At the Utilities Committee Meeting of January 13, 2020, Chris Howard, City Engineer, reported on the decommissioned water tower anchor bolt inspection.
Howard reported that he received an inspection report from Dixon Engineering, and it was provided to Council for review. In summary, the water tower currently has 36 anchor bolts that are in poor condition. The original anchor bolt diameter was 1.750 inches, while the measured values at the corroded section ranged from 1.233 to 1.705 inches. The configuration of the baseplate and the anchor bolt chairs have created an environment for excess moisture to accumulate in this region.
Dixon Engineering performed the anchor bolt analysis per the American Water Works Association requirements, assuming all the anchor bolts have corroded to a diameter of 1 inch and that 25% of the anchor bolts, which would be nine, have corroded to the point that they no longer contributed to the strength of the group of anchors. Based on these assumptions, Dixon Engineering has determined that the corroded conditions of the anchor bolts were structurally sufficient to meet the loading requirements per the AWWA.
Dixon Engineering did recommend that exterior repairs on the anchor bolts be done within the near future to prevent further damage to the anchor bolts. Their recommendation is abrasive blast cleaning and applying an epoxy coat to all surfaces, and welding a steel plate to enclose each anchor bolt, at an estimated cost of $15,000. Therefore, Howard asked Council to make a recommendation to prepare the plans so they can bid it out.
Chairman Loucka asked if it would be prudent to replace some bolts with a stainless-steel bowl. Howard said they can’t because they’re imbedded.
Council At Large Stark said she has been asked why the city doesn’t keep water in the tower to keep it heavier at the base. Howard said there is no way to get in there right now and he isn’t sure they would want water sitting in there.
Councilman Holovacs MOVED; Stark seconded to authorize Dixon Engineering to proceed with preparing the design plans and specs as recommended. All members voted in favor.