COLUMBIA, SC — Columbia’s experiment with nature-friendly flood control in a small area of Shandon is behind schedule but still offers neighbors a chance of relief and the city a shot at an alternative to underground stormwater pipes.

The so-called “green infrastructure” pilot plan would alleviate flooding caused by downpours for about 400 homes.

The project is likely to get started in June and be in ready by November, landscape architect Betsy Kaemmerlen told about two dozen interested Shandon residents who turned out at Sims Park on a rainy Monday night.

When City Council approved the project last summer, the timetable called for completion this summer, said Kaemmerlen, whose firm, Fuss & O’Neill, has the contract to design the project.

Council approved $985,000 for two areas – along Amherst Avenue, Maple Street and Wilmot Avenue – of the sprawling Shandon neighborhood. A portion of Wheat Street might see improvements if construction bids come in lower than projected.

The pilot plan is innovative for Columbia. Instead of replacing drainage pipes, the city will install giant underground storage bins under roads. The bins capture then slowly release rainwater. In addition, permeable pavement would be installed along parking lanes to absorb water and landscaped retention areas called “bump-outs” would narrow some intersections and calm traffic.

But natural flood control will require neighbors to agree to take on the responsibility of maintaining the bump-outs and of putting up with regularly closing off one side of a street to parking so the city can clean the permeable pavement, Kaemmerlen said. The pavement likely will require cleaning every six weeks to maintain its absorption, she said.

The city also is promoting private rain gardens and will offer workshops on how to set them up.

“These kinds of logistics are what’s going to make or break this project,” Kaemmerlen told the audience.

Heavy rains have flooded the most low-lying and impermeable areas of Shandon to depths of as much as 31/2 feet

During the last of four such neighborhood meetings, residents on Monday largely endorsed the plan.

But some had questions about:

•  How the city will notify neighbors when cleaning is scheduled. The answer: Columbia’s website, Facebook and communication with neighborhood organizations

•  Whether trees will be removed. The answer: The contract does not address that unless the company that wins the bid kills a tree.

•  Whether the six bump-outs will further shrink parking in a neighborhood where parking is at a premium. The answer: Parking already is prohibited in the spaces where the bump-outs are to be constructed.

Gene Dinkins, president of the engineering firm Cox and Dinkins, said the city has asked his firm to find chokepoints in underground pipes above and below the neighborhood to determine whether to pair traditional and innovative flood control programs.

That effort is just getting started. City engineer Dana Higgins said money for that project is likely to be in next fiscal year’s budget.

Natural flood control would cost about half as much as traditional pipes, then-city manager Steve Gantt said when council approved the pilot program. “If it works, we’ll be able to do twice as many projects,” Gantt said.

Reach LeBlanc at (803) 771-8664.