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Mounds View Stormwater Pond Assessment <br />4 RECOMMENDATIONS <br />July 2023 <br />The next steps for dredging would be sediment sampling and permitting requirements, which is discussed <br />later in this section. <br />4.1.3 SEDIMENT SAMPLING RECOMMENDATIONS <br />The MPCA requires owners or responsible parties to sample pond sediment prior to disposal to determine <br />concentrations of 17 cPAHs, 10 noncarcinogenic PAHs, and the metals arsenic and copper. It is the <br />responsibility of the owner or responsible party to evaluate the drainage area of each stormwater <br />collection system to determine whether spills, improper disposal, or the potential for a release from <br />commercial or industrial operations indicate that sampling for other contaminants is needed. <br />The number of samples to be collected depends on the surface area of the pond and/or the area of <br />planned dredging. The goal is to collect sediment samples that are representative of the material that will <br />be removed to maintain the functionality of the stormwater pond. Multiple samples need to be collected, <br />particularly since some compounds may not be detected in all areas of the pond. To provide a measure of <br />field precision, one field replicate sample should be collected for every 10 samples or less collected for <br />analysis. <br />Dredged material is divided into three management levels based on the amount of contamination and <br />therefore has different restrictions on disposal of the material. (Managing Stormwater Sediment Best <br />Management Practices Guidance, MPCA 2017) <br />Level 1 materials have the lowest levels of contamination and are suitable for use or reuse on <br />properties with a residential or recreational use category. <br />Level 2 materials are suitable for use or reuse on properties with an industrial use category. <br />• Level 3 materials are considered to be significantly contaminated and must be managed <br />specifically for the contaminants present. These likely need to be disposed of in a regulated landfill. <br />Laboratory analysis for sediment characterization will determine the disposal options for dredged <br />sediment. Recommendations for sediment sampling and characterization are provided in Table 4.3. <br />23 <br />