May 2, 2024
In the matter of PETITION FOR MODIFICATION
Nevada Gold Mines LLC
Twin Underground Mine
Mine I.D. No. 26-02693 Docket No. M-2022-007-M
PROPOSED DECISION AND ORDER
On February 11, 2022, Nevada Gold Mines LLC (NGM), Mine I.D. No. 26-02693, filed a petition seeking modification of the application of 30 CFR § 57.11052(d) at its Twin Underground Mine in Humboldt County, Nevada. The petitioner alleges that the alternative method in the petition will at all times guarantee no less than the same measure of protection afforded to the miners by the standard.
The petitioned standard, 30 Code of Federal Regulations (30 C.F.R.) § 57.11052(d) –states, in relevant part,
Refuge areas shall be –
(d) provided with compressed air lines, waterlines, suitable handtools, and stopping materials.
Petitioner is requesting a modification of the standard to permit the use of sealed, purified drinking water in lieu of providing potable water through waterlines. The petitioner states that:
1. The Twin Underground Mine is an underground portal gold mine that began operating in 2011 and expects to continue mining for another 3 to 5 years. The mine is located 30 miles northeast of Golconda, Nevada, in Humboldt County, and the mine’s mailing address is 1655 Mountain City Highway, Elko, Nevada 89801.
2. The Twin Underground Mine currently has 5 refuge chambers located throughout the underground portion of the mine. In these refuge areas, drinkable water is currently supplied via commercially purchased water in sealed pouches.
3. At the present time, each refuge chamber is provided with a waterline. However, due to the configuration and condition of the waterlines and the quality of the water source, the water flowing through these lines is not potable. Installing waterlines that provide potable drinking water to each refuge chamber is not feasible due to the lack of essential infrastructure. Further, the waterlines may be susceptible to damage during certain mine emergencies, thus the water supply could be cut off completely. Given the suspect source of the water and the potential for waterline damage, there is no guarantee that potable drinking water can be provided via the waterlines, as required by 30 C.F.R § 57.11052(d). Application of the standard could adversely impact the safety of miners using the refuge area if they were to rely on the waterlines that run from the portal to the refuge chambers. The alternative method of storing sealed, purified water inside each refuge chamber provides certainty that miners will have sanitary drinking water available to them regardless of the current condition of the water supply or the nature of any emergency that might occur in the future.
4. The 5 refuge chambers at the Twin Underground Mine are portable. By allowing the use of refuge chambers that are not connected to waterlines, the mine will have greater flexibility in locating the refuge chambers. This will allow the refuge chambers to be located near where miners are working, and to be relocated more quickly to working areas where needed.
5. The mine seeks an alternative method of compliance with 30 C.F.R. §
57.11052(d) and proposes the following:
a) The refuge chambers in use at the Twin Underground Mine are MineARC refuge chambers and are made of steel. All the refuge chambers are equipped for a maximum capacity of 16 miners. This capacity exceeds the normal maximum work crew of approximately 20 miners underground on any given day during any shift.
b) Drinking water will be supplied via commercially purchased water in sealed individual portion-sized pouches in each refuge chamber. The water will be supplied by the case and packaged into 4.227-fluid ounce/125-milliliter portions with 50 individual portions per case.
c) While MSHA's standard at 30 C.F.R. § 57.11052(d) is silent on the amount of water required, MSHA's underground coal standard at 30 C.F.R. § 75.1507(d)(l) requires a minimum of 2.25 quarts of potable water per person per day for at least 96 hours (4 days). At present, the refuge chambers at the Twin Underground Mine are equipped for a maximum of 16 miners each, for a maximum of 36 hours. This includes a 36-hour supply of water in the amount of 2.25 quarts per day per person. The mine proposes providing this quantity of water in each refuge chamber, sufficient for 36 hours of shelter time.
d) The water will have a maximum shelf life of five years. The operator will replace the existing water supply with fresh water before the expiration date of the water. The condition and quantity of water will be confirmed by inspection, on no less than a monthly basis.
e) Written instructions for conservation of water will be provided with the refuge chamber supplies.
f) All miners affected will receive training in the operation of the refuge chambers and will receive refresher training annually.
g) The refuge chambers will be inspected monthly, and the inspections will be documented by the Mine Manager or his designee.
NGM requests this Petition for Modification apply to the existing refuge chambers and to future refuge chambers and locations. NGM asserts that the proposed alternative method will guarantee at all times no less than the same measure of protection as that afforded by the existing standard.
There are presently no miners’ representatives at the Twin Underground Mine. NGM posted a copy of the Petition on the mine’s bulletin board. It shall remain posted until the Petition becomes final. After the Petition was filed, NGM gave a copy of the petition to 18 miners, a mixture of supervisors and hourly personnel. All read the Petition and indicated by their signature that they had no comments or concerns.
Findings of Fact and Conclusions of Law
MSHA investigators conducted an investigation of the Twin Underground Mine Petition on
April 4, 2022. Yasser Akbarzadeh, MSHA’s Staff Assistant, met with Dayne Heese, the Health
& Safety Superintendent for NGM’s mining contractor Small Mines Development (SMD). The
Petition was reviewed the refuge chambers were inspected. During the period February 14-24, 2023, MSHA Safety Division Specialist Harvey Kirk followed up with NGM’s Safety and Health Manager, Michelle Matheus, via telephone conversations and emails.
The mining method at the Twin Underground Mine is mechanized, cut-and-fill stope mining. The mine employs a total of 76 miners, all of whom work underground. Approximately 25 miners are employees of Nevada Gold Mine and 51 are employees of contractor Small Mine Development. The mine works two, 12-hour shifts, seven days a week. Shift changes occur on the surface; the maximum number of miners underground on at any time dayshift, Monday through Thursday, is 20 persons, but normally there are only 18 miners. There are fewer miners on nightshifts and Friday through Sunday.
During the initial mine visit, the information provided by the mine operator was verified. Each of the refuge chambers is provided with a waterline, however the water has a light brown color and is not potable. The mine operator has in the meantime provided packaged purified potable water in each refuge chamber. The water packages are sized as individual portions and miners can drink from the containers without a cup.
The mine intends to preserve the existing waterlines, but not for drinking water provision. The waterlines may be used for firefighting, although they are not part of the mine’s firefighting plan.
In February 2023, the mine operator provided additional and updated information including mine life expectancy, workforce utilization and distribution, equipment list, refuge chamber’s original design, a mine map showing the current and projected work locations, and the locations of the refuge chambers. Although the mine may continue in operation for 3 to 5 more years, the company expects to discontinue mining in less than one year.
The normal underground workforce consists of 7 drivers, 4 production operators, 2 each mechanics/lubrication persons, drillers, geologists, and one surveyor. The geologists and surveyor are underground only about 30% of the workday. Mechanized equipment includes muckers, tractor buggies, bolters, drills, Skytrax, haul trucks, water trucks, and lubricant and powder trucks. Although some of the personnel and equipment are primarily working in or near the active headings, at any time during the workday, some of the miners and equipment are likely distributed at various locations throughout the mine. Table 1 shows the refuge chamber models, types and capacities.
| MineARC Model | Refuge Chamber Number | Capacity in Persons |
|---|---|---|
| MS-SDC-16-SIV-36 | MineARC 4500 | 16 |
| MS-SDC-16-SIV-36 | MineARC 4320 | 16 |
| MS-SDC-16-SIV-36 | MineARC 4560 | 16 |
| MS-SDC-16-SIV-36 | MineARC 4380 | 16 |
| MS-SDC-16-SIV-36 | MineARC 4140 | 16 |
The mine has a North Portal and a South Portal, and the respective elevations are 4,845 and 4,855 feet above sea level. The refuge chambers are located between 155 feet and 955 feet below the average portal elevation level at elevations 3,895, 4,105, 4,285, 4,526, and 4,695 feet above sea level. Distances from the refuge chambers to the exits range from 2,500 feet to 9,250 feet. Distances from the current work areas to the refuge chambers range from 1,550 feet to 2,650 feet.
All refuge chambers are portable. They are all equipped with gas monitoring equipment, packaged drinking water, oxygen bottles, backup compressed air sufficient to provide 36 hours of air to the rated maximum number of refuge chamber occupants (16 miners in each refuge chamber), toilet, radio, phone, air conditioning, blankets and food rations. The total capacity of the refuge chambers is 80 persons, which far exceeds the normal workforce underground. In the event of an emergency, the mine expects that some of the miners would be able to completely exit the mine. Also, due to limited workforce dispersal, not all miners would enter one refuge chamber. Therefore, there would be an excess of supplies available to those who remain inside the mine and take refuge.
When refuge chamber manufacturer Mine Safe designed the MineARC refuge chambers for this mine, the maximum expected shelter time needed was 24 hours. MineARC provided a 50% safety factor and designed for 36 hours of shelter time. It is not feasible to extend the refuge chambers’ shelter time beyond 36 hours because the batteries were originally sized for only 36 hours. If larger batteries could be procured from the manufacturer, it is doubtful if they could be delivered and installed before the mine’s expected closure date.
According to materials published by Mine Safe, the MineARC refuge chambers are also equipped with an electrical scrubbing system and pre-packaged MARCISORB chemical absorber cartridges to remove the buildup of harmful carbon dioxide (CO2) and carbon monoxide (CO) from the air inside the refuge chamber.
Concern about the condition of the mine’s water lines prompted MSHA to verify that the compressed air lines are in good condition, not susceptible to damage during mine emergencies, nor in danger of the air supply being cut off completely. The airlines now in use are hardpiped, one-inch inside diameter. If a refuge chamber is relocated, the mine plans to install additional hard air pipe to the new location, with the last portion of the line being a flexible hose.
The quality of compressed air was also investigated. Compressed air is produced by oil-lubricated compressors that have their air intake on the surface. The supplied air is breathable. Air passes through a MineARC CAMS (Compressed Air Management System), which consists of 4 filters: a water separator, a pre-filter, a coalescing filter, and an absorption filter. All filters are equipped with an auto-drain feature. The system also includes an air toxicity monitor. The compressed air system is inspected weekly, monthly, and every 120 days. During the 120-day inspection, the pre-filter, coalescing filter, and absorption filter are replaced, and the water separator is examined and is replaced if needed. All brass check valves are replaced during the 120-day inspection. The filter system inspection and maintenance schedule is per MineARC’s instruction, which has been tested to ISO 12500-1 (Filters for compressed air – Test methods – Part 1: Oil aerosols) and is designed to meet AS/NZS 1716:2003 (the Australian/New Zealand Standard for Respiratory protection devices).
MSHA verified that the scrubbers provided for the refuge chambers are properly equipped. The five, 16-person refuge chambers are each currently equipped with CO2 and CO scrubbers. The scrubbers are stocked to MineARC specifications and sufficient for 36 hours of use. Every refuge is equipped with a gas detection unit.
MSHA investigated ambient temperatures in the mine to determine if the mine’s depth might cause temperatures in the refuge chambers to be overly warm, and if so, require more than the proposed supply of 2.25 quarts of water per person per day. The mine stated that mine temperatures vary throughout the year depending on the surface temperature. The mine provided a July 2022 ambient temperature survey showing that temperatures in the refuge chamber areas usually varies between 72oF and 78oF. The temperature at the mine refuge chambers typically does not drop below 32oF, even during cold weather. The refuge chambers are equipped with temperature sensors that warn at 50oF and 32oF. The refuge chambers are equipped with air conditioning units that maintain the chamber’s internal temperatures at 86oF when at full capacity and running on battery power.
ORDER
Wherefore, pursuant to the authority delegated by the Secretary of Labor to the Administrator for Mine Safety and Health Enforcement 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 Nevada Gold Mines LLC’s Petition
for Modification for relief of the application of 30 C.F.R. § 57.11052(d) in the Twin Underground Mine is hereby:
GRANTED, for the operator to provide life sustaining potable water and life sustaining breathable air to all refuge areas including each existing refuge chamber, and all future newly constructed or repositioned refuge chambers. Potable water will be provided via commercially available packaged water, sealed in individually consumable portions. Life sustaining breathable air will be provided using compressed air supply lines, with backup oxygen provided in accordance with the specifications of a refuge chamber manufacturer that produces Part 7approved refuge alternatives, subject to the conditions of this Order:
TERMS AND CONDITIONS
Nevada Gold and MSHA agree to modify the standard 30 C.F.R. § 57.11052(d) at Nevada Gold’s Twin Underground Mine in Humboldt County, Nevada as follows:
1. This Order shall apply to the existing refuge chambers, to relocated refuge chambers and to future refuge chambers.
2. Refuge chambers shall accommodate the maximum number of persons that can be expected to be working in the mine at any time.
3. Each refuge chamber shall be supplied with water sufficient for the number of miners for which the refuge is designed, for up to 4 days.
4. Potable Water Supply:
a. Drinking water shall be provided via commercially purchased purified water in individual portioned packaged pouches.
b. Sufficient water shall be provided in each refuge area to provide 2.25 quarts of water for each person per day, for at least 4 days.
c. Water shall be stored in a manner that makes the expiration dates readily visible for inspection.
d. Water shall be exchanged with a fresh supply prior to the water manufacturer’s specified expiration dates, or at intervals not to exceed five years, whichever occurs first. If the expiration dates are not legible, or if they become illegible, the water shall be replaced by the end of the next working shift.
e. The condition and quantity of stored water shall be confirmed by inspection on at least a monthly basis, and the inspections shall be documented.
f. A weekly examination of the exterior of the refuge chamber shall be conducted to verify the condition of the compressed air line and its connection, roof and rib conditions, and for the presence of the tamper-evidence seals. If the refuge area is in an active work area, the exterior of the refuge chamber shall be inspected in the same manner as part of the regular workplace examination. If the tamper-evident seals are found to have been removed or broken, an examination of the interior of the chamber shall be conducted to assure the required amount of potable water is present. After the examination, a tamper-evident seal shall be replaced.
g. Written instructions for conservation of water shall be provided in the refuge chamber.
5. The mine shall leave existing waterlines in close proximity to refuge areas intact. The waterlines will be conspicuously labeled as “non-potable” and shall be maintained legible to miners.
6. Refuge chamber environmental systems shall be maintained in functional operating condition and inspected and maintained per the manufacturer’s specifications and instructions. These systems include but are not limited to; electrically powered scrubbing system MARCISORB chemical absorber cartridges, air conditioning units to maintain temperatures at 86°F when at full capacity and running on battery power.
7. Refuge chambers shall contain gas detection equipment capable of monitoring concentrations of oxygen, carbon dioxide, carbon monoxide, and other harmful gases specific to the mine. The detection equipment must be functional for up to 96 hours.
8. Training on refuge chambers and their environmental systems and instructions for use shall be provided for affected personnel at least semi-annually. Training shall include:
a. The hazards associated with insufficient and excessive concentrations of oxygen, carbon dioxide, carbon monoxide and other harmful gases specific to the mine,
b. The use of gas detector(s) to monitor concentrations of oxygen and potentially harmful concentrations of gases, and
c. The operation and chemical recharging of the refuge chamber’s interior atmosphere scrubbing and other environmental systems.
9. Applicable revisions or appropriate changes to the mine’s 30 C.F.R. Part 48 training plan regarding the conditions in this Order shall be submitted to the MSHA District Manager for revision and approval prior to implementation of the training plan by the Petitioner. Nevada Gold Mines LLC shall include the above terms and conditions in the initial and annual refresher training to ensure that miners are aware of the stipulations contained in this Order.
10. The mine shall comply with all other requirements of 30 C.F.R. § 57.11052 – Refuge areas.
Unless specifically mentioned herein, nothing in this Order changes or supersedes the requirements otherwise imposed by the Mine Act, other mandatory standards or regulations, or approved plans.
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 Mine Safety and Health Enforcement, 201 12th Street South, Arlington, Virginia 22202.
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 the 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 bulletin board at the mine.
__________________________________________
Brian Goepfert, Administrator for
Mine Safety and Health Enforcement
Certificate of Service
I hereby certify that a copy of this proposed decision was served personally or mailed, postage paid, or provided by other electronic means this ___2nd___day of _____May____, 2024 to:
Laura E. Beverage
Karen L. Johnston
Jackson Kelly PLLC
1099 18th Street, Suite 2150
Denver, CO 80202
lbeverage@jacksonkelly.com
kjohnston@jacksonkelly.com
Michelle Matheus,
Safety & Health Mgr.
Nevada Gold Mines LLC
1655 Mountain City Hwy
Elko, NV 89801
mmatheus@nevadagoldmines.com
___________________________
Michele Gussie
Secretary for Mine Safety and Health Enforcement