Permit identification signs shall: Be displayed at each point of access to the permit area from public roads; Contain information identifying the name, business address, and telephone number of the operator, the Bureau of Mines permit number, the Water Resources Administration discharge permit number, and NPDES discharge permit number; Be constructed of metal or wood and be a minimum of 2 feet by 2 feet, affixed to a suitably located tree, or a 2 inch diameter metal or wood post driven into the earth at least 3 feet with a minimum of 4 feet exposed; Be retained and maintained until after the release of all bonds for the permit area.