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The field QA program included the collection and analysis of trip blank and field duplicate samples.The trip blanks were prepared by the laboratory and contained deionized water.The trip blanks were analyzed for VOCs to evaluate the possibility of sample contamination introduced during the storage and transport of the samples.The field duplicate samples were also analyzed for VOCs to evaluate repeatability of the steps in the sampling and analysis program. Results for analytes detected in the duplicate sample collected from well MW-13 (MW-13-DUP) are provided in Table 7.VOCs were not detected in the trip blank. Relative percent differences(RPDs) are calculated when the sample results are more than two times the reporting limit for organic compounds.As such, no RPD was calculated for this sampling event.Absolute difference between primary and duplicate samples are presented in Table 7.The results are considered acceptable when the absolute difference between the detected result and the reporting limit is less than the reporting limit.The absolute value difference for chloroform results for field duplicate pair MW-13 and MW-13-DUP was greater than the reporting limit. Due to the difference in values the results were qualified as estimated,with a"J"flag.All other compounds were considered acceptable. Conclusions Recent depth-to-water data confirm that the groundwater flow direction in the Upper, Middle,and Lower Horizons is to the northeast,consistent with the regional groundwater flow direction.The recent drought and pumping of the Banta production wells are likely responsible for the decline in water levels since 2005; however,the historically wet 2022/23 winter season has resulted in a cessation of the declining trend and a higher groundwater elevation was observed at MW-13. Carbon tetrachloride and chloroform are the contaminants of concern at the Site.These compounds remain below the MCL in both the upper and lower horizons in this event and historical groundwater quality data indicates overall stable or decreasing concentration trends at all wells,with the exception of upper horizon well MW-9,where chloroform concentrations have increased since May 2020.VOCs detected in 2023 were within the historical range of results for the Site. Carbon tetrachloride exceeds the MCL only in the Middle Horizon wells. Chloroform and other VOCs remain below their respective MCLs. Recommendations Groundwater data collected to date continues to support MNA as the preferred remedial alternative,as first presented in the September 2001 Feasibility Study/Remedial Options Evaluation Report(SECOR,2001) and confirmed in the 2017 CSM (Amec Foster Wheeler,2017a). Proper destruction of well MW-6 will be conducted once an access agreement can be established with the property owner. MW-5 has been used as a replacement well until the access agreement is established.The https://woodplc.sharepoint.com/teams/olintracy/shared documents/general/03.0 docctrl/2021 biennial report/01_text/tcy 2021 biennial_text_rev.docx Page 7