The pristine Waiareka Valley will be transformed into an industrial corridor by a cement plant and sand and coal mines, according to the Waiareka Valley Preservation Society.


Society spokesman Rodney Jones said yesterday Holcim (New Zealand) Ltd’s proposals for the cement plant, an open cast coal pit at Ngapara and an open cast sand pit at Windsor placed the local environment at risk.


Holcim is sending out 8000 information sheets about the mining activities, two of a series since its plans for a $200 million cement plant at Weston were announced in May.


Mr Jones said the latest information had finally revealed the extraordinary scope of what Holcim was proposing in the Waiareka Valley.


"This is much more than a cement plant in Weston. With a large open cast coal mine in Ngapara and a large sand pit in Windsor, one of Otago’s most pristine historical valleys will be transformed into an industrial corridor," he said.


The coal pit at Ngapara was a dramatic change in use, unacceptable for a rural zone.


The coal mine would be easily visible from the Ngapara-Georgetown Rd.


Holcim’s claim that Ngapara coal was suitable for a cement plant, citing data from Burnside in the 1970s, was misleading, Mr Jones said.


Ngapara coal had a 2% to 4% sulphur content, which guaranteed high levels of sulphur dioxide emissions, even with the best available pollution control technology.


Ngapara coal was also believed to have a high mercury content. Emissions of mercury into the local environment from the plant were likely to be 100kg or more per annum, which translated to 5 tonnes of mercury over the life of the plant.


"This is an unacceptable and dangerous amount. Our society has repeatedly asked Holcim for details of the analysis on Ngapara coal, most recently only two weeks ago. Holcim continues to refuse to release any details," he said.


The largest cement plant in New Zealand, New Zealand-owned Golden Bay Cement in Whangarei, used high quality low sulphur, low mercury coal imported from Australia.


If Holcim was concerned about minimising adverse impacts on the local environment, it would do the same, Mr Jones said.


In electing to use Ngapara coal, as opposed to a high quality coal, Holcim was putting profits before the environment, he said.