A Caribbean Island Installer Develops System To Protect Dolphin Habitat

A complex new onsite system on two Caribbean island keys will ensure proper long-term wastewater treatment in a delicate environment.
A Caribbean Island Installer Develops System To Protect Dolphin Habitat
The island of Roatan is along the top of the photo, and near the center are the headquarter buildings and docks of Anthony’s Key Resort. Most divers stay in cabins on Anthony’s Key, the small island at left. At right is Bailey’s Key with the dolphin pens clearly shown.

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Divers have been coming to the Caribbean island of Roatan for decades, and no wonder. The island is surrounded by a coral reef that in some places is so close you can wade to it from shore. The reef is home to hundreds of species of fish, and that makes for spectacular scuba diving in the bathtub-warm sea. As time passed, however, this ideal place developed problems. Samir Galindo could see them. He is general manager of Anthony’s Key Resort, which has been around for about 40 years and is one of the oldest dive operations on the island. In 20 years Galindo has seen changes in the environment, but what prompted the resort to call in Acme Environmental Solutions were the dolphins.

The resort occupies a spot on the north shore of Roatan and includes two smaller islands (keys in Caribbean terminology) that create a partially sheltered bay. One of these smaller islands is Anthony’s Key, which holds most of the cabins for visiting divers. The other is Bailey’s Key and is home to dolphins, the stars of dolphin encounters at Anthony’s Key Resort and at the Mahogany Bay cruise port on the south shore of the island.

Performing dolphins live at the port where they entertain cruise ship passengers. Bailey’s Key has pens for pregnant and nursing females, but the dolphins were not as healthy as they could be. Resort staff and the resident biologist consulted with experts at aquariums elsewhere in the world, and the experts concluded currents were not flushing the area thoroughly and contamination from untreated wastewater was making the dolphins ill. The resort took a bold step and updated the wastewater systems for its entire complex.

Typically the resort runs at 80 percent capacity with about 100 guests present every day during the height of the season. Guests dive twice a day and shower after each dive to wash off the sea salt. Anthony’s Key was originally equipped with septic tanks. “Some were good. Some were bad, but all of them were causing algae blooms on the edge of the island,” says engineer Samuel Rivera, operations manager and head of Acme’s projects division.

Self-Contained Solution

For the key, a rough triangle about 1,200 feet along its base and 800 feet from base to tip, Acme designed a 9,000 gpd system using a Bio-Microbics MicroFAST plant fed by a series of collection tanks.

From each cabin, wastewater flows by gravity 60 to 70 feet through 3-inch pipes buried 10 inches beneath the ground. Pipes are pitched 0.5 to 1.5 percent. “Gravity is a bit of a problem because the whole key is as flat as a pancake,” Rivera says. Ideally there would be a vacuum system to pull waste through the pipes, but it wasn’t doable. Pipes flow into one of five collection tanks that are 4 feet wide, 8 feet long and 4 feet high. Some were new. Others were reused septic tanks. Each tank has a lift station equipped with an Orenco ProSTEP pump package to feed wastewater to the Bio-Microbics plant through about 600 feet of 2-inch HDPE pipe. There is one more lift station. It serves the bar and pool area near the center of the key, and this station is equipped with a small trap to catch cherry stems, lime rinds and other light kitchen waste.

The Bio-Microbics plant has three chambers, one each for settling, aerobic treatment and clarification. Wastewater in the aerobic portion is pumped up by air to a sprayer dosing two 4,500 gpd units housing bacterial media. Treated water then flows to a dosing tank run by an Orenco panel that discharges it through 1,200 feet of Netafim underground tubing to irrigate a huge tropical plant garden that benefits from both the water and the extra nitrogen.

Construction Challenges

Behind a camouflaging wall of plants the Bio-Microbics system is 8 feet tall, 10 feet wide and 22 feet long, and it needs the vegetation because it is sunk only 2 feet into the island. The collection tanks are likewise shallowly set by typical measures. At most they’re 2 or 3 inches below grade. Some show a few inches above grade. Shallow excavation is the rule here because of the nature of the island: It is 2 to 40 inches of sand on top of coral. “The key is old coral. It’s as hard as steel,” Rivera says.

Work was done in the fall during the rainy season. In the tropics this means every few hours the clouds spill water like a fire hose before the small storm cell blows off over the ocean. Some cabins for the divers stand on stilts, so plumbers worked in the ocean in their bathing suits as they replaced sagging, thin-walled wastewater pipes with modern pipe and traps.

It was water from below that proved the real challenge on one collection tank excavation. Jackhammers broke about every hour on the iron-hard coral, Rivera says. Workers floated a skid-steer with a big hammer to the key. Because the key is a few hundred feet from the main island, all the equipment, workers and material had to fit on boats or barges.

The skid-steer hammer broke. They got bigger hammers. Then they made progress until one day, “We pretty much nailed a rock that acted as a plug for the Caribbean Sea,” Rivera says. Water flowed in fast, and the crew fought back with pumps. They started with a couple of 2-inch bilge pumps. They added a 4-inch pump. The sea kept coming. “We jackhammered the rest underwater. So it was a whole dive operation right in that hole,” Rivera says. They poured concrete for the tank underwater as well.

Ready For Storms

Acme has emergency plans for this system in the event a major storm sweeps across the Caribbean. The surface of the key is only a few feet above sea level, so waves from a strong storm can wash all the way across the key and flood the collection tanks, Rivera says. In that event, the plan is to pull salt water out of the collection tanks with a bilge pump and send it to small tanks on a barge. The barge would haul the saltwater-contaminated wastewater to shore where a vacuum truck would take it away for treatment.

Work on the key was not the only renovation Acme performed. At the resort headquarters on the main island the company put in a HighStrengthFAST system from Bio-Microbics along with Goulds pumps and other gear to handle the waste from the kitchen, laundry, offices, clinic, dive shop and the building where raw fish are prepared to feed the dolphins.

Bailey’s Key, the dolphin island, also received a new system, a scaled-down version of the Anthony’s Key installation to handle the small amount of wastewater from the dolphin staff and visiting tourists.

Experience so far shows tanks on the island are not accumulating sludge rapidly. That was the plan, says Dan Taylor, general manager and managing partner of Acme. The system was designed with more capacity and retention time than usual in order to reduce solids. The goal is to reduce the maintenance costs for the resort.

“The primary goal of this effort was to reduce the water pollution to protect the dolphins and the reef while cleaning up the resort environment.  The secondary goal was to reduce the maintenance costs for the resort. Pumping the tanks will require putting a vacuum truck on a barge and hauling it to the island, so we want to do that as infrequently as possible,” Taylor says.

More than in many places, the people at Anthony’s Key Resort see the connection between proper wastewater systems and the environment. Without a clean environment their livelihood is not sustainable, and their investment in modern wastewater equipment ensures the sustainability of this life, these people and the island for years to come.


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