ARCHIVED REPORTS 2011 YEAR 5 PHYTOREMEDIATION TREE MONITORING REPORT

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SECTION 3:TREE SYSTEM MONITORING METHODOLOGY 3.1.2 Plant-Survivorship Success Criterion If plant survivorship drops below the 5-year,80 percent survivorship criterion in any year, replanting will be required. Information obtained on tree health and vigor and qualitative assessments performed during the annual monitoring and site inspection visits will be used to determine the appropriate species and location to be replanted. ' 3.1.3 Health and Vigor Assessment A quantitative assessment of plant health and vigor will be conducted during monitoring. ' Observations such as leaf color,bud development, new growth,herbivory, drought stress, and damage will be noted. Because boron levels were detected at high to very high levels in some agronomic soil samples, particular attention will be paid to abnormal leaf tissue color and burn patterns, should this occur. The overall health and vigor of each tree will be ranked and scored, and then rated as high, medium,or low, as follows: • High (3) 67 to 100 percent healthy foliage • Medium(2) 34 to 66 percent healthy foliage • Low (1) 0 to 33 percent healthy foliage Average health and vigor scores will be tallied and provided in annual reports. Data from previous years will be compared to identify trends in overall health and vigor. 3.1.4 Plant-Establishment Monitoring The purpose of plant-establishment monitoring is to determine the progress of the phytoremediation system during the period in which the most active site maintenance is occurring (for example,irrigation is applied). Water needs of the trees are expected to decrease as the roots reach the natural water table, and, eventually,supplemental water will no longer be needed. Once trees no longer require irrigation,approximately 3 years, they are considered to be established,and post plant-establishment monitoring would commence. The need for weed control and other site maintenance actions is also expected to decrease as the trees increase in size. The frequency of irrigation will also be decreased if the trees are growing vigorously and have acceptable survivorship, so that the trees adjust gradually to less frequent watering intervals. Trees planted in the most disturbed areas (for example, on the compacted engineered fill and gravel layer in Area C, and in Area D),may need supplemental irrigation for a longer period. The frequency of other maintenance actions, such as weed control,is also expected to decrease over time. However,some amount of 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 that may adversely affect the success of the phytoremediation system,remedial measures will be identified and implemented as part of ongoing site maintenance activities. 32 SAC/4203071113570001(YEAR5.2011_HOLTTREE_MONITORING-REPORT-FINAL.DOCXI