Monday, February 26, 2024

$3M fix: Portion of riverwalk built in 2014 is sinking, needs repairs

The northern part of the downtown riverwalk near Marina Grill and Pier 33 apartments needs $3 million repair, despite being only eight years old. (Port City Daily/Shea Carver)

WILMINGTON — “I am continually amazed at the amount of work that has to be done on projects that we have put into place five, six, seven, eight, nine, 10 years after they’re built,” councilman Charlie Rivenbark said Monday. “And not just a Band-Aid — I’m talking about major construction projects and repairs.”

He was speaking during the City of Wilmington’s agenda briefing as staff unveiled costs for repairs needed along a portion of the riverwalk. It could be a $3-million to $7.6-million fix. 

READ MORE: City commits $750K as it considers downtown building purchase

Roughly 1,000 linear feet of the downtown attraction needs remediation. Some areas have sunk upward of 5 inches since the project was completed in 2014 near the now-erected Marina Grill and Pier 33 apartments. It cost $2.2 million to finish that portion of the riverwalk.

“This is a lot of money for something not that old,” Rivenbark said. 

He alluded to staff and council doing a better job when it comes to planning. In particular, Rivernbark said it will save time and money for constituents and City of Wilmington personnel and government officials who are left to spend more on repairs than necessary at a future date.

“Something wasn’t done right or what we did was poorly engineered,” Rivenbark added of the nine-year-old construction; he has served on council since 2009. “There’s no accountability. That’s not a complaint aimed at you, Mike.” 

Pictures presented by the City of Wilmington of cracks and flooding problems on the riverwalk. (Courtesy photo)

Mike Naklicki, a division project manager for the city’s engineering department gave a presentation to council Monday, showing how soil settlement has caused concrete to shift and crack in the marina area of the riverwalk. In effect, it has posed tripping hazards to passersby. Parts of the riverwalk also flood heavily during rainstorms, causing detours in certain areas. 

With the help of geotechnical and structural engineers, the city investigated soils underneath that area of the decking to assess vulnerabilities. It showed debris interweaving soft compressible ground. 

Engineers also used ground-penetrating radar to study anchor rods holding in place the bulkhead — an underwater retaining wall to help control landslide erosion. They checked 10 borings “to a depth of at least 50 feet,” Naklicki said, and determined some cracks or voids were filled with water and air

“It’s within tolerance in the bulkhead system’s capacity — no concerns currently with that bulkhead or in the future,” Naklicki said. 

Two options are on the table to correct the riverwalk issues: One would require the concrete walkway to be demolished and reconstructed with “advance piles” driven 50 feet down to stabilize the structure. It comes with a price tag of $7.6 million, though requires less future maintenance. 

It also would mean closing that portion of the riverwalk for the duration of construction, up to 20 months, primarily affecting those who live in the immediate area. 

“Obviously, that would be extremely disruptive to both the marina users and some folks at Pier 33,” Naklicki said.

He added in 2014 it was easier to move in large, heavy equipment and fulfill construction needs; now, it is encumbered by buildings. When the project was completed nine years ago the surrounding riverbanks were a blank slate. There were no apartments, no Live Oak Bank Pavilion at Riverfront Park, no restaurants — only the PPD building was located in the vicinity.

Naklicki said a full construction rebuild of the section could also “disturb” adjacent infrastructure. Therefore, staff suggested a second option, also less expensive at $3 million, that would not impact surroundings.

The concrete decking would remain in place but holes would be drilled and filled with polyurethane grout. The design alternate will stabilize soils and fill any voids. Naklicki said adding the filler would “help lift that surface back into place to address any of the tripping hazards and also promote positive drainage.” 

The goal is to raise 5 inches in some areas, maybe more on the backside to deter pooling water.

The solution could last 10 years, though possibly longer with “tweaks” being made as needed, according to Naklicki. The duration of the project would be shorter as well, up to 10 months. 

Injections would be done intermittently, so only small closures of the riverwalk would take place and patrons could still utilize the pedestrian path. Multiple injections are expected after the first year, Naklicki confirmed. Structural engineers advised if any shifts happen in that section again, staff could opt to fill in areas with more product as long as the bulkheads remain steady. 

“If we have to, we will come back 10 or 15 years later to ensure this is a long-term solution,” Naklicki said. “Any adjustments needed has been factored into the cost.”

A contingency was built in, so $3 million is a conservative number and takes into account repairs of damaged concrete.

Staff pulled case studies from other areas that utilized the same injection on similar projects. In New Bern, the floor slab of the convention center, built atop a riverbed with poor soils, was shifting. 

“They were able to lift it in place,” Naklicki said. “In Chicago, Illinois, they had a very large apartment complex where they were able to inject this underneath the building slab and lift it into place without really disrupting the tenants that were there.” 

Mayor Bill Saffo brought up how areas of the riverwalk laid with concrete seem to face more problems and significant upkeep. Specifically, he addressed construction that took place in front of the federal building on Water Street from 2019 to 2022 on replacement of bulkheads, owned by the U.S. Coast Guard. It cost the federal government $8 million to repair.

“When it’s pile-driven, you know, when we have the pier system, it seems to work much better, correct?” he asked.

“That’s correct. And it’s not necessarily the material, it just so happens to be the areas that aren’t pile supported are concrete,” Naklicki said. 

The concrete decking has a longer lifespan than wood, which also comprises the riverwalk. The city has spot-replaced boards throughout the riverwalk’s lifespan but is planning on full replacements and upgrading to a better quality wood, such as Brazilian, or a composite material, which has a longer lifespan.

The mayor wanted to know whether staff would have approached the marina’s concrete portion differently if development was already in place along the northern riverfront in 2014.

“We could have put it on piles,” Naklicki said. “You don’t want to pound it now with all the bulkhead and infrastructure in place. But that was a possibility, I guess. Thinking back, lessons learned — it is a little more challenging when you have that much infrastructure out here.”

With more construction on the horizon in the northern part of downtown, council inquired if staff had contacted developers to account for other projects that may take place as the riverwalk repairs are made. The mayor pointed to a vacant lot owned by the Pier 33 group, developed by Raleigh, North Carolina-based Dewitt Carolinas Inc. Saffo said “there’s anticipation” it has plans to add to its 300 apartments by building an additional 100 units.

“It’s going to run into the same thing in regards to load and weight,” Saffo said. “Tying back into the riverwalk — are we going to address that before that thing is built? Because you know, it’s going to put pressure on it.”

Naklicki confirmed discussions are underway with the group. 

“If they do it the same way they did the northern building — it’s on piles, you know, slabs or spread footings — we really don’t think that impacted much of this riverwalk,” he said. “There were a couple large soil piles out there for the longest time; we do feel like that did put some pressure on that bulkhead and caused some of that deflection. Those soil piles have since been graded down, spread out and are not causing that impact. But we will still have those conversations with them.”

Anderson chimed in that the financial maintenance of the riverwalk — called “downtown’s beachfront” by deputy city manager Thom Moton — is worth the price. It’s the city’s most visited attraction.

Primarily, Anderson compared pictures taken from the same viewpoint in 2014 versus today.

“There’s a whole other city there,” he said, pointing north of the convention center to the newer mixed-use growth.

The city estimates it has brought in $250 million worth of riverfront development that has direct access to the riverwalk.

“If this riverwalk instigated that property value going in there and the property taxes we’re getting from that — guys, that’s a good investment,” Anderson added. “I’m not saying that we ought to not get it right the first time, but that’s just amazing.”

Plans to create a riverwalk in the downtown area began in the 1980s. To date, the city has invested more than $33 million on its construction and preservation across 1.7 miles. In the last three years, the city has spent more than $10 million, according to its website.

The riverwalk ranked second and third nationally in 2021 and 2022 by USA Today, and in 2014 upon its completion, it came in first place. The annual poll released its 2023 results last week and Wilmington fell to number seven.

“It’s one of the top riverwalks in the country,” Saffo added, “but it comes with a pretty significant expense just to maintain it over time.” 

That price tag could grow should another expansion get the greenlight. Currently, the city and Off the Hook Yachts founder and CEO Jason Ruegg have paid $50,000 for a feasibility study to explore options for a riverwalk extension. It currently stops at Riverfront Park, but considerations are being made to build it out under and beyond the Isabel Holmes Bridge.

It would create a pathway for more development, including a brewery and restaurant possibly on the table (read more here). According to internal emails, results from the study could be ready as early as May.

Staff is moving forward with a proposal in hand from Andrews Engineering to cover design and construction administration for the marina area repairs. After design is complete, the city will solicit bids before executing a contract.

Repairs have been funded in the 2023 budget. According to county spokesperson Dylan Lee, $7.6 million was allocated from the capital improvement plan fund balance.

“The entire amount won’t be needed for this repair so the remainder will be allocated to other riverwalk needs,” he said.

The project could begin this fall and take three or four months to complete, Lee added.

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Shea Carver
Shea Carver
Shea Carver is the editor in chief at Port City Daily. A UNCW alumna, Shea worked in the print media business in Wilmington for 22 years before joining the PCD team in October 2020. She specializes in arts coverage — music, film, literature, theatre — the dining scene, and can often be tapped on where to go, what to do and who to see in Wilmington. When she isn’t hanging with her pup, Shadow Wolf, tending the garden or spinning vinyl, she’s attending concerts and live theater.

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