If sewer manholes and storm drains are outside of the facility, is the organization required to label them as a permit-required confined space?

Signs are not technically required to mark permit-required confined spaces (PRCS) in 1910.146(c)(2) but are the easiest way to communicate it effectively. Training can be used to communicate that they are PRCS. Train employees that they are PRCS and that they are not to enter them. The recommendation would be to maintain a list of your PRCS on the property and include them on that list and train employees.

An OSHA letter of interpretation states the following:

Ordinarily, information about permit spaces is most effectively and economically communicated through the use of signs. Consequently, signs would be the principal method of warning under the standard. Alternative methods, such as additional training, may be used where they are truly effective in warning all employees who could reasonably be expected to enter the space. It is the employer’s obligation to assure that an alternative method is at least as effective as a sign.

NOTE: A sign reading DANGER — PERMIT-REQUIRED CONFINED SPACE, DO NOT ENTER or using other similar language would satisfy the requirement for a sign.