Crane Flat Heli-Rappel Simulator

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This project entails a soil investigation, rappel tower design and heli-rappel simulator installation. The Crane Flat Lookout Parking area was specifically called out as the location of the future heli-rappel simulator in the Fire Management Plan.

The first step will be to have a qualified geotechnical engineer do a soil analysis at both locations. The soil analysis will allow the engineer to make a determination of foundation material and allowable soil pressure.

The foundation will be comprised of four concrete piers measuring 3 feet round at a depth of 2.5 feet below the finished soil elevation. The exact size and depth of the pier foundation will be determined once the soils engineer has completed the soil sample analysis. The maximum disturbed area (in a previously disturbed area being the parking lot or the quarry) would be a rectangular area measuring 26 feet by 20 feet. The interior of the rectangular footprint would be undisturbed. The majority of the soil excavated for the pier foundation would be placed back on top of the pier foundation.

The heli-rappel simulator will be 40 feet tall and have side dimensions of 21 feet by 15 feet. The tower will be constructed of an open steel frame. The simulator will be painted to blend in with the surrounding stand of Sugar pine and Ponderosa trees. There will be a stairway leading from the ground level to the platform located on the top of the simulator. A hoist may be installed to simulate a lowering from a helicopter with a hoist. The rappel simulator would need to be protected by lightening in the form of a copper grounding rod placed at each of the four pier foundations to a depth of 10 feet below the finished ground elevation.

The tower will be located down slope from the northwest corner of the parking lot. The slope is such that it will reduce the overall height of the tower by taking advantage of this natural terrain feature. Consideration will be given to eliminate any erosion the tower may enhance.

The heli-rappel simulator is needed in order to mitigate the impact to the visitor experience and to mitigate the safety hazards inherent in doing helicopter rappels. Fire Fighters and Rescue Technicians must maintain currency in the skill of helicopter rappelling. A live rappel from a helicopter must be done every 14 days, or 28 days if a rappel tower is available. There are about 25 employees that need to maintain their currency. A rappel simulator would half the number of times that the helicopter would impact a visitor's experience.

A helicopter is a mechanical device subject failure and human errors in judgment. The less the helicopter flies the less exposure to park employees. Accidents and mishaps happen during training exercises. The rappel simulator allows the opportunity for fire fighters and rescue technicians to practice a life saving technique is a safe and controlled environment.

The March 2004 Yosemite Fire Management Plan and EIS identified the need for a rappel simulator. Site selection and cultural issues where discussed. Section II p. 25-26, IV p. 151.

1. Once soil analysis become available, consult with HAL personnel to determine exact location of Rappel Tower.
2. The tower should be placed so that the maximum height of the tower it is below surrounding tree line.
3. Recommend tower color be flat back to blend into the landscape.