What Are the Rules for Hand Digging Near Underground Utilities? Seeking Guidance

Regulations for Hand Digging Near Underground Utilities

Is there any regulation specifically mentioned for hand digging distances near underground utilities? I need help on this case. I had a meeting with the government, and they explained that somewhere in the regulations, there is a mention of the tolerance distance when doing a hand dig near underground utilities.

Example:
- Maintain a 36-inch distance from marks. If digging within 36 inches, hand dig to expose and verify lines.

Regards,

Thanks, Mr. Pon. I went through OSHA 1926 & 1910, and EM 385-1-1 as well, but didn't find any regulation. However, my client strongly insists it's addressed in an international standard (He gave me a chance to find it...).

In OSHA, it only states regarding Excavation:

Before any excavation actually begins, the standard requires the employer to determine the estimated location of utility installations—sewer, telephone, fuel, electric, water lines, or any other underground installations—that may be encountered during digging. Also, before starting the excavation, the contractor must contact the utility companies or owners involved and inform them, within established or customary local response times, of the proposed work. The contractor must also ask the utility companies or owners to find the exact location of the underground installations. If they cannot respond within 24 hours (unless the period required by state or local law is longer), or if they cannot find the exact location of the utility installations, the contractor may proceed with caution.

Team, if someone could help with this case, it would be highly appreciated...