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verified by tree growth on the Tract 1 area of the Queen's Canyon Quarry, although such a comparison is questionably valid because of considerable differences in microclimate and growth medium compositim between this site and the Tract 1 area. The vertical elevation difference in the area to be benched is about 200 feet while the horizontal distance is about 500 feet. An average bench length of 325 feet was used. A wall height of 30 feet was used for the lift of each bench. From this it is determined that 7 benches would be produced with an average width of 71 feet and a total bench area of 3.71 acres. Based upon the backfill depth and width of the benches, it was calculated the surface of the fill would slope 4.03 degrees. If a minimum medium depth of 3 feet is selected as suitable for tree growth (i. e. trees would be planted where the medium is 3 or more feet deep), there is a total of 3.62 acres suitable for tree growth, including the 1.4 acres under the South Peak. If the minirtum depth is taken at 2 feet then 4.37 acres is available. An average of the 3 foot minimum and 2 foot minimum calculations produces an area of 4 acres where the growth medium would be suitable for tree establishment and growth to adult dimensions. The next portion of the model (page 2) calculates the available water capacity of the growth medium. The current soils, assuming an average depth of 10 inches, has a gross available water capacity of 0.94 inches. This is calculated from data in the SCS Soil Survey of E1 Paso County. For the sake of calculations the mean value of the current soils was used as the available water capacity of the final plant growth medium (0.094 inches of available water per inch of depth). The water consumption levels of the vegetation was based on the proportions of biomass in the three physiognomic components of the community. It was estimated that 70% of the living biomass is in the trees, ZO% in the shrubs, and 10% in the grasses and fortis. Thus a division of the total available water capacity of the soil, based on biomass proportions, resulted in 0.658 inches consumed by trees, 0.188 inches consumed by shrubs, and 0.094 inches consumed by grasses and fortis. Because the vegetation has not been harvested to determine actual biomass proportions and because the water needs of the individual species are not actually known, the biomass proportion is the only available basis for predicting the available water budget in the community. Based upon the final growth medium depths and keeping biomass proportions the same in the mature community resulting from revegetation, it was determined that of the 3.7788 inches of maximum available water in the plant growth medium (assuming a mean depth of 3.5 feet) the trees would have available 2.7636 inches, the shrubs 0.78% inches, and the grasses 0.2256 inches, with an excess amount of water of PACE 2 TREE P'DDEI_ SM'DER NW AhFAmhII~IT EVIDENCE