Okla. Stat. tit. 45 § 508
When the opening or outlet other than the main opening is a shaft and does not exceed seventy-five (75) feet in vertical depth, and is used by the employees for the purpose of ingress and egress from the mine, it shall be kept in a safe and available condition and free from steam and dangerous gases and all other obstructions, and shall be fitted with safe and convenient stairs, with steps of an average tread of ten (10) inches, and ten (10) inches raise, not less than two (2) feet wide and not to exceed an angle of forty-five (45 lsco lsc) degrees descent, with landings of not less than eighteen (18) inches wide and four (4) feet long, at easy and convenient distances, and water coming from the surface or out of the strata in the shaft shall be conducted away by rings, cases or otherwise, and be prevented from falling upon persons who are ascending or descending the stairway of the shaft.
Okla. Stat. tit. 45, § 508