Wawona Tunnel Ventilation System Repairs

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The project includes repairing the failed ventilation system in the Wawona Tunnel. The purpose of the project is to reduce the hazards associated with the current failed Wawona Tunnel Ventilation System. The work plan is to replace the existing fan motors with new fan motors, upgrade the existing hazardous gas monitoring system (the current hazardous gas monitoring system is inactive) and then tie the upgraded gas monitoring system into a remote sensor that would notify emergency response via the existing phone line in the tunnel, such as thru dispatch so that when the gas levels become hazardous additional fans can be turned on or if need be the tunnel closed until the gas levels are no longer hazardous to someone driving or walking thru the tunnel. If the tunnel would need to be closed we would try to activate the existing semiphore arms(gate) at the end of the tunnel. Then if enough funding would still be available the tunnel would be cleaned. It currently uncertain how specifically a contractor may propose to clean the tunnel, but the following is a likely process for cleaning the tunnel. A special tunnel washer truck with large rotating brushes on an articulated arm spreads a soap and water mix while scrubbing the tunnel walls. A flush truck follows and sprays water from an arc of nozzles that removes the soap and grime leaving behind clean surfaces and yes all of the soap and grime would be contained/filtered. The tunnel ventilation system is then turned up full blast to dry the roadway. Gas monitoring / analyser monitors the level of carbon monoxide and nitrous oxide emitted via the exhaust fumes and activates the exhaust fans to clear and maintain air quality and visibility. The exhaust fans can be independently switched to allow the operation of one or more pairs of fans to reduce the exhaust gas concentration to an acceptable level. These fans generate a thrust that can propel air along the tunnel in either direction. If the gas levels are hazardous it could also trigger an emergency alarm or phone call to the appropriate emergency response, such as dispatch.