Mo. Rev. Stat. § 319.033
By January 1, 2016, if new lateral sewer pipes or water service lines are installed and connected to an underground facility within the public right-of-way, as defined in section 319.015, or if such infrastructure is fully replaced by excavation within the public right-of-way, the facility owner shall be required to place tracer wire or other utility location technology and an access point within a protective enclosure over water lines and cleanouts for gravity sewer laterals. For sewer laterals operating under pressure or vacuum, the facility owner shall be required to place an access point within a protective enclosure and shall not be required to place a cleanout. All protective enclosures and cleanouts shall be extended to grade and installed so that it is easily accessible. For water service lines and sewer laterals operating under pressure or vacuum, tracer wire, or other utility location technology, shall be placed within the protective enclosure to provide approximate location of the underground facilities in these areas that are located within a public right-of-way. An underground facility owner shall not be liable to any party for damages or injuries resulting from an excavation if they are in compliance with this section. This section shall apply to all installations of water service lines and sewer laterals without regard to their status as underground facilities under section 319.015. Nothing in this section shall require any owner of underground facilities who is not otherwise required under sections 319.010 to 319.050 to become a notification center participant.
§ 319.033, RSMo