The breakthrough to the seam was originally scheduled for the end of August but is now set for the end of September.
The tunnel currently sits at 2147m and has been advanced 29m since August 4.
Pike general manager Peter Whittall said the tunnel completion was within grasp.
“With only 153 metres to go we’re getting close to breaking through,” Whittall said.
“However, we were expecting to average 5 metres per day at this point. Those rates are not yet being achieved due to variable rock conditions so we have reforecast completion at slower rates.”
Earlier this month the tunnel cut through the Hawera fault and advance rates were expected to improve.
Pike said tunnelling rates had improved to 3–4m on some days but variable rock conditions had dropped tunnelling rates to 1–2m on other days.
The miner is continuing with pit bottom roadways and is still targeting coal production of 200,000 tonnes by June 2009.
The coal mine being developed by Pike near the New Zealand town of Greymouth is expected to produce 1 million tonnes a year for at least 18 years.