ARCHIVED REPORTS_YEAR SIX (2013) PHYTOREMEDIATION TREE MONITORING REPORT

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' SECTION 5 Year 6 Success Criterion Evaluation and 1 Recommendations This section provides an assessment of success criterion attainment and a summary of the results of the Year 6 (2012) tree and irrigation system monitoring. The five-year success criterion of 80 percent survivorship was attained in Year 5 (2011). In Year 6,one additional year of tree monitoring was performed to determine if the trees have continued to successfully establish and verify that survivorship goals have been achieved. 5.1 Attainment of success Criterion The five-year success criterion was attained in Year 5 (2011). As described in the P14ytoremediation Cleanup Plan (CH2M HILL,2004) and summarized in Section 3, the 5-year success criterion for the tree phytoremediation system is an average tree survivorship rate of 80 percent or greater (average for all six planting sub areas). Once the 5-year success criterion was to have been attained, site monitoring and annual reporting of the plant system would cease. In Year 6 (2012), one additional year of tree monitoring was performed. The objective of the Year 6 (2012) monitoring is to verify that trees continue to successfully establish and survivorship goals are attained. The overall site tree survivorship success criterion of 80 percent (average for all six sub areas) was exceeded by a fairly large margin(10 percent or more) in all monitoring years, including Year 6 (2012) (Table 4-1).The Year 6 (2012) tree survivorship rate was 92 percent (Table 4-1). In Year 5 (2011), the overall survivorship rate was 91 percent.In Year 4 (2010), the average survivorship rate was 93 percent (Table 4-1 and Appendix A).The average Year 3 survivorship rate was 91 percent. The average Year 2 (2008) survivorship rate was 89.6 percent(rounded in Table 4-1 to 90 percent).This was essentially the same survivorship rate as observed in Year 1 (2007),which was 89.5 percent. 5.2 Recommendations at ons ' The 5-year 80 percent survivorship success criterion was attained in Year 5 (2011). One additional year of monitoring was performed in 2012 to verify that conditions were stable and that the trees continue to become well-established. As described in Section 5.1,the 80 percent survivorship success criterion was attained in all six monitoring years by a relatively large margin(10 percent or more) (Table 4-1). ' The trees in Areas A, Addition to A,Area AA,and Area B are well-established and no longer need supplemental irrigation. Irrigation was last applied to these trees in 2009.As shown in the representative photographs provided in Appendix B, the trees in these planting sub areas continue to grow vigorously and have a dense canopy that provides substantial wildlife habitat benefits.