My knowledge base does not contain specific documentation on fixed safety barrier specifications and regulatory compliance standards for wastewater treatment plants. However, I can provide general safety guidance based on industry best practices.

In wastewater treatment plants, falls can be prevented and worker safety ensured by:

• Installing protective barriers or suitable guards when covers over openings are removed or excavations are made in places accessible to vehicular or pedestrian traffic. Warning lights or flares shall be displayed if work is being done at night. These protective measures shall be maintained until permanent or adequate covers or barricades are in place or the hazard removed.
• Stationing a watchperson where temporary conditions do not permit safeguarding of employees through the use of warning signs, lights, protective barriers, or covers. [1] [1]