Acid rain from cement plant threat to Oamaru
Waiareka Valley Preservation Society Inc.
Acid rain from the Holcim cement plant represents extreme threat to Oamaru’s historic precinct
Embargoed until 7pm 12 December 2006
Today the Waiareka Valley Preservation Society held its first public meeting in Weston where the Society spokesman Rodney Jones presented what information the group had collected so far on the impact of Holcim’s planned cement plant at Weston.
At this meeting Mr Jones highlighted the risks posed to Oamaru’s and North Otago’s future by the Holcim cement works.
In particular, acid rain from the Holcim cement plant represents an extreme threat both to Oamaru’s historic precinct, and to the large number of historic limestone homes, barns and other historic buildings in the broader Oamaru and Waiareka Valley area.
Historic Oamaru is now recognised as being a key part of our national heritage as New Zealanders. This would all be threatened if Holcim – a foreign company with no significant New Zealand shareholders - were to be granted resource consent to construct their cement plant.
With a planned capacity of one million tonnes p.a, the Holcim cement plant would emit up to 600 to 700kg of nitrogen oxide (NO2) and sulphur dioxide (SO2) per hour. The exact amounts emitted would depend on the pollution control equipment at the plant and the sulphur content of the Ngapara coal that Holcim intends to use. Irrespective, the volumes of oxides emitted would be extraordinarily large, reaching up to or in excess of 6m kg per annum.
When sulphur dioxide gets into the atmosphere, it oxidizes to first form a sulphate ion. It then becomes sulphuric acid as it joins with hydrogen atoms in the air and falls back to the earth as acid rain.
In the case of the Holcim cement plant, evidence from the United States and Canada suggests a high proportion of the acid rain would occur within a 15km radius of the cement plant. And this includes Oamaru, with its historic heritage of limestone buildings, for the historic precinct is only 7.5km from the smoke stack.
When this acid rain lands on a limestone building, the sulphuric acid is neutralised as mineral gypsum and carbon dioxide are produced. Gypsum is 100 times more soluble than the calcite, and therefore gets washed away with the rain water.
Because of the relatively large volumes of acid rain that will fall on buildings that have had no exposure to acidic rain in 120-130 years, the historic buildings will deteriorate with extraordinary rapidity. The intensity of the acid rain will be highly corrosive. Rapid deterioration and eventual erosion will occur.
If the Holcim cement plant is granted consent, historic Oamaru will quite literally begin to dissolve before our eyes.
Oamaru has survived with Victorian architecture and design intact due to the lack of heavy industry. To introduce heavy sulphur dioxide and nitrogen oxide emitting industry now will quickly destroy all that is precious and of value to our community.
The Holcim cement plant must not go ahead.