(a) For any quarry originally licensed before January 1, 1981, the maximum allowable property line sound levels for all operations, including blasting, must not exceed 80 A-weighted decibels between 7 a.m. and 5 p.m. Between 5 p.m. and 7 a.m., the maximum allowable property line sound levels must not exceed the levels specified in Chapter 31B.
(b) For any quarry originally licensed after January 1, 1981, the maximum allowable property line sound levels for all operations except blasting must not exceed the levels specified in Chapter 31B. The maximum allowable property line sound levels for blasting must not exceed 80 A-weighted decibels between 7 a.m. and 5 p.m.
(c) During 5 p.m. to 7 a.m., blasting is prohibited at any quarry.
(d) The Director may set stricter noise standards than those set in subsections (a) and (b) as license conditions for any quarry if the Director finds that stricter standards will better protect the public health, safety, or welfare.
(e) The Director may waive any noise monitoring requirement with respect to a minor quarry if the Director finds that the monitoring is unnecessary to protect the public health, safety, or welfare or the environment. (Mont. Co. Code 1965, § 98-14; 1972 L.M.C., ch. 16, § 5; 1981 L.M.C., ch. 30, § 2; 1992 L.M.C., ch. 1, § 1.)