Pitwall slide halts production at Deep Post

Denver — Newmont Mining (NEM-N) has halted production at the Deep Post gold mine in northern Nevada following a pitwall slide on the southern side of the Betze-Post pit.

The pit, which is operated by Barrick Gold (ABX-N), will remain closed for several days until federal and state inspectors have completed their investigation.

The Deep Post, which sits beneath the Betze-Post pit, was supposed to be protected from open-pit operations by a 150-ft. buttress covering the bottom of the pit, nearest the Deep Post workings.

The buttress, consisting of chain-link fencing covered by cemented backfill and reinforced with steel cabling, was designed to allow mining from Deep Post right up to the surface of the pit.

“At this point, we don’t know what role the buttress played in the slide,” says Newmont spokesman Douglas Hock.

The two companies had been monitoring the southern pit wall for the past several months after it showed signs of movement. The decision to evacuate Deep Post was made Aug. 28. All personnel were safely evacuated, and no injuries were reported before the slippage occurred. However, power was disrupted for a short time, and debris from the slide buried the buttress and several pieces of equipment owned by a contractor.

Debris also covered a secondary portal, though the main portals, 600 ft. east of the slide, were unaffected. At presstime, Newmont had yet to inspect the damage to the underground workings, though it does not believe reserves at Deep Post will be affected. What impact the slide will have on production is also not known.

Newmont and Barrick have been jointly operating the Betze-Post deposit, in Nevada’s Carlin trend, since 1992. Deep Post, which began operations in February, contributes 160,000 oz. gold annually to Newmont’s bottom line.

At year-end, Barrick reported that total reserves at Betze-Post stood at 18 million oz. gold. Last year the operation turned out 1.6 million oz. gold at a total cash cost of US$195 per oz.