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Spencer County’s radio tower, located at the county’s road maintenance barn on Fairgrounds Road, underwent remediation work last week to make sure the tower’s anchorage points could perform correctly and safely.
The work came as a result of a report issued by Qk4, an engineering company in Louisville. Antennas Unlimited, the company that installed the county’s antenna, commissioned the report, paid for the review by Qk4 and paid for the remediation work.
Spencer County Judge-Executive Bill Karrer read aloud a memorandum accompanying the report during last Monday night’s Fiscal Court meeting.
The Spencer Magnet has since received a copy of the report from Karrer.
The memo notes that Antennas Unlimited has been in business since 1974 and “per discussions with company representatives, they have had no tower failures due to installation issues.”
The memo also notes that Rohn Products, the company that provided the tower design and materials, has been in business since 1948. Qk4 obtained design information from Rohn, according to the report.
The memo states that the radio tower location at the maintenance lot is “in a largely unoccupied area.”
“Per information from the manufacturer, if one of the tower anchors is compromised to the point of failure ... the tower will collapse upon itself, with the tower falling within approximately 1/3 the height,” the memo says, going on to mention that there are no structures, except the tower’s out building, within 300 feet of the tower.
The tower is also to be protected by fencing, which as of last Monday’s Fiscal Court meeting, had not yet been installed.
Under the subheading of “Structural Analysis,” the memo states that the county tower is a guyed tower.
Unlike cantilever flagpole type structures, “the guyed tower must rely on the guy wires and their anchorage at the base of each guy wire to resist the horizontal wind loads,” the memo says.
“As the guy wires are stressed during a wind event, the loads must be resisted by the concrete anchorage system,” the memo continues. “The concrete must have a sufficient bond between the anchorage rod and the foundation concrete to transmit the anchorage forces to the foundation ... Based upon our review of materials supplied to Qk4, we feel the concrete and anchorage rods are adequate to develop this bond.”
“Records indicate that a total of 8 cubic yards of concrete was placed for the 3 exterior anchors, 3 interior anchors and the base pad,” the memo says.
“Total concrete needed for this work per the design document is 6.5 cubic yards, so the 8 cubic yards used is sufficient to meet the requirements of the project,” the memo says. “However, no steel reinforcement was used. Also it appears the exterior anchors may not have sufficient soil cover or concrete mass to meet the design requirements. To know for sure would take a destructive inspection, which would be counter-productive.”
Qk4 provided a plan for remediation work to add additional reinforced concrete to the exterior anchors. That work was completed last week.
In summary, the memo from Qk4 says that “the tower has performed as per designed.”
“Based upon the review of the in situ foundations, it is reasonable to predict that the tower will continue to perform as designed upon completion of the remediation work,” the memo says.
Qk4 also recommended the county grade the area surrounding the anchors (outside of 10 feet) to divert water away using a berm on the upstream end.
The memo also noted the tower should be inspected periodically for distress after high wind gusts. Karrer said the tower will require annual inspections, so this will not be an issue.
The fence work and berm work are yet to be completed, and the state may perform an inspection of the tower.