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Sinkholes have become a serious problem for a cemetery just outside of Paris — a military resting place for more than 1,500 American soldiers who gave their lives in World War I.

The Suresnes American Cemetery and Memorial has been beset by sinkholes and stormwater runoff for years due to the memorial park’s outdated and insufficient stormwater drainage system.

The American Battle Monuments Commission (ABMC), which administers, operates and maintains 26 permanent American military cemeteries and 31 federal memorials, monuments and markers, partnered with our Federal Programs professionals in the U.S. to develop civil and environmental engineering solutions for an improved stormwater system that will help with long-term preservation of the site.

Location

  • Paris, Île-de-France, France

Client

  • American Battle Monuments Commission

Project Status

  • Ongoing

WSP Role

  • Civil and Environmental Engineering

Sinking Headstones

Suresnes American Cemetery is a 7.5-acre memorial park just five miles outside of the center of Paris, with a panoramic view of the Eiffel Tower and cityscape. The land was a gift from the French government to the U.S. after World War I. The cemetery was dedicated in 1937.

Due to extensive gypsum mining that occurred on the property before the cemetery was founded, the site suffered infrequent but manageable sinkholes over the years. But the problem worsened over the past several years. Their frequency has sharply risen, and they are expanding, with one sinkhole measuring 15 meters in diameter and six meters deep, swallowing multiple headstones within its radius.

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©WSP
Suresnes American Cemetery is a 7.5-acre memorial park just five miles outside of the center of Paris.

We have been partnering with international design firm Page to investigate the situation, which revealed poor and deteriorating conditions of the existing stormwater system. It is primarily a red clay water pipe system of undersized pipes that are broken or clogged and date to the cemetery’s original construction in the 1930s.

Adding to the problem is a deep, natural spring that continues to seep water into the ground.

“We learned that grout injections were performed on site to fill below grade voids detected during an earlier geotechnical investigation,” said Thomas Payne, senior vice president of water resources engineering at WSP in the U.S. “A side effect of the grout injection was that it stopped the spring water flow to a dry well specifically installed to infiltrate the flow from the spring. However, we’ve confirmed that water from the spring is still flowing. It’s only a couple gallons of water a minute, but that water has to go somewhere, and it’s only a matter of time before more voids, depressions and sinkholes start to show.”

Speaking their Language

We are conducting a topographic survey for the study and redesign of the cemetery’s stormwater drainage system. This field survey is supplemented with historical drawings of the cemetery’s construction — which were primarily sourced from the National Archives in Washington, D.C. — and CCTV footage of the drainage system.

The team is evaluating potential renovations of the cemetery’s welcome center and asphalt pathways around the property, plus various other repairs tied to site stabilization, such as pillars, fence supports and retaining walls.

“We can reach out to our colleagues in WSP’s offices worldwide to hire surveyors, understand local regulations, get local rainfall data and anything else we need, and that’s been a key component for this project, as well as speaking the local language,” said Chadi Srour, PE, vice president of project management at WSP in the U.S.

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©WSP
There are 1,559 American World War I veterans interred at Surenes American Cemetery, as well as 24 unidentified dead from World War II.

Speaking the language helped Srour and his colleagues communicate more personally and effectively with the French cemetery maintenance crew, who led the team down a manhole nestled in the cemetery grass and into nearly century-old cobblestone tunnels, about 30 feet below the headstones.

“Going down there was another surprise about this site,” said Nathan James, AIA, NCARB, senior vice president and project delivery leader for federal programs at WSP in the U.S . “It showed us how complex it all is, and how passionate ABMC is about taking care of the site. Seeing how hard the maintenance crew, our colleagues in France and our partners in ABMC and Page are working on this cemetery has really made me impassioned for this project.”

Memorial park size
7.5 acres
American soldiers buried at cemetery
1,500+
Depth of tunnels under cemetery
30 feet
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©WSP
Nathan James navigates the cobblestone tunnels that are about 30 feet below the ground at Surenes American Cemetery, where they found signs of the natural spring in the site.

Lasting Solutions

The team developed a hydrologic model of Suresnes American Cemetery and its existing stormwater drainage system to simulate 10-year storm events and identify flood-prone areas.

“We’ve divided the site into several catchment areas where stormwater is collected, then divided those further into sub-catchment areas, for modeling these 10-year storms,” Payne said.

Using data compiled from their findings on the dry wells installed in the cemetery over the years, as well as pending results of their topographic survey, Payne and his colleagues are honing their recommendations for a permanent solution that will improve the site’s stormwater mitigation.

 

Options include building and facility expansions, cross sections for pedestrian walkways and paths for maintenance vehicles and other vehicular traffic and equipment.

“We’re developing plans for replacing the drainage system, which includes upsizing the lines to increase capacity,” Payne said. “We’re also proposing different types of inlets for runoff collection and exploring different water pathways to get the stormwater off site and into the area’s municipal system.”

Honoring Fallen Heroes

Our team is now working with ABMC to review the team’s findings and preliminary recommendations, which are expected to be finalized this summer.

Work in France is part of a task order that encompasses other cemetery investigations, including a recently completed project in Manila, the Philippines and another, upcoming assignment in Cambridge, England.

Leveraging our global network of resources and relationships, Payne and his colleagues continue to find preservation solutions for cherished sites like Suresnes.

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©WSP
Suresnes American Cemetery has a panoramic view of the Eiffel Tower and Paris cityscape.

Meet the Visioneers

Chadi Srour, vice president of project management, and his colleagues have been enriched by the experiences that this project has offered.

We’re traveling across the Atlantic Ocean to find solutions for a site that’s over 100 years old, where American soldiers are buried and honored. It’s been a really rewarding experience.

For Nathan James, our project delivery leader for federal programs, collaborating with his fellow WSP colleagues abroad was a thrilling endeavor, as well as working with ABMC and the locals at Surenes American Cemetery.

Seeing how hard the maintenance crew, our colleagues in France and our partners in ABMC and Page are working on this cemetery has really made me impassioned for this project.

But above all else, assisting in the protection of this military burial site was the most enriching aspect for Thomas Payne, one of our leaders in water resources engineering.

It’s personally gratifying to be part of a project like this, where we get to provide our expertise to help support such an important and honored resting place for veterans.

Other challenges that we have overcome