CHARLESTON — Fixing the structural issues that forced Dockside condominium tower residents to evacuate could cost $151 million, the building's homeowner association now estimates.
In February, some 200 residents were forced from their homes inside Charleston's tallest building — other than a church steeple — and also from the surrounding townhomes after engineers found the condo tower unsafe.
The evacuated owners are still in the process of gathering their possessions from the 19-story building, but will soon have to make a difficult decision: repair or sell.
A spokeswoman for the building's association board said all owners will first consider whether to repair the structural issues. No date has been set for holding that vote, but the spokeswoman said it would likely take place early this summer.
The costly repair bill would be apportioned across all owners. That includes not only the tower's 112 condominiums, but also the surrounding 21 townhomes, which don't have the same structural deficiencies — an argument made in a lawsuit challenging the evacuation order.
Each owner's share of the bill is based on their ownership percentage of the building, which varies condo to condo. A larger apartment might bear more than 1 percent share, meaning that owner would pay more than $1.5 million for the repairs.
Up until recently, the condos typically sold for upward of $500,000.
In some cases, the repairs could cost some owner three times what they paid for their home.
The repairs
It's unclear exactly what the $151 million projected price tag would cover.
But a March letter from the engineers hired by the condo association laid out several next steps that include installation of temporary shoring, asbestos remediation, further testing and design of the necessary retrofits.
Engineers from Wiss, Janney and Elstner, a national construction engineering firm that Dockside hired after a condo in Florida collapsed killing 98 people, found that the concrete slabs that make up Dockside's upper stories aren’t strong or thick enough to carry the weight of the building, its furnishings and residents. Any additional load could cause the building's columns to burst through the slab.
Engineers call this "punching shear failure."
Brandon E. Ross, professor at the Glenn Department of Civil Engineering at Clemson University, explained the concept in layman's terms using a pencil and a Styrofoam plate. A pencil standing vertically represents a building's columns, and the plate is the slab floor. Excessive pressure on the plate causes the pencil to punch through and the plate to collapse.
That's what happened to Champlain Towers South in Florida, according to WJE, the same firm now assessing Dockside. A primary structural element failed on the ground floor, resulting in the failure of adjoining elements that ultimately caused the eastern half of the 12-story tower to pancake.
The structural defects in Dockside stem from the building's construction more than 50 years ago, and are not the result of degradation over time.
But there are ways to address punching shear issues, Ross said.
"Basically, punching shear is all about how strong is the connection between the floors and the columns, and you need to improve that," he said. "Some ways that they can do that is go to the top of the column, right underneath the floor, and add additional structure around the column."
That could take the form of steel angles, carbon fiber wraps, or a cap or crown around the top of the column, the professor described.
"Basically, you're creating a pedestal at the top of the column for the slab to sit on," he said.
Returning to his pencil and plate analogy, he continued: "It would be like if you glued a quarter to the top of the pencil before you tried to push it through the Styrofoam. You've spread out the column. You made it bigger, so to speak, and that makes it harder for the slab to punch through. It increases the punching capacity."
According to the March letter, WJE has already designed conceptual "collars and corbels" that will serve a similar function as Ross' quarter.
In order to access the column, the existing floor and ceiling finishes must be removed from around each of Dockside's 702 columns, according to WJE. This demolition work prompts the asbestos remediation, which can be costly on its own because it requires special permitting and expertise to remove and contain the cancer-causing fibers.
This also indicates why the evacuation was necessary, aside from the concerns over safety should the building collapse. Many of the columns are inside condos where residents were living.
No timeline
There has been no timeline given for repairs.
The WJE letter said it would take nine months to a year for their engineers to preform additional testing, and that is only after temporary supports are installed and the demo is done.
No demolition or repair work is likely to start until all residents have removed their belongings. The protracted move-out, two apartments at a time, is expected to take through the end of June.
If the former residents decide not to save the harbor front property at 330 Concord Street, just south of Union Pier, they could vote to sell to a developer.
But all owners would have to agree to the sale.
Reach Ali Rockett at 843-901-1708. Follow her on Twitter @AliRockettPC.