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I I I Page nine Battlement HeseL Development Storm Drainage and Flood Plain Study drainage basim; indicate that some of the larger apparent channels have little or no tributary drainage basins. I It will therefore be necessary to carefully control road grades and overlot grading operations on the development site to collect the diffuse overland flow into specific drainageway locations and convey it to the Colorado River. I The soils properties as reported in the soils reports prepared by Zeff, Cogorno & Sealy Associates and Chen & Associates have a distinct bearing on the drainage facilities. Those soils properties which must be considered consist of the following: I I I I 1. Unnecessary saturation of areas adjacent to escarpment should be avoided whenever possible. 2. The channel bottoms are highly erosive and have not reached a stabilized elevation. Steps must be taken to prevent erosion in channels and to hold velocities to the range of 2' to 4' per second. I I I I 3. F:xtreme erosion may occur to the steep channel banks if water is allowed to flow down the channel banks in an uncontrolled manner. Care will have to be taken to collect water from the mesa areas and convey it in protected structures to the bottom of the channels. 4. Relatively frequent mud flows are likely to occur in Dry Gulch, Honument Gulch, an unnamed qulch near the center of the property and Pattlement Creek. Any drainage facilities provided within t~ese gulches must be capable of functioning durina mud flow concUtions or of being overtopped by mud flows without damage to structures. I v. Special Drainage Considerations .. II II II The unique drainage patterns and soils conditions give rise to special drainaae considerations on the site. Prelimi- nary profiles have been set for all major roads proposed on the site to assure that the drainage basin boundaries indicated on th," Storm Drainage Analysis Map are compatible ~li th the proposed development. These drainage basin boundaries