Sloping designs for deep excavations

December 22, 2003 [Reviewed May 31, 2018]

Mr. David V. Dow

Trench Safety and Supply, Inc.

[Recipient address omitted]

Re: Whether a sloping system used in conjunction with trench shields in an excavation that exceeds 20 feet in depth must be approved by a registered professional engineer; whether that engineer must be registered in the state where the excavation work is taking place.

Dear Mr. Dow:

This is in response to your letter dated June 16, 2003, to the Occupational Safety and Health Administration (OSHA). You ask about the requirements in OSHA's excavation standard (29 CFR Part 1926 Subpart P). We apologize for the delay in responding.

We have paraphrased your questions as follows:

Question (1): Scenario: A combination of trench shields and sloping is used, as follows:

SCENARIO:

[Schematic appears in the source document.]

• D is greater than 20 feet

• Under the manufacturer’s tabulated data ("MTD"), the trench shields have a depth rating equal to or greater than D

• MTD says to slope "in accordance with OSHA requirements" when sloping is used in conjunction with these shields

• MTD meets all Subpart P requirements

• The shield is used in accordance with the MTD.

In this scenario, is it sufficient to slope in accordance with the manufacturer's tabulated data (which says to slope "in accordance with OSHA requirements"), or does Subpart P require that a registered professional engineer (RPE) specify and approve a specific sloping scheme for this particular project?

Answer

Title 29 CFR 1926.652(a) provides employers with the ability to choose from four options listed under §1926.652(b) in order to protect employees working in excavations. Those options not only include utilizing support systems drawn from tabulated data but using a sloping system designed by a registered professional engineer as well. Section 1926.652(b) states in part:

(b)(3) Option (3) - Designs Using Other Tabulated Data

(i) Design of sloping or benching systems shall be selected from and in accordance with tabulated data, such as tables and charts.

(b)(4) Option (4) - Design by a registered professional engineer

(i) Sloping and benching systems not utilizing Option (1) or Option (2) or Option (3) under paragraph (b) of this section shall be approved by a registered professional engineer.

Section 1926.650(b) defines "tabulated data" as:

Tabulated data means tables and charts approved by a registered professional engineer...

It is permissible to use manufacturer's tabulated data to create a sloping system so long as the tabulated data was approved by a registered professional engineer. Part 1926 Subpart P (Excavations) §1926.652(a) states:

Protection of employees in excavations (1) Each employee in an excavation shall be protected from cave-ins by an adequate protective system designed in accordance with paragraph (b) or (c) of this section...

In your scenario you state that Manufacturer's Tabulated Data (MTD) "says to slope in accordance with OSHA requirements" and that it "meets all Subpart P requirements." However, as illustrated in your schematics, your excavation (D) is greater than 20 feet deep. The sloping designs listed in the Appendices apply to excavations that are less than 20 feet. Appendix B, Table B-1 "Maximum Allowable Slopes" states in Note 3:

Sloping or benching for excavations greater than 20 feet deep shall be designed by a registered professional engineer.

Since the standard does not list specific sloping criteria for an excavation with a depth greater than 20 feet, your MTD cannot meet all Subpart P requirements by simply stating that you must "slope in accordance with OSHA requirements." For an employer to use tabulated data for a sloping system for an excavation beyond the parameters listed in appendices A and B of Subpart P, a specific sloping design must be included and approved by a registered engineer.(1)

Question (2): Same Scenario as above: If I rely on a RPE to design and approve a sloping and benching system, in what state must the RPE be registered?

Answer

Section 1926.650(b) defines "registered professional engineer" as:

Registered professional engineer means a person who is registered as a professional engineer in the state where the work is to be performed. However, a professional engineer, registered in any state is deemed to be a "registered professional engineer" within the meaning of this standard when approving designs for "manufactured protective systems" or "tabulated data" to be used in interstate commerce.

Under §1926.652(a) a professional engineer registered in any state who approves designs for tabulated data is considered as being "registered" within the meaning of §1926.650(b). As such, there is no requirement that a professional engineer be registered in any specific state, so long as they are approving manufacturer's tabulated data used in interstate commerce.

An employer also has the option to have its sloping system approved by a registered professional engineer under §1926.652(b)(4). If the employer chooses to reply on this option, then, under §1926.650(b), that engineer must be registered in the state where the work will be performed.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA requirements are set by statute, standards, and regulations. Our letters of interpretation do not create new or additional requirements but rather explain these requirements and how they apply to particular circumstances. This letter constitutes OSHA's interpretation of the requirements discussed. From time to time, letters are affected when the Agency updates a standard, a legal decision impact a standard, or changes in technology affect the interpretation. To assure that you are using the correct information and guidance, please consult OSHA's website at https://www.osha.gov. If you have further questions, please feel free to contact the Directorate of Construction at (202) 693-2020.*

Sincerely,

Russell B. Swanson, Director

Directorate of Construction

*[This letter has been modified (non-substantive changes) on May 31, 2018, and reflects current OSHA regulations and policies.]

1 §1926.652(a) considers a professional engineer who approves designs for tabulated data as being "registered" within the meaning of §1926.650(b). As such, there is no requirement that the professional engineer be registered in any specific state, so long as they are approving manufacturer's tabulated data. [Back to Text]