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Table F-9. Groundwater pH Data for Excavation Sequencing Area E <br />Project No. 110207, Everett, Washington <br />Date BA-MW-2 BA-MW-3 BA-MW-1 UST71-MW-104 UST71-MW-103 PM-MW-6 <br />8/26/2020 9.03 7.41 7.50 7.56 6.43 7.12 <br />8/27/2020 9.05 7.44 7.49 7.58 6.46 7.11 <br />8/28/2020 9.03 7.40 7.52 7.57 6.47 7.09 <br />Average Baseline 9.04 7.42 7.50 7.57 6.45 7.11 <br />"Trigger pH"9.54 7.92 8.00 8.07 6.95 7.61 <br />9/8/2020 8.88 7.25 <br />9/14/2020 8.79 7.50 <br />9/22/2020 8.90 7.27 <br />9/28/2020 9.15 7.58 <br />Notes <br />"Trigger pH" for downgradient wells is the pH that, if exceeded for 1 week, triggers consultation with <br />Ecology regarding response action. <br />pH Reading in Standard Units <br />Proximal Wells <br />Downgradient Wells <br />to Monitor if pH Increase >0.5 unit is Observed in <br />Proximal Well(s) <br />Baseline Readings for this Sequencing Area (3x in 1 week) <br />Weekly (at least) Compliance Readings During CM Removal in this Sequencing Area <br />Weekly (at least) Compliance Readings for 3 Weeks After CM Removal is Done in this Sequencing <br />Area <br />"Trigger pH" for proximal wells is the pH that, if exceeded for 3 weeks, triggers daily monitoring of <br />proximal well and start monitoring of downgradient wells. <br />Aspect Consulting <br />12/17/2020 <br />V:\110207 KC Everett Mill\Deliverables\Interim Action Report 2020\Client Review Draft\App F pH monitoring\Appendix F pH Data Tables <br />Table F-9 <br />Report for Second Interim Action <br />Page 1 of 1