Wheal Jane

Overview

Wheal Jane, near Chacewater, was one of Cornwall's last major working tin mines, closing in 1991. It's better known today for what happened next: in January 1992, acid mine water burst out of the flooding, abandoned workings and turned the Carnon River and Fal estuary ochre-yellow, in one of the most notorious mine-water pollution incidents in British history — one still being actively treated more than three decades later.

History

Individual workings on the site date back to the mid-18th century; Wheal Jane itself was formed in 1861 through the amalgamation of five smaller mines. The mine was reworked in 1906 as part of Falmouth Consolidated, and again from 1969 in a major modern redevelopment that eventually brought it under the ownership of Rio Tinto Zinc. Through the 1970s and 1980s the mine produced tin, alongside copper and zinc as by-products — tin output peaked at 4,828 tons in 1987, zinc at 10,855 tons in 1981, and copper at 945 tons in 1990. Employment peaked at 1,061 workers in 1985 before falling sharply to 216 by 1991, the year underground operations finally ceased as tin prices collapsed.

Geology

The mine worked polymetallic lodes in the Carnon Valley producing tin, copper, lead, silver and zinc, alongside pyrite and arsenopyrite as associated minerals.

Workings

Modern underground workings dated mainly from the 1969 redevelopment onward, though the site incorporated much older workings from the mid-18th century amalgamated mines.

Closure

Underground mining ceased in 1991 as falling tin prices made the operation uneconomic, ending regular pumping of the workings.

What remains

With pumping stopped after closure, water levels in the abandoned workings rose steadily. On 13 January 1992, roughly 50,000 m³ of highly acidic mine water (pH 3.1), laden with iron, zinc, cadmium and arsenic, escaped through the Nangiles adit over about 24 hours, discolouring the Carnon River a distinctive ochre-yellow as the iron oxidised, and flowing on through Restonguet Creek, Carrick Roads and into the Fal estuary. The discharge killed fish and affected wildfowl, and drew international media attention.

Little remains of the working mine above ground beyond the water-treatment infrastructure built in response to the 1992 incident.

Redevelopment

Emergency and then permanent treatment measures were developed from 1992 onward. Settling ponds, including the Clemows Valley Tailings Dam, were in place by 1994, and a lime-dosing treatment plant was built to precipitate dissolved metals before water is released. By 2002 the treatment programme had cost more than £20 million, and mine-water treatment at the site continues on an ongoing basis today.

Abandoned workings can be dangerous — unstable ground, uncapped shafts, flooding and bad air are common even where a site looks safe from the surface. This entry describes history and general location only; it is not an access guide.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• On 13 January 1992, an estimated 50,000 m³ of acidic mine water (pH 3.1) escaped through the Nangiles adit over roughly 24 hours, discolouring the Carnon River and flowing into the Fal estuary via Restonguet Creek and Carrick Roads. ^1,2
• By 2002 the water-treatment programme responding to the 1992 incident had cost more than £20 million; treatment at the site continues on an ongoing basis. ¹
• Wheal Jane's recorded production peaked at 4,828 tons of tin in 1987, 10,855 tons of zinc in 1981, and 945 tons of copper in 1990. ¹
• A January 2007 report describes an emergency light still on and a transformer still humming in the main processing building at Wheal Jane several years after closure, alongside catwalks, control panels and floors under one to three inches of red mine water. (uncertain) ³

Photographs & further reading

This page doesn't try to reproduce everything — these are the best original sources found for this mine.

Images

Sources

1. (secondary) Wheal Jane — Wikipedia
2. (primary) Wheal Jane Tin Mine: Pollution — Hansard, House of Lords
3. (observational) Wheal Jane Mine, Baldhu, Cornwall — 13/01/07 — 28DaysLater