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Rolling Hills Development Environmental Sampling Report <br />Elk River, Minnesota <br />October 10, 2023 <br />AET Report No. P-0025977 AIM IN SCAN <br />€HGINEEHlNG TESTING <br />4.2 Sediment Description <br />The sediments encountered at all locations were mostly silty sand or clayey sand with organic material. <br />Sediments encountered at B-3a and B-3b were more saturated than the other sites. <br />4.3 Analytical Results <br />AET submitted one sample from each boring location (12 total) for laboratory analysis. Laboratory <br />analytical results are shown in the attached Table 1 and compared to regulatory criteria published by <br />the MPCA. The laboratory reports are included as Appendix B. <br />4.3.1 PAHs <br />Various PAHs were detected in each sample. Most individual parameters were not detected above <br />their respective Tier 1 Residential/Recreational SRVs or Tier 1 SLVs. However, the BaP equivalent was <br />calculated for each sample based on the PAHs detected. The calculated BaP equivalent was above the <br />Tier 1 Residential/Recreational SRV and Tier 1 SLV in B-1A. <br />4.3.2 Metals <br />Arsenic and copper were detected at varying concentrations in the sediment samples analyzed. None <br />of the concentrations detected exceed their respective Tier 1 Residential/Recreational SRV or Tier 1 <br />SLV. <br />5.0 DISCUSSION/CONCLUSIONS <br />The calculated BaP equivalent for one sample (B-1A) was above the Tier 1 Residential/Recreational <br />SRV and Tier 1 SLV. <br />Arsenic and copper were detected in each of the samples collected at concentrations below their <br />respective Tier 1 Residential/Recreational SRVs and Tier 1 SLVs. Both metals occur naturally in the <br />environment and the measured concentrations of arsenic and copper appear to be consistent with <br />typical background concentrations. <br />Based on the laboratory analysis of sediment samples, most of the excavated sediment from the ponds <br />would be classified as "unregulated fill" and re -use of this material should follow MPCA's Best <br />Management Practices for Offsite Use of Unregulated Fill (MPCA BMP Guidance). According to their <br />guidance, the MPCA recommends avoiding placing unregulated fill at schools, playgrounds, daycares, <br />residential properties, in gardens where food will be produced, and near lakes, rivers or streams. The <br />MPCA indicates that unregulated fill is best suited for use at industrial or commercial properties. The <br />MPCA BMP Guidance is attached (Appendix D). <br />Excavated sediments from areas near B-1A would be classified as "regulated fill". Regulated fill is <br />considered solid waste by the MPCA and requires proper disposal. <br />Page 3 of 4 <br />