1910.106(b)(2)(vii): Drainage and Dikes for Aboveground Flammable Liquid Tanks
The area around aboveground flammable liquid tanks must have drainage or dikes to keep spills from endangering nearby property or reaching waterways. Drainage must end in a safe area or an impounding basin at least as large as the largest tank, and diked areas must generally hold at least the greatest amount that can be released from the largest tank inside.
Key takeaways
- 1910.106(b)(2)(vii) is part of OSHA's general industry standards (29 CFR Part 1910, Subpart H).
- OSHA cited it 13 times in the last 3 years, in 13 inspections, with $21,056 in current penalties.
- Most citations: NY (4), VA (3), MO (2).
- Related part: 1910.106(b) Tank storage (99 citations).
- Free 5-minute toolbox talk for your crew below.
In this article
What this rule covers
29 CFR 1910.106(b)(2)(vii) ("Drainage, dikes, and walls for aboveground tanks—") is one requirement inside 1910.106 Flammable liquids, an OSHA general industry standard (Part 1910, Subpart H). The official text below is copied word for word from the Electronic Code of Federal Regulations (eCFR). The numbers, injury cases and training on this page show how OSHA enforces it on real job sites.
Official text
(vii) Drainage, dikes, and walls for aboveground tanks— 13 citations
(a) Drainage and diked areas. The area surrounding a tank or a group of tanks shall be provided with drainage as in subdivision (b) of this subdivision, or shall be diked as provided in subdivision (c) of this subdivision, to prevent accidental discharge of liquid from endangering adjoining property or reaching waterways.
(b) Drainage. Where protection of adjoining property or waterways is by means of a natural or manmade drainage system, such systems shall comply with the following:
(1) [Reserved]
(2) The drainage system shall terminate in vacant land or other area or in an impounding basin having a capacity not smaller than that of the largest tank served. This termination area and the route of the drainage system shall be so located that, if the flammable liquids in the drainage system are ignited, the fire will not seriously expose tanks or adjoining property.
(c) Diked areas. Where protection of adjoining property or waterways is accomplished by retaining the liquid around the tank by means of a dike, the volume of the diked area shall comply with the following requirements:
(1) Except as provided in subdivision (2) of this subdivision, the volumetric capacity of the diked area shall not be less than the greatest amount of liquid that can be released from the largest tank within the diked area, assuming a full tank. The capacity of the diked area enclosing more than one tank shall be calculated by deducting the volume of the tanks other than the largest tank below the height of the dike.
(2) For a tank or group of tanks with fixed roofs containing crude petroleum with boilover characteristics, the volumetric capacity of the diked area shall be not less than the capacity of the largest tank served by the enclosure, assuming a full tank. The capacity of the diked enclosure shall be calculated by deducting the volume below the height of the dike of all tanks within the enclosure.
(3) Walls of the diked area shall be of earth, steel, concrete or solid masonry designed to be liquidtight and to withstand a full hydrostatic head. Earthen walls 3 feet or more in height shall have a flat section at the top not less than 2 feet wide. The slope of an earthen wall shall be consistent with the angle of repose of the material of which the wall is constructed.
(4) The walls of the diked area shall be restricted to an average height of 6 feet above interior grade.
(5) [Reserved]
(6) No loose combustible material, empty or full drum or barrel, shall be permitted within the diked area.
Source: eCFR, text current as of 2026-10-15. Read all of 1910.106.
Where and how often it was cited
| Year | Citations |
|---|---|
| 2023 | 1 |
| 2024 | 2 |
| 2025 | 7 |
| 2026 | 3 |
Top states: NY (4), VA (3), MO (2), TN (2), DE (1)
Largest penalties
| Employer | Location | Penalty for this rule |
|---|---|---|
| ERNEST MAIER, INC. | MILLSBORO, DE | $13,260 |
| HIGGINS PALLET CO INC. | LAMAR, MO | $3,310 |
| STORM LUMBER ACQUSITION | LICKING, MO | $2,514 |
| EMANUEL TIRE MANAGEMENT VIRGINIA LLC | WAVERLY, VA | $1,227 |
| MAYRA MALDONADO TORRES | VILLALBA, PR | $745 |
Free toolbox talk
A 5-minute crew talk on 1910.106(b)(2)(vii), plus alerts when this rule changes. Free.
OSHA interpretation letters
None exist. OSHA has not published a letter of interpretation for 1910.106(b)(2)(vii).
Related parts of this rule
- 1910.106(b) Tank storage 99 citations
- 1910.106(b)(6) Sources of ignition 59 citations
- 1910.106(b)(2) Installation of outside aboveground tanks 23 citations
- 1910.106(b)(4) Installation of tanks inside of buildings 6 citations
- 1910.106(b)(2)(ii) Spacing (shell-to-shell) between aboveground tanks 5 citations
- 1910.106(b)(5) Supports, foundations, and anchorage for all tank locations 5 citations
- 1910.106(b)(1) Design and construction of tanks 4 citations
- 1910.106(b)(4)(ii) Vents 2 citations
- 1910.106(b)(4)(iv) Tank openings other than vents 2 citations
- 1910.106(b)(7) Testing 2 citations
- 1910.106(b)(1)(i) Materials 1 citations
- 1910.106(b)(5)(ii) Fire resistance
Get your crew competent
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Frequently asked questions
Why are drainage or dikes required around tanks?
To prevent accidental discharge of liquid from endangering adjoining property or reaching waterways.
How big must an impounding basin be?
Not smaller than the capacity of the largest tank served.
How much must a diked area hold?
Except as noted in the rule, not less than the greatest amount of liquid that can be released from the largest tank in the dike, assuming a full tank.
About this page
Sources
- 29 CFR 1910.106 (eCFR), text current as of 2026-10-15
- U.S. Department of Labor enforcement data: OSHA inspections, citations and accident records, copied nightly; data as of 2026-10-21
3-year window. Federal OSHA only; state-plan rules are not counted. Plain-language text is a summary, not legal advice; the official text controls. Black Belt Safety is not part of OSHA or the Department of Labor.