•  Carrier

In 1997, a devastating flood engulfed the sister cities of Grand Forks, N.D., and East Grand Forks, Minn. The Red River of the North poured over the existing levees, forcing massive evacuations and causing extensive damage to many buildings in Grand Fork’s historic downtown. After the flood the city responded aggressively, working with the U.S. Army Corps of Engineers (USACE) to develop a comprehensive flood plan that called for 30-mi of levees and floodwalls to protect the cities. It required buildings, and in some cases entire neighborhoods, be sacrificed to make way for the flood protection structures. Historic St. Anne’s, constructed in 1907, lay directly in the path of a proposed floodwall. Many feared St. Anne’s would join the long list of buildings sacrificed for the greater good of the city.

St. Anne’s was originally St. Michael’s Hospital and Nurses Residence. When a new hospital opened in 1952, the building was converted into St. Anne’s Guest Home, and for 30 years provided elder care. It sat empty for 10 years and narrowly avoided demolition. In 1990, it was listed on the National Registry of Historic Places and refurbished into a senior living center. It now contains 42 apartments for senior citizens.

Meeting Unique Requirements
Weak soil near the river proved problematic to efforts to save the building. Because the soil was prone to landslides, the flood control structures had to be constructed inland, away from the river. This meant that neither a levee nor a floodwall could be built between the river and St. Anne’s. Relocating the massive structure was out of the question. Demolishing the building to make room for the floodwall appeared to be the only option.

USACE was out of options when it turned to Stanley Consultants. The firm recommended the floodwall be built as an 8-ft-wide porch around St. Anne’s.

“Grand Forks and USACE had considered many possible alternatives to save St. Anne’s,” said Bonnie Greenleaf, USACE Project Manager. “We had focused on getting the floodwall as far from the building as possible. Then Stanley Consultants came in with the idea of having it hug the building. “I don’t know of anything ever being done before like this.”

The floodwall itself was located just 8-ft from the building. This close proximity did not allow the use of the usual inverted T-shape used for most floodwalls in Grand Forks with the supporting footings buried deep underground, projecting outward from both the flood side and protected side of the wall stem. In this case, in order to allow utilities to be located between the wall and St. Anne’s, and to mitigate potential adverse impacts of excavating soils from the grounds adjacent to or beneath St. Anne’s foundations, the wall and footings had more of an L-shape appearance, with the entire footing extending outward from the flood side of the wall stem. In addition, a foundation sub-drainage system was added to reduce potential uplift pressures along the base of the uniquely designed floodwall to provide additional overturning and sliding stability.

To save St. Anne’s, a different kind of floodwall had to be designed that met seemingly conflicting requirements. To satisfy historical commission criteria, the “porch” part of the floodwall could literally not touch the building’s exterior. But to look like a porch, it had to hug the varied exterior contours, wrapping around every corner and mimicking the building’s architectural features. To satisfy both requirements, every corner and bend was painstakingly poured so that the porch is very close to, but doesn’t touch, the building.

Construction of the 8-foot-wide floodwall “porch” required that the bricks and intricate ceramic tile from two original landings be carefully removed. These pieces were meticulously integrated back into the newly constructed staircases and landings after the landings were extended away from the building to allow space for the floodwall and the removable aluminum stop log closure panels that are inserted if floodwaters approach the level of the entry landings.

Floodwalls do not typically have pleasant aesthetic appearances. However, great pains were taken to make the St. Anne’s concrete and porch match the architecture of the existing building. To achieve this effect, form liners were molded out of plastic. Meticulous care was taken to smooth out the small voids resulting from bubbles in the concrete. In addition, great effort was put into the staining of the concrete work to successfully mimic the coloring of the existing structure.

While weak soils required that the floodwall be constructed inland from the river, the city’s fire code stipulated that the firewall not be constructed in a manner that could potentially trap firefighters between the wall and the building in the event of a fire. Constructing the floodwall as a porch eliminates this concern, plus provides easy emergency access in and out of the building to ensure the safety of both residents and rescue workers.

Preservation and Recognition
Construction of the floodwall, even with its many architectural elements, was more economical than demolition. Construction was completed in 2007 at a cost of $1.1 million. In 2008, the project received national recognition, being ranked among the country’s top 24 projects by the American Council of Engineering Companies. The project received a National Honor Award for demonstrating a high degree of achievement, value and ingenuity.

Throughout its 100-year history, St. Anne’s sheltered its occupants through many floods. It nobly survived the devastating 1997 flood with minimal damage. Then, ironically, it was slated to be sacrificed to make way for a floodwall. The building that had served the city for 100 years deserved to be spared. Saving St. Anne’s from demolition was a way to give back to a community that had suffered tremendous loss, helping to preserve the historical character of its riverfront site for residents and the community to enjoy, and saving a historical landmark for future generations.

Bill Holman, P.E., M.SAME, Stanley Consultants; 952-546-3669, or This email address is being protected from spambots. You need JavaScript enabled to view it..