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4.2.2 <br />4.2.3 <br />sediment, and staining. Well No. 4 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 />Water Treatment <br />Like Well No. 3, water from Well No. 4 went through both treatment trains provided by the SEH <br />pilot water treatment plant. The chemical doses to treat water from Well No. 4 are provided in <br />Table 3. All four filters in the pilot water plant were operated at a rate of 3.0 gpm/ft2. <br />Table 6—Well No. 4 Chemical Dosages <br />rain 1 — Filters 1 and 2 (Direct Filt <br />Chlorine (mg/L as C12) <br />KMn04 (mg/L) <br />Min. <br />Avg. <br />Max. <br />Min. <br />Avg. <br />Max. <br />1.43 <br />2.57 <br />3.43 <br />0.49 <br />0.49 <br />0.52 <br />rain 2 — <br />Alk <br />Filters and 4 <br />C12) <br />(Aeration and Detention <br />Chlorine (mg/L as <br />KMn04 (mg/L) <br />Min. <br />Avg. <br />Max. <br />Min. <br />Avg. <br />Max. <br />1.95 <br />2.66 <br />2.72 <br />0.21 <br />0.21 <br />0.21 <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 />of detention allows for additional chemical reaction time to increase iron oxidation. The <br />potassium permanganate dosage in Train 2 was able to be lowered to less than half of that in <br />Train 1, as the added chemical reaction time with 30 minutes of detention increases manganese <br />oxidation. <br />Finished Water Quality <br />The SEH pilot water plant was able to treat water from Well No. 4, on average, to levels that meet <br />the EPA secondary standards, as well as MDH's HBV for manganese. Although the average iron <br />and manganese levels were below those standards, the pilot water plant was not able to remove <br />iron below the method detection limit on average like it did with Well No. 3. Filter 4 also saw a <br />spike in manganese at the beginning of the filter run, which was above the MDH HBV, but quickly <br />reduced manganese below the secondary standard and MDH HBV thereafter. <br />The finished water quality for Well No. 4 during the pilot study is summarized in Table 7 below. <br />Table 7 — Weil No. 4 Finished Water Quality <br />Filter <br />ilk <br />Min. illimivg. <br />Iron (mg/L) <br />Manganese <br />Min. <br />(m/L) <br />Avg. <br />ax. <br />ax <br />1 <br />nd <br />0.018 <br />0.080 <br />nd <br />nd <br />0.044 <br />nd <br />0.014 <br />0.080 <br />nd <br />nd <br />0.028 <br />3 <br />nd <br />0.014 <br />0.080 <br />nd <br />nd <br />0.031 <br />4 <br />nd <br />0.015 <br />0.090 <br />nd <br />nd <br />0.128 <br />Notes: nd = below method detection limit <br />PILOT STUDY REPORT RAMSY 154354 <br />Page 7 <br />