a minimum. and heavy cross drainage will be handled by the use of "Arizona dips*. (An "Arizona dip" is a depression in the road surface of sufficient width to permit the passage of flash floods over the travel way with the minimum obstruction and restriction. Both upstream and downstream sides of the road will be stabilized by hand-placed rock. The rock will extend a sufficient distance along the channel on the upstream side to prevent erosion behind the Installation. The invert elevation of the lowest section will be approximately three to four inches (7.6 to 10.2 centimeters) above the existing stream bed to minimize deposition of the roadway proper).

    6. Barring unforeseen delays, the works herein mentioned, exclusive of the second armor coat, will be carried out within a period of three to four years.

    7. During construction, the unimproved portions of the road will continue to be maintained in reasonable condition, but without retorting to major rebuilding.