How deep are utilities typically buried?

Question

What are the recommended or relevant standards for US city planning with regards to depth ranges for various utilities such as water, natural gas, and power, as well as for subway or rail, etc...?

For example, water and gas lines should be buried well below the frost line to prevent damage from ground movement. What standard(s) dictate those depths?

I am primarily interested in standards applicable to major cities such as Atlanta, Boston, Chicago, Dallas, Denver, New York, San Diego, Seattle, Washington, etc... My assumption is that there are enough similarities between the cities that a standard would have been developed.

Answer 1

First, if you care about a certain city, look up the information. This should be information that is readily available. Big cities are usually go about publishing this information online.

Tunnels (subway or vehicle) are different enough that they don't have standard depths. They are designed to be far enough below ground to miss utilities and basements, unless they can't be for some other reason.

That being said, below is the information for a random location that I found first (Washington County, Texas):

Depth of Underground Lines - The depth of underground lines shall be as specified herein for each type of utility. Where placements at such depths are impractical or where unusual conditions exist, the department shall specify other protection as may be appropriate in lieu of the depth of bury required for the particular utility line. Any and all buried utility lines will be placed at a minimum depth of 36". A ny deviation from the specified depth must be requested in writing and approved before Commissioners Court.

• High pressure gas and liquid petroleum lines will be constructed no less than forty-eight inches (48") lower than the lowest part of the drainage or bar ditch, and the drainage is to be considered at least two feet (2') below the center of the roadway.
• Fiber Optic lines will be constructed no less than forty-eight inches (48") lower than the lowest part of the drainage or bar ditch, and the drainage is to be considered at least two feet (2') below the center of the roadway.
• Communications cable will be constructed no less than thirty-six inches (36") lower than the lowest part of the drainage or bar ditch, and the drainage is to be considered at least two feet (2') below the center of the roadway.
• Water Lines will be constructed no less than thirty-six inches (36") lower than the lowest part of the drainage or bar ditch, and the drainage is to be considered at least two feet (2') below the center of the roadway; crossings to be encased.
• Underground Power line crossings and longitudinal shall be encased (placed in conduit) and buried a minimum of thirty-six inches (36") under roadway ditches, and sixty inches (60") below the pavement surface.
• Cable television and copper cable communication lines shall have a minimum depth of cover twenty-four inches 24") under ditches or 18 inches beneath the bottom of the pavement structure, whichever is greater.

Warning! - Do not rely on these for digging!

Call 811 to have utilities marked before you dig!