adequacy of the harmful gas removal systems to meet the needs of the occupants for 96 hours. The applicant can calculate the amount of purge air available or scrubbing capability for a range of expected conditions. MSHA expects the application to contain sufficient information to enable the Agency to determine whether the refuge alternative or component meets the technical and performance requirements of this subpart.

Proposed § 7.503(e) is not included in the final rule. It would have required the applicant to certify that each component was constructed of suitable materials, was of good quality workmanship, was based on sound engineering principles, was safe for its intended use, and was designed to be compatible with other components in the refuge alternative, within the limitations specified in the approval.

Several commenters objected to the Agency's use of “subjective terms.” One commenter stated that the provision “leaves itself open to a broad range of interpretations that will result in considerable confusion on the part of applicants and reviewers.” Commenters stated that the final rule “must have specific parameters that are measurable and have a clear limit beyond which they fail” and “stipulate what these phrases exactly mean” or remove the provision.

Due to commenters concerns, MSHA evaluated the information, design criteria, and testing results required to be specified in the application for approval. Based on this evaluation, MSHA determined that the content of the application will be sufficient to allow MSHA to evaluate whether the refuge alternative or component meets the requirements for approval. In addition, existing § 7.3(f) requires an applicant's certification that the product meets the requirements specified in the appropriate subpart. Also, to clarify the Agency's intent, and in response to comments, MSHA added a requirement, final § 7.503(a)(2)(iv), that the application provide a statement that the component is compatible with other components. With this change, and with the existing requirements, the Agency determined that it is not necessary to include proposed § 7.503(e) in the final rule.

Section 7.504 Refuge Alternatives and Components; General Requirements

Final § 7.504, like the proposal, addresses safety and health requirements that refuge alternatives and components must meet to gain MSHA approval.

Final § 7.504(a)(1) clarifies the proposal and requires that electrical components that are exposed to the mine atmosphere must be approved as intrinsically safe for use in an underground coal mine. Further, it provides that electrical components located inside the refuge alternative must be either approved as intrinsically safe or approved as permissible.

One commenter supported the proposal stating that refuge alternatives and components should be explosion-proof or intrinsically safe. Another commenter stated that the rule should clarify the use of approved permissible electrical equipment and approved intrinsically safe equipment.

The final rule clarifies MSHA's intent that electrical components of refuge alternatives that are exposed to the mine atmosphere must be approved as intrinsically safe. However, because a non-explosive atmosphere exists inside a refuge alternative, electrical components located inside the unit must be either approved as intrinsically safe or approved as permissible. This provision helps assure that the refuge alternative or component will not contribute to a secondary fire or explosion.

Final paragraph (a)(2), like the proposal, requires that a refuge alternative or component not produce continuous noise levels in excess of 85 dBA in the structure's interior. One commenter stated that noise is not likely to be a problem in a shelter during occupancy and questioned the logic for the proposal. MSHA included this requirement in the final rule because continuous noise above 85 dBA can interfere with communication and could adversely affect hearing, and the Agency is aware that noise controls, such as dampening material, are available to control noise levels.

Final paragraph (a)(3), like the proposal, requires that the refuge alternative or component not liberate harmful or irritating gases or particulates into the structure's interior or airlock. The Agency is aware that some nonmetallic materials off-gas. Vapors, aerosols or particulates should not be released into the refuge alternative. The provision requires that materials used in a refuge alternative or component be tested and evaluated to verify that they do not release harmful or irritating gases. The application would have to include the results of the tests and evaluation. No commenters opposed the proposal.

Final paragraph (a)(4), like the proposal, requires that the refuge alternative or component be designed to be moved safely with the use of appropriate devices, such as tow bars. MSHA recognizes that refuge alternatives could be a hazard to miners during transport. Based on MSHA's experience, the Agency believes that inadequate rigging and towing devices could result in hazards to miners. The refuge alternative should be designed with proper connections and devices to eliminate or reduce hazards that may occur when chains, ropes, or slings are used.

Commenters supported the proposal. One commenter noted that the refuge alternative can be moved safely using a tow bar. The final rule remains unchanged from the proposal.

Final paragraph (a)(5), like the proposal, requires that the refuge alternative and components be designed to withstand forces from collisions of the structure during transport and handling. This provision helps assure that the refuge alternative and components are not damaged during transport and handling.

One commenter suggested that all components be subjected to shock testing. Another commenter noted that many mines have required special attachments or bumpers, and requested that the final rule include these modifications.

Different mining conditions warrant different designs. The final rule is performance-oriented, allowing operators to tailor refuge alternative and component designs to the specific conditions in their mines. Designs can incorporate bumpers, guarding, skids, packing and securing devices, and rigging components. In addition, components should be configured, arranged, and stored to minimize shifting, movement, or damage during handling and routine transport. MSHA has evaluated all comments, and determined that the final rule should be the same as the proposal.

Final paragraph § 7.504(b), like the proposal, requires that the apparent inside temperature be controlled. Body heat and heat generated by chemical reactions (

i.e.

, carbon dioxide scrubbing chemicals) are inherent heat-producing sources within a refuge alternative. Ambient temperature in a refuge alternative also is affected by the mine temperature compounded by high humidity in the sealed environment. High humidity reduces a body's ability to regulate temperature by sweating, which could result in a dangerously elevated internal body temperature. The carbon dioxide absorption process also generates heat and humidity. There is currently no permissible air conditioning equipment that will address heat and humidity in underground coal mines.

Final paragraph (b)(1), like the proposal, requires that when a refuge alternative is fully occupied and used in accordance with the manufacturer's instructions and defined limitations, the apparent temperature in the refuge alternative must not exceed 95° Fahrenheit. MSHA requested comments on the apparent temperature and mitigation of heat stress and heat stroke, and requested that commenters address

the generation of heat and the methods for measuring heat stress on persons occupying the refuge alternative.

Most commenters generally supported the proposal. Some commenters noted that the proposal did not include air-conditioning to address metabolic heat buildup. One commenter stated that the proposal stifles creativity and eliminates innovative new technology, and one commenter suggested using chemical cooling packs or cooling vests to maintain core body temperature at a safe level. MSHA believes that there could be methods, including air conditioning, for controlling temperature that would be acceptable under the final rule. Chemical cooling packs or cooling vests may be used to supplement maintaining core body temperature. However, these devices have not been established as reliable, and therefore, may not be used as a substitute to the requirement for maintaining the apparent temperature inside the refuge alternative.

One commenter suggested that it was not appropriate to require an interior temperature without a corresponding ambient rock temperature. MSHA reviewed NIOSH/Raytheon UTD's Report on Miner Refuge Chamber Thermal Analysis (NIOSH/Raytheon report). The NIOSH/Raytheon report concluded that the rock type has a negligible effect on the conduction of heat away from a refuge alternative in an underground mine. In addition, the NIOSH/Raytheon report stated that the amount of heat conducted through the floor of a refuge alternative is small compared to the amount of heat that is carried away by convection. Accordingly, the final rule does not include a provision for corresponding ambient rock temperature.

One commenter stated that the International Standards Organization (ISO) standard, ISO 7243:1989(E), “Hot environments—Estimation of the heat stress on working man, based on the WBGT-index (wet bulb globe temperature),” should be used to evaluate heat stress.

ISO 7243 specifies periods of work and rest based on the air temperature and the level of activity throughout a workday for working in a hot environment daily, with breaks during the day and periods of relief between exposures. The ISO standard does not apply to the conditions addressed by the final rule because persons in a refuge alternative could be exposed for several days without an opportunity to recover.

Apparent temperature is a measure of relative discomfort due to the combined effect of heat and humidity. The concept of apparent temperature was developed by R.G. Steadman (1979) and was based on physiological studies of evaporative skin cooling for various combinations of ambient temperature and humidity. The likelihood of adverse effects from heat may vary with a person's age, health, and body characteristics; however, apparent temperatures greater than 80 °F are generally associated with some discomfort. Core body temperatures in excess of 104 °F are considered life-threatening, with severe heat exhaustion or heat stroke possible after prolonged exposure or significant physical activity. The December 2007 Foster Miller Report

1

concluded that the apparent temperature within a confined space occupied by humans should not exceed 95 °F.

1

Foster Miller.

Phase II Report

, December 2007.

Based on the Agency's review of many standards, studies, and reports, and the comments and testimony, MSHA believes that applying ISO 7243 could result in dangerously high apparent temperatures in the refuge alternative. This is because the limit specified in ISO 7243 is an 8-hour average, not a maximum continuous exposure. Therefore, using the ISO 7243 average as a maximum exposure level would allow as much as 50% higher temperature than even the ISO 7243 standard allows, and for a continuous 96-hour period as opposed to 8 hours. This would be fatal to the occupants. Accordingly, the final rule is the same as proposed.

Final paragraph (b)(2) clarifies the proposal and requires that tests be conducted to determine the maximum apparent temperature in the refuge alternative when used at maximum occupancy and in conjunction with required components. In addition, the final rule requires that an application include these test results including calculations. The final rule clarifies MSHA's intent that tests be conducted and that the test results including calculations be reported on the application. Test results could also include data, records, and other supporting documentation reported on the application. MSHA received no comments on this provision.

Final § 7.504(c), like the proposal, requires that refuge alternatives include additional measures to protect the safety and survival of miners. These requirements include a means for communicating with persons on the surface, lighting, sanitation, first aid, and repairs.

Final paragraph (c)(1), requires a two-way communication facility that is a part of the mine communication system, which can be used from inside the refuge alternative; and accommodations for an additional communication system and other requirements as defined in the communications portion of the operator's approved Emergency Response Plan (ERP). MSHA is aware that these additional systems may not yet be available, but as they are developed, mine operators will be required to include them in their ERPs. The MINER Act requires, by June 15, 2009, that ERPs contain wireless communication systems. MSHA is working with NIOSH on this emerging technology and will provide further guidance to the mining community with respect to the Agency's expectations for “wireless communication” systems in ERPs. Manufacturers may need to provide other accommodations for these systems. In the final rule, this provision has been revised to reflect the language in the safety standards for communications facilities in this rulemaking. Comments addressing these communication systems are addressed in that section.

In the preamble to the proposed rule and in the Agency's opening statements at the public hearings, MSHA requested comments on including a requirement that refuge alternatives be designed with a means to signal rescuers on the surface. This was intended to be a means to assure that rescuers on the surface could be contacted if the communications systems become inoperable. This signal would have been similar to what miners had done in the past by hammering on the roof, ribs, or floor to create sounds that can be detected by seismic devices located on the surface.

One commenter stated that the final rule should not require the use of a seismic location device unless MSHA is willing to obtain significant upgrades to its seismic capabilities. However, most commenters did not respond to MSHA's request on this issue.

MSHA also requested comments on whether the final rule should include a requirement that the manufacturer design refuge alternatives with a means to signal underground rescuers with a homing device. Such a requirement would assure that rescuers could detect the trapped miners within the mine.

Some commenters supported adding a provision for a homing device in refuge alternatives. They stated that the signal could help rescuers determine whether anyone was in the refuge alternative. Several opposed such a provision, for example, stating that the homing device was unnecessary because there already is a requirement to identify the locations of the units on the escapeway maps.

The final rule, like the proposal, does not contain a provision addressing

signaling or homing devices. After reviewing the comments, MSHA agrees with commenters opposing such provisions and has determined that the requirements for a signaling device that would create a seismic sound to be detected by rescuers on the surface should not be included in the final rule. Likewise, the Agency has determined that the requirements for a homing device that would create an electronic signal to be detected by rescuers underground should not be included in the final rule.

Final paragraph (c)(2), like the proposal, requires that refuge alternatives include lighting sufficient for persons to perform tasks. Lighting is essential to allow persons to read instructions, warnings, and gauges; operate gas monitoring detectors; and perform other activities related to the operation of the refuge alternatives.

In the preamble to the proposal, MSHA recommended a minimum of 1 foot candle of lighting be provided per miner per day.

2

The Agency also noted that lighting should not generate significant heat, or require continual manual power for light generation.

2

MIL-STD-1472F, Lighting for bomb shelters, NOTICE 1, 05 December 2003.

Several commenters recommended light sticks and cap lamps. Another commenter stated that MSHA should be flexible with respect to a lighting requirement and that the proposal requires technology that may not be currently available. One commenter stated that MSHA should not require 1 foot-candle per day per miner. Another commenter pointed out that there may be added risks of electrical hazards and requested that, as the provision presents more potential problems than it solves, it be omitted from the final rule.

Although MSHA agrees that light sticks can be used, higher intensity lighting may be required for certain tasks. The final rule includes the same performance-oriented requirement as the proposal. The final rule includes a non-substantive change. It includes the term “for persons.”

Final paragraph (c)(3), like the proposal, requires that refuge alternatives include a means to contain human waste effectively and minimize objectionable odors. A plastic bag and closed receptacle could be used to contain waste and prevent objectionable odors. The final rule does not require a specific method of waste disposal. The length, width, and height of the container housing the sanitation system, including operating instructions, should be in the refuge alternative's manual. Information regarding sanitation assures that the applicant has included an adequate means for containing waste.

One commenter pointed out a number of options for sanitation and waste disposal that are currently available. Some commenters requested that the final rule require that human waste be disposed of outside the refuge alternative. Under the final rule, waste can be disposed of from the interior of the refuge alternative, as long as the disposal does not compromise the integrity of the refuge alternative or affect its operation. The final rule is the same as proposed.

Final paragraph (c)(4), like the proposal, requires that refuge alternatives include first aid supplies. This requirement assures that first aid supplies are available for treating injured miners.

One commenter requested that the Agency specify the nature and quantity of required supplies. Another commenter stated that first aid kits should contain instructions for treating injuries that could be anticipated in the aftermath of an accident and warned that the inclusion of “anxiety and or sleep inducing drugs” could present medical issues.

First aid supplies must be adequate to provide for the number of persons injured in an emergency. In an underground mine emergency, MSHA expects that there will be a proportionally higher number of injuries related to lacerations, burns, and fractures resulting from explosions and fires. The refuge alternative must contain first aid supplies to address these injuries, but the final rule does not specify the content of the first aid kit. The final rule is the same as the proposal and is consistent with the safety standards for ERPs in this final rule.

Final paragraph (c)(5), like the proposal, requires that refuge alternatives be stocked with materials, parts, and tools for repair of components. Manufacturers could provide a repair kit with necessary materials and appropriate tools to perform repairs. Materials and tools should include metal repair materials, fiber material, adhesives, sealants, tapes, and general hardware (

i.e.

, screws, bolts, rivets, wire, zippers and clips). Powered tools must be approved as intrinsically safe and permissible. One commenter supported and no commenters opposed the proposal. The final rule is the same as the proposal.

Final paragraph (c)(6), is redesignated and clarified from proposed § 7.506(i). It requires a fire extinguisher that meets the requirements for portable fire extinguishers used in underground coal mines under part 75; and that is appropriate for fires involving the chemicals used for harmful gas removal; and that uses a low-toxicity extinguishing agent that does not produce a hazardous by-product when activated. One commenter supported and no commenters opposed the proposal. The final rule clarifies MSHA's intent. MSHA's intent is that the fire extinguisher must protect miners from potentially toxic chemicals in the confined atmosphere of a refuge alternative. The final rule requires that a fire extinguisher meet the requirements of MSHA's existing standards for portable fire extinguishers. It changes the proposed requirement limited to carbon dioxide chemicals to chemicals used for harmful gas removal, and non-toxic extinguishing agent to low-toxicity extinguishing agent. The final rule does not include the proposed requirement that the fire extinguisher not produce hazardous by-product when heated.

Final § 7.504(d)(1), (2), and (3) are substantively the same as the proposal, and require that containers used for storage of refuge alternative components or provisions be airtight, waterproof, and rodent-proof; easy to open and close without the use of tools; and conspicuously marked with an expiration date and instructions for use. These requirements assure that the containers' contents will be useable when needed.

One commenter requested clarification of the components that are covered by this provision. Another commenter requested that the final rule only apply to specific items, such as food and water, which are subject to degradation.

The final rule clarifies the proposal by including the term “or provisions.” Provisions include items such as supplies, materials, systems, and food and water. Food and water would need to be contained in airtight, waterproof, and rodent-proof containers because these provisions are subject to degradation.

Section 7.505 Structural Components

Final § 7.505, like the proposal, addresses structural component requirements for refuge alternatives.

Final paragraph (a)(1) requires that refuge alternatives provide at least 15 square feet of floor space per person, like the proposal, but includes changes in the required cubic feet of volume per person according to the following chart for mining heights:

Mining height (inches)

Unrestricted volume (cubic feet) per person *

36 or less

30

>36−≤42

37.5

>42−≤48

45

>48−≤54

52.5

>54

60

* Includes an adjustment of 12 inches for clearances.

In addition, the final rule clarifies that the airlock can be included in the space and volume if waste is disposed outside the refuge alternative.

The volume of the refuge alternative is calculated by assuming two factors: (1) 6 inches is necessary to allow for clearance of the refuge alternative to be moved; and (2) the usable interior height of the refuge alternative is reduced by 6 inches for the roof and floor beams. As an example, a 36-inch mine height is reduced by 6 inches for clearance and 6 inches for inside beams leaving 24 inches or 2 feet. The 24 inches or 2 feet multiplied by 15 square feet of floor space equals 30 cubic feet of volume per person. Under the final rule, MSHA intends for persons to have this space without being affected by other factors such as stored items.

In the preamble to the proposed rule and in the Agency's opening statements at the public hearings, MSHA requested comments on the proposed requirement of at least 15 square feet of floor space and 60 cubic feet of volume per person, particularly in low mining heights. MSHA received comments in support of and opposed to the proposal.

Some commenters supported 15 square feet of floor space per person, but stated that the 60 cubic feet of volume per person was not a sufficient amount of space for each miner and could result in a higher risk of carbon dioxide exposure or excessive heat within the refuge alternative. These commenters urged MSHA to adopt the 85 cubic feet recommendation of NIOSH. In its comment on the proposed rule, NIOSH stated that the NIOSH recommendation of 85 cubic feet was “based on published research conducted under the old civil defense program [OCDM 1958], and it is difficult to apply those findings directly to mining applications.” NIOSH further stated that in the absence of NIOSH testing, it supports the interior volume requirement in the proposed rule.

Other commenters stated that both the proposed space and volume requirements were excessive in an emergency because persons could survive with less space. In addition, some stated that larger refuge alternatives were hard to transport, would require more compressed air and oxygen cylinders, or may not be feasible in all seam heights. Others stated that due to the orientation of the occupants, floor space per person is the critical measurement, and not volume. Some commenters stated that less space was needed because most of the time the maximum number of persons to be accommodated would be less than half because overlapping crews, i.e., hot-seating, occurs only during a small part of the work day.

Many commenters suggested space and volume criteria that were less than those in the proposal. In support of their position, some of these commenters relied on the South African standard for spacing while others relied on various engineering studies or manufacturer findings. Commenters suggestions ranged from 6.4 to 10 square feet of floor space and from 30 to 46.5 cubic feet of volume. Other commenters suggested a performance-oriented approach, stating that MSHA should not specify any space and volume requirements.

Finally, some commenters stated that the proposal omitted consideration of seam height. These commenters stated that compliance with the proposal would be difficult in mines with low seam heights.

For mining heights greater than 54 inches, the final rule requires 60 cubic feet of volume. However, in response to commenters' concerns, the final rule includes varying requirements for volume, based on mining heights that are less than or equal to 54 inches. These varying volume requirements accommodate commenters' concerns regarding the ability to maneuver, deploy, or use larger units in mines with low seam heights.

After reviewing the comments, MSHA determined that the proposed 15 square feet of floor space per person is necessary to assure that persons can conduct necessary activities in the refuge alternative. Occupants will need to attend to harmful gas removal; monitor gas levels; attend to basic needs, such as drinking, eating, and using the sanitation facilities; and provide care to injured miners. Adequate space is needed to accommodate larger than average persons. In addition, adequate volume is needed for proper function of passive harmful gas removal systems. It is also important to note that larger volumes are more effective at dissipating heat because of increased surface area, which helps control the apparent temperature in the interior space of the refuge alternative. MSHA recognizes that the lower mining height refuge alternatives may have less volume per person, but must still maintain apparent temperature as required in this final rule.

Some commenters expressed concern regarding the statement in the preamble to the proposal that the space requirements do not include the airlock. They stated that, once everyone was inside, the airlock was usable space and should be included in calculating the space and volume per person. To clarify the Agency's intent with respect to the proposal and in response to comments, under the final rule, the airlock may be included in calculating space and volume provided that waste is disposed of outside the refuge alternative.

Final paragraph (a)(2), like the proposal, requires that refuge alternatives include storage space that secures and protects the components during transportation and that permits ready access to components for maintenance examinations. Paragraph (a)(2) has been clarified to reflect the Agency's intent that this requirement applies to maintenance examinations rather than preshift visual examinations.

MSHA clarified the final rule in response to a comment asking for clarification regarding the type of examinations required under this paragraph. MSHA intends that a refuge alternative must be designed to allow maintenance examinations to be conducted. The components must be secured to prevent shifting during transport or moves. Maintenance examinations assure that the components will be readily available for deployment. Preshift examinations are discussed elsewhere in this preamble under §§ 7.505(d)(1) and 75.360(d).

Final paragraph (a)(3), like the proposal, requires that refuge alternatives include an airlock that creates a barrier and isolates the interior space from the mine atmosphere, except for a refuge alternative capable of maintaining adequate positive pressure. This provision addresses the need to provide breathable air to persons entering the refuge alternative if the mine atmosphere is contaminated. In this case, pressures need to be incrementally higher in the interior space as compared to the airlock and the airlock pressure needs to be higher than the mine atmosphere. Persons will pass through the airlock via airtight doors into the interior space. The exception to the requirement for an airlock recognizes that the positive pressure would prevent outside air from contaminating the refuge alternative; therefore, an airlock would not be necessary.

One commenter stated that both positive pressure inside the shelter and

an airlock must be required for all types of shelters. Another commenter asked that MSHA clarify “adequate positive pressure” and the scenario under which this exception will be accepted. In the final rule, the Agency uses the commonly understood definition of “adequate” to mean that there would be sufficient positive pressure to allow the refuge alternative to function as it would with an airlock. After considering the comments received, the final rule is the same as the proposal.

Final paragraph (a)(3)(i), like the proposal, requires that the airlock be designed for multiple uses to accommodate the structure's maximum occupancy. This requirement assures access for the maximum number of persons for which the refuge alternative is designed.

One commenter requested clarification of the proposed requirement relating to the number of purges. MSHA has performed limited carbon monoxide purge testing that indicates a 50 percent carbon monoxide concentration reduction with each purge. In PIB P07-03, under Safe Haven Assumptions providing breathable air, MSHA addressed carbon monoxide (CO) purging. Purging “efficiency” was estimated to require compressed air cylinders providing at least three times the amount of safe haven volume. Miners are to be inside the volume being purged wearing an SCSR until purging is accomplished. The Agency anticipated using compressed air cylinders as necessary to reduce Safe Haven concentration to less than 25 parts per million (ppm) for safe havens with a captive volume (not using positive pressure forced air from either a compressed air line or borehole from the surface).

Final paragraph (a)(3)(ii), like the proposal, requires that the airlock be configured to accommodate a stretcher without compromising its function. The airlock must be large enough to accommodate a stretcher with an injured miner while the outside door is closed and the inside door is open.

One commenter, who supported the proposal, stated that this proposed requirement was absolutely necessary to accommodate the need to bring injured miners into an airlock. Another commenter noted that a large amount of space would be required to accommodate a stretcher in the airlock. MSHA believes that this final requirement is necessary to accommodate a stretcher in the air lock and to allow transfer of the injured miner on the stretcher into the refuge alternative's interior space. MSHA notes that elsewhere in the final rule, in response to comments, the Agency has clarified its intent with respect to the maximum volume of refuge alternatives and stated that the airlock can be included in calculating space and volume. After a review of all comments, the final rule is the same as the proposal.

Final paragraph (a)(4) makes editorial changes, but is substantively the same as the proposal and requires that refuge alternatives be designed and made to withstand 15 pounds per square inch (psi) overpressure for 0.2 seconds prior to deployment. This requirement assures that the refuge alternative is capable of withstanding an initial explosion and that the components are not damaged and are able to function as intended.

MSHA received comments both in support of and opposed to the proposal. One commenter who supported the proposal stated that “the 15 psi value for the survivability of the shelter is sufficient as levels higher than that would not likely result in survivors.” Other commenters who supported the proposal referred to the West Virginia Mine Safety Technology Task Force Report of May 29, 2006, which recommended that refuge alternatives only be designed to survive an initial event.

Commenters who opposed the proposal stated that the proposal was inadequate because explosions can create pressures greater than 20 psi, that refuge alternatives should be capable of withstanding a second explosion, and that inflatable shelters are unsafe because they may not endure a second explosion.

The final rule is consistent with the NIOSH Report, which recommended a 15 psi overpressure for 0.2 seconds. NIOSH test results from the Lake Lynn Laboratory support a 15 psi overpressure and a 0.2 second duration for a typical blast wave propagation in an underground mine. MSHA notes that the Agency has reviewed information from the U.S. Department of Defense weapon designers which use a 13 psi peak overpressure as the 100% lethal threshold.

With respect to secondary explosions, the NIOSH report states that a number of factors make optimal design of refuge chambers difficult. These factors include the complexity of mine explosions and the interaction of the explosion with the physical environment. The Report further states: “[t]he most likely locations of an initial explosion can be predicted with some certainty,” and “[i]f there is an ignition source, there could be subsequent explosions, although the location and strength of these are more difficult to forecast.” Because of the difficulty in predicting the likelihood and strength of a secondary explosion, the final rule does not include strength requirements with respect to a second explosion. After reviewing all the comments, the final rule is substantively the same as the proposal.

Final paragraph (a)(5) makes an editorial change, but is substantively the same as the proposal, and requires that refuge alternatives be designed and made to withstand exposure to a fl ash fire of 300 °Fahrenheit for 3 seconds prior to deployment. This requirement assures that the refuge alternative is capable of withstanding a fire and that the components will not be damaged and are able to function as intended.

One commenter agreed with the proposal. The final rule is substantively the same as the proposal.

Final paragraph (a)(6), substantively the same as the proposal, requires that structural components of refuge alternatives be made with materials that do not have a potential to ignite or are MSHA-approved. Materials under this final rule could include, but are not limited to, inflatable shelters and any materials providing a secure space to protect the inside atmosphere from the hazardous outside atmosphere. MSHA notes that materials are generally tested for noncombustibility under American Society for Testing and Materials (ASTM) E136 “Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750 Degrees C” (2004), although a similar ISO test, ISO 1182:2002 also exists. Tests for flame resistance in existing 30 CFR 7.27 could be used to determine the flame resistance of materials that have the potential to ignite.

One commenter requested that MSHA clarify the extent of materials that must be flame resistant or noncombustible and clarify whether the requirement applies to materials that will be deployed and used only after the event occurs.

This provision applies to any materials used to provide a secure space to protect persons from the hazardous outside atmosphere. This final rule assures that the refuge alternative is capable of withstanding a fire and that the components will not be damaged and are able to function as intended in case of an emergency. Taken together, paragraphs (a)(4), (a)(5), and (a)(6) would assure that the refuge alternative is able to withstand an initial fire and that the structure and internal components and provisions will not be damaged and will function as intended following the emergency. The final rule

remains substantively the same as the proposal.

Final paragraph (a)(7) makes an editorial change, but is substantively the same as the proposal, and requires that refuge alternatives be made from reinforced material that has sufficient durability to withstand routine handling and resist puncture and tearing during deployment and use. Refuge alternatives need to be made from reinforced material to be capable of withstanding the harsh underground mining environment. This especially applies to refuge alternatives with inflatable structures.

One commenter supported and no commenters opposed the proposed requirement. The final rule is substantively the same as the proposal.

Final paragraph (a)(8), makes an editorial change, but is substantively the same as the proposal, and requires that refuge alternatives be guarded or reinforced to prevent damage to the structure that would hinder deployment, entry, or use. This requirement assures that the refuge alternative will be designed to incorporate protective features to protect the integrity of the structure and operation of doors, inflatable extensions of the refuge alternative, and other functions necessary to deploy, enter, or use the refuge alternative.

One commenter supported and no commenters opposed the proposal. The final rule is substantively the same as the proposal.

Final paragraph (a)(9), like the proposal, requires that refuge alternatives permit measurement of outside gas concentrations without exiting the structure or allowing entry of the outside atmosphere. Gas monitoring of the atmosphere outside the refuge alternative is needed when there is a lack of communication with rescuers and persons are considering whether evacuation is a viable option.

Several commenters supported the proposal. One commenter stated that it was absolutely essential to be able to measure outside gas concentrations without exiting the structure or allowing outside air to enter. The final rule is the same as the proposal.

Final paragraph § 7.505(b), like the proposal, requires inspections or tests of the structural components. Final paragraph (b)(1) clarifies the proposal and requires that a test be conducted to demonstrate that trained persons can fully deploy the structure, without the use of tools, within 10 minutes of reaching the refuge alternative. This provision assures that persons can deploy and use the refuge alternative in a short amount of time upon reaching it. In a worst-case scenario, where only one SCSR is available to provide 60 minutes of breathable air, the first 30 minutes could be used to evacuate and, if evacuation is not possible, return to the refuge alternative. If the person returns to the refuge alternative, 10 minutes could be used to establish a secure space between the interior and exterior atmospheres, and 20 minutes could be used to purge the interior space to establish a breathable atmosphere. Under the final rule, testing should be conducted simulating real-life situations and conditions, such as smoke, heat, humidity and darkness while using SCSRs.

Several commenters questioned whether miners could activate the refuge alternative within 10 minutes. MSHA recognizes there may be differences in refuge alternatives necessitating different start-up procedures. Training requirements for persons deploying and using refuge alternatives are addressed in part 75. The Agency has included this training requirement in recognition of the limited time available for persons to establish a secure space between the interior and exterior atmospheres and to purge the refuge alternative to establish a breathable air atmosphere. The final rule clarifies the Agency's intent that a “test” be conducted. The final rule is substantively the same as the proposal.

Final paragraph (b)(2) clarifies the proposal and requires that a test be conducted to demonstrate that an overpressure of 15 psi applied to the pre-deployed refuge alternative structure for 0.2 seconds will not allow gases to pass through the structure. The test must verify that the refuge alternative structure is capable of withstanding an initial explosion, and that gases do not pass through the structure following an explosion. The test should demonstrate the integrity of the structure and that doors remain operational.

MSHA did not receive any comments on this proposal. The final rule clarifies that a “test” be conducted and makes an editorial change. The final rule is substantively the same as proposed.

Final paragraph (b)(3) clarifies the proposal and requires that a test be conducted to demonstrate that a flash fire of 300 °F for 3 seconds will not allow gases to pass from the outside to the inside of the structure. The test must verify that the refuge alternative structure is capable of withstanding a flash fire, and that gases do not pass through the structure following a flash fire. The test should demonstrate the integrity of the structure and that doors remain operational.

MSHA did not receive any comments on this proposal. The final rule clarifies that a “test” be conducted. The final rule is substantively the same as proposed.

Final paragraph (b)(4) clarifies the proposal and requires inspections to determine that overpressure forces of 15 psi applied to the pre-deployed structure for 0.2 seconds do not prevent the stored components from operating. This provision helps assure that stored components are capable of withstanding an initial explosion and will function as intended following an explosion.

One commenter supported and no commenters opposed the proposal. The final rule clarifies that an “inspection” be conducted and makes an editorial change. The final rule is substantively the same as proposed.

Final paragraph (b)(5) clarifies the proposal and requires an inspection to determine that a flash fire of 300 °F for 3 seconds does not prevent the stored components from operating. This provision helps assure that stored components are capable of withstanding a flash fire and will function as intended following a flash fire.

One commenter supported and no commenters opposed the proposal. The final rule clarifies that an “inspection” be conducted. The final rule is substantively the same as proposed.

Final paragraph (b)(6) clarifies the proposal and requires a test to demonstrate that each structure resists puncture and tearing when tested in accordance with ASTM D2582-07 “Standard Test Method for Puncture-Propagation Tear Resistance of Plastic Film and Thin Sheeting.” This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above address or at 610-832-9585 (phone), 610-832-9555 (fax), or

service@astm.org

(e-mail); or through the ASTM Web site (

http://www.astm.org

). A copy may be inspected at any MSHA Coal Mine Safety and Health district office, or at MSHA's Office of Standards, 1100 Wilson Blvd., Room 2353, Arlington, Virginia, 22209, or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to:

http://www.archives.gov/federal_register/code_of_federal _regulations/ibr_ locations.html.

This requirement assures that the material used to make the refuge alternative is capable of withstanding the harsh mining environment and

abrasion, tears, and punctures which might result during handling, transportation, and deployment. This especially applies to inflatable-type refuge alternatives and tent refuge alternative structures. These materials must be capable of maintaining a secure space without compromising the interior atmosphere of the refuge alternative.

One commenter supported and no commenters opposed the proposal. The final rule clarifies that a “test” be conducted. The final rule is substantively the same as proposed.

Final paragraph (b)(7) clarifies the proposal and requires a test to demonstrate that each reasonably anticipated repair can be completed within 10 minutes of opening the storage space for repair materials and tools. MSHA is concerned that inflatable-type refuge alternative structures have the potential to be ripped, torn, or develop a leak. A leak or tear must be repaired without delay to avoid jeopardizing the safety of persons occupying the refuge alternative. The atmosphere of a refuge alternative must remain isolated at all times. The test would demonstrate that a miner would be able to make a repair such as mending a tear or resealing the fabric within 10 minutes of opening the storage space.

Some commenters questioned whether a person could repair the refuge alternative structure within 10 minutes. A commenter stated that the manufacturer cannot guarantee any particular time frame for repairs, especially during an emergency, and that mandating a time limit is neither practical nor enforceable.

MSHA recognizes there may be differences in refuge alternatives, and, hence, in refuge alternatives' repair procedures. This requirement in included in the final rule in recognition of the limited time available, to repair a structure or to re-establish a secure space between the interior and exterior atmospheres of the refuge alternative to maintain a breathable air atmosphere. Training requirements for miners for refuge alternatives, which are addressed in part 75, must cover repairs. Training will help prepare miners for the possible need to repair a refuge alternative after a protective isolated atmosphere has been established. After considering the comments, the final rule clarifies that a “test” be conducted, but the final rule is substantively the same as the proposal.

Final paragraph (b)(8) clarifies the proposal and requires a test to demonstrate that no harmful gases or noticeable odors are released from nonmetallic materials before or after the flash fire test. It also requires a test to identify the gases released and determine their concentrations. This requirement assures that the nonmetallic materials will not emit odors that may sicken persons occupying the refuge alternative. Noticeable odors also might indicate that a material is giving off vapors or gas. Although a noticeable odor may not be objectionable, it could still be harmful. Testing should include instruments used for detecting any released gases. Nonmetallic materials such as paints, plastics, and fiber that are used in the manufacturing of the refuge alternative structure should not release harmful fumes, vapors, or gases.

One commenter stated that, when the refuge alternative is stored, only the externally exposed components need to be tested for toxic gases when exposed to a flash fire test. This commenter suggested that the final rule clarify that requirement only applies to materials potentially exposed to flash fires in the stored configuration.

MSHA expects that a number of different types and combinations of refuge alternatives and components will be used, and that some of these will likely be stored inside the structural components. Testing would address the interior materials and components to assure that they do not release harmful fumes, vapors, or gases under normal conditions. An inspection must be performed to determine that no harmful gases or harsh odors are released from nonmetallic materials after the flash fire test. A properly designed system also would control heat penetration inside the refuge alternative to protect the components and materials in the interior of the refuge alternative.

The Agency agrees with the commenter that the flash fire test would be performed on a stored refuge alternative and its components with the contents of the refuge alternative inside. However, the contents of a refuge alternative should remain inside the refuge alternative when a test is performed.

The final rule clarifies that an “inspection” be conducted after the flash fire test. The final rule is substantively the same as the proposal.

Final § 7.505(c) makes an editorial change, but is substantively the same as the proposal, and provides requirements for pressurized air if it is used to deploy the structure or maintain its shape. Final paragraph (c)(1), like the proposal, requires a pressure regulator or other means to prevent over-pressurization of the structure. Over-pressurization of the interior space or airlock space would create a safety hazard. The regulator must be designed to assure that effective relief of overpressure can be accomplished.

Final paragraph (c)(2), like the proposal, requires a means to repair and re-pressurize the structure in case of failure of the structure or loss of air pressure. If the inflatable-type refuge alternative is damaged or leaks, it will need repair and additional compressed air to re-establish the pressure and volume of air that was lost.

One commenter supported and no commenters opposed the proposal. The final rule remains the same as the proposal.

Final § 7.505(d)(1) makes an editorial change, but is substantively the same as the proposal, and requires that the refuge alternative structure provide a means to conduct a preshift examination of the components critical for deployment, without entering the structure. This requirement assures that necessary inspections can be performed to identify problems that may occur in case of an emergency. The gauges and controls for critical components, such as compressed air and oxygen, should be easy to observe to determine the readiness of those components.

Some commenters supported the proposal. Other commenters opposed it, stating that the final rule should require that a preshift examination be conducted inside the refuge alternative to examine critical components.

MSHA does not encourage entering a refuge alternative for pre-shift examinations. The Agency believes that the structure should be designed so that components critical for deployment, such as gauges and controls, can be easily observed externally. After considering the comments, the final rule remains substantively unchanged from the proposal.

Final paragraph (d)(2), like the proposal, requires that the refuge alternative structure provide a means to indicate unauthorized entry or tampering. This requirement assures that a refuge alternative is intact and ready for use, if necessary.

One commenter supported the proposal. Another commenter requested that the proposal be changed to permit operators to enter the refuge to examine the cylinders on a regular basis, and that there should be a requirement for a means to detect tampering with components and materials stored inside the refuge.

As stated in the proposal, tamper-proof seals are necessary and must be provided for visual indication of unauthorized entry into the refuge alternative. This deters tampering with

or pilfering of the contents of the refuge alternative. Refuge alternatives would need to be designed so that if examination or repair requires entry into the refuge alternative, then the seal or other means can be replaced. The final rule remains unchanged from the proposal.

Section 7.506 Breathable Air Components

Requirements in this section assure that there is adequate breathable air inside the refuge alternative because maintaining breathable air inside the refuge alternative is vital to sustain persons trapped underground. The Agency recognizes that different types and combinations of breathable air components from several manufacturers may be used to provide breathable air for refuge alternatives.

Final § 7.506(a), clarifies the proposal and requires that breathable air must be supplied by compressed air cylinders, compressed breathable-oxygen cylinders, or boreholes with fans installed on the surface or compressors installed on the surface. The final rule clarifies MSHA's intent that fans or compressors installed on the surface are to be used with boreholes. In addition, the final rule contains an editorial change, but remains substantively unchanged from the proposal. It requires that only uncontaminated breathable air be supplied to the refuge alternative. These final requirements assure that the breathable air component is reliable and ready to be deployed and used.

One commenter stated that specific approval requirements could stifle innovation and technological advances, and that MSHA should follow a performance-oriented approach and specify only the quantity and quality of air or oxygen entering the shelter. MSHA is promulgating this final rule to implement the MINER Act's goal related to the maintenance of individuals trapped underground in the event that miners are not able to evacuate the mine. To achieve this goal, the Agency's final rule must provide requirements that assure that refuge alternatives will operate effectively. To allow for innovations in technology, the Agency has developed a final rule that is largely performance-oriented. Under the final rule, applicants have a variety of options for developing refuge alternatives that will maintain trapped miners. In addition, final § 7.510 allows MSHA to approve refuge alternatives and components that incorporate new technology if the applicant demonstrates that the refuge alternative or component provides at least the same level of protection as those meeting the requirements of Subpart L—Refuge Alternatives.

One commenter observed that, in at least two mines outside the United States, operators had installed backup systems for providing breathable air. Another commenter also supported backup systems for providing breathable air. While the final rule does not require the use of a secondary, independent breathable air component (a backup system), operators are encouraged to provide backup breathable air systems for use with refuge alternatives.

One commenter suggested that the final rule include an option that would permit mines with existing exhaust ventilation systems to ventilate through boreholes to provide breathable air in the refuge alternative. The final rule does not permit this type of option because it is not reliable. Breathable air systems must be able to operate following an explosion or fire. Main mine fans are sometimes damaged by explosions and may not be operable following an explosion or fire.

Final § 7.506(b) clarifies the proposal and provides requirements that assist MSHA in evaluating the effectiveness, compatibility, and supply of the breathable air component. The final rule, which is substantively the same as the proposal, states that the procedures must be “included” rather than “followed”.

Final paragraph (b)(1) requires that mechanisms be provided and procedures be included so that, within the refuge alternative, the breathable air will sustain each person for 96 hours.

Several commenters requested an explanation with respect to the requirement for providing 96 hours of breathable air, some stating that 48 hours of breathable air would be sufficient. Other commenters supported the 96-hour requirement.

Each mine emergency is a unique event and it is impossible to predict with precision the period of time required to maintain miners prior to rescue. To provide for an added margin of safety, the Agency has determined that it is necessary to require a 96-hour supply of breathable air. The 96-hour supply of breathable air in the final rule will assist the rescue effort by providing necessary time for rescuers to safely reach trapped miners. The depth of the mine, the geology of the overburden, and the terrain above the mine significantly affect rescue activities. Mine rescue protocol requires monitoring of mine atmospheres and assessing the risk prior to mine rescue teams entering the mine and making progressive steps underground toward trapped miners. Successful mine rescue progression often requires repairs to damaged infrastructure,

e.g.

, roof control systems, and ventilation controls. History has shown there can be delays associated with implementing successful mine rescue protocols and procedures that can delay reaching trapped miners.

In MSHA's February 8, 2007, PIB P07-03, the Agency stated that it considered 96 hours of breathable air to be necessary, and concluded that a 96-hour supply was warranted. In arriving at the 96-hour requirement in this final rule, MSHA reviewed recent and historical data on entrapments. While most safety and health professionals and researchers agree that refuge alternatives can sustain trapped persons, there is not general agreement on the amount of time that the refuge alternative should be capable of sustaining miners. After reviewing Agency data and comments, the Agency continues to believe that the 96-hour requirement is necessary and the final rule is the same as proposed.

Final paragraph (b)(2), like the proposal, requires that mechanisms be provided and procedures be included so that, within the refuge alternative, the oxygen concentration is maintained at levels between 18.5 and 23 percent. This requirement is consistent with the NIOSH report.

A commenter stated that the minimum oxygen level in refuge chambers should be 19.5 percent. Existing § 75.321 requires that the air in areas where persons work or travel must contain at least 19.5 percent oxygen. MSHA believes that the recommendation in the NIOSH Report for a minimum of 18.5 percent will be adequate to sustain miners in the isolated atmosphere of the refuge alternative. Like the proposal, the final rule includes a range for oxygen due to the variety of oxygen delivery systems used. Further, MSHA has included the upper limit to lessen the risk of fire or explosion.

MSHA believes that the atmosphere in refuge alternatives would experience levels of 18.5 percent only intermittently and of short duration and expects that the level of 19.5 percent would be available to persons for most of the time. Data show that short-term levels of 18.5 percent are not harmful to the persons who are normally at rest, not working, and are not likely to experience difficulty breathing, conditions that are likely to be present in the refuge alternative. The Foster

Miller Report

3

cites a large body of work, from a number of sources, indicating safe working levels for oxygen below 19.5 percent. Based on its review of comments and data, the Agency has kept the final rule the same as proposed.

3

Foster Miller.

Phase II Report,

Chapter 4, Table 2, page 3, December 2007; and U.S. Bureau of Mines.

Development of Guidelines for Rescue Chambers, Volume I,

Table 2, page 20, October 1983.

Final paragraph (b)(3) clarifies the proposal and requires that mechanisms be provided and procedures be included so that, within the refuge alternative, the average carbon dioxide concentration is 1.0 percent or less, and excursions do not exceed 2.5 percent.

MSHA calculated oxygen consumption rates for persons using a refuge alternative. Because most activity would involve sleeping or resting, and because a small amount of activity would involve taking readings or changing curtains, MSHA estimated activity levels of

4/5

of the time at rest and

1/5

of the time engaged in moderate activity. Oxygen consumption at the assumed breathing rate would be 1.32 cubic feet per hour per person (0.022 cubic feet per minute per person). These oxygen consumption rates were based on the U.S. Bureau of Mines, Foster Miller Report, “Development of Guidelines for Rescue Chambers,” Volume I, 1983.

In PIB P07-03, MSHA demonstrated the rate at which a person would experience adverse health effects from carbon dioxide if it were not removed from the environment. MSHA used air supply calculations and activity levels based on information provided in the Foster Miller report. The Agency used a hypothetical sealed space with a volume of 1,800 cubic feet (20 feet long, 18 feet wide and 5 feet high) that contained one person. The initial air quality was assumed to be 19.5 percent oxygen and 0.03 percent carbon dioxide, and the breathing rate (

4/5

of the time at rest and

1/5

of the time engaged in moderate activity) for oxygen inhaled is 0.022 cubic feet per minute per person.

For this example, MSHA found that one person could be maintained 49.5 hours in an 1,800 cubic foot enclosed space with an initial air quality of 19.5 percent oxygen and 0.03 percent carbon dioxide. This equates to 1.65 minutes per cubic foot of enclosed space (volume). Using these same parameters, 10 persons could be maintained for 4.95 hours before the carbon dioxide concentration reached the defined unacceptable level of 3 percent based on Peele Mining Engineers' Handbook and MSHA's current Short Term Exposure Limit. Further, under the circumstances, 10 persons would reach 10 percent carbon dioxide and resulting unconsciousness in approximately 16.6 hours.

One commenter stated that the MSHA requirement for carbon dioxide levels was too stringent and cited international standards that were 5 percent. Several commenters discussed the ill effects of high levels of carbon dioxide and supported MSHA's proposal.

The NIOSH report recommends that components operate to maintain carbon dioxide at or below the levels in the final rule (1 percent with excursions not exceeding 2.5 percent) and, based on a review of medical information, research, and accident experience, MSHA is aware of ill effects associated with exposure to concentrations of carbon dioxide greater than the levels in the final rule. MSHA reviewed international standards for safe levels of carbon dioxide and found none to be higher than 1.25 percent for extended periods. The concentrations of carbon dioxide in the enclosed atmosphere of a refuge alternative need to be within established limits to prevent debilitating or even lethal effects. Based on comment, data, and Agency experience, the final rule remains at 1 percent and excursions must not exceed 2.5 percent.

Final § 7.506(c) makes an editorial change, but is substantively the same as the proposal and requires that breathable air supplied by compressed air from cylinders, fans, or compressors provide a minimum flow rate of 12.5 cubic feet per minute (cfm) of breathable air for each person. Compressor air intakes should be installed and maintained to assure that only clean, uncontaminated air enters the compressors. In addition, compressors must have the capacity to deliver the required volume of air at the point of expected usage.

MSHA notes that the use of compressed air cylinders as the sole means of providing breathable air may be impractical and the Agency encourages mine operators to consider other options. As MSHA pointed out in PIB P07-03, when using a borehole to deliver sufficient quantities of breathable air, a fan or equivalent method should be used to force fresh air into the hole with enough positive pressure to overcome total mine pressure.

During the rulemaking process and at each public hearing, MSHA requested comments on the proposed flow rate and asked that commenters be specific including alternatives, rationale, safety benefits to miners, technological and economic feasibility, and supporting data.

Several commenters opposed the proposal. Some of these commenters stated that the minimum flow rate was too high. Other commenters requested clarification that the minimum flow rate only applied when carbon dioxide is not scrubbed. One commenter suggested that the manufacturer determine flow rate based on the refuge alternative design.

The minimum flow rate in this final rule is based on MSHA studies, comparisons with existing OSHA requirements, and engineering handbooks. MSHA has determined that the flow rate of 12.5 cfm is the minimum amount of air needed for respiration and dilution of carbon dioxide and other harmful gases. In addition, the 12.5 cfm flow rate assures positive pressure to prevent contamination from the mine atmosphere. This requirement applies to breathable air systems that do not incorporate carbon dioxide scrubbing components. The Agency's intent is for breathable air supplied by compressed air from cylinders, fans, or compressors to be used from the surface through a borehole or with an in-mine horizontal piping system that is protected from explosions. Based on comment, data, and Agency experience, the final rule remains the same as the proposal.

Final paragraph (c)(1), like the proposal, provides requirements for fans or compressors. In PIB P07-03, MSHA provided a number of recommendations that should be followed when compressors are used to provide breathable air underground. These recommendations would also apply when fans are used for the same purpose. MSHA recommended that compressor air intakes should assure that only clean, uncontaminated air enters the compressors.

Final paragraph (c)(1)(i), like the proposal, requires that fans or compressors be equipped with a carbon monoxide detector located at the surface that automatically provides a visual and audible alarm if carbon monoxide in supplied air exceeds 10 parts per million (ppm). This provision helps assure that harmful levels of carbon monoxide are not transferred into the refuge alternative. This requirement is the same as the carbon monoxide concentration in supplied breathable air from oil-lubricated compressors as established by OSHA in 29 CFR 1910.134(i)(7), which will maintain uniformity in requirements for the use of this specialized equipment. Although the NIOSH recommended value of maximum concentration of carbon

monoxide is 25 ppm, MSHA believes that, based on the Agency's experience, controlling supplied air delivered to a refuge alternative should contain no more than 10 ppm.

One commenter stated that a carbon monoxide detector should not be required when systems are not equipped with internal combustion engines. One commenter supported the proposed requirement for a carbon monoxide detector located on the surface.

The final rule, like the proposal, requires the use of carbon monoxide detectors when fans and compressors are used on the surface. The Agency recognizes that compressors or fans may operate in the vicinity of other equipment having gas or diesel engines and the carbon monoxide detector safety feature is necessary to assure the persons in the refuge alternative are delivered uncontaminated air.

Final paragraph (c)(1)(ii) merged proposed paragraphs (c)(1)(ii) and (iii) and requires fans or compressors to include in-line air-purifying sorbent beds and filters or other equivalent means to assure the breathing air quality and prevent condensation. Further, it requires maintenance instructions that provide specifications for periodic replacement or refurbishment. Sorbent beds and filters and maintenance instructions help assure that the air quality is maintained and condensation is prevented.

One commenter stated that purifying sorbent beds should not be required when systems are not equipped with internal combustion engines. Regardless of whether internal combustion engines are used, in-line air-purifying sorbent beds and filters or other equivalent means are necessary to assure the breathing air quality and to prevent condensation when fans and compressors are used on the surface.

Final paragraph (c)(1)(iii) is redesignated from proposed paragraph (c)(1)(iv) and clarifies that fans or compressors provide positive pressure and an automatic means to assure that the pressure is relieved at 0.18 psi, or as specified by the manufacturer, above mine atmospheric pressure in the refuge alternative.

Positive pressure in the refuge alternative that exceeds total mine pressure will prevent contamination and allow sufficient quantities of breathable air. An automatic means, such as a relief valve, must be provided to assure that the refuge alternative is not over-pressurized when breathable air is supplied. Excessive pressure creates adverse physiological effects. MSHA requested comments on the proposed setting for pressure relief and whether a higher pressure relief should be required.

Some commenters stated that the proposed relief pressure should be modified, especially with inflatable refuge alternatives. Some commenters noted that most steel-type refuge alternatives have pressure relief set at 0.25 psi.

The Foster Miller report specifies a minimum of 5 inches of water gauge overpressure in the refuge alternative which is equivalent to approximately 0.18 psi. Although most manufactured refuge alternatives presently have pressure relief valves set at 0.25 psi, too much pressure differential makes opening doors difficult for persons entering the refuge alternative. The final rule addresses all types of refuge alternatives and clarifies the required setting for pressure relief. For prefabricated units, the pressure must automatically be relieved at 0.18 psi, or as specified by manufacturer, above mine atmospheric pressure. For refuge alternatives consisting of 15 psi stoppings constructed prior to an event, the pressure must automatically be relieved at 0.18 psi above mine atmospheric pressure.

Final paragraph (c)(1)(iv), redesignated from proposed paragraph (c)(1)(v), requires that fans or compressors include warnings to assure that only uncontaminated breathable air is supplied to the refuge alternative. MSHA expects that the warning could be a highly visible tag or label affixed to the supplied air fans or compressors stating that only uncontaminated breathable air may be supplied to the trapped persons in the refuge alternative. Care should be exercised when using compressors in the vicinity of other equipment having gas or diesel internal combustion engines because these engines emit toxic gases, such as carbon monoxide, sulfur dioxide, and nitrogen oxides, which can contaminate the air being supplied by the compressor. In addition, compressors requiring oil can generate carbon monoxide (CO) which can be supplied inadvertently to miners. Oil-type compressors could be used; however, the air quality should be sampled and controlled using carbon monoxide filtration. Oil-less compressors that do not generate carbon monoxide do not require carbon monoxide filtering.

There were no comments related to the proposal. The final rule is unchanged from the proposal.

Final paragraph (c)(1)(v), redesignated from proposed paragraph (c)(1)(vi), requires that fans or compressors include air lines to supply breathable air to the refuge alternative. Final paragraph (c)(1)(v)(A) requires that air lines be capable of preventing or removing water accumulation. This requirement helps prevent the accumulation of water, which could affect the quantity and quality of breathable air provided underground. MSHA understands that coal mines are not entirely horizontal and may contain dips where water can accumulate in the piping. Moisture-laden air should not be piped into the area where miners are trapped. If moisture is not removed, water could accumulate in the refuge alternative. MSHA anticipates air dryers with drain valves will be used. In addition, air lines or pipes that are pre-installed should be capped to prevent the entry of rain or moisture-laden air. If horizontal air lines or pipes are used, they should be provided with a means to automatically drain any water accumulation.

One commenter requested that the proposal be modified to require the applicant to explain how preventing or removing water accumulation will be accomplished, if necessary, because many mines in the southwest desert do not have significant rainfall or humidity.

Regardless of the location of the mine, all compressed air systems must have moisture removal capabilities because all atmospheric air contains water vapor. During compression, air temperature is increased significantly, which allows the air to retain moisture. After compression, air is typically cooled reducing its ability to retain water vapor. A proportion of this water vapor condenses into liquid water which must be removed, for example, by a drain fitted to the compressor after-cooler. The final rule is the same as the proposal.

Under final paragraph (c)(1)(v)(B), air lines must be designed and protected to prevent damage during normal mining operations, a flash fire of 300° Fahrenheit for 3 seconds, a pressure wave of 15 psi overpressure for 0.2 seconds, and ground failure. This requirement provides protection for air lines that come from boreholes or air lines from the surface that are extended underground to a refuge alternative. Operators could achieve protection required under this final rule by burying pipes by through trenching. Trenching would have to be deep enough to protect the pipes from mine traffic, explosions, ground movement, or equipment damage.

One commenter supported the proposal, but stated that it may sometimes be impossible to protect air lines due to geologic conditions. MSHA recommended trenching and burying air

lines as one method of protecting air lines from damage; however, the final rule is performance-oriented, allowing other methods of protecting air lines to be used. The final rule remains unchanged from the proposal.

Final paragraph (c)(1)(vi), redesignated and the same as proposed paragraph (c)(1)(vii), requires that fans or compressors assure that harmful or explosive gases, water, and other materials cannot enter the breathable air. Harmful gases could contaminate filters or other components or collect in the equipment and affect the quality of the air being supplied to trapped miners.

There were no comments on this proposal and the final rule remains the same as the proposal.

Final paragraph (c)(2) clarifies the proposal and requires that redundant fans or compressors and power sources be provided to permit prompt re-activation of equipment in the event of failure. This requirement assures that breathable air will be maintained in the event of failure of one of the sources of breathable air. The final rule clarifies that redundant fans or compressors and power sources are required rather than a “redundancy of ” fans or compressors and “each power source” in the proposal.

There were no comments to this proposal and the final rule is substantively the same as the proposal.

Final paragraph (d), like the proposal, provides requirements for compressed breathable oxygen. Final paragraph (d)(1) requires that compressed breathable oxygen include instructions for activation and operation. This information will assure that persons activating and operating the cylinders have the proper information to correctly perform the task so as to not imperil the lives of persons within the refuge alternative.

One commenter suggested that the operating instructions cover adjustment of oxygen flow to prevent oxygen toxicity in the refuge alternative.

Under the final rule, instructions should include topics such as adjusting oxygen flow rates and checking for loose connections, sounds of leaking gas, damage to hoses along the length or at the fittings, and broken gauges. These instructions assure that compressed air tanks are secure and pressure regulators are properly set and that wrenches and pliers will be in proper working order. Instructions could be developed from sources such as ASTM Stock No.: MNL 36, “Safe Use of Oxygen and Oxygen Systems: Guidelines for Oxygen System Design, Materials Selection, Operations, Storage, and Transportation.”

The final rule remains the same as the proposed rule.

Final paragraph (d)(2), like the proposal, requires that compressed, breathable oxygen provide oxygen at a minimum flow rate of 1.32 cubic feet per hour per person.

One commenter supported the proposal, but requested clarification of the activity levels that MSHA relied on to support the proposed minimum flow rate.

MSHA relied on the activity levels stated in PIB P07-03, which contains breathing rates and calculations for persons who need to use a refuge alternative. No commenters opposed the proposal. The final rule remains the same as the proposed rule.

Final paragraph (d)(3), like the proposal, requires that compressed breathable oxygen include a means to readily regulate the pressure and volume of the compressed oxygen. Regulating compressed breathable oxygen is necessary to assure that oxygen levels remain within the recommended values. In addition, all oxygen valves should be opened slowly to prevent the oxygen from heating.

One commenter agreed and no commenters opposed the proposal. The final rule remains the same as the proposed rule.

Final paragraph (d)(4), like the proposal, would require that compressed breathable oxygen include an independent regulator as a backup in case of failure. It is crucial to maintain a continuous supply of breathable air to persons trapped underground.

Some commenters opposed the proposal. These commenters stated that backup regulators are not necessary because these devices have been used for decades with an excellent safety record and minimal failure. Some commenters also stated that the proposal would require additional piping and fittings which would increase the risk of oxygen leaks.

A backup regulator assures that breathable air will be maintained during an emergency. Based on MSHA's review of literature and system analyses, MSHA notes that there is the potential for failure and instances where regulators have failed. Persons who need to use the refuge alternative must be able to rely on oxygen regulators for survival. If a regulator fails during an emergency, it would take too much time and would be too difficult to repair and re-establish breathable air especially if persons inside the unit are injured. In addition, based on MSHA's review of costs, the Agency believes that the cost of a backup regulator is small compared to the cost of an entire unit. Further, the Agency believes that there is no additional risk of an oxygen leak because these regulators are safe to use and must be checked periodically to assure that they will function properly. Accordingly, backup regulators must be provided. The final rule remains the same as the proposed rule.

Final paragraph (d)(5), like the proposal, requires that compressed breathable oxygen be used only with regulators, piping, and other equipment that is certified and maintained to prevent ignition or combustion. A compressed breathable oxygen system should not be used with a previously used compressed air system because a fire or explosion could occur when pure oxygen contacts oil and grease from the previously used compressed air system.

One commenter supported the proposal. One commenter opposed the requirement for certified equipment and materials that are used downstream of the regulator because the equipment and materials carry oxygen that is not under high pressure and, therefore, is not a hazard. Based on MSHA's experience, the Agency believes that there is a risk of fire or explosion for all oxygen supply piping and equipment and, therefore, it is necessary that the equipment and materials be certified. The final rule remains the same as the proposal.

In the final rule, MSHA has moved proposed § 7.506(e) and (f) addressing carbon dioxide removal components' instructions and testing to final § 7.508(a), (b), and (c) addressing harmful gas removal components. This move places all the instructions and testing requirements for harmful gas removal in the same section (discussed later in this preamble).

The final rule does not include proposed § 7.506(g), which addressed the use of respirators as a breathable air component. Proposed paragraph (g)(1) would have required respirators or breathing apparatus to be NIOSH-approved with a means of flow and pressure regulation. Proposed paragraph (g)(2) would have required that respirators or breathing apparatus be equipped with fittings that connect only to a breathable air compressed line. Proposed paragraph (g)(3) would have required that respirators or breathing apparatus allow for communication, and the provision of food and water while preventing the entry of any outside atmosphere. Proposed paragraph (g)(4) would have required that respirators or breathing apparatus be capable of being worn for up to 96 hours.

Several comments opposed the use of respirators, citing uncertainties regarding the wearing of respirators for

prolonged periods. They also questioned how the respirator type system would provide refuge.

After reviewing the comments, MSHA considered possible adverse effects that might be associated with respirator use and determined that this provision should not be included in the final rule. The use of respirators for 96 hours may present medical problems, such as lung damage due to lack of humidity or poisoning due to skin exposure to toxic gases. In addition, the use of masks would require special individual fitting to prevent leakage. Further, injured persons may not physically be able to don the mask. Accordingly, the final rule does not include the use of respirators as a breathable air component.

Final paragraph (e) is redesignated from and clarifies proposed paragraph (h) and requires that an applicant prepare and submit an analysis or study demonstrating that the breathable air component will not cause an ignition. The final rule clarifies MSHA's intent that an analysis or study should evaluate the potential fire and ignition risks of breathable air components, equipment, or materials. Final paragraph (e)(1) requires that the analysis or study specifically address oxygen fire hazards and fire hazards from chemicals used for removal of carbon dioxide. Final paragraph (e)(2) requires that the analysis or study identify the means used to prevent any ignition source. These requirements minimize or prevent the inherent potential fire hazard from oxygen and the fire hazards from chemicals used for removal of carbon dioxide. Applicants should analyze inherent potential fire hazards and include a mitigation plan to minimize or prevent ignition of breathable air component equipment or materials.

One commenter supported the proposal, stating that the analysis should be completed to assure all potential fire and ignition risks are analyzed and addressed by design. Another commenter suggested that there should be a Material Safety Data Sheet (MSDS) on everything within the refuge alternative because MSDSs have all the information requested in a form familiar to users.

Under the final rule, fire and ignition hazards must be analyzed and addressed in the breathable air component design; however, applicants may provide MSDSs for persons using refuge alternatives. While the language has been changed slightly, the final rule requirements are the same as the proposal.

Proposed paragraph (i), concerning fire extinguishers, is moved to final § 7.504(c)(6).

Section 7.507 Air-Monitoring Components

Final § 7.507(a), like the proposal, requires that each refuge alternative have an air-monitoring component that provides persons inside with the ability to determine the concentrations of carbon dioxide, carbon monoxide, oxygen, and methane, inside and outside the structure, including the airlock. The ability to monitor these gases inside the refuge alternative is critical to the survival of persons occupying the refuge alternative. For example, monitoring methane minimizes possible oxygen deficiency or explosion. In addition, the ability to monitor the atmosphere outside the refuge alternative assists persons inside the refuge alternative in making crucial decisions regarding rescue and evacuation.

One commenter stated that the air monitoring component should be portable and permit use inside and outside the refuge alternative. The final rule does not specify that the air monitoring component has to be either portable or fixed nor does it state that only electronic type instruments be used. Any measurements taken outside the refuge alternative should be through ports that prevent contamination of the refuge alternative. Under the final rule, monitoring outside the refuge alternative should be periodic, as needed, and would not need to be continuous. Pumps attached to hoses could be used to safely draw samples from outside the refuge alternative.

One commenter supported the proposal to monitor the outside atmosphere while another commenter opposed the proposal, stating that persons should stay in the refuge alternative until rescued. MSHA believes that the measurement of the outside atmosphere will be important so that refuge alternative occupants will have necessary information to relay to rescuers on the surface and make crucial decisions regarding evacuation. MSHA reiterates the longstanding principle in mine rescue that miners should first attempt to evacuate the mine, and if evacuation is impossible, then retreat to the refuge alternative.

One commenter stated that part 75 did not have a comparable monitoring requirement. This is not correct; the emergency response plan provision in part 75 requires monitoring inside and outside the refuge alternative.

One commenter stated that the airlock monitoring requirement should be eliminated. The Agency believes that the monitoring of all the inside atmosphere, including the airlock, is necessary because persons occupying the refuge alternative will be accessing the airlock. The final rule remains as proposed.

Final § 7.507(b), like the proposal, requires that refuge alternatives designed for use in mines with a history of harmful gases, other than carbon monoxide, carbon dioxide, and methane, be equipped to measure those harmful gas concentrations. Some mines have a history of liberating harmful gases such as hydrogen sulfide, volatile hydrocarbons, or sulfur dioxide. The ability to detect and measure harmful gases is necessary for the safety of the persons using the refuge alternative.

A commenter requested that the final rule specify each gas that would need to be monitored because monitors are gas specific. Under the final rule, the Agency intends that refuge alternatives designed for use in mines with a history of harmful gases, other than those mentioned, must be equipped to measure the gases encountered. Manufacturers will know the conditions in the mines in which their refuge alternatives will be used. The final rule remains as proposed.

Final § 7.507(c), like the proposal, requires that the air-monitoring component be inspected or tested and the test results be included in the application. This requirement assures that the monitors or detectors are suitable for and will perform under mining conditions. Air monitoring component must be approved as intrinsically safe or permissible in accordance with the general requirements for approval of refuge alternative components under § 7.504(a)(1).

MSHA received no comments on the proposal. The final rule is the same as the proposal.

In the final rule, MSHA has included proposed § 7.507(d), addressing air-monitoring component approval numbers in the approval application, in final § 7.503(2)(i), which addresses application requirements.

Final § 7.507(d), redesignated from proposed § 7.507(e), like the proposal, addresses requirements for air-monitoring components. Final paragraph (d)(1) requires that the total measurement error, including the cross-sensitivity to other gases, not exceed ±10 percent of the reading, except as specified in the approval. Gas analyzer specifications under existing part 7, concerning diesel engine approvals under existing § 7.86(b)(9), specify the gas analyzer instrument error, including

cross-sensitivity to other gases, as ±5 percent. The ±10 percent accuracy in this final rule allows for random and systematic errors in measurement. It is important to control the measurement error and cross-sensitivity because of the uncertainty inherent with the instrument and measurement, and the need for reproducibility of the instrument measurements. This final requirement is necessary to assure the readings taken by persons in the refuge alternative verify that the air is breathable and does not have the potential for fires and explosions.

MSHA did not receive comments on this provision. The final rule remains the same as the proposal.

Final paragraph (d)(2), redesignated from paragraph (e)(2), like the proposal, requires that the measurement error limits not be exceeded after start-up, after 8 hours of continuous operation, after 96 hours of storage, and after exposure to atmospheres with a carbon monoxide concentration of 999 ppm (full-scale), a carbon dioxide concentration of 3 percent, and full-scale concentrations of other gases. Full-scale concentrations are those at the upper limit of the air monitoring instrument's capability to measure accurately within the instrument's error factor.

This requirement allows persons using gas monitors or detectors to determine accurate gas concentrations throughout the duration of occupancy in the refuge alternative and at different parameters such as startup, after 8 hours of continuous operation, during storage when continuously exposed to the maximum recommended gas concentrations, and at other concentrations much higher than the recommended maximum values. It takes into account the effects high gas concentration levels may have on these measurements over extended periods of time. For example, MSHA reviewed the ANSI standard for carbon monoxide detection instruments to evaluate the performance testing of instruments at different levels of carbon monoxide, including high levels.

A commenter stated that the proposed concentration of 999 ppm for carbon monoxide was too high and that the wording of the provision was unclear. MSHA reviewed data from previous accidents and found that a carbon monoxide concentration of 999 ppm may exist following an explosion or fire. It is necessary to evaluate the effects of the higher concentrations on the instruments because the higher limits may exist prior to purging the airlock. The carbon monoxide limit for the atmosphere inside the refuge alternative is 25 ppm. After considering the comments, the Agency has determined that the final rule should remain the same as the proposal.

Final paragraph (d)(3), redesignated from proposed paragraph (e)(3), like the proposal, requires that calibration gas values be traceable to the National Institute for Standards and Technology (NIST) “Standard Reference Materials” (SRMs). This requirement, which is based on existing § 7.86(b)(16), assures that the air-monitoring equipment is properly calibrated. The NIST SRMs are recognized and accepted industry standards. There were no comments to the proposal. The final rule is the same as the proposal.

Final paragraph (d)(4) merged proposed paragraphs (e)(4) and (e)(5) and requires that the analytical accuracy of the calibration gas and span gas values be within 2.0 percent of NIST gas standards. This requirement is based on existing § 7.86(b)(16) and (17), which also reference analytical accuracy of calibration gases within 2.0 percent of NIST gas standards.

There were no comments on the proposal. The final rule is substantively the same as the proposal.

Final paragraph (d)(5), redesignated from proposed paragraph (e)(6), like the proposal, requires that the detectors must be capable of being kept fully charged and ready for immediate use. This requirement assures that persons using refuge alternatives have detectors that are reliable and ready for use.

One commenter stated that keeping the detector batteries charged requires too much maintenance. The final rule requires that the methods of charging and calibrating be stated in the emergency response plan. It is imperative that the detectors be inspected and ready for immediate use in the event of an emergency that requires using the refuge alternative. After considering the comments, the final rule remains the same as the proposal.

Section 7.508 Harmful Gas Removal Components

Final § 7.508, like the proposal, provides requirements for harmful gas removal. Final paragraph (a)(1) requires that purging or other effective procedures be provided for the airlock to dilute the carbon monoxide concentration to 25 ppm or less and the methane concentration to 1.0 percent or less as persons enter, within 20 minutes of persons deploying the refuge alternative.

Some commenters opposed the 25 ppm carbon monoxide limit and suggested a limit of 50 ppm. One commenter stated that a 50 ppm level will reduce the required time in the airlock and allow persons to enter the refuge main chamber more quickly. This commenter added that further dilution will occur between the airlock and the main chamber of the refuge alternative estimating that the time it takes to reach 50 ppm will be 25 percent shorter than the time it takes to reach 25 ppm.

MSHA understands that the airlock may contain carbon monoxide concentrations as high as 50 ppm when persons are entering the refuge alternative. The carbon monoxide concentration of 50 ppm recommended by some commenters is generally based on an 8-hour exposure per day. However, after all persons have entered the refuge alternative, the interior of the refuge alternative, including the airlock, must be maintained at 25 ppm or less because, under the final rule, the airlock is usable space that persons may occupy. MSHA reviewed other standards pertaining to carbon monoxide exposure, and considered that persons could be entrapped for periods up to 96 hours. For these reasons, the final rule remains at 25 ppm for carbon monoxide, since the Agency believes that the interior space of the refuge alternative must be maintained at this level. This carbon monoxide limit is consistent with the NIOSH report. The methane concentration limit has been changed from the proposal to be consistent with existing standards governing methane limits.

One commenter stated that MSHA should clarify that purge air must be in addition to the 96 hours of breathable air that each person must have. Under the final rule, MSHA intends that the air that is used to purge the airlock must be in addition to the breathable air needed to sustain persons for 96 hours.

One commenter stated that the entire interior, and not just the airlock, should be purged. The final rule, like the proposal, provides that refuge alternatives should be configured to assure that the inside air is isolated from the mine atmosphere, which minimizes the quantity of purge air needed to purge the interior space. An airlock, which provides a transition area between the mine atmosphere and the refuge alternative's interior space, minimizes contamination of the interior space. Therefore, airlocks need to be capable of removing contaminants or configured in a way that assures that contaminated mine atmosphere is prevented from migrating through the airlock into the interior space of the refuge alternative. This requirement assures that contaminated air is forced

out of the refuge alternative. Purge air should be provided from compressed air cylinders.

Another commenter stated that purging the airlock within 20 minutes of persons activating the refuge alternative is an excessive amount of time. Based on MSHA's experience, the Agency believes that 20 minutes to purge the airlock and to establish a breathable air atmosphere is appropriate and necessary.

One commenter requested clarification of the initial concentration of methane so that purge air volumes can be computed. The final rule does not specify an initial concentration of methane, but the Agency expects that the initial test concentration, prior to purging, should be a minimum of 12 percent.

Another commenter stated that MSHA should specify that all flow rates be defined at “Standard Temperature and Pressure” (STP) conditions, “including the assumptions of CO

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production from humans.” The Agency contacted an author of the Foster Miller Report and determined that 60 °F was used as the standard temperature and that there is general agreement that 14.7 psi is the standard pressure at 1 atmosphere. Because approved permissible electrical components may be present in the refuge alternative, in the final rule, the proposed 1.5 percent concentration of methane was reduced to 1.0 percent to be consistent with existing § 75.323(b)(1)(i) and (ii).

Final paragraph (a)(2), like the proposal, requires that chemical scrubbing or other effective procedures be provided so that the average carbon dioxide concentration in the occupied structure does not exceed 1.0 percent over the rated duration and excursions do not exceed 2.5 percent. Carbon dioxide is an asphyxiant produced by human respiration. The carbon dioxide concentration limit is consistent with the NIOSH report.

To prevent the accumulation of harmful concentrations of carbon dioxide, scrubbing systems have been developed to chemically absorb the carbon dioxide. Carbon dioxide scrubbing systems may be active or passive. Passive systems rely solely on natural air currents for the air to react with the chemical bed. Passive system chemicals are usually packaged in curtains. These curtains would be suspended in the refuge chamber. Active systems force air through a chemical bed by fans or compressed air, and are generally more efficient than passive systems.

One commenter supported and no commenters opposed the proposal. The final rule is the same as proposed with one editorial change.

Final paragraph (a)(2)(i), redesignated from proposed § 7.506(e)(2), like the proposal, requires that carbon dioxide removal components be used with breathable air cylinders or oxygen cylinders. Carbon dioxide removal components must be compatible with the overall system for providing breathable air. The carbon dioxide removal systems are dependent on the occupancy and volume of the refuge alternative. The breathable air system is also dependent on those same factors.

One commenter supported and no commenters opposed the proposal. The final rule is the same as proposed.

Final paragraph (a)(2)(ii), redesignated from proposed § 7.506(e)(3), like the proposal, requires that carbon dioxide removal components remove carbon dioxide at a rate of 1.08 cubic feet per hour per person. As stated previously, MSHA is assuming that breathing rates for persons who have reached refuge alternatives reflect activity levels of

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at rest and

1/5

moderate activity. Therefore, using the respiratory quotient, which is the ratio of CO

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expelled to O

2

consumed, the average carbon dioxide generation is 1.08 cubic feet per hour per person. These breathing rates were based on the Foster Miller report.

One commenter supported and no commenters opposed the proposal. The final rule is the same as proposed with one editorial change.

Final paragraph (a)(3), redesignated from proposed § 7.506(e)(1), requires that harmful gas removal components must include instructions for deployment and operation. The final rule clarifies that instructions are required for harmful gas removal components, which include carbon dioxide removal components.

One commenter supported and no commenters opposed the proposal. The final rule is substantively the same as the proposal.

Final paragraph (b), like the proposal, addresses requirements for each chemical used for removal of harmful gas. Final paragraph (b)(1), like the proposal, requires that each chemical for removal of harmful gas be contained such that when stored or used it cannot come in contact with persons and it cannot release airborne particles. This provision is consistent with the NIOSH report which stated that the scrubbing material must not become airborne or otherwise cause respiratory distress or other acute reaction.

Because harmful gas removal chemicals are caustic, each would need to be contained. One way of packaging these chemicals is in curtains or cartridges that are isolated so that contact with or exposure to the chemicals is prevented. For example, commonly used CO

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removal systems include lithium hydroxide or soda lime curtains or soda lime cartridges. These curtains or cartridges assure that persons do not contact the caustic chemicals, which can cause burns. Chemicals must be activated without compromising the packaging materials and exposing persons to chemical hazards.

MSHA received no comments on this proposal. The final rule includes proposed § 7.506(e)(4), concerning carbon dioxide removal components, and contains editorial changes, but remains substantively the same as the proposal.

Final paragraph (b)(2) requires that each chemical used for removal of harmful gas be provided with all materials; parts, such as hangers, racks, and clips; equipment; and instructions necessary for its deployment and use. Depending on the type of CO

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removal system, instructions could include deployment and proper handling of materials. These instructions would assure that mine operators have the proper information to correctly perform tasks involving carbon dioxide removal components. This provision clarifies the proposal and will expedite deployment of the scrubbing system to reduce start-up time and make the system easy to use for the occupants. MSHA's intent is that the steps required to deploy the harmful gas removal component should not be difficult and should be designed on a per-person incremental basis to make the system easily understood by occupants.

MSHA received no comments on the proposal. The final rule includes proposed § 7.506(e)(1) and (5) concerning carbon dioxide removal components, but remains substantively the same as the proposal.

Final paragraph (b)(3), like the proposal, requires that each chemical used for removal of harmful gas be stored in an approved container that is conspicuously marked with the manufacturer's instructions for disposal of used chemicals. This requirement assures appropriate containment during shipping and storage. MSHA's intent is that an approved container is one that is accepted under general chemical industry practice and appropriate for pre-deployment transport and storage. Deployment and disposal instructions should be provided to assure persons are not exposed or otherwise injured while handling chemicals.

MSHA received no comments on the proposal. The final rule includes proposed § 7.506(e)(6) concerning carbon dioxide removal components, but remains substantively the same as the proposal.

Final § 7.508(c), like the proposal, provides requirements for testing each harmful gas removal component to determine its ability to remove harmful gases. Final paragraph (c)(1) requires that the component be tested in a refuge alternative structure that is representative of the configuration and maximum volume for which the component is designed. The requirement assures that the test results are representative of actual conditions.

A commenter stated that purging a contaminated space should not be an accepted practice unless the purging process can be proven totally effective at providing a safe, livable atmosphere for all of the occupants in every situation. Under the final rule, test results should confirm that purging or scrubbing is effective in removing harmful gases. If the data are from small-scale tests or prototype testing, interpretations and assumptions should represent full-scale performance.

One commenter supported the proposal. The final rule makes editorial changes, but is substantively the same as proposed.

Final paragraph (c)(1)(i), like the proposal, requires that the test include three sampling points located vertically along the centerlines of the length and width of the structure and equally spaced over the horizontal centerline of the height of the structure. The required sampling points assure an accurate representation of the gas concentration found in the middle of the structure as opposed to the ends, corners, top, sides, or bottom.

MSHA did not receive comments on the proposal; the final rule is the same as the proposal.

Final paragraph (c)(1)(ii), like the proposal, requires that the structure be sealed airtight. This requirement helps prevent contamination which could interfere with the testing. MSHA did not receive comments on the proposal; the final rule is the same as the proposal.

Final paragraph (c)(1)(iii), like the proposal, requires that the operating gas sampling instruments be placed inside the structure and continuously exposed to the test atmosphere. This requirement is necessary to assure that the instruments operate as designed in the actual space and representative atmosphere including higher temperatures and humidity.

A commenter stated that the electronics of some precision carbon dioxide analyzers can be affected by high temperature and humidity and can negatively impact analyzer accuracy. MSHA intends that the tests required by the final rule will verify the accuracy of the instruments in high temperature and high humidity to assure that measurements are accurate.

One commenter recommended that as an alternative, the final rule permit external analyzers and require that these analyzers have a response time of less than 1.5 minutes and that a minimum 99.5% of sampled gases be returned into the refuge alternative. An external analyzer would be inappropriate for tests requiring the monitors to be exposed to the inside atmosphere. However, an external analyzer would be acceptable as a supplemental testing instrument for this test. MSHA would allow for tests of gas monitoring components to be simultaneous with the harmful gas removal tests.

After evaluating the comments, MSHA has determined that the final rule should remain the same as the proposal.

Final paragraph (c)(1)(iv), like the proposal, requires that the sampling instruments simultaneously measure the gas concentrations at the three sampling points. Simultaneous sampling helps determine the interior atmosphere at different locations at a given point in time, eliminates any sampling variability introduced by sequential sampling, and determines if a homogenous atmosphere is maintained throughout the refuge alternative.

MSHA received no comments on the proposed provision; the final rule is the same as the proposal.

Final paragraph (c)(2) is substantively the same as the proposal and requires that when testing the component's ability to remove carbon monoxide, the structure be filled with a test gas of either purified synthetic air or purified nitrogen that contains 400 ppm carbon monoxide, ±5 percent. The final rule includes the ±5 percent to be consistent with final paragraph (c)(2)(i). The 400 ppm testing concentration was selected based on the American Conference of Industrial Hygienists (ACGIH) Short Term Exposure Limit (STEL). The test should determine the performance of the gas purification/decontamination system in achieving gas concentration level reductions for the entire ingress/egress process at maximum occupancy. MSHA received no comments on the proposal.

Final paragraph (c)(2)(i), like the proposal, requires that, after a stable concentration of 400 ppm, ±5 percent, carbon monoxide has been obtained for 5 minutes at all three sampling points, a timer be started and the structure purged or CO otherwise removed. The stabilization of the concentration will assure that gas is distributed throughout the structure and the test is properly performed.

MSHA received no comments on the proposed provision; the final rule is the same as the proposal. Comments related to the ending concentration were addressed earlier in the harmful gas removal section.

Final paragraph (c)(2)(ii), like the proposal, requires that the carbon monoxide concentration readings from each of the three sampling instruments be recorded every 2 minutes. This requirement assures that there are sufficient data points to constitute a valid test. Recording should continue until stabilization is reached at the lowest concentration.

MSHA received no comments on the proposed provision; the final rule is the same as the proposal.

Final paragraph (c)(2)(iii), like the proposal, requires that the time be recorded from the start of harmful gas removal until the readings of the three sampling instruments all indicate a carbon monoxide concentration of 25 ppm or less. This requirement assures that the time to remove carbon monoxide and deploy the refuge alternative is less than the time to deplete the SCSR. All occupants should be able to be located safely inside the refuge alternative prior to depletion of their SCSRs.

Comments related to the 25 ppm concentration were addressed earlier in this section. The final rule makes editorial changes, but is substantively the same as the proposal.

Final § 7.508(c)(3), redesignated from proposed § 7.506(f), requires that the carbon dioxide removal component be tested to demonstrate that it can maintain average carbon dioxide concentration at 1.0 percent or less, with excursions not to exceed 2.5 percent under the following conditions: (i) at 55 °F (±4 °F), 1 atmosphere (±1 percent), and 50 percent (±5 percent) relative humidity; (ii) at 55 °F (±4 °F), 1 atmosphere (±1 percent), and 100 percent (±5 percent) relative humidity; (iii) at 90 °F (±4 °F), 1 atmosphere (±1 percent), and 50 percent (±5 percent) relative humidity; (iv) at 82 °F (±4 °F), 1 atmosphere (±1 percent), and 100 percent (±5 percent) relative humidity. MSHA uses the standard error terminology of ±5 percent, but recognizes that +5 percent does not apply to relative humidity at 100 percent. This requirement is consistent with the NIOSH report.

Some CO

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scrubbing components may not perform as well as others. The most commonly used CO

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scrubbing chemicals performed within an acceptable range in underground mines. Testing under final paragraphs (c)(3)(i) through (iv) represents extreme conditions that CO

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scrubbing components may be exposed to in underground coal mines. The increased temperature and humidity ranges reflect increases in the occupancy of a refuge alternative, although MSHA assumes that some body heat and moisture generation will be dissipated through the refuge alternative into the mine air, roof, ribs, and floor. Testing and evaluation of the CO

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scrubbing components will enable mine operators to make informed choices in selecting scrubbing components.

One commenter stated that there is difficulty in controlling humidity to these extremely tight tolerances and that there is difficulty in measuring relative humidity to the required level of precision in the proposed rule. The commenter added that very high quality chilled mirror humidity sensors are typically unable to measure 100 percent relative humidity to 5 parts in 1,000. Other comments included questions concerning the temperatures and if they were starting values only, and if the four temperatures were to be maintained throughout the test. Another comment recommended that the requirements specify that the addition of water vapor into the testing chamber be maximized at the metabolic rate being simulated.

The proposed tolerances for humidity were based on an instrument specification and not a measurement specification. However, based on comments, MSHA believes that there could be difficulty in measuring relative humidity to the proposed level of precision. Therefore, MSHA has changed the proposed tolerances for relative humidity to ±5 percent.

Under the final rule, MSHA has not changed the proposed tolerances for temperature. Temperature must be measured inside the refuge alternative, and held constant within the tolerances of ±4 °F. Tests should simulate the occupancy and accurate metabolic rates per number of persons.

Final paragraph (c)(4) is new and requires that testing demonstrate the component's continued ability to remove harmful gases effectively throughout its designated shelf-life, specifically addressing the effects of storage and transportation.

One commenter requested that the harmful gas removal component be subjected to shock testing prior to approval. In response to this comment, MSHA believes that there may be potential chemical degradation associated with time, transport, and environmental conditions. The final rule, however, does not include a specific requirement for shock testing. Instead, it includes a performance-oriented requirement that testing demonstrate the component's continued ability to remove harmful gases effectively throughout its designated shelf-life.

Final paragraph (d), like the proposal, provides that alternate performance tests may be conducted if the tests provide the same level of assurance of the harmful gas removal component's capability as the tests specified in this final rule. If the applicant plans to use alternate tests, they must be specified in the approval application. The applicant must demonstrate that the alternate tests will assure the same degree of protection as that provided in this final rule. There were no comments on the proposal; the final rule is the same as the proposal.

Section 7.509 Approval Markings

Final § 7.509(a), like the proposal, requires that each approved refuge alternative or component be identified by a legible, permanent approval marking that is securely and conspicuously attached to the component or its container. The marking should be placed to avoid damage or removal.

Final § 7.509(b) clarifies the proposal and requires that each approval marking be inscribed with the component's MSHA approval number, and any additional markings required by the approval. The final rule clarifies MSHA's intent that the approval marking be “inscribed with the component's MSHA approval number” rather than “include the refuge alternative's and component's MSHA approval number”. In addition, the final rule does not include the proposed expiration date.

Final paragraphs (a) and (b) assure that only approved materials and components are used in refuge alternatives. MSHA did not receive any comments on the proposal. The final rule makes clarifications, but is substantively the same as the proposal.

Final § 7.509(c), like the proposal, requires that each refuge alternative structure provide a conspicuous means for indicating an out-of-service status, including the reason it is out of service. This requirement will provide information necessary for maintenance and repair.

MSHA did not receive any comments on the proposal. The final rule is the same as the proposal.

Final paragraph § 7.509(d), like the proposal, requires that the airlock be conspicuously marked with the recommended maximum number of persons that can use it at one time. This requirement assures that the airlock will be used as intended to allow safe passage of persons and to prevent any contamination of the interior space atmosphere.

MSHA did not receive any comments on the proposal. The final rule is the same as the proposal.

Section 7.510 New Technology

Final § 7.510, like the proposal, provides that MSHA may approve a refuge alternative or a component that incorporates new knowledge or technology, if the applicant demonstrates that the refuge alternative or component provides no less protection than those meeting the requirements of the final rule. Because some aspects surrounding the use of refuge alternatives involve developing technology, MSHA believes that innovations in technology will continue, resulting in further improvements in miner safety and health. The final rule would permit applicants to incorporate technological improvements so long as they provide equivalent protection to that in the final rule.

MSHA believes that credible scientific research supports the use of refuge alternatives. Refuge alternatives are technologically feasible. They use commercially available technology that can reasonably be integrated into most

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