Council votes 5-2 to repair concrete at wastewater plant
Published 4:08 pm Friday, August 14, 2020
Repairs needed for the city’s wastewater treatment were discussed at the Aug. 10 meeting of the Albemarle City Council.
Adam Kiker of LKC Engineering in Aberdeen presented a slideshow to Mayor Ronnie Michael and the City Council showing repairs needed in parts of the concrete, a project Kiker said had been a couple years in the making which stemmed from problems during construction. The slides included pictures of the problems with the concrete.
The changes will require additional city funds as well, Kiker said, and would include repairs in the cement walls on the outside sedimentation basins. The subcontractor, Crom, selected a repair method different from what the city had specified.
Kiker said the product was not installed in alignment with the manufacturer’s recommendations. The subcontractor has proposed to remove what the company had applied and use the method specified by the city at no cost.
“With precision and care, we will remove what is there,” Kiker said referring to the repairs.
Councilwoman Martha Sue Hall asked if Crom did not end up applying the changes on which they had bid, which Kiker affirmed was accurate. Hall asked if the city allowed the subcontractor to use a substitute product for repairs. Kiker said yes, but in doing so the contract did not relieve Crom of meeting the requirements of the work.
In evaluating the issue, Kiker said in the presentation patches removed to expose the old concrete revealed more problems, including the condition of walls in Basins 1, 2 and 3, which were “in poor condition and can not remain in service.”
It was the opinion of LKC, Kiker added, damage to the old concrete came due to the incorrect usage of the substitute methods.
“(The concrete’s) useful life has passed,” Kiker said.
Early last year, LKC hired American Engineering Testing of Minnesota to remove concrete cores in the affected areas for further testing. Those tests revealed the original concrete poured in 1949 does not have an effective air void system, meaning there is not enough air content to protect against freezing and thawing weather conditions.
Further tests indicated the micro and macro cracks were in the concrete years before the recent rehabilitation efforts, according to the presentation.
“There was a smoking gun relative to a couple of the cases and this particular area was one of them,” Kiker said about the photo of damage underneath an eight-foot section of the initial repairs which was removed.
Kiker explained concrete has a level on the acidity chart on the base side when poured (about 12 or 13 on the 0 to 14 scale), which protects the rebars in it.
When exposed to air the level goes to neutral causing rebar to rust and the concrete to fail. A depth of carbonation analysis tests the pH level of a concrete sample to see how long it has been exposed to air.
The example shown to the council showed a microfracture in the concrete with a neutral pH, meaning the crack had been there before Crom’s repair efforts.
Kiker said the affected areas in the basins are outside the scope of what the engineering company had specified, meaning additional city funds will be needed to complete new repairs on the older problem areas.
The original U.S. 52 WTP Rehab project also repaired the elevator and added a new generator at the Old Whitney pump station.
“If we knew three years ago what we know now, we would have used profit funds because there was about $200,000 left over at the end of this project,” Kiker said.
In early November 2019, Crom agreed to do repairs but the work had to wait through the winter, Kiker said, because one does not normally pour concrete in the winter. The process continued this year with the plans now going to the city council.
Crom has presented an estimate to the city of $77,000 for the additional repairs to the concrete. The request at the Aug. 10 meeting was to authorize Crom to start, then come back later for a budget amendment.
Kiker said the tests performed on the walls cost about $2,000 each, but they did not do a comprehensive test of the bases “so we don’t know if this is a problem you should expect to budget for…or if this is something which will never show its face.”
He added the industry standard is not to do a comprehensive lab test then a major capital outlay project, but to fix it when the problems come up, which Kiker added usually manifest slowly.
The tests were all on the 1949 expansion and not the 1960 expansion, he added.
City Manager Michael Ferris said he and the city staff have been firm to not have to pay for anything that has already paid for, or pay twice.
“What’s being proposed is Crom would pay for replacement of what they did incorrectly,” Ferris said.
Councilman Chris Bramlett asked if other concrete structures in the county have been standing for more than 100 or 200 years, “how on earth did we end up with something that went bad on us in 50 years?”
Kiker said the relevance of the pH in this issue is only part of the testing analysis.
“If this crack was new and had been caused by the activities of the subcontractor, then all of this would have been purple instead of a grey stretch,” Kiker said referring to a slide of a sample of the No. 2 basin.
Ferris said authorization was needed from the council to begin the work.
Councilman Dexter Townsend asked Ferris if LKC should absorb some of the costs of the project.
“What LKC has explained to us and what you are seeing tonight, if you are putting your faith in a contractor, engineer or otherwise…where we have arrived is an amount we would have been paying at the time of the project,” Ferris said.
Kiker said his company “will contribute to this,” adding “it won’t be a couple of thousand. It will be a noticeable number coming off your contribution.”
Hall asked if the amendment would be $77,000. Ferris said the actual cost will not be known until work is completed, but that figure “is the estimate on the high end.” Hopefully, he said, it would be significantly less.
Bramlett asked how a budget amendment would be used on a project which was on a previous fiscal year budget.
“If we are going to pay for this, we have to find the money somewhere. This is a water and sewer project, so we will utilize water and sewer reserves, not what was in the project reserves,” Ferris said.
When Bramlett asked why the problem surfaced two years later, Kiker said “we observe phenomena like this six to nine months after it was applied…it got bad fast and got slowly worse over time.”
Councilwoman Martha Hughes moved to authorize the repairs, seconded by Chris Whitley, and the motion passed 5-2. Bramlett and Shirley Lowder voted against the motion.