Redcorp Ventures Ltd. -

The ACB is not a hovercraft. The ACB is a robust marine barge that uses high volumes of low-pressure air to hover on the surface of the water. A hovercraft, on the other hand, uses much higher pressures to hover above the water and utilizes loud aircraft propellers for propulsion to attain high speeds that can create significant waves and wake. The ACB moves slowly, uses regular diesel engines and blowers to compress air and, as a result, is relatively quiet and does not create significant waves or wake.

Movement of mine supplies, equipment, and mineral concentrate will be by barge operating out of Juneau and travelling the Taku River to within 12 km of the mine site. A road will be built to connect the barge-landing site to the mine site. Mineral concentrate will be barged in containers to Skagway where it will be loaded into bulk ocean carriers for transporting to smelter in Asia.

The Tulsequah Chief mine project is located in a remote area of northwestern British Columbia, far from existing road, rail or marine transportation systems. The means of shipping ore concentrate off site and re-supplying the mine during operations has been a major consideration for this project. Although conventional barging was investigated in 1995, road access had, until recently, been viewed as the only viable transportation alternative for operation of the mine because it provided year-round transportation. Approval for construction, operation and maintenance of a 160-km road from the mine to Atlin, BC was granted under the British Columbia Project Approval Certificate issued in 1998 and subsequently re-issued in 2002. A Special Use Permit was conditionally issued jointly by the BC Ministry of Forests and Ministry of Mines in 1999 for the construction of the road. Redfern Resources Ltd. (Redfern) is now seeking an amendment to the Project Approval Certificate that will permit the use of a barging transportation system as described below.

The river access option described here is considered to be more technically and economically feasible than road access.

Access via the Taku River has been selected as the Base Case for this study for the following reasons:

Compared to access by road, the Taku River is a shorter route that will require little capital development and will have lower operating costs.

The Taku River was the mine access route when the mine was operated in the 1950s. Mine supplies and concentrate were moved on it by river tug and barge; however, the water level in the Taku River is too low for conventional draft tugs and barges during half the year thus ruling it out as a viable year-round access route.

Redfern has recently identified air cushion barges as a viable means of using the Taku River year-round. Air cushion barges are amphibious and can operate on deep water, shallow water, ice, and land, and are able to accommodate all conditions found on the Taku River.

ACBs are a mature technology; their use in this project is feasible based on their successful operation in environments more challenging than at the Tulsequah Chief property.

The primary means of accessing the site will be by air cushion barge, towed by conventional marine tugs when the river has sufficient depth of water, and towed by existing towing vehicles such as Tracked Articulated Vehicles (TAV) and Rolligons when there is insufficient water in the river for conventional tug. Typically there is sufficient depth of water for tugs between October and April, but this varies year by year.

Photo: Yukon Princess
Used on the Yukon River in 1976 during the construction of the Alaska Pipeline

Consumable supplies and mineral concentrate will be stockpiled on mine site to cover periods when river transport is not possible.

Equipment and supplies for mine construction and operation will be shipped to site via Juneau, Alaska. Once production commences, ACBs will carry mineral concentrate from the mine to Juneau where it will be trans-shipped to conventional barges which travel regularly to Skagway, Alaska. At Skagway, mineral concentrate will be loaded into bulk ocean-carriers for transport to smelter overseas.

In September 2006, Redfern commissioned Hovertrans Inc. to provide a feasibility assessment of the applicability of hover technology to meet the haulage requirements of the mine .

Hovertrans is a leading expert in hover technology. The company was formed in 2006 by the managers of Mackley Air Cushion Equipment (Mackace), who have over 30 years experience in commercial hover systems design.

The managers of Hovertrans have constructed ACBs for use as drill platforms, and as cargo transport vessels operating in open water, mud, swamp and bogs. Their largest operating ACB is a 900-tonne unit (330-tonne payload) operated as a drill platform in a swamp in Suriname. The same management team designed and built the two 160-ton Yukon Princess ACBs, used in 1976 on the Yukon River in Alaska during the building of the Alaskan pipeline.

Concentrate containers cycle between mine site and Skagway. The segment between mine site and Juneau is by ACB, and the segment between Juneau and Skagway is by conventional barge owned and operated by Alaska Marine Lines.

Concentrate containers are offloaded and emptied at the bulk concentrate terminal at Skagway, prior to loading onto bulk ocean-carriers bound for a smelter in Asia.

ACBs hover at a height of 1.82 m above the water's surface. The draft will be 0.6 m (on and off-hover) and the vessel will float off-hover with a freeboard of 0.5 m. The ACBs will operate on land with a ground pressure of one psi, and will negotiate ground obtrusions up to the height of hover.

ACBs will use diesel engines totalling 2,000 hp to drive the fans pressurizing the skirts and to provide power for lighting, heat, and cable winching. Engines on the ACBs under tow will be remotely controlled by its tow vehicle.

Conventional towing vessels - marine tugs will tow the ACB from Taku Inlet to Juneau and shallow draft river tugs such as Redfern's own RDV- Gator and RDV - Kid Commando will tow the ACB along the Taku River during the aquatic season.

During the winter and shoulder seasons (fall and spring) where there is insufficient flow in the River for shallow draft tuges to operate, including Amphibious Tractors (ATs), Morgan Skidders, will be used. These tractors will essentially operate over land, snow and ice during the winter season. The aquatic capability of these vehicles will be limited to crossing open leads during the winter and crossing the main river channel between gravel bars during the shoulder season.

The TAV is a rubber tracked amphibious vehicle that is manufactured by ST Kinetics. It is a two-pod vehicle that is connected by a joint and articulates in both vertical and horizontal planes. The TAV is a rugged unit that will operate in nearly all terrain including ice and snow. As both pods are water-tight, it will float in open water with a draft of approximately 1.5m (5 ft). Its propulsion in water is limited, coming only from the tracks. There are no modifications anticipated to the these vehicles.

Two Morgans will be used behind the ACB to push it, provide brake force to stop it and to steer the stern.

The adapted Morgan will be a four-wheel drive vehicle with six large soft tires that exert very low ground pressure. This makes it an ideal vehicle for operating in environmentally sensitive areas. Buoyancy provided primarily by the tires and Styrofoam-filled frame. Its propulsion in water is limited, coming only from the tires.

One Hagglunds BV206 will be used in a support role for the haulage system. It will be driven by a route master who will monitor the safety of the operation, direct the activities of the towing crew and scout ahead of the ACB to assess the condition of the route. The BV206 will also be used for crew changes.

BV206's are widely used in Tracked and military applications. It is a standard rubber tracked NATO troop carrier and several are operated in the State of Alaska by the US Military. Its design is similar to the TAV; a two-pod articulated vehicle with flotation provided by both watertight pods. Its propulsion on land and in water is provided by two sets of rubber tracks on the front and rear units. There are no modifications anticipated for this vehicle.

Snow grooming will be done as needed to pack fresh snow along the route. Grooming will also be done to maintain safe snow cover over exposed ground during operations in the shoulder season.

Snow grooming machines are not amphibious. In applications where ice integrity is in question, a BV206 fitted with a dozer blade will be used for snow grooming.

Snowmobiles will be used as backup evacuation or crew change vehicles when necessary.

Augmenting the haulage fleet will be two snow grooming machines and snowmobiles as required.