Skip to main content
ESH Manual Page: 4000: Industrial Hygiene

Permit-Required Confined Spaces (PRCS) at The Sanford Underground Laboratory at
Homestake (hereafter referred to as Sanford Laboratory) may be entered only after written and
authorized Confine Space Entry Work Permit (Permit) has authorized that entry, and all
requirements of this program for safe entry are accomplished. In addition, no confined space
will be entered until it has been categorized as either a Permit-Required or Non-Permit Required
Confined Space.


This policy applies to all Sanford Laboratory personnel, including experimenters and project
sponsors, temporary employees and contract/subcontractor/term employees. Permit-required
confined spaces are defined in OSHA regulation 29CFR 1910.146.


3.1. Department Directors:

  • Develops confined space entry notification procedures in coordination with other departments.
  • Maintains an inventory of confined spaces for which they are responsible.
  • Ensures confined spaces located in areas under their control are properly labeled.
  • Evaluate their confined space entry program on an annual basis against the requirements defined in this policy.
  • Provide safety equipment required for confined space entry ( gas monitors, tripods, ventilation systems, lighting, etc)

3.2. EHS Department

  • Provides a confined space training program
  • Provides expertise to departments on all aspects of confined space entry.
  • Maintains lab-wide confined space documentation, including a master inventory.
  • Maintains monitoring equipment (including calibration) for confined space entry.
  • Review contractors confined space programs

3.3. Supervisors

  • Classifying confined spaces in their areas
  • Ensuring only properly trained employees perform confines space related work activities.
  • Ensuring Confined Space Entry Permits are in place prior to any PRCS entry

3.4. Project Manager

  • Identifies any confined spaces associated with the contracted work.
  • If available, arranges for the review of contractor confined space entry program.
  • Ensures that contractors who will be entering confined spaces are properly trained to do so.
  • Ensures the contractor utilizes Confined Space Entry Permits (either their own, or Sanford Laboratories).
  • Apprises the subcontractor of any precautions or procedures that have been implemented for the protection of employees in or near the confined space where contractor personnel will be working.
  • Coordinates entry operations with the contractor when both Sanford Laboratory and subcontractor personnel will be working in or near the confined space.
  • Notifies the EHS Department prior to entry. Information shall include the location of the entry, the number of entrants and the nature of the work.

Acceptable Entry Conditions - Conditions that must exist in a confined space to allow entry
and to ensure that employees involved can safely enter into and work within the space.

Authorized Attendant - A trained employee, subcontractor, or scientific user who is stationed
and remains outside of the confined space for the purpose of monitoring the entrants and who
performs all attendant's duties. An attendant shall be stationed outside any confined space
requiring a permit for each job assignment.

Authorized Entrant - A trained employee, subcontractor, or scientific user who will enter a
confined space.

Confined Space - A space that:

  • Is large enough and so configured that an employee can bodily enter and perform assigned work; and
  • Has limited or restricted means for entry or exit; and
  • Is not designed for continuous employee occupancy

“Restricted entry or exit,” means physical impediment of the body, e.g., use of the hand or a
contortion of the body to enter into, or exit from, the space. Enclosures that can be accessed by
a ladder with no other access/egress points are considered confined spaces. The Landlord EHS
Department shall evaluate large-scale excavations on a case-by-case basis.

Confined Space Entry Permit - The written or printed document established by Sanford
Laboratory, the contents of which are based on the hazard identification and evaluation for that
confined space and is the instrument by which Sanford Laboratory authorizes its authorized
entrants to enter confined spaces.

Confined Space Reclassification Form – A form that allows a reclassification of a permit-
required confined space as a non-permit confined space provided that certain conditions are met.

 Engulfment - The surrounding and effective capture of a person by a liquid or finely divided
(flowable) solid substance.

Entry - The act by which a person passes through the opening into a confined space. The
entrant is considered to have entered as soon as any part of the entrant's body breaks the plane of
an opening into the space.

Entry Supervisor – A trained employee, subcontractor or scientific user responsible for
determining if acceptable entry conditions are present where entry into a confined space is
planned, for authorizing entry and overseeing entry operations, and for terminating entry.

Hazardous Atmosphere - An atmosphere that may expose employees to the risk of death,
incapacitation, impairment of ability to self-rescue (that is, escape unaided from a confined
space) injury, or acute illness from one or more of the following causes: (1) Flammable gas,
vapor, or mist in excess of 10 percent of its lower explosive limit; (2) Airborne combustible dust
at a concentration that meets or exceeds the lower explosive limit; (3) Atmospheric oxygen
concentration below 19.5% or above 23.5%; (4) Atmospheric concentration of any substance
which may exceed either the OSHA PEL or the ACGIH TLV for that substance; (5) Any other
atmospheric condition that is immediately dangerous to life or health.

NOTE: For air contaminants for which ACGIH or OSHA has not determined a dose or
permissible exposure limit, other sources of information, such as Material Safety Data
Sheet, published information, and internal documents can provide guidance in
establishing acceptable atmospheric conditions.

IDLH (Immediately Dangerous to Life or Health) - Any condition which poses an immediate
or delayed threat to life or that would cause irreversible adverse effects or that would interfere
with an individual's ability to escape unaided from the confined space.

LEL (Lower Explosive Limit) - The lowest concentration of gas or vapor (% by volume in air)
that will burn or explode if an ignition source is present at ambient temperatures.

Non-Classified Confined Space – A confined space that has not yet been classified by a
qualified person as either a Permit required or Non-Permit Required confined space.

Non-Permit Required Confined Space - A confined space that does not contain or, have the
potential to contain any hazard capable of causing death or serious physical harm. Introducing a
hazard (e.g., welding, painting, chemical use, etc.) into a non-permit confined space may cause
the space to become a permit-required confined space.

Oxygen Deficient Atmosphere - An atmosphere containing less than 19.5% oxygen by volume.

Oxygen Enriched Atmosphere - An atmosphere containing more than 23.5% oxygen by

PEL (Permissible Exposure Limit) - An exposure limit established by OSHA.

Permit-Required Confined Space:

If the confined space has one or more of the following characteristics, the entry will require a
permit to be valid for the duration of the job as long as the conditions specified on the permit do
not change:

  • Contains, or has a potential to contain, a hazardous atmosphere;
  • Contains a material that has the potential for engulfing an entrant;
  • Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section; or
  • Contains any other recognized serious safety or health hazard.

TLV (Threshold Limit Value) - An exposure limit that is published by ACGIH.

Toxicity - All of the adverse biological effects resulting from an exposure to a harmful

Welding/Burning/Brazing Permit (Thermal Hot Work Permit) - An operation that requires a
Welding/Burning/Brazing Permit per Sanford Laboratory’s Hot Work Policy (to be developed).


5.1. Confined Space Inventory: Each Department will identify confined spaces in their
workplaces, and maintain an inventory of the spaces. A template for this inventory is
shown in Appendix A. Confined spaces will be classified (by the area Supervisor) as
either a Permit Required or Non Permit Required Confined Space (PRCS or NPRCS,
respectively). This inventory must be updated when every a new confined space is
indentified, or an existing confined space is reclassified (see Section 7.0). An updated
version of the inventory must be supplied to EHS on a Monthly basis.

5.2. Signage: All confined spaces permanently identified as PRCS must be labeled using a
Laboratory approved sign that states “DANGER – PERMIT REQUIRED CONFINED
SPACE Please see EHS for sign requirements and purchasing information.


6.1. Non Classified Confined Spaces

If a confined space is discovered that has not yet been categorized as either a PRCS or
NPRCS, it must first be categorized by the area supervisor or a qualified person before
any work can proceed.

6.2. Non-permit Required Confined Spaces

Entry requirement to NPRCS are at the discretion of the area Supervisor. However,
careful consideration must be given to any work conducted in NPRCS to determine if the
work has the potential of introducing a hazard that would cause the space to become a
permit-required confined space (e.g., welding, painting, chemical use, etc.). If this is the case, then all the requirements for a PRCS must be followed (see Section 6.3). It is the
responsibility of the area supervisor, work leads, and the individual worker to identify
such occurrences.

6.3. Permit Required Confined Spaces

Entries into PRCS are limited to only trained individuals and are controlled and
authorized through the Confined Space Entry Permit (an example is provided in
Appendix B). A Confined Space Entry Permit must be filled out before work
commences and updated as necessary during work operations. It must be visible to any
individual that may visit the work site. The specific procedures for PRCS entry and using
the Confined Space Entry Permits are provided in Appendix C.


A space classified as a Permit-Required Confined Space may be reclassified as a Non-Permit Confined Space by an individual trained in confined space entry. However, if entry into the PRCS is required for the reclassification, permit-required confined space entry procedures must be followed. The basis for reclassification must be documented using the Confined Space Reclassification Form (Appendix D). This form must be posted at the job site as evidence that work is being conducted safely. All completed confined space reclassification forms shall be retained by the Department making the reclassification for a minimum of one(1) year. The EHS Department and Project Manager (if applicable) shall be notified of any reclassification prior to entry or as soon as reasonable feasible.

Reclassification status may be maintained for the duration of the entry as long as the hazards remain eliminated. If the reclassification is to be permanent, the Confined Space Inventory must be updated to reflect the change, and the all signage indentifying the confined space as a PRCS removed.


Sanford Laboratory employees and scientific users who may be involved with confined space entries shall receive training prior to initial entry into a confined space.

Training shall include a review of:

  1. The Sanford Laboratory Confined Space policy and procedures, as well as other applicable environment, safety and health procedures.
  2. Hazards associated with confined space entry.
  3. Signs and symptoms that may be present during or after an exposure to a hazard.
  4. Consequences of exposure to potential hazards.
  5. Methods of communication/contact.
  6. When to initiate self-evacuation.
  7. External safeguards that may be needed for safe entry.
  8. Audio alarms and what the alarms mean.
  9. How to deal with unauthorized personnel.
  10. Monitoring methods, techniques and instructions on the use of approved monitoring devices.
  11. Emergency response procedures.
  12. Proper method and procedure for completing the entry permit.
  13. Justification for, and instructions on, the proper use and wearing of personal protective equipment.
  14. Instructions on how a confined space is identified and classified.
  15. How to fill out a Confined Space Entry Permit
  16. Proper use of retrieval equipment (if applicable).
  1. 1. If a contractor is required to enter a permit required confined space as part of their contract with Sanford Laboratory, the contractor shall provide the Sanford Laboratory Project Manager with the following information to allow for adequate review prior to entry:
    • a. A written copy of their confined space entry program. This will be reviewed by EHS to ensure it meets Sanford Laboratory requirements. If the program fails to meet the requirements, the contactor will be asked to modify their program, or work under the Laboratory’s Program.
    • b. Training records for potential entrants, attendants, and entry supervisors.
    • c. Evidence that all air monitoring equipment is properly calibrated within the calibration period specified by the subcontractor's program or manufacturer's instructions. This may be in the form of a calibration log, certification indicator on the instrument, or other means. (It is imperative that the equipment used by the subcontractor be capable of monitoring for the contaminants associated with the confined space to be entered.)
  2. It will be the subcontractor's responsibility to provide all of their own personal protective equipment (PPE), such as lifelines, harnesses, respirators, tripods, ventilators, etc., as specified by the entry permit.
  3. In addition to complying with the permit space requirements listed above, each contractor retained to perform permit space entry operations shall:
    • a. Obtain any available information regarding permit space hazards and entry operations from Sanford Laboratory.
    • b. Coordinate entry operations with Sanford Laboratory, when both Sanford Laboratory personnel and subcontractor personnel will be working in or near permit spaces.
    • c. Inform the Sanford Laboratory Project Manager prior to entering the space.
    • d. Inform Sanford Laboratory Project Manager of any unanticipated hazards confronted during the confined space entry.
    • e. Provide the Sanford Laboratory Project Manager with a copy of the subcontractor's confined space permit, reclassification form or written certification once the work has been completed.
  4. 4. Per OSHA 1910.146 (c) (5), if the subcontractor can demonstrate that continuous forced air ventilation alone is sufficient to maintain safe entry conditions, then the job specific confined space entry procedures can be modified by the Sanford Laboratory EHS Department.

10.1. Standards

  • American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit
  • Values (TLV) for Chemical Substances and Physical Agents, and Biological Exposure
  • Indices
  • Occupational Safety and Health Administration (OSHA) 29 Code of Federal Regulations 1910.146 – Permit-required confined spaces
  • OSHA 29 CFR 1910 Subpart Z – Toxic and Hazardous Substances – Permissible Exposure Limits (PEL)

10.2. Related Documents

  • Lockout/ Tagout Verification
  • Surface Emergency Reporting System Flowchart
  • Underground Emergency Reporting System Flowchart
  • Hot Work Policy
  • Hot Work Permit

10.3. Appendices

  • Appendix A: Confined Space Inventory Template
  • Appendix B: Confined Space Entry Permit
  • Appendix C: Procedures for PRCS entry
  • Appendix D: Confined Space Reclassification Form
  • Appendix E: Supervisor, Attendant, and Entrant Responsibilities