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74 <br />ability to aid in the reestablishment of diverse and functional <br />ecosystems on retorted shale disposal sites. <br />Field Season 1977 <br />Construction of the Retorted Shale Successional Study began in <br />June 1977 with the removal of vegetation from six rectangular panels <br />measuring 23x109 m. Five of the panels were then excavated to specified <br />depths according to the designated profile configuration for each panel <br />(Figure 25). Excavated topsoil and subsoil were stockpiled separately. <br />Following excavation the long sides of each panel were lined with cresote <br />treated plywood to confine root growth to the artificial soil-shale <br />profile. <br />Paraho retorted shale was then transported from the Anvil Points <br />facility west of Rifle, Colorado, to the Intensive Study Site. Each of <br />• the five excavated panels received 61 cm of retorted shale material. In <br />order to simulate industry's proposals, the lower 15 cm of the retorted <br />shale was compacted to a density range of 1,360 to 1,520 kg/cu m. The <br />compaction was undertaken in an attempt to make the lower layer of <br />retorted shale impervious to water movement and root penetration. The <br />upper 46 cm of shale material in the profile was compacted to a density <br />range of 1,200 to 1,360 kg/cu m by normal equipment traffic. <br />Topsoil, subsoil, and gravel material were then deposited over the <br />retorted shale according to the experimental design (Figure 25). The <br />gravel treatment in Panel 6 was composed of a coarse gravel layer of <br />large pond rock (5-15 cm diameter) topped with a layer of fine gravel <br />(less than 4 cm diameter). This layer will test the erfectiveness of <br />• gravel as a barrier to the capillary rise of salts from the retorted <br />