766
Modifications.
80 Stat. 384.
PUBLIC LAW 91-173-DEC. 30, 1969
[83 STAT.
improved standards promptly that will provide increased protection to the miners, particularly in connection with hazards from trolley wires, trolley feeder wires, and signal wires, the splicing and use of trailing cables, and in connection with improvements in vulcanizing of electric conductors, improvement in roof control measures, methane drainage in advance of mining, improved methods of measuring methane and other explosive gases and oxygen concentrations, and the use of improved underground equipment and other sources of power for such equipment. (^^.^ Upou petition by the operator or the representative of miners, the Secretary may modify the application of any mandatory safety standard to a mine if the Secretary determines that an alternative method of achieving the result of such standard exists which will at all times guarantee no less than the same measure of protection afforded the miners of such mine by such standard, or that the application of such standard to such mine will result in a diminution of safety to the miners in such mine. Upon receipt of such petition the Secretary shall publish notice thereof and give notice to the operator or the representative of miners in the afl'ected mine, as appropriate, and shall cause such investigation to be made as he deems appropriate. Such investigation shall provide an opportunity for a public hearing, at the request of such operator or representative or other interested party, to enable the operator and the representative of miners in such mine or other interested party to present information relating to the modification of such standard. The Secretary shall issue a decision incorporating his findings of fact therein, and send a copy thereof to the operator or the representative of the miners, as appropriate. Any such hearing shall be of record and shall be subiect to section 554 of title 5 ^^ ^j^^ United States Code. (d) In any case where the provisions of sections 302 to 818, inclusive, of this title provide that certain actions, conditions, or requirements shall be carried out as prescribed by the Secretary, or the Secretary of Health, Education, and Welfare, as appropriate, the provisions of section 553 of title 5 of the United States Code shall apply unless either Secretary otherwise provides. Before granting any exception to a mandatory safety standard as authorized by this title, the findings of the Secretary or his authorized representative shall be made public and shall be available to the representative of the miners at the affected coal mine. ROOF
SUPPORT
SEC. 302. (a) Each operator shall undertake to carry out on a continuing basis a program to improve the roof control system of each coal mine and the means and measures to accomplish such system. The roof and ribs of all active underground roadways, travelways, and working places shall be supported or otherwise controlled adequately to protect persons from falls of the roof or ribs. A roof control plan and revisions thereof suitable to the roof conditions and mining system of each coal mine and approved by the Secretary shall be adopted and set out in printed form within sixty days after the operative date of this title. The plan shall show the type of support and spacing approved by the Secretary. Such plan shall be reviewed perioclically, at least every six months by the Secretary, taking into consideration any falls of roof or ribs or inadequacy of support of roof or ribs. No person shall proceed beyond the last permanent sup-
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