Contract awarded for Montana water-treatment plant, ahead of mine dewatering
miningweekly.com
By: Liezel Hill
24th August 2009
Updated 4 hours ago
TORONTO (miningweekly.com) – Canadian junior Rx Exploration has awarded a contract to CDM Inc, for the construction of a water treatment plant to remove arsenic from Rx's Drumlummon mine waters, so that the historic Montana gold mine can be dewatered.
CDM, an international consulting, engineering and construction firm, headquartered in Cambridge, Massachusetts, provided the plant design, and will manage the contract and construction through its Helena, Montana office on a turnkey basis.
Rx had previously announced it was considering driving a new decline to give access to the Charly vein, which it discovered in 2008.
The firm has calculated initial inferred resources of 155 518 t, containing 70 703 oz of gold and 1,92-million ounces of silver at the Charly vein.
The proposed portal will be collared on the surface at mine level 465 and initially driven 2 000 ft to the 600-ft level. The mine is flooded to the 400 foot level.
The Montana Department of Environmental Quality (DEQ) has approved the plan to dispose of groundwater pumped from the Drumlummon mine and the new treatment plant is being built to satisfy the water treatment stipulations of the DEQ approval.
It will be located in the underground hoist room on the 400-foot level of the Drumlummon mine, adjacent to the collar of the 1 200-ft deep No 1 internal shaft.
The plant design uses proven arsenic-specific absorption technology to lower arsenic in the water to three parts per billion or less to ensure that the arsenic content of the discharged water will be equal to, or less than, the Federal and Montana drinking water standards and the existing arsenic loading in the adjacent Silver Creek water.
Water discharge rates through the plant will initially be at a 40 gallons per minute (gpm) rate and it is expected that the discharge will quickly ramp up to the design flow-rate of 300 gpm, well below the 400 gpm rate approved by the DEQ, Rx said.
A small head frame has been constructed over the No 1 shaft collar to enable the controlled lowering of the electric pump on the existing rail in the footwall of the inclined shaft.
Initial plans are to dewater to about the 620 ft level.
This will allow access to both the existing 500 and 600 ft levels to inspect old workings and conduct sampling and mapping programmes.
Once the de-watering is completed, the company will also be able to complete the proposed decline being considered and connect it to the existing 600-ft level.
CDM expects to have the water treatment plant operational by November 10.
Financed by the Rothschilds in the late 1800s the Drumlummon is reported to have produced $29-million of gold and silver at historical prices, primarily between 1883 and 1910.
The operation was shut down in 1910 and flooded at the deeper levels when the operators lost a court case alleging they had mined onto the neighbour's adjacent property.
Although mining continued under subsequent owners and operators, substantial areas of the mine at depth have remained flooded since 1910. |
