The chambers of a grease interceptor shall be accessible from the surface by means of a separate _______________ inch opening.

A grease interceptor is an essential component in plumbing systems, designed to separate grease and solids from wastewater before it enters the sewage system. For maintenance and inspection purposes, the chambers of a grease interceptor should be easily accessible. This accessibility is critical for ensuring proper cleaning and functionality to prevent clogs and backups.

The requirement for a 24-inch opening aligns with industry standards that facilitate access for routine maintenance and cleaning. This size is appropriate as it allows a maintenance worker to effectively enter and inspect the chamber, ensuring that any built-up grease or debris can be managed adequately. Access points that are too small would hinder maintenance efforts and could lead to issues with the system's operation.

Smaller access openings, such as 6 or 18 inches, would not provide sufficient space for the required cleaning equipment or personnel to carry out their duties effectively. Inadequate access could compromise the intercepting function of the unit, leading to environmental concerns or compliance issues with local plumbing regulations. Thus, the specified 24-inch opening is the correct choice, as it maintains the balance between sufficient access for maintenance and compliance with code requirements.