These thicker seams have historically delivered an increase in RoM production in the quarter they are mined.
Werris Creek RoM coal production of 385,000 tonnes in the March quarter was 20% down on the previous corresponding period and 28% down on year to date.
"This decrease reflects localised geological losses in the pit, a continuation of difficult mining conditions around uncharted underground workings and rain delays," the company said.
"This decrease in RoM coal production has resulted in lower saleable coal production and sales of produced coal."
