Petition Docket No. M-2021-005-M

December 2, 2022

In the matter of                      PETITION FOR MODIFICATION
U.S. Silica Company
Pacific Plant
Mine I.D. No. 23-00544        Docket No. M-2021-005-M

PROPOSED DECISION AND ORDER

On December 10, 2021, U.S Silica Company filed an updated petition with the Mine Safety and Health Administration (MSHA) seeking modification of 30 Code of Federal Regulations (30 C.F.R.) § 56.13020 for the Petitioner’s Pacific Plant, MSHA I.D. No. 23-00544. The Pacific Plant produces crushed and broken sandstone in its nearby open pit mine, mills it into finely ground quartz and ships the finished product to customers. The mine and mill are located at 819 East Osage Road, Pacific, Franklin County, Missouri 63069. The Petitioner alleges that the alternative method, consisting of a clothes cleaning booth that uses regulated compressed air for
cleaning miners’ dust-laden clothing, will at all times guarantee no less than the same measure of protection afforded the miners by the standard.

The standard at 30 C.F.R. § 56.13020, Use of compressed air, provides:
At no time shall compressed air be directed toward a person. When compressed air is used, all necessary precautions shall be taken to protect persons from injury.

On June 14 and 23, September 20, and October 6, 2022, MSHA investigators met with Pacific Plant personnel at the plant’s Mine Safety Office to discuss the details and merits of the petition and inspect the subject clothes cleaning booth. Those present at the meetings and inspections were Alyssa Veit, U.S. Silica’s Pacific Plant EHS Manager and Kevin Martin, Miners’ Representative. Participating for MSHA were Mine Inspector Jeremy Kennedy and Field Office Supervisor Shawn Pratt, both of the Rolla, Missouri, Field Office. The MSHA investigators subsequently filed a report of their findings with the Administrator for Mine Safety and Health Enforcement (Administrator). After a careful review of the entire record, including the petition and MSHA's investigative report, the Administrator issues this Proposed Decision and Order.

Findings of Fact and Conclusions of Law
The proposed alternative method uses a standalone clothes cleaning system developed under a cooperative research effort between the Unimin Corporation and the National Institute for Occupational Safety and Health (NIOSH).

Studies have shown that when an ore containing quartz or silica-bearing material is milled, work clothing becomes contaminated with respirable dust. Once a worker's clothing is contaminated, it continuously emits dust, exposing workers to high levels of respirable silica. Dust emission and exposure continues until the worker cleans or changes his/her clothing.

According to NIOSH, using compressed air inside a properly designed and operated clothes- cleaning booth (booth) can quickly, effectively, and safely remove dust from a worker's clothing without further exposing the worker, co-workers, or the work environment during the cleaning process. NIOSH has determined that a minimum of 2,000 cubic feet per minute (cfm) airflow is necessary to maintain sufficient negative pressure inside a 48-inch by 42-inch booth throughout the entire clothes cleaning cycle. MSHA’s Directorate of Technical Support has advised that airflow through the booth can be measured by using a high-speed anemometer at the exhaust pipe outlet, or by using a pitot tube inserted in or a velometer tapped into a straight section of the discharge pipe downstream of the exhaust from the HEPA filter system. The booth manufacturer has advised that negative pressure can also be measured by using a differential pressure gauge. Before a booth is initially placed in operation, the user must measure and record air flow and booth negative pressure as a reference for the future, and to assure that the negative pressure switch is functioning and properly calibrated.

NIOSH has further determined that, to ensure worker safety while using the booth, air pressure delivered to the nozzles must be regulated to not exceed 30 pounds per square inch (psi). In addition, workers must wear personal protective equipment including a half mask, fit-tested respirator with an N95 filter, or better, hearing protection, and at a minimum, plant-standard eye protection. Standard eye protection worn during normal work in the Pacific Plant consists of safety glasses with side shields. Additional eye protection, such as safety glasses, is not required for an employee using a full-face respirator. When the clothes cleaning booth is built according to specifications, operated under negative pressure and according to NIOSH’s and the booth manufacturer’s instructions, all dust removed from workers’ clothing is contained and HEPA- filtered, and clean air is exhausted either to a Local Exhaust Ventilation (LEV) system or to the outside through an exhaust stack.

The Pacific Plant employs approximately 53 persons, of which 7 work in the quarry, 35 work in the mill, and 11 persons are office workers. The employees are represented by two labor unions, the Laborers Union of North America, Local No. 110, and Pacific Engineers Local 513. MSHA investigators determined that the plant operator had posted a copy of the petition on the bulletin board in the employees’ break room and personally notified the Miners Representative. Plant supervisors who were interviewed and the Miners’ Representative all stated that they had no objection to the petition and that they believe that the alternative method will provide no less than the same measure of protection as the standard and will improve safety and health for the miners.

Inspection of the booth determined that U.S. Silica had installed the equipment as designed and instructed by manufacturer S. K. Bowling Co. of Wilson, North Carolina, and in accordance with the terms and conditions as proposed in the petition for modification. (See cleaning booth diagrams in Appendices A and B). The unit was operationally tested and key performance parameters were checked and verified as meeting NIOSH’s and the manufacturer’s design specifications.

Specifically checked and verified were:
1. a fan has been provided to continuously move contaminants away from the user’s breathing zone. The fan, which is located at the booth’s ceiling level, draws fresh intake air in through an opening at the top of the booth, forces it downward through the booth and to the airflow exit in the floor. The fan is driven directly from its motor to prevent reduction or variation in fan speed and airflow loss,

2. airflow through the booth was measured on November 2, 2022, using a rotating vane anemometer and determined to be 2,832 cfm, which is well above the required minimum airflow of 2,000 cfm. This measurement also verifies that the manufacturer-provided negative pressure switch which is designed to prevent activation of the air spray manifold unless an acceptable negative pressure is maintained within the cleaning booth, is functioning properly and is properly calibrated.

3. the booth’s filtered air exhaust vent is directed away from the booth’s fresh intake air opening to prevent the possibility of potentially dust-laden air being drawn into the booth,

4. the cleaning air spray manifold is constructed of Schedule 80 steel pipe with a failure rating of 1,300 psi,

5. the manifold is capped at the base and actuated by an electrically controlled ball valve at the top; air pressure through the manifold and at the spray nozzles is limited to a maximum of 29 psi by two regulators arranged in parallel,

6. the regulators are locked to prevent tampering or changing their setting, and the keys are controlled by the plant manager,

7. the uppermost portion of the spray manifold is located below the average user’s breathing zone,

8. the air nozzles mounted on the manifold are shielded on the sides to prevent damage from inadvertent contact during use,

9. a sliding mechanical device is provided to cover the upper air nozzles to adjust the air spray to the specific height of each individual user,

10. the unit’s manufacturer-supplied 240-gallon air receiver tank is sized to:
a. supply a minimum of 20 seconds of continuous air flow, more than enough to supply the 10 to 18 seconds of continuous air flow that NIOSH and the manufacturer state is needed to clean the average miner’s clothes,
b. supply sufficient compressed air for two successive cleanings without a delay to recharge the receiver. This is predicated on a supply of compressed air at a minimum of 90 psi,

11. the air receiver is equipped with a pressure relief valve,

12. an in-line filter is provided between the air receiver and the manifold to remove any moisture from the air, and to protect users from any debris that might be entrained in the compressed air stream,

13. the booth is equipped with a pressure control switch that guarantees sufficient air flow is present to maintain a 0.2 psi negative pressure inside the booth when the cleaning cycle is actuated,

14. the booth is equipped with a control panel with four operator controls:

a. a switch that turns on the interior light and starts the exhaust fan,
b. a “system ready” light that verifies the ceiling fan is operational and providing the correct airflow in the booth, and that sufficient compressed air is available for cleaning,
c. a pushbutton operated by the user to confirm that he/she is wearing the proper personal protective equipment, and
d. a pushbutton to start the cleaning cycle. The booth’s cleaning cycle shuts down automatically after 18 seconds,

15. signs have been posted at the entrance of the booth warning of “Compressed Air” and “Respirable Dust”, and

16. the mine operator has revised its Part 46 Training Plan to include in its New Miner, Experienced Miner, Annual Refresher and Task Training, the manufacturer’s clothes cleaning booth instruction manual, and NIOSH’s Clothes Cleaning Process instruction manual.
The alternative method proposed by the Petitioner, together with the terms and conditions below, will at all times guarantee no less than the same measure of protection afforded the miners under 30 C.F.R. § 56.13020.

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:
U.S. Silica Company's petition for modification of the application of 30 C.F.R. § 56.13020, consisting of an alternative method of using a standalone clothes cleaning booth at its Pacific Plant, MSHA I.D. No. 23-00544, is hereby:

GRANTED, conditioned upon compliance with the following terms and conditions:
1. Only miners trained in the operation of the clothes cleaning booth shall be permitted to use the booth to clean their clothes.

2. The Petitioner shall incorporate the NIOSH Clothes Cleaning Process (Process) that was published in 2012, and the Manufacturer's Instruction Manual into its MSHA Part 46 Training Plan and train affected miners in the process. Two exceptions and modifications to the NIOSH Process are permitted, both regarding personal protective equipment.
a. A half-face, fit-tested respirator with N95 respiratory protection is acceptable in lieu of an N100-rated respirator.
b. If a half-face respirator is worn, standard plant-worn safety glasses with side shields are acceptable in lieu of full-seal goggles.
In 2022, NIOSH advised MSHA that the agency’s experience over time has shown that these modifications are acceptable.

3. Miners entering the booth shall examine the valves and nozzles for damage or malfunction and shall close the door fully before opening the air valve. Any defects shall be repaired prior to using the booth.

4. Miners entering the booth shall wear, at a minimum, eye protection in standard use within the plant, ear plugs or muffs for hearing protection, and respiratory protection. Respiratory protection means a full-face or half-mask respirator that meets or exceeds the minimum requirements of an N95 filter to which the miner has been fit-tested. As an alternative, the use of a full-face N95 respirator will meet the requirement for combination eye and respiratory protection. A sign shall be conspicuously posted requiring that the above personal protective equipment be used when the booth is entered.

5. The booth shall be operated under negative pressure. To achieve this, air flow of at least 2,000 cfm shall be provided and propelled downwards, thereby moving contaminants away from the miner’s breathing zone and into the filter system. To assure that negative pressure is provided and maintained during booth operation, air flow must be verified before putting the booth into operation and on a semiannual basis thereafter. Measurements may be taken by using a pitot tube or velometer tapped into a straight section of the discharge pipe downstream from the HEPA filter system, by using an in-calibration, high-speed anemometer at the exhaust pipe outlet, by using a differential pressure gauge, or by using another reliable and accepted engineering method. The airflow measurements shall be recorded and preserved for the active life of the booth, and the records be made available to an Authorized Representative of the Secretary. If the air flow falls below 2,000 cfm, or negative pressure inside the booth falls below 0.2 psi, the cause shall be promptly determined and corrected.

6. Air pressure through the air spray manifold shall be regulated to less than 30 psi or the manufacturer’s recommendation, whichever is lower, for the full 18-second cleaning cycle time that the manufacturer has designed. Two lock boxes, each with a single, plant manager-controlled key shall be used to prevent tampering with the regulators or changing the pressure setpoint.

7. The air spray manifold shall consist of schedule 80 steel pipe that has a failure pressure of 1,300 psi minimum, be capped at the base and actuated by an electrically controlled ball valve at the top.

8. The uppermost active nozzle of the spray manifold shall be located below the booth user’s breathing zone. A mechanical device that can be manually adjusted shall be used to cover the upper air nozzles as necessary to meet the specific height of the user.
9. Air nozzles attached to the manifold shall be shielded on both sides to protect them from being mechanically damaged by inadvertent, incidental contact during booth use.

10. The Petitioner shall conduct pre-use, daily, monthly, semi-annual, and annual maintenance checks of the booth in accordance with the recommendations contained in the Manufacturer’s Instruction Manual.

11. The air compressor or plant compressed air system supplying the booth’s air receiver shall provide a minimum pressure of 90 psi, to assure the availability of no less than 18 seconds of sufficiently pressurized continuous cleaning airflow.

12. A pressure relief valve designed for the booth’s compressed air receiver shall be installed and maintained in functioning condition.

13. An in-line filter shall be provided and maintained between the air receiver and the manifold to remove moisture and protect users from any debris that might be entrained in the compressed air stream.

14. Appropriate hazard warning signs shall be posted and maintained on the booth to state, at a minimum, “Respirable Crystalline Silica” and “Compressed Air”.

15. The Petitioner shall use a pre-filter and HEPA filtration system and follow the manufacturer’s recommendations for maintenance of that system.

16. The Petitioner shall inspect the pre-filter gauge and ensure that the differential pressure across the pre-filter remains at an acceptable range of between 0 and 2 inches of water. If the reading rises to 2.0 inches of water, the pleated pre-filters shall be changed. If changing the pre-filters does not reduce the gauge reading to below 1.25 inches of water, then the manufacturer must be contacted for guidance. The Petitioner shall also inspect the HEPA filter gauge and ensure that the differential pressure across the HEPA filter remains at an acceptable range of between 0 and 1.25 inches of water. If the reading rises to 1.25 inches of water, then the HEPA filter cartridge shall be changed. If changing the filter cartridge does not reduce the gauge reading to below 0.5 inches of water, then the manufacturer must be contacted for guidance.

17. Air that has passed through the booth and the pre- and HEPA-filter system shall be exhausted to the outside through an exhaust stack. The exhaust shall be oriented in a direction that prevents any entrained dust from entering the inlet opening at the top of the booth.

18. Petitioner shall maintain a copy of the Manufacturer’s Instruction Manual at the clothes cleaning booth.
Any party to this action desiring a hearing must file a request for hearing within 30 days after service of the Proposed Decision and Order, in accordance with 30 C.F.R. Part § 44.14, with the Administrator for Mine Safety and Health Enforcement, 201 12th Street South, Suite 401, Arlington, Virginia 22202-5450.

If a hearing is requested, the request must 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 and Order. A party other than the petitioner who has requested a hearing shall also comment upon all issues of fact or law presented in the petition. 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, this Proposed Decision and Order will become final and shall be posted by the mine bulletin board at the mine.
Timothy R. Watkins Deputy Administrator for
Mine Safety and Health Enforcement

Appendix A (Attached Below)
Clothes Cleaning Booth - General Arrangement Drawing

Appendix B (Attached below)
Clothes Cleaning Booth – Filter Changeout Instructions Drawing

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 2nd day of December, 2022, to:

Alyssa Veit EHS Manager
U.S. Silica Company
Veit@USSilica.com

Kevin Martin
Miners Representative
U.S. Silica Company
Martin@USSilica.com

L. Harvey Kirk III, CSP
Sr. Mine Safety and Health Specialist
sn
cc: Mr. David Attebery, Assistant Director, Division of Labor Standards, 3315 W. Truman Blvd., Rm. 205, P.O. Box 449, Jefferson City, MO 65102-0449, David.Attebery@labor.mo.gov