30 CFR §75.1712-6

1. (a)Except as provided in § 75.1712-7, each operator of an underground coal mine shall provide and maintain one sanitary toilet in a dry location under protected roof, within 500 feet of each working place in the mine where miners are regularly employed during the mining cycle. A single sanitary toilet may serve two or more working places in the same mine, if it is located within 500 feet of each such working place.
2. (b)Sanitary toilets shall have an attached toilet seat with a hinged lid and a toilet paper holder together with an adequate supply of toilet tissue, except that a toilet paper holder is not required for an unenclosed toilet facility.
3. (c)Only flush or nonflush chemical or biological toilets, sealed bag toilets, and vault toilets meet the requirements of this section. Privies and combustion or incinerating toilets are prohibited underground.