Petition - Docket No. M-2014-028-C

MAY 20 2015

In the matter of:                                                      Petition for Modification

Bridger Coal Company

Bridger Underground Coal

Mine I.D. No. 48-01646                                        Docket No. M-2014-028-C



PROPOSED DECISION AND ORDER



On August 19, 2014, a petition was filed seeking a modification of the application of 30 C.F.R. § 75.350(a) to the Bridger Coal Company's Bridger Underground Coal Mine (Bridger) located in Sweetwater County, Wyoming. The Petitioner alleges that "[a]pplication of the existing standard results in a diminution of safety to the miners and that the alternative method will at all times guarantee no less than the same measure of protection afforded by the standard." The standard for which the modification is requested states:



The belt air course must not be used as a return air course; and except as provided in paragraph (b) of this section, the belt air course must not be used to provide air to working sections or to areas where mechanized mining equipment is being installed or removed.



The Petitioner requests this modification of the application of 30 C.F.R. § 75.350(a) to allow the belt air course to be used as a return air course so that a two-entry system of longwall panel development can be utilized. The Petitioner also requests to use the belt air course for ventilating the longwall working section. Under 30 C.F.R. § 75.350(b), the District Manager has the authority to approve the use of air from a belt air course to ventilate a working section in the mine's ventilation plan if the requirements listed under 30 C.F.R. § 75.350(b) are met and justification is provided. One of the criteria, 30 C.F.R. § 75.350(b)(5), requires that the area of the mine with a belt air course must be developed with three or more entries. Therefore, should this petition be granted for the purpose of allowing two-entry development, the District Manager would not have the authority to grant approval to use air from the belt air course to ventilate the longwall working section and a granted petition for modification to do so becomes necessary.



The Petitioner alleges that "[t]he two-entry longwall development mining system reduces the exposure of the soft tertiary strata, roof falls, rib instability and other hazards related to mining under these conditions." The Petitioner states that a "2-entry system greatly reduces the number of 4-way intersections, a definite plus regarding ground control." The Petitioner also alleges the following: "Therefore, developing with additional entries to comply with isolation of the belt entry from a separate return entry

You can now file your MSHA forms online at www.MSHA.gov. It's easy, it's fast, and it saves you money! and diverting belt air directly into a return air course diminishes the safety of rruners as compared to utilizing the belt entry as a return air course during development mining. The use of the belt entry to aid in the ventilation of the working section will help in diluting and rendering harmless methane gas that is released in the mine atmosphere during the mining cycle."



Maleki Technologies, Inc. (Maleki) assisted the Petitioner with comparative convergence and pillar stability analyses of longwall gateroads using two-entry and three-entry systems. The objective was to quantify the stability advantages of an equivalent two-entry system using 160-foot wide pillars vs. the existing three-entry system using 80-foot and 60-foot wide pillars. According to Maleki's report submitted with the petition, "Bridger has been able to control overburden deformation through conservative gate pillar designs and controlled subsidence." The report also indicates that Bridger has realized some success in controlling roof movement by reducing entry widths from 20 feet to 17 feet. Maleki's report further indicates that rib control has not been problematic but problems are expected to increase in the neighboring Eastern District where cover exceeds 1,000 feet over the northern portion of the block. The analysis performed by Maleki was a direct comparison between two-entry and threeentry systems with the same width across the development, and factored out any effects in strata arching or horizontal stress concentrations about the gateroads. In essence, Maleki's two-entry assessment used the same total development width as the threeentry system and removed the center entry, creating a larger pillar between the two remaining gateroad entries. The report also indicates that the existing layout is adequate under development and headgate loading conditions but the risk of pillar failure is significantly increased at the tailgate for the 60-foot wide pillar in the Eastern Mining District. The model used by Maleki predicts a higher rib loading and potential for rib failure for the existing system near the face areas, which will lead to greater convergence.



The alternative method proposed by the Petitioner addresses provisions related to AMS installation, rock dusting, air velocity in belt entries, fire doors, communication and tracking systems, firehose outlets, fire suppression systems, compressor placement, hydraulic fluid pump stations and related transformer stations, diesel equipment operation, diesel fuel storage, and training.



MSHA personnel conducted an investigation of the petition and filed a report of their findings and recommendations with the Administrator for Coal Mine Safety and Health. In October, 2014, the United Mine Workers of America (UMWA) filed comments on behalf of the miners. In these comments, the UMWA indicated that the petition should not be granted because the proposal is confusing and appears contradictory, does not provide adequate justification for using air from the belt air ( (course to ventilate the longwall working section, does not address permissibility in the belt air course, and does not guarantee the same measure of protection as provided by the standard. After a careful review of the entire record, including the petition, Maleki's report, comments provided by the UMWA, and MSHA's investigative report and recommendations, this Proposed Decision and Order is issued.



Findings of Fact and Conclusions of Law



According to the MSHA investigation, Bridger was opened in July, 2004, through three portal entries. The mine currently employs 230 underground miners and has a total employment of 250 persons. The mine is expected to remain operational until 2023.

Bridger mines coal from the D41 Coal Seam, which ranges in thickness from about 7 feet to 18 feet, and dips approximately 2.5 degrees. The average depth of overburden is approximately 600 feet.



Multiple entry mains and gateroads are developed with continuous mining machines. Mined material is transported to the loading point via electrically powered shuttle cars where the material is loaded onto, and transported out of the mine by way of, a conveyor belt haulage system. Bridger currently develops longwall panels utilizing a three-entry system. Diesel-powered equipment is used for transporting personnel and materials.



The mine is ventilated with one blowing fan producing approximately 393,600 cubic feet per minute of air at about 7.10 inches of water gauge. Total methane liberation air samples taken at the mine each quarter of calendar year 2014 was O cubic feet per 24 hours.

The MSHA investigation revealed that two-entry petitions have been granted for deep cover mines that are susceptible to rock and coal outbursts. The most recent such petition limited the use of the two-entry system to areas within the mine exceeding 1,000 feet of overburden depth due to the mine's susceptibility to rock and coal outbursts. The current average depth of overburden at Bridger is approximately 600 feet. The depth of overburden for mining projections to the east ranges from 280 feet to 900 feet. The depth of overburden for mining projections to the west ranges from 280 feet to 540 feet. The mine has not demonstrated susceptibility to rock and coal outbursts and the Petitioner has made no such claims relative to outbursts.



Developing gateroads with only two entries instead of using the current three-entry gateroad development system would reduce the exposure of roof and the number of four-way intersections. Visual observations made during the investigation revealed that the ribs were straight without any discernible convergence and the junctions between roof and ribs appeared stable in the current three-entry configuration. Currently, the mine is required to design longwall panels with an Analysis of Longwall Pillar Stability (ALPS) stability factor of 1.4 or greater for loading conditions. The Petitioner did not define the resulting required ALPS stability factors for the proposed two-entry system. According to the investigation, Bridger proposes to increase the size of the pillar between the two entries to improve ground control instead of using a smaller yield pillar for load transference. The Petitioner has not prepared any additional studies or research to show the effects on convergence realized by altering pillar sizes in the current three-entry development system, and has not employed other development strategies, such as staggering pillars, to avoid four-way intersections.



Bridger, due to the propensity for spontaneous combustion, employs a bleederless ventilation system for longwall mining to reduce the potential for spontaneous combustion. The two-entry system is not suited for the back-return longwall ventilation system employed at Bridger as part of the bleederless system. The back-return ventilation system is needed to maintain consistent acceptable air quality at the tailgate end of a longwall working section operating in a bleederless system. The back-return system is also necessary to maintain proper airflow direction away from the working face. If bleederless longwall panels at Bridger were to be mined in the traditional adjacent manner with only two development entries, there would be no open entry remaining between panels through which air that has ventilated the worked-out area on the tailgate end can course into and flow to dilute, render harmless, and carry away flammable, explosive, noxious, and harmful gases, dusts, smoke, and fumes.



Other considerations related to a two-entry system involve the limited routes of egress from longwall and developing working sections, including routes of egress for examiners should a blockage occur outby the examiner along an isolated examination route, and the potential for increased ground stress in the single tailgate entry of the longwall working section. 



The factors listed above, along with the petition and comments received from the UMWA, must be considered when determining whether the application of the existing standard results in a diminution of safety to the miners and whether the alternative method will at all times guarantee no less than the same measure of protection afforded by the standard .



The Petitioner requested a modification of the application of 30 C.F.R. § 75.350(a) so that a two-entry gateroad development mining system could be utilized for ground control purposes. Such petitions are typically granted for mines when the hazards and risks associated with rock and coal outbursts are greater than those associated with using the ( (belt air course as a return air course. Such mines are typically deep cover mines with depths exceeding 1,000 feet. Neither the Petitioner nor the MSHA investigation indicated that Bridger is susceptible to rock and coal outbursts and the mine is not currently one that is considered to be under deep cover. Maleki's report indicated that the existing layout is adequate under development and headgate loading conditions but the risk of pillar failure is significantly increased at the tailgate for the 60-foot wide pillar in the Eastern Mining District. The Petitioner did not include any additional studies or research to show the effects realized by altering pillar sizes in the current three-entry development system, and has not employed other development strategies, such as staggering pillars, to avoid four-way intersections. Maleki's analysis did not contemplate potential benefits related to altering pillar sizes in the current three-entry development system and/ or staggering pillars to reduce the number of four-way intersections. MSHA data indicates that there was one reported non-injury roof fall during the six-month period from October 8, 2014 to April 7, 2015. Over the four quarters from April 1, 2014 to March 31, 2015, Bridger's non-injury roof fall incident rate was 0.74, which is less than the national average of 1.06 over the same period of time. Under 30 C.F.R. § 75.223(a)(l), revisions to the roof control plan must be proposed "[w]hen conditions indicate that the plan is not suitable for controlling the roof, face, ribs, or coal or rock bursts." Pillar sizing and placement may need to be addressed in the roof control plan now or in the future should conditions warrant.



For the foregoing reasons, it has been determined that the Petitioner did not include sufficient evidence indicating that compliance with the standard presents a diminution of safety to the miners.



In a two-entry development system, the belt air course must be used as a return air course for the developing working section. The air entering the belt/ return air course will contain the coal dust and methane generated during the mining process. The conveyor belt and its components are subject to misalignment and malfunction, which are often sources of frictional heating leading to belt fires. If a belt fire was to occur, it would appear, at first glance, that having a fire in the return air course would be preferable because smoke would be coursed away from the working section. However, the same result can be achieved in a three-entry system by coursing the intake air ventilating the belt air course into the return air course at a location outby the loading point or by coursing intake air in an outby direction in the belt air course. These hazards must be weighed against the potential hazards presented by rock and coal outbursts or other ground control issues at the mine.



The effects of two-entry gateroad development on the ventilation system for which the gateroads are developed must also be considered. Gateroads are developed for the purpose of mining a longwall working section. A bleederless longwall mining system



has been employed at Bridger for controlling spontaneous combustion. The back-return used for ventilating the longwall working section is an important part of the bleederless system, and is needed to maintain consistent acceptable air quality and airflow direction away from the working face at the tailgate end. In a two-entry development system, there would be no open entry remaining between panels through which air that has ventilated the worked-out area at the tailgate end can course into and flow to dilute, render harmless, and carry away flammable, explosive, noxious, and harmful gases, dusts, smoke, and fumes. The use of a two-entry gateroad development system would be detrimental to the ability to effectively ventilate Bridger's bleederless longwall mining system, thereby providing less safety to miners than that which would be afforded by developing gateroads with three or more entries.



For the foregoing reasons, it has been determined that the Petitioner has not proposed an alternative method that will at all times guarantee no less than the same measure of protection afforded by the standard.



As to the request to utilize air ventilating the belt air course to ventilate the longwall working section, 30 C.F.R. § 75.350(b) grants the District Manager the authority to approve such use in the mine's ventilation plan provided all criteria under 30 C.F.R. § 75.350(b) are met and justification is provided. One of the criteria is that the area of the mine with the belt air course must be developed with three or more entries. Due to the foregoing determinations, a decision related to this request is not required. The District Manager retains the authority to grant approval in Bridger's ventilation plan for the use of air from the belt air course to ventilate a working section.



ORDER



Wherefore, pursuant to the authority delegated by the Secretary of Labor to the Administrator for Coal Mine Safety and Health, and pursuant to Section 101(c) of the Federal Mine Safety and Health Act of 1977, 30 U.S.C., § 811(c), it is ordered that Bridger Coal Company's Petition for Modification of the application of 30 C.F.R. § 75.350(a) to its Bridger Underground Coal Mine is hereby:



DENIED



Any party to this action desiring a hearing on this matter must file in accordance with 30 C.F.R. § 44.14, within 30 days. The request for hearing must be filed with the Administrator for Coal Mine Safety and Health, 1100 Wilson Boulevard, Arlington, Virginia 22209-3939.



If a hearing is requested, the request shall contain a concise summary of position on the issues of fact or law desired to be raised by the party requesting the hearing, including specific objections to the proposed decision. A party other than Petitioner who has requested a hearing may also comment upon all issues of fact or law presented in the petition, and any party to this action requesting a hearing may indicate a desired hearing site. If no request for a hearing is filed within 30 days after service thereof, the Decision and Order will become final and must be posted by the operator on the mine bulletin board at the mine.



/s/

Charles J. Thomas

Deputy Administrator for Coal Mine Safety and Health



Certificate of Service



I hereby certify that a copy of this proposed decision was served personally or mailed, postage prepaid, or provided by other electronic means this 20th day of

May , 2015, to:



James Poulson,

Safety Superintendent

Bridger Coal Company

1088 Nine Mile Road

Point of Rocks,

WY 82942



Don Braenovich

cc: Mr. Terry Adcock, State Inspector of Mines, State of Wyoming