Proactive Investors - Cornish Metals Inc. (LON:CUSN) said the dewatering of the South Crofty mine in Cornwall has been steady since the operation got underway in early November.
Around 25,000 cubic metres per day of water is being pumped to the water treatment plant (WTP) after which it is discharged into the Red River, which has improved the river's quality overall.
The discharge also powers a 75 kW hydro-turbine that generates up to 20% of the power consumed by the WTP.
Water levels around the New Cook's Kitchen shaft are 155 metres below the surface currently and falling faster than expected though the rate of decline is expected to slow as pumping goes deeper.
Cornish Metals said it still expects the dewatering to take 18 months from start to finish.
Richard Williams, chief executive, added: "The start of dewatering of South Crofty Mine was an important milestone for the company and it is pleasing to see the water level in the NCK shaft dropping faster than expected over the last month.
“We remain focussed on our objective to complete the dewatering of South Crofty within 18 months."