Government’s Mining Plan For Thames Is Reckless  –
Opens The Floodgates To Extreme Hazards

Government plans to allow gold mining in steep, unstable conservation land above and bordering Thames township are “stupid and reckless, because mining will increase the risk of catastrophic flooding and landslides in the town”, says Coromandel Watchdog spokesperson and Thames lawyer Denis Tegg.  “The risk is not just from conventional floodwater but from an even more disastrous and life-threatening landslide hazard called a debris flow.”

A 2006 Report by GNS Science1 warns that in a weather bomb, a debris flow could sweep car-sized boulders weighing up to 50 tonnes, and other debris into the town without warning, at up to 50 km per hour, endangering lives and devastating homes and businesses.  The Report says a debris flow is more “lethal and destructive” than floodwater alone.

“Exploration activities by mining companies include forest clearance, cutting of tracks, roads, and grid lines, excavations for drilling platforms, test pits, and drilling. Mining would mean frequent explosions, major excavations for access roads, rock crushing and chemical processing plants, and possibly a tailings dam.  And Mr. Brownlee won’t rule out even open pit mining!. These activities all increase the chance of landslips and debris falling into streams, flooding, and a debris flow”.  Four at-risk streams flow out of the Conservation land.

“Taxpayers and ratepayers have spent $millions on flood protection, pest control, erosion and landslip control measures in the Conservation land.   Mr. Brownlee’s mining plan is just plain dumb, and its foolhardy.  It jeopardises all that good work, and puts the interests of foreign-owned gold mining companies ahead of protecting the lives, houses and businesses of local people.”

“The conservation land is very steep and unstable.  It has emergent forest cover and is starting to heal after past devastation from logging and mining.  It’s a no-brainer that mining excavations and vegetation clearance must be avoided at all costs.”

“Mining increases the risks of flooding and landslips.  These are extra risks the townsfolk and taxpayers don’t need to take and will not stand for.” says Mr. Tegg.  “Mr Key and Mr Brownlee need to realise that for Thames, and the country, the immense wealth of this land lies in conserving the soil and keeping it’s protective mantle of forest cover, not in digging it up for any gold beneath.”

1 The Potential For Debris Flows from Karaka Stream at Thames  M.J. McSaveney, R.D. Beetham.  GNS Science February 2006
http://www.ew.govt.nz/Publications/Technical-Reports/The-potential-for-debris-flows-from-Karaka-stream-at-Thames-Coromandel/

Background

As reported by TVNZ News, the Government proposes to remove 2,500 ha of Conservation land right beside and above Thames township from Schedule 4 of Crown Minerals. Act (see map).  This would open this land to mining, including open pit mining.

Schedule 4 (enacted by a National Government in 1997 with cross party support after 30 years of public campaigning) currently prohibits mining on this land.

All 4 streams that have their catchments in this Conservation land have caused devastating floods in Thames, including to the Central Business District  (see maps of projected flood levels) There have been 7 major floods since 1881.

3 of these streams (Karaka, Moanataiari, and Waiotahi) have the potential for the additional “lethal and destructive” debris flow hazard. (see Pp iii, 18 of GNS report)

The GNS Report states that a debris flow is a lahar-like mass of boulders, (up to 3m wide and weighing up to 50 tonnes) and other debris.  In a rainstorm a debris flow could sweep down from the hills without warning at 25 — 50 km an hour, and spill out of the stream channel in Thames Township.  A debris flow poses a much greater danger to people’s lives and property than floodwater alone.  (Pp. 25, 29, GNS Report)

3 people died when a debris flow hit Te Aroha in 1985, and another devastated Matata in 2005. (see photos)   Past flows in Thames have been as big as or larger than Matata  (P.1 GNS Report)

The GNS Report led to a large reinforced wall being built upstream of the Thames hospital at a cost of $1 million approx.(see photo). The wall was built to prevent large boulders and debris smashing in to the newly extended hospital complex.  But houses and businesses have been left unprotected from this extreme hazard. (P. iv)

Thames is built on past debris flows and up to 20 have occurred in recent history.  4 have occurred in the Karaka stream in the past 140 years, but fortunately did not reach the town. Climate change could bring more frequent weather bombs and greater risk of debris flows.

Millions of dollars have been spent on flood protection work within the town, on raising bridges on the State Highway, and other infrastructure improvements, as well as on pest control, tree planting, and erosion control in the Conservation land.  This has been a co-ordinated effort involving DoC, Environment Waikato and Thames Coromandel District Council, called the Peninsula Project.  Improvements to soil conservation have already been recorded.

“Human activities such as mining, quarrying and road construction can remove the base or toe of a slope or old slide and once this support is gone, sliding may occur in a heavy rainstorm. Other activities, including explosions and the use of heavy equipment, can also start landslides”  – Thames Coromandel District Council “Blueprint” Report October 2007 on Natural Hazards. P.6

Photos and maps in attached pdf file.