Skip to main content
ESH Manual Page: 7000: Occupational Safety

It is the policy of the Sanford Underground Laboratory at Homestake (here after referred to as Sanford Laboratory), that all excavating and trenching activities be carried out in accordance with the requirements of OSHA 1926.650 to 1926.652, the Occupational Safety and Health Administration’s (OSHA) Excavation and Trenching Standard. Only qualified Operations, Engineering and Contractor personnel will actively participate in excavation and trenching activities. All excavation and trenching activities must be approved by the Sanford Laboratory Operations Department.


This policy applies to all Laboratory Personnel and is intended to protect them from the hazards associated with work in and around Trenches and Excavations.


3.1. Operations and Engineering Department Directors:

The Department Directors have the responsibility to implement this excavation policy by:

  • Directing all supervisors to assess the hazards of each excavation and to identify the Laboratory Personnel this may affect.
  • Providing all Laboratory Personnel with information, training, and the equipment they need to protect themselves and others form excavation hazards.
  • Ensuring that all necessary equipment is available to comply with this policy.
  • Enforce compliance with this policy. All appropriate Laboratory Personnel must be trained and responsible as to the purpose and use of this excavation safety policy.
  • Ensuring a qualified individual with respect to excavation and trenching is on staff; this responsibility can be shared between the Operations and Engineering Departments.

3.2. Supervisors/Forman:

The Supervisor/Forman has the responsibility to:

  • Identify and assess the hazards of each excavation area.
  • Ensure that Laboratory Personnel receive the appropriate training and equipment they need to protect them and others.
  • Enforce compliance with this policy.
  • Assure that all underground utility installations have been located and marked prior to excavation.
  • Designate a Competent Person to complete all required testing and inspections, and to fill out the daily trenching log.

3.3. Project Managers:

Project Managers have the responsibility to:

  • Ensure that contractors have on staff a Competent Person for excavation (as defined by OSHA) for all jobs under their supervision involving excavation.
  • Ensure any excavation and trenching activities performed by the contractor under their supervision have been approved by the Operations Department.  
  • Ensure contractors understand and follow all requirements of this policy.
  • Assure that all underground utility installations have been located and marked prior to excavation.
  • Immediately notify Operations in the event that a utility is damaged during the excavation process.

3.4. Laboratory Personnel:

Laboratory Personnel have the responsibility to:

  • Understand their assigned tasks relating to excavation safety.
  • Apply the proper training and equipment to safely work in excavations and trenches.
  • Assist with the assessment and identification of excavation hazards.
  • Comply with the directives of this policy.

3.5. EHS Department:

EHS Personnel have the responsibility to:

  • Provide guidance with interpretation of the OSHA requirements.
  • Maintain this policy.
  • Assist with the assessment and identification of excavation hazards.
  • Review contractor’s qualifications with respect to excavation and trenching.

Benching: A method of protecting Laboratory Personnel from cave-ins by excavating the sides of an excavation to form one or a series of horizontal levels or steps, usually with vertical or near vertical surfaces between levels.

Cave – in: The separation of a mass of rock or soil material from the side of the excavation, or the loss of soil under a trench shield or support system, and its sudden movement into the excavation, either by falling or sliding, in sufficient quantity so that it could entrap, bury or otherwise and immobilize a person.

Competent Person: One who is capable to identify existing and predictable hazards in the surroundings or working conditions that may affect the Laboratory Personnel, and who has the authority to take prompt corrective actions top eliminate them.

The competent person(s):

A. Must be trained in and knowledgeable of excavation and trenching standards, and other programs that may apply (hazard communication, confined space, respiratory protection)

B. Must be capable of recognizing hazardous conditions and must have the authority to stop work and ensure that hazards are corrected

C. Performs and documents the Daily Trenching Log, Appendix A, and knows when inspections should be performed.

D. Must assure that the location of underground utilities have been properly located

E. Must identify and ensure the use of adequate protective systems, work methods and personal protective equipment (PPE) on the excavation site.

Daily Trenching Log: Log used to record required soil tests and inspections with respect to excavation and trenching.

Designated Supervisor: The individual within The Laboratory that will oversee excavation work and is responsible for assuring compliance with the Trenching and Excavating Policy.

Excavation: Any made-made cut, cavity, trench, or depression in an earth surface, formed by earth removal.

Excavation Permit: A permit issued to a contractor or SURF individual for the purpose of excavation activities required on a construction project.

Professional Engineer: A person who is registered as a professional engineer in the state where the work is to be performed. However, an engineer registered in any state is deemed to be a registered engineer within the meaning of this policy when approving designs for manufactured protective systems.

Shield (Shield System): A structure that is able to withstand the forces imposed on it by a cave-in and thereby protects Laboratory Personnel with the structure. Shields can be permanent structures or can be designed to be portable and moved along as work progresses. Also know as trench boxes or trench shields.

Shoring (Shoring System): A structure such as a metal hydraulic, mechanical or timber shoring system that supports the sides of an excavation and which is designed to prevent cave-ins.

Sloping (Sloping System): A method of protecting Laboratory Personnel from cave-ins by excavating to form sides of an excavation that are inclined away from the excavation so as to prevent cave-ins. The angle of incline varies with differences in such factors as the soil type, environmental exposure conditions, and applications of surcharge loads.

Soil Type A – The most stable: clay, silty clay, and hardpan. No soil is Type A if it is fissured, is subject to vibration of any type, has previously been disturbed, or is seeping water.

Soil Type B – Medium stability: silt, sandy loam, medium clay and unstable dry rock; previously disturbed soils unless otherwise classified as Type C.

Soil Type C – Least stable: gravel, loamy sand, soft clay, submerged soil or dense, heavy unstable rock, and soil from which water is seeping.

Soil Mixed Types (Layered Geological Strata) – The soil must be classified on the basis of the soil classification of the weakest soil layer. Each layer may be classified individually if a more stable layer lies below the less stable layer.

Trench (Trench Excavation): A narrow excavation, in relation to its length, made below the surface of the ground. In general, the depth is greater than the width, but the width if the trench is not greater than fifteen feet. If forms or other structures are installed or constructed in an excavation as to reduce the dimension measured from the

forms or structure to the side of the excavation to fifteen feet or less, the excavation is to be considered a trench.


5.1. Excavation Procedures:

5.1.1. Excavation Permitting and Inspection

All entities performing excavating and trenching activities at Sanford Laboratory must obtain an Excavation Permit from the Project Manager before the work begins and maintain a Daily Trenching Log every day the work continues. The permit and log must be kept at the job site and be available upon request.

5.1.2. Project Development and Impact on Utilities

The Designated Supervisor shall ensure that the project is coordinated with Operations early in the programming and development stages, so that conflicts with utilities can be resolved early. The Designated Supervisor shall obtain written approval from Operations indicating the impact to utilities has been reviewed and approved prior to proceeding with excavation.

5.1.3. Utilities and Pre-work Inspection

The Designated Supervisor shall inspect the site before the excavation is started to determine what safety measures are to be taken and shall follow the Construction EHS Manual. All underground utilities shall be located and clearly marked. The local procedures for marking utilities before excavation shall be applied. (Jim’s Private Utility Locating, LLC, 605-342-0240, 605-381-1940 cell, Excavation shall be done in accordance with the Construction EHS Manual. Utilities left in place shall be protected by barricades, shoring, suspension or other means as necessary.

5.1.4. Stability of Adjacent Structures

The Designated Supervisor shall take precautions as needed to protect Laboratory Personnel, nearby buildings or other structures. A Registered Professional Engineer should evaluate these structures and recommend precautions such as shoring, bracing, or underpinning.

5.1.5. Protection of the Public

Barricades, walkways, lighting and signs shall be provided for the protection of the public prior to the start of excavating operations. Guardrails, fences, or barricades shall be provided adjacent to walkways, driveways and other pedestrian or vehicle thoroughfares.

5.1.6. Protection of Workers in Excavations

The Designated Supervisor shall assure that workers are protected from hazards that may arise during excavation work.

A. Stairs, ladders or ramps shall be provided when workers enter excavations over four feet deep. Two or more means of exit shall be provided if the excavation is more than twenty feet in length. A means of exit shall be provided every twenty-five feet of trench length.

B. No one shall work under loads handled by lifting or digging equipment.

C. A warning system shall be used when mobile equipment is operated next to the edge of an excavation if the operator does not have a clear and direct view of the edge of the excavation.

D. Materials and equipment should be kept at least two feet from the edge of the excavation with the proper protective system in place.

5.2. Hazardous Atmospheres and Confined Spaces

Workers shall not be permitted to work in hazardous and/or toxic atmospheres. Such atmospheres include those with the following:

A. Atmospheric oxygen concentration below 19.5% or above 23.5%.

B. A combustible gas concentration greater than 10% of the lower flammable limit.

C. Concentrations of hazardous substances that exceed those specified in the Threshold Limit Values (TLVs) for airborne contaminants established by the American Conference of Industrial Hygienists (ACGIH).

If there is any possibility that the trench or excavation could contain a hazardous atmosphere, the Designated Supervisor shall consider the space as a “Permit Required Confined Space”, and follow the requirement of Sanford Laboratory’s Confined Space Policy.

5.3. Personal Protective Equipment

The Designated Supervisor shall ensure that all workers wear all required safety equipment, as detailed in The Laboratory policy on PPE. Additionally those workers entering excavations over four feet in depth or confined excavations shall wear a harness with a lifeline attached to it. The lifeline shall be separate from any line used to handle material. The lifeline shall be attended by a person at all times that the worker is in the excavation.

5.4. Walkways and Guardrails

Walkways shall be provided where workers or equipment are allowed to cross over excavations. Guardrails shall be provided on walkways used by the general public regardless of the height above the excavation. Guardrails shall be provided on walkways used only by workers if the walkway is four feet or more above the lower level. If workers pass below a walkway, then guardrails and toeboards shall be provided.

5.5. Hazards Associated with Water Accumulation

No one shall work in excavations with standing water or where water is collecting unless prior approval or instruction is given by the Designated Supervisor. Methods for controlling water accumulation must be provided and should consist of the following if anyone must work in the excavation:

A. Use of special support or shield systems approved by a Registered Engineer

B. Water removal equipment, such as well pointing, used and monitored by the Designated Supervisor

C. Use of safety harnesses and lifelines

D. Trenches shall be inspected by the Designated Supervisor after each rain and before anyone is permitted to re-enter the excavation.

5.6. Protection of Workers from Falling Objects

The Designated Supervisor shall ensure that workers are protected from loose rock or soil that could fall or roll from the excavation face. Such protection shall consist of:

A. Scaling to remove loose material

B. Installation of barricades such as wire mesh or timber as needed to stop and contain the falling material; Or

C. Sloping. Sloping may be used instead of barricades when practical.

Workers shall be protected from excavated materials, equipment or other objects that could pose a hazard by falling or rolling into the excavation. These materials or equipment shall be kept at least two feet from the edge of the excavation or otherwise restrained. Material piled, grouped, or stacked near the edge of the excavation must be stable and self-supporting.

5.7. Inspections

The Designated Supervisor shall conduct daily inspections of excavations, adjacent areas, and protective systems for evidence of a situation that could result in a hazardous condition. Inspections shall be conducted prior to the start of work, and after every rainstorm. These inspections are only required when the trench will be or is occupied.

5.8. Requirements for Protective Systems

5.8.1. Protection of Workers in Excavations

Personnel working in excavations shall be protected from cave-ins by using either an adequate sloping and benching system or an adequate support and protective system. The only exceptions are when the excavation is made in stable rock or the excavation is less than five feet in depth and an inspection by the Competent Person provides no indication for a potential cave-in.

5.8.2. Soil Classification

In order to design the most appropriate protective system, a Competent Person shall determine the soil type using a visual test with one or more manual test. See the OSHA Excavation Standard for instructions on how to conduct these tests. The results of these tests are to be recorded in the Daily Trenching Log.

5.9. Types of Protective Systems

Sloping, Benching, Shoring, and Shielding are systems that may be used to protect workers from cave-ins in trenches of more than five feet deep. A Competent Person should select the method of protection that is most suitable for the particular job site, taking into account the soil type and surrounding structures. If the soil type is not classified, then the excavation must be sloped at an angle not steeper than 1.5 horizontal to 1.0 vertical. For additional information on the various systems, see Appendix B – Protective Systems and the OSHA Excavation Standard.

5.9.1. Design Requirements

Sloping, and benching systems may be designed by either a Competent Person or a Registered Professional Engineer. Shoring and shielding systems must be designed by a Registered Professional Engineer. The design shall be written and include the following:

  • A plan indicating the sizes, types, and configurations of the materials to be used in the protective system.
  • The identity of the Registered Professional Engineer approving the design.

5.9.2. All excavations over twenty feet in depth must be approved by a Registered Professional Engineer.


6.1. Standards

  • OSHA Trenching and Excavating 26 CFR 1926.650 to 1926.652, and associated appendices.

6.2. Reference Documents

  • Excavation Permit
  • Daily Trenching Log
  • Protective Systems