2018-07-18_REVISION - M1977534 - Laserfiche WebLink

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Revegetation Assessment-Revised Guanella Reservoir Clear Creek County,Colorado As shown in Table 2,the soil textures at the May 2018 S1 sites were sandy clay loam and sandy loam. At the May 2018 S2 site,the subsoils were loamy sand. All three S1 samples taken in May (Appendix A— June 4, 2018 Research Soil Analysis Report) were very high in salts and, therefore,were detrimental to plant growth. The soils taken in the middle subsoil (S1b)—between 4 and 27 inches below the surface— were also very alkaline. In contrast, the topsoil (S1a) and lower subsoil (S1c) were within the adequate levels for soil alkalinity. The species seeded in 2013 from the Reclamation Permit Seed Mix were analyzed to ascertain if they were compatible with the soil and other conditions within the project area, as shown in Table 3. This seed mix consists entirely of introduced species, which are not as well adapted to local conditions as native species. Additionally, at least two of the species are intolerant or moderately intolerant of saline conditions. The two fescue species were not observed in the reclaimed Phase II area DRMS 2016)and are more typically used in lawn or golf courses and not revegetation applications. Table 3. Reclamation permit seed mix tolerances. W&oducedSoW oep6- ca�aA Mauve tiName Nave(N)� pH R-W y/"Sak Tokrance R4k%kvvmn -) Ephraim crested wheatgrass Agropyron cristatum 1 .0-8.2 Medium;under saline conditions,18 Igor/production is reduced Dwarf perennial ryegrass Lolium perenne I .0-8.0 High 10 SR3200 blue fescue Festuca glauca I Not rated* Not rated* Not rated* Reubens Canada bluegrass Poo compress I .0-7.0 No 10 Chewings fescue Festuca glauca Not rated* Not rated* Not rated* Not rated* *Tolerance data is not available for either fescue. Source:U.S.Department of Agriculture(USDA),Natural Resource Conservation Service(NRCS)Plant Database 2018. Recommended Revegetation Plan Revisions Soil Recommendations To remove the salts, the CSU Soil Testing Lab (Appendix A—March 13, 2018 Agricultural Test Report) recommends adding gypsum and water to leach the gypsum through the soil and remove the sodium (salts)from the root zones. However, based on ERO'S assessment of the project area,there is concern that the salts would continue to leach up and prevent sufficient vegetation from growing in the project area. To prevent salts from leaching to the surface, ERO recommends excavating the project area about 30 inches and removing the excavated soil to a designated location. The excavated area would extend 1 foot outside the salt-crusted project area. Then a clay cap of approximately 6 inches would be placed at the bottom of the excavated area extending to the surface on at least the eastern (upslope) side. A ERO Project#7158 5 ERO Resources Corporation