MORGANTOWN, W.Va. (AP) -- CONSOL Energy says it still doesn't know when it will be safe to send workers back inside the Blacksville No. 2 mine.
The mine straddles the Pennsylvania-West Virginia border. CONSOL removed 120 workers last week after a fire broke out and smoke began pouring from the Orndoff shaft in Wayne Township, Pa.
Spokeswoman Lynn Seay said Monday that 15 boreholes have been drilled to tackle the fire.
Two are being used to pump in water.
Others are being used monitor both the fire and the atmosphere, to remotely install plugs, and to inject nitrogen and deplete the oxygen that helps feed the fire.
Gas levels spiked in the mine spiked over the weekend.
CONSOL says the Kuhntown portal building was evacuated for 12 hours until safe levels were restored.