515 Walnut Tower in Des Moines, Iowa, a $148M project, will be the city's tallest residential building. With 390 units and diverse amenities, it aims to address housing needs and boost the local economy. Challenges include tight construction site and unforeseen historical structures.
Drew Dau Photography photo
The $148 million 515 Walnut Tower in Des Moines, Iowa, will offer almost 400 residential units when construction is completed in 2027.
As the tallest and largest residential structure ever constructed in downtown Des Moines, Iowa, 515 Walnut Tower will offer almost 400 residential units when construction is completed in 2027. Plans for the $148 million, 33-story apartment building include a coffee shop, bike storage, dog park, coworking spaces, fitness rooms and a rooftop deck with a pool.
"This project helps address the growing demand for housing in downtown Des Moines to accommodate our growing population and workforce," said
Carrie Kruse, the city's economic development administrator. "This development aims to provide modern housing options that meet the needs of residents seeking proximity to employment, entertainment and cultural amenities. Supporting housing projects like this is crucial for maintaining housing affordability and supporting the city's continued economic growth."
The new tower will occupy the former site of the Kaleidoscope Mall and is the most significant addition to the city's skyline since the 1990s.
Drew Dau Photography photo
"The last major high-rise building constructed in Des Moines was the 19-story EMC Insurance building in 1996 at 700 Walnut Street. Upon completion, this tower will become one of the tallest residential buildings between Chicago and Denver. This transformational project will attract new residents and businesses, fostering further economic development opportunities in the city's downtown area.
"By introducing 390 new residential units, including 39 units with affordability restrictions, the 515 Walnut Tower projects will attract a diverse array of households to the heart of our downtown and complement the city's growing housing and employment demands," said Kruse.
The project will create more than 700 construction jobs as well.
"Beyond direct employment, construction projects generate demand for local goods and services," said Kruse. "Suppliers of materials, equipment and services experience increased business, leading to job creation in these sectors.
"Projects like this contribute to the vibrancy and lively urban atmosphere that also helps to attract significant events and tourism opportunities to Des Moines, which has a multiplier of spin-off economic impacts for our downtown."
The former mall on the job site was demolished in July 2023 to prepare it for future development. Kruse explained the property is an excellent choice for the new tower project because of its central location.
"It's close to key amenities, entertainment venues, employment, hospitality, dining, parks, trails and parking. The proximity to all these downtown amenities makes it an ideal location for residential development. Additionally, the site was underutilized and transforming it aligns with urban revitalization efforts to maximize development density downtown, increase housing options and enhance the city's appeal."
Kruse noted the project also will reconnect a key portion of the downtown skywalk network.
"These details matter when attracting economic development investments into our city. Reconnecting a vital segment of the downtown skywalk system enhances pedestrian mobility, safety, accessibility and wayfinding throughout the system.
"This reconnection will help to ensure seamless connectivity between businesses, residences, parking, hotels and public spaces, fostering a more integrated and vibrant urban environment that's easy to navigate for residents, our downtown workforce, guests and visitors.
Foundation work started in January 2025. According to Andy Beal, co-owner, Beal Derkenne Construction LLC, logistics is a key component to any tower project.
Beal Derkenne Construction photo
"There's an immense amount of pre-planning, coordination and communication that goes into the day-to-day activities. There's significant focus on delivery schedules, hoisting requirements and understanding workflow needs to meet or exceed schedule expectations.
"With the heights involved on this project, there is an increased awareness for 100 percent compliance with safety protocols and ensuring all trades are informed, trained and confirming with current OSHA regulations at all times."
Currently, sub-grade crews are wrapping up the shallow foundation and mass excavation scopes of work. Utility tie-ins are under way, and MEP underground will trail shortly thereafter. The main building core and first lift of columns going vertical above grade are next.
Site stabilization and deep foundations are complete. The structure is about to come out of the ground, which leads to exterior skin elements, followed by interiors and, ultimately, getting the building enclosed to a point where elevators can be installed.
Beal said working in a limited space is a definite challenge for crews.
"With any postage stamp-sized site, movement around the site is very precise and exact. Site work on this project was limited to basic stabilization, which led into our deep foundation package. The building footprint takes up approximately 95 percent of the site property line to property line, so there really isn't a lot of room left over for much else."
When work commenced in December 2024, the site had already been backfilled and graded flat to grade.
"Ironically, during the deep foundation drilling, we encountered significant unforeseen/unknown structures from a previous building that occupied the site in the early 1900s," said Beal. "We unearthed some unique reinforcing steel that dated back to that era, approximately 18 to 30 feet below grade. This slowed the drilling operation, as we were forced to drill through the steel and concrete elements to maintain the current design intent and location of caissons for the tower footprint."
To date, the weather has not been a significant issue.
"Breaking ground in December in Iowa is never a pleasant thing to do; however, we've been fortunate enough to have had a pretty mild winter and were spared of snow-related impacts. We did, however, experience some arctic type temperatures, which ultimately impacted the project for approximately one week of ceased operations."
During the deep foundation package, crews had a 110-ton mobile crane to facilitate caisson cage hoisting, along with a drill rig with drill bit diameters varying from 3 ft. to 8 ft., with drill depth capacity to 126 meters.
"During shallow foundations and moving into the vertical work, our tower crane was mobilized which has 35,000-pound max capacity, and 19,000-pound capacity at the end of the jib. The crane will be jumped two times during the course of the project."
Primary materials for the building are concrete and glass. The structure itself is post tensioned concrete slabs, and the entire façade is a turnkey slab to slab storefront style window wall system with integral metal louvers throughout.
Approximately 3,500 yds. of dirt/earth was removed during the deep foundation process, and a further 3,500 yds. was pulled out to facilitate the shallow foundation systems and geotechnical over excavation requirements.
Beal said working on a project that will serve so many people is truly rewarding.
"It's fun to be able to lead and execute one of these in our own backyard. This is Beal Derkenne Construction's twelfth high-rise project, and the fifteenth tower I've been a part of across the nation. We have a wealth of experience and are appreciative of the opportunity to showcase our skill, expertise and ultimately deliver a project to the market that will change the Des Moines skyline. It will become the tallest building built in Des Moines this century, and the fourth tallest in Iowa."
Kruse added, "The construction of 515 Walnut Tower is a momentous occasion for Des Moines, symbolizing the city's dynamic growth, our community's resilience and forward-looking vision, generating excitement among residents and stakeholders alike. We are very fortunate to have a local development community that dreams big for Des Moines, and who is bold enough to never give up on those dreams." CEG
Cindy Riley
Birmingham, Ala., native Cindy RIley originally planned on a career in law, but during her sophomore year in college realized journalism was her true calling. A magna cum laude graduate of Samford University, Riley first worked in radio and TV. Named Best News Anchor, Best News Reporter and Best Investigative Reporter by the Associated Press, she interviewed numerous personalities, ranging from Dr. Henry Kissinger and President Bush to Michael Jordan and Captain Kangaroo.
As a print journalist, Riley has covered a variety of topics, including construction, business, health and the arts. In addition to CEG, her work has appeared in special reports for USA Today and the L.A. Times. Other publications have included New South Magazine, Portico, Thicket, Alabama Heritage, B-Metro, Business First and Birmingham Business Journal.
Read more from Cindy Riley here.
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