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water. The finished water quality met the EPA secondary standards for iron and manganese, as <br />well as MDH's HBV for manganese, for both treatment processes and filter media types. <br />4.1 Well No. 3 Results <br />4.1.1 Raw Water Quality <br />The pilot study for Well No. 3 was completed between January 21, 2020 and January 22, 2020. <br />Well No. 3 currently pumps approximately 1,450 gpm directly into the distribution system with <br />polyphosphate, chlorine, and fluoride added in a shared pump house with Well No. 4. Table 2 <br />below summarizes the raw water results collected from Well No. 3 during the pilot study. <br />i awe t — Well No..) raw vvarer tatuauLy <br />Manganese (mg/L) <br />Min. <br />0.500 <br />Avg. I Max <br />0.640 I 0.850 <br />Min. <br />0.160 <br />Avg. <br />0.200 <br />Max. <br />0.240 <br />Min. <br />7.46 <br />Avg. <br />7.72 <br />Max. <br />7.85 <br />Results from the raw water sampling show that Well No. 3 exceeds EPA's secondary standards <br />for iron and manganese, which can cause aesthetic water quality issues related to color, taste, <br />sediment, and staining. Well No. 3 also exceeds MDH's HBV 0.1 mg/L for manganese for bottle- <br />fed infants less than one year of age. Infants who drink water with manganese above 0.1 mg/L <br />may develop learning and behavior problems. <br />4.1.2 Water Treatment <br />Water from Well No. 3 went through both treatment trains provided by the SEH pilot water <br />treatment plant. Train 1 utilized direct filtration through Filters 1 and 2 after chlorine and <br />potassium permanganate injection, while Train 2 utilized aeration and detention prior to filtration <br />through Filters 3 and 4. With Train 2, aeration was provided prior to chemical injection to help <br />oxidize iron, followed by chlorine and potassium permanganate injection, and then 30 minutes of <br />detention time to allow for adequate chemical reaction time before filtration. The chemical doses <br />to treat water from Well No. 3 are provided in Table 3. All four filters in the pilot water plant were <br />operated at a rate of 3.0 gpm/ft2. <br />Table 3 — Well No. 3 Chemical Dosages <br />Train 1 — Filters 1 and 2 (Direct Filtration) <br />Chlorine (mg/L as C12) <br />Min. Avg. Max. <br />2.15 2.92 3.58 <br />Min. <br />0.49 <br />KMnO4 (mg/L) <br />Avg. <br />0.49 <br />Max. <br />0.49 <br />Train 2 — Filters 3 and 4 (Aeration and Detention) <br />Chlorine (mg/L as C12) <br />Min. Avg. Max. <br />1.95 3.24 4.53 <br />Min. <br />0.10 <br />KMnO4 (mg/L) <br />Avg. <br />0.10 <br />Max. <br />0.10 <br />The chlorine dosages for the two treatment trains were similar, although the chlorine dosage with <br />Train 2 may be able to be reduced as aeration provides significant iron oxidation, and 30 minutes <br />PILOT STUDY REPORT RAMSY 154354 <br />Page 5 <br />