Little orange flags.
They start popping up along Mississippi beaches every year when the weather gets warm, but beachgoers and tourists might not know that they signal a warning: Do not enter.
They don’t mean the beach is closed, just that there’s so much bacteria in the water it might make you sick. And frequently a beach is under a bacteria advisory even though there are no flags out.
How does that bacteria get there? Well, it could have something to do with the straight-line cement pipes shooting all manner of contaminated water and trash into the Mississippi Sound. The pipes, called outfalls, are also unsightly and stick out above the waterline along the white beaches.
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Realizing this design flaw, the Mississippi Department of Environmental Quality created a challenge to gather ideas and solutions. Funded by a grant from National Fish and Wildlife Foundation Gulf Environmental Benefit Fund, the Beach Outfalls Challenge invited anyone to submit a plan. The winner will have their prototype built and could potentially contract with the state to implement it.
Teams included everyone from architects and design firms to high school students and environmentalists. They submitted videos of their ideas, and the public was able to vote on the top 12 videos. On Wednesday, the top six teams presented their ideas at the University of Southern Mississippi’s Gulf Park campus in Long Beach, and the top three were chosen to move on.
All three teams’ ideas involve replacing the culverts with mini man-made wetland areas to naturally filter the water before it reaches the Sound. That’s how water used to be filtered from waterways before a man-made beach was built. MDEQ said in a press release the next phase of the challenge will involve engineers building pilot-scale versions of each idea to test viability and how well it improves water quality.
The top three teams:
Allen Engineering and Science
Allen Engineering is headquartered in Jackson but has locations across the Southeast. They pulled no punches in describing the severity of the problem:
“Flooding and overflow introduce pollution into the shallow waters where families play. Streets and gutters are overloaded even in a mild rain. Even worse, treatment systems flood, pouring harmful waste and E. coli into drains and down to the beach. That’s where people get exposed to it, and that’s when beaches close.”
Their solution involves a “treatment train approach.” Storm water flows into an underground vault or tank, which diverts some of the water into another vault that creates a vortex to remove “oil, grease, trash and suspended solids.” The filtered water then flows into a dune filtration system. Any overflow would go into a large marsh area of smooth cordgrass and native plants that filter the water, and is protected from wind and waves by dunes topped with vegetation. They would also build oyster breaks to protect the marsh area from waves.
The Biloxi-based team’s four M’s stand for Mississippi State University, Moffatt & Nichol, Mississippi’s Pascagoula Audubon Center and Mississippi’s Gulf Coast Research Lab.
Team MMMM would create an infiltration system along the sidewalk by the road, creating modified rain gardens with native plants to catch storm water, and send it underground to pumps powered by solar panels. Water would be pumped either to a man-made lagoon on the beach, or to a nearby golf course to be used as irrigation water, and any runoff would be sent to pipes in the surrounding soil.
The lagoon would be bordered by sand berms with a walkable bridge, and walkway on the west side covered by solar panels. From the lagoon, filtered water would pass under the bridge and form a natural, shallow sand cove to the water. The team would also recycle culverts to use as a breakwater reef topped with walkable steel grating. The culverts would protect the lagoon and create habitat for marine life as well as an oyster garden. An estimated 80 oyster baskets could grow 20,000 adult oysters in about 18 months, which can filter up to 500,000 gallons of water per day, the team’s video said.
“In addition to alleviating nuisance flooding, these infiltration systems are very effective at reducing pollutants in the runoff, particularly nutrients and fecal bacteria,” the video said, and they estimated they could improve pollution by 90 percent.
The Sustainable Active Landscapes Team is based in Bay St. Louis and led by Allison Anderson at unabridged Architecture.
Team SALT’s solution recreates the tidal creek deltas that were there before the beach was built. The winding delta would be created by a series of dunes anchored not only by vegetation but also trees and larger plants to create a shady canopy.
There would also be a series of artificial reefs made of stone gabions (square bundles of large rocks bound by wire) topped with plants that would create an oyster habitat.
“Gabions intercept water from the outfall and prevents it from resuspending sediment in the water,” the video said. “Pathogens such as vibrio bond to the sediment, and when fast-moving water stirs it up, the pathogens can be released, causing them to seek a new host.”
The idea is modeled after a similar system built in 1950s in New York’s Rockaway Beach, which remained intact after Hurricane Sandy’s three-story-high waves.