Results 201 - 201 of 201

• Use of Vertical Boreholes for Assisting Ventilation of Longwall Gob Areas
  3/1/1969 - Technical Progress Reports
  An experimental degasification program using a vertical borehole and vacuum pump to drain gas from the gob area of a longwall panel was successful at Bethlehem Mines Corporation, Cambria Division, No. 33 coal mine. Sixty-one million cubic feet of methan...