Okla. Stat. tit. 45, § 45-508: Shaft not more than seventy-five feet deep

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 ofnot 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.