ARCHIVED REPORTS 2009 YEAR 3 PHYTOEMEDIATION TREE MONITORING REPORT

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' SECTION 5 Summary and Recommendations This section provides a summary and recommendations from the Year 3 monitoring results. 5.1 Summary ' The success criterion for the tree phytoremediation system is an average tree survivorship rate of 80 percent or greater (following the removal of irrigation for more than 1 year). Once the 5-year success criterion has been attained, site monitoring and annual reporting of the 1 plant system will cease. A total of 22 trees (out of 239 planted in the six sub areas) were recorded as dead in Year 3 (2009) (Appendix A).This number is slightly less than the number of dead trees recorded in Years 1 and 2 (2007 and 2008). Limited replanting has been performed in 2007 and 2008 based on results of Year 1 (2007) and Year 2(2008) tree monitoring; therefore,the species composition of dead trees in 2009 differed slightly from that observed in 2007 and 2008. ' The average Year 3 (2009) survivorship rate is 91 percent (Table 4-1 and Appendix A). The average Year 2 (2008) survivorship rate was 89.6 percent(rounded in Table 4-1 and ' Appendix A to 90 percent). This was essentially the same survivorship rate as observed in Year 1 (2007),which was 89.5 percent.Overall, the average tree survivorship success criterion of 80 percent(for all six sub areas) was exceeded in all monitoring years. ' Limited tree planting in Areas C and D was conducted in late-November 2008 subsequent to the annual Year 2 (2008) tree monitoring counts. Because tree mortality is high and health t and vigor is low in these two planting sub areas, additional planting in these two sub areas may be needed in future years. Continued irrigation in these two planting sub areas is expected to be needed for an additional two years,and possibly more. Soil texture (for example,compaction),and the amount of available water to the growing plant(supplemental irrigation or groundwater) are likely the most important factors contributing to tree mortality and tree heath and vigor in Areas C and D.Site conditions are ' very challenging in Areas C and D. Recommendations to increase tree survivorship and health and vigor, particularly in these sites,are presented below. 5.2 Recommendations The overall average site survivorship criterion of 80 percent was attained in Years 1 (2007), Year 2 (2008) and Year 3 (2009).On a site-specific basis,this criterion was only met(not exceeded) in Area D, despite replanting some dead trees in these planting sub areas in 2007 ' and 2008.The following recommendations are presented to maintain and/or increase percent survivorship and tree heath and vigor,particularly in Areas C and D,where site conditions are most challenging. SAC/1667491PANAGON(YEAR3_2009_HOLTTREE MONITORING_REPORT.DOC) 51