How do you make an iconic landmark better? In St. Louis, the $380 million CityArchRiver project, an extensive public-private partnership, is building new recreation and learning options while creating a seamless park experience from the city to the famous Gateway Arch to the Mississippi River.

How do you make that experience more available to visitors? To start, the $33 million Central Riverfront project, one of 12 CityArchRiver projects (see "City + Arch + River" sidebar), raised the street along the river by an average of 2 feet to reduce flooding and increase access.

"We can't completely prevent flooding events, but we're returning more days each year that the riverfront is usable for residents and visitors alike," said Anne Milford, Communications Coordinator for Great Rivers Greenway in St. Louis, the region's parks and trails district and lead agency on the project.

During construction, the weather chose to prove the point with historic flooding that delayed the schedule, but the new riverfront area opened last June in time for summer activities. Construction Manager BSI Constructors, Inc., of St. Louis totally rebuilt a 1.5-mile stretch of the riverfront, including Leonor K. Sullivan Boulevard, walls between the road and levee, underground infrastructure, sidewalks, a separate bike path that connects to existing trails, and a street-level stage.

"It used to be just a city street; now it's an event space," said Joe Kaiser, BSI's Project Executive.

Inclusive Bidding

BSI won the construction management contract through a qualifications-based selection process. Great Rivers Greenway then used a public bid opening process with 10 subcontracts awarded to low bidders. Thanks to extensive efforts before the bidding, they awarded 51 percent of total contract dollars to Disadvantaged Business Enterprises (DBE).

First, Great Rivers Greenway hosted a meeting attended by more than 50 organizations and leaders focused on promoting skills, careers, and capacity of DBE/MBE firms. After getting their input and assistance, the agency held a networking session following the pre-bid conference to encourage collaboration and minority participation.

In addition, "Both BSI and Great Rivers Greenway sent out a lot of outreach notifications," Kaiser said. "We made personal phone calls to DBE contractors to encourage them to bid and make sure they knew who the prime bidders were so they could make connections."

With 32 percent MBE participation and 19 percent WBE participation, the project exceeded minority participation goals. Workforce participation also met the goal of 14.7 percent minority workers. "The riverfront is a place where everyone is welcome, and it was important that the construction of the project reflect that, too," said Susan Trautman, Great Rivers Greenway Executive Director.

Building Around Historic Flooding

Not everything went as smoothly as the bidding process, though. Construction crews dealt with historic levels of flooding that complicated the work. "Before we could rebuild the road, we had to rebuild the wall that separated it from the levee," Kaiser explained. "The footings for that new wall are down at much lower elevations closer to the river, so even if the road stayed dry, we could still have water in our footing area." During construction of the new walls, they lost three prime summer months, from mid-May to mid-August 2015, due to water levels.

Flooding occurred numerous other times during the project, with the worst in January 2016. "The entire road was under 9 feet of water after very heavy rains and we lost another month," Kaiser said. "We just had to wait. We couldn't put temporary flood protection around that massive an area."

Despite the high water levels, all the work stood. In one flooding event, "Giant trees and all kinds of debris floated down the Mississippi River, but all the walls and stainless steel structures held," Milford said. "It was really a testament to the quality of the work."

The original schedule estimated project completion by late 2015, but delays due to flooding pushed the end date back to May 2016. "When you're working alongside the largest drainage system in the North American continent, the river can be in charge sometimes," Milford said.

Adapting for Tourists, Surprises, and History

BSI built the original work schedule around tourist activity in the park. The project broke ground at the end of November 2013, after the busy Thanksgiving weekend, then BSI divided construction into two phases to allow continuous pedestrian and tour bus access to the riverboats. Crews finished the area from the south end of the project to the midpoint of the Arch in January 2015, then completed the north end.

Rebuilding all the concrete walls impacted existing utilities, so crews installed new infrastructure. "It was a major effort underground," Kaiser said. "There were many unknowns not identified on previous drawings, including active gas lines and sewer lines that had to be accommodated or relocated."

Even some of the known utility work created challenges. "We had a major force main that served the boats and we needed to keep it in operation even as we relocated it," Kaiser said. "It was fairly tricky - planning, sequencing, timing. We used some temporary bypasses."

The roadway was totally torn up, then reused or recycled. Large quantities of granular material raised the road to the desired level, then crews covered the surface with concrete (except for a 1,500-foot asphalt section to accommodate more industrial use at one end).

As they worked, the construction team needed to accommodate historic features. "We removed quite a few cobblestones," Kaiser said. "As you raise the road you change the exact location, but we put them all back in place. We also had to protect the Grand Stairs for the Arch and the Eads Bridge. Near the bridge, we used different equipment - smaller saws and hand tools instead of big breakers - so we didn't generate vibrations that would damage it."

New amenities include benches, bike racks, lights, and power outlets. "It's all ADA accessible with more space for people to gather, walk, and ride their bikes," Milford said.

After the Riverfront reopened to visitors and events last summer, the majority of landscaping for the Arch grounds finished in the fall. The entire CityArchRiver project is scheduled for completion in 2017. Funded by a number of sources - including Great Rivers Greenway, the U.S. Department of Transportation through Transportation Investment Generating Economic Recovery (TIGER) funds, the National Park Service, CityArchRiver Foundation, and Bi-State Development - the CityArchRiver project is expected to bring more visitors and encourage them to stay longer, with an economic impact of $367 million and 4,400 permanent jobs.