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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br /> <br />Photograph 29 - Typical Condition of Interior Bowl- Note Brown Areas in this Photograph are <br />Sediment, Not Corrosion <br /> <br />The results of the total system dry-film thickness measurements from various <br />locations on the interior of the tank are summarized in the following table. <br /> <br />Area DFT Range (mils) DFT Average (mils) <br />Bowl 9.4 to 13.9 11.6 <br />Access Tube 7.8 to 15.3 13.2 <br />Roof (adjacent to manway) 8.1 to 17.2 12.1 <br /> <br />A SOX microscope was used to examine the substrate in random areas to <br />determine if mill scale, intercoat contamination, voids, underlying rust, mill scale, and/or <br />pinholes existed. The substrate appeared to be blasted and free from any of the fore <br />mentioned conditions. <br /> <br />The adhesion on the interior bowl, access tube, and roof was found to be good <br />(SA). The coating system consisted of one layer of white paint, however, similar colored <br />coats can be difficult to distinguish in the field and it is possible that more than one coat <br />was present. The plate thickness was measured on the bowl. The thickness ranged from <br />0.289 inches to 0.290 inches. <br /> <br />Interior Dry Coatings <br /> <br />The coatings on the interior of the pedestal, both sides of condensate ceiling, the <br />underside of the tank bowl, the overflow pipe, and the inside of the access tube were all <br />in good condition. However, isolated areas of minor corrosion were observed on the <br /> <br />Elevated Water Storage Tank <br />City of Arden Hills South Tank <br /> <br />28 <br />