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City of Arden Hills Project B2502087 May 15, 2025 Page 4 Laboratory reporting limits were compared against Dredge Management Level 1 limits which utilize MPCA Residential/Recreational SRVs for soil samples. Detection limits for the compounds analyzed during the investigation met their respective regulatory standards. The recoveries and/or relative percent differences (RPD) of benzo(g,h,i)perylene, fluoranthene, phenanthrene, and pyrene were outside of method acceptance criteria in the matrix spike/duplicate (MS/D) samples for parent sample O-1. These analytes are considered estimated in O-1, but their regulatory limits are several orders of magnitude greater than the results. The recoveries and/or RPDs of numerous cPAHs were outside of method acceptance criteria in the MS/D samples for parent sample O-1. The recoveries of the affected analytes are within the expanded lower acceptance limits according to the National Functional Guidelines and are acceptable for use in this investigation. Detections of the affected analytes are considered estimated, and non-detected analytes have estimated quantitation limits. The RPDs of chromium, nickel, and zinc were above method acceptance criteria in the duplicate of sample O-4. These results are considered estimated, but they are below the regulatory limits. The recoveries of nitrite and nitrate-nitrite as N were below method acceptance criteria in the MS/D samples for parent sample O-1. These analytes were not detected in O-1, and the quantitation limits are considered estimated; however, regulatory limits have not been established for these analytes. In summary, data quality control items identified during the quality review were evaluated and all data collected are acceptable for use in this investigation for the intended purpose of identifying sediment impacts within the area of concern. Recommendations Based on the analytical results from our sampling, sediments at the Site fall into each of the dredge management levels established by MPCA. Level 1 Dredged Material is suitable for beneficial use on properties with a residential or recreational use category. Sediment at O-1 is at or below the Tier 1 SRVs, and as such, meets the Level 1 characteristic. Level 2 Dredged Material is suitable for beneficial use on properties with an industrial use category. Sediment at O-2, O-4, and O-5 is at or below the Tier 2 SRVs, and as such, meets the Level 2 characteristic.