ARCHIVED REPORTS 2011 YEAR 5 PHYTOREMEDIATION TREE MONITORING REPORT

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SECTION 3:TREE SYSTEM MONITORING METHODOLOGY 3.1.5 Post Plant-Establishment Monitoring ' The purpose of post plant-establishment monitoring is to assess tree survivorship and health and vigor of the phytoremediation system following the period in which most active site maintenance was performed (for example,irrigation). Typically,water needs decrease as the roots reach the natural water table, and, eventually, supplemental water will no longer be needed. Once trees no longer require irrigation or other active maintenance they are considered to be established. ' The need for weed control and other site maintenance actions was also expected to decrease as the trees established. Weed control was conducted on an as-needed basis during the entire 5-year monitoring period. Weed control is to decrease the water demands of the trees due to competing weeds,and reduce the risk of fire due to dense weeds and grasses at the site. If problems are identified during the post plant-establishment period that may adversely affect the success of the phytoremediation system,remedial measures will be identified and implemented as part of ongoing site maintenance activities. 3.2 Site Maintenance Site maintenance was performed during the 3-year plant establishment period as described in the Phytoretnediatfon Cleanup Plan. As the largest trees have continued to grow in Year 4 (2010) and Year 5 (2011),their roots have reached the water table.These trees are considered to be naturally established and irrigation is no longer needed in these areas(Area A, Addition to Area A, Area AA,and Area B).Trees planted in Areas C and D, in compacted soil,were still irrigated in Years 4 and 5.Weeds were controlled throughout the site in Year 4 (2010) and Year 5 (2011). Maintenance activities performed to date include: • Replacement of trees damaged by beavers • Irrigation of planted trees Irrigation system inspection checks • Periodic irrigation system repairs and maintenance • Weed control within planting basins and within the planting area • Maintenance of the watering basins and mulch • Other plant replacement (as needed) • Installation and maintenance of wire cages around trees for beaver protection • Limited pruning of trees that are outgrowing wire cages SA04203071113570001(YEAR5-2011_HOLTTREE MONITORIN(;_REPORT-FINAL.DOCX) 3-3