Avian Invasion

Bird-deterrent strategies for wastewater treatment plants

Credit: ISTOCK/SPONDYLOLITHESIS

Credit: ISTOCK/SPONDYLOLITHESIS

When Levi Fuller cut his teeth in the water treatment industry, manning the desalination system on a Navy ship, he didn’t expect some of his more troublesome obstacles on the mainland to be birds and their excrement.

Fuller, wastewater treatment plant operations supervisor for the Dublin San Ramon Services District in the San Francisco Bay Area, has spent the past 16 years managing equipment and people. But despite the upgrades in technology during that time, he says, one of the obstacles that hasn’t changed has been birds that contaminate open-air effluent treatment sites with fecal bacteria.

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“It’s not doing the job that’s tough,” he says. “It’s the unexpected and unintended challenges you have from nature.”

“The birds adapt,” he continues. “Most of the things that people use to deter the birds—the sound cannons or the water cannons—it may work for a few weeks.”

Soon enough, however, the pigeons that trot along the recycled water storage pits realize that the decoy owls aren’t real and will perch on their heads. The geese that swim in concrete basins, filled with water that is scheduled to be discharged into the San Francisco Bay, get accustomed to loud booms or spritzes of water.

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It becomes the flock’s new reality, Fuller says, and after a month, they’re back to lounging where they shouldn’t.

Over the years, wastewater plant employees across the industry have tried various methods to eliminate their fowl foes.

Nets were popular for a while, but they didn’t work since the birds realized they could sit on the netting and have a bull’s eye seat straight into the effluent basins, Fuller says.

Some sites have tried dogs, but the birds not only get used to them, they can dodge dogs fairly easily by flying away. Plus, in some states like California, employees aren’t allowed to hurt or kill the birds. They can only scare them. Cats are often poor substitutes, at least for Fuller’s site, since the local geese are larger than any domesticated cat.

“Birds literally flock to our wastewater, both post treated and the not-so-treated,” says San Jose-Santa Clara Regional Wastewater Facility spokeswoman Jennie Loft.

At the San Jose-Santa Clara Regional Wastewater Facility, the staff deals with seagulls in the primary clarifiers, ducks in the secondary clarifiers, and goslings in the outfall channels, Loft says.

“The point is, we have a lot of birds at our facility and in our final treated effluent that is discharged to the Bay,” she says. “Our process and the water we discharge must not harm wildlife.”

She notes that the agency disinfects all wastewater in serpentine tanks before it is discharged using sodium hypochlorite, eliminating human pathogens and bacteria. Sodium bisulfite is then used to deactivate the chlorine in any water that is discharged to the San Francisco Bay.

“A dose of hypochlorite and ammonia is added at the head of these serpentine tanks. The serpentine tanks are designed to provide the water with enough contact time with chlorine to kill microbes,” she says.

The birds aren’t a major hassle until they defecate into water that has already gone through the chlorination treatment. Water that is stored to be used for recycled water, either in purple pipes or for new residential recycled water pickup programs, can exceed the bacterial threshold allowed if there is too much fecal matter from the birds, Fuller says.

The California Department of Public Health defines acceptable levels of coliform bacteria in treated recycled water.

“(Recycled water’s) median concentration of total coliform bacteria in the disinfected effluent does not exceed a most probable number (MPN) of 2.2 per 100 milliliters utilizing the bacteriological results of the last seven days for which analyses have been completed, and the number of total coliform bacteria does not exceed an MPN of 23 per 100 milliliters in more than one sample in any 30 day period,” according to state regulations.

The US Environmental Protection Agency’s requirements are that facilities adhere to state rules regulating fecal coliform for water in general, including recycled water and water that is released into the environment.

Occasionally, Dublin San Ramon Services District employees have to pump the ready-to-use recycled water back to the start of the treatment process if bacteria levels get too high, which costs $1,000 per every million gallons, he says.

“The only thing we can think of that is a contributing factor is the birds,” says Fuller, moments after he watched four pigeons fly from the recycled water treatment area.

That’s also an issue if the birds get into water that has already been treated to required standards for discharge into streams, lakes, or the ocean.

The fecal matter can increase maintenance costs because employees have to spend time scrubbing the concrete basins after the water is discharged. Plus, there’s the concern about the water meeting bacteria standards for discharge.

On a sunny summer day, Fuller pulled his department sedan up to a basin where about a dozen geese were swimming.

“This water is on its way to the San Francisco Bay,” he says, “but you can see the birds hanging out in it.”

So, what are wastewater managers supposed to do?

The industry gold standard is easier said than done: physical barriers.

“The best thing you can do is cover the treatment area so they can’t get to them,” says Fuller. “That’s the only foolproof way.”

Loft says the San Jose-Santa Clara Regional Wastewater Facility doesn’t have any issues with swimming or roosting birds in their recycled water storage system for that very reason. Once wastewater is treated, it is diverted away from the open-air system, unlike other facilities where recycled water is stored above ground.

“The recycled portion flows in underground pipes from this point on and is not dechlorinated. Recycled water is not exposed to potential roosting or swimming birds,” she says.

Other industries have had to cope with birds getting in the way of business. The Federal Aviation Administration has to deal with birds flying near runways and hitting planes’ engines, which could be dangerous and can cause equipment damage. More than 255 people have been killed by birds hitting airplanes worldwide since 1988, according to the Bird Strike Committee USA.

“Improved reporting, studies, documentation, and statistics clearly show that aircraft collisions with birds and other wildlife are a serious economic and public safety problem,” according to a 2007 FAA advisory circular. “While many species of wildlife can pose a threat to aircraft safety, they are not equally hazardous.”

In fact, water, wastewater, and stormwater treatment sites on and near airports have been cited by the FAA as an attractant for birds looking for a place to swim.

Wire and netting is sometimes used to keep birds away from runways, and the FAA has set guidelines for new construction of water treatment sites and artificial marshes near airports. Habitat management is one of the primary methods airports use to keep away gulls, doves, and other fowl.

And some airports also use a traditional but temporary method: yelling at the birds until they’re shooed away.

Warehouses often have to rid their rafters of nesting birds who seek a cool place to roost away from predators. Pressure-washing, sonic high-pitched sound cannons, and heavy mesh netting are some options warehouses have used to keep away birds, according to the bird control company Bird B Gone.

Vinyl strap doors are another method, but birds have been known to slip in through the flapping gaps. Just like at water treatment plants, bird droppings present an employee health hazard and a product contamination hazard at warehouses.

Plus, there’s the unwanted surprise of a nest hitting an employee’s head. A warehouse near Dublin San Ramon Services District’s wastewater treatment plant recently had to call in a local animal service expert from the nearby police department because a nest with fledgling owls had fallen from a rafter, and they were hopping around the warehouse floor. The owls were checked for injuries and returned to their mother, but it’s a problem employees of most industries prefer to avoid.

Aquaculture is another industry that has to deal with birds—in this case, the birds want to eat the fish they’re farming. Pyrotechnics, live ammunition, and recorded bird distress calls are used, along with barrier methods such as netting, according to a 1997 study of controlling bird predation at aquaculture sites by the Southern Regional Aquaculture Center.

Geese swim in water that is scheduled to be discharged to the San Francisco Bay at the Dublin San Ramon Services District.

Credit: MEREDITH RUTLAND BAUER
Geese swim in water that is scheduled to be discharged to the San Francisco Bay at the Dublin San Ramon Services District.

Those methods can be tricky, the study points out, and it’s unlikely that a wastewater treatment plant would be able to use guns or fireworks since their facilities are near residential areas, schools, and an Army Reserve facility.

“Dispersing birds from night roosts can be logistically difficult because it requires from one to eight people firing pyrotechnics for approximately two hours as birds arrive in the evening,” the study notes.

Some states have laws prohibiting residents from shooting nuisance birds, such as Illinois’ Humane Care for Animals Act. Fuller says California law forbids his employees from harming the birds, their nests, or their eggs.

PHOTOS: MEREDITH RUTLAND BAUER

Credit: MEREDITH RUTLAND BAUER
Dublin San Ramon Services District Wastewater Treatment Plant operations supervisor Levi Fuller stands by water that will be pumped to the district’s purple pipes and residential recycled water stations. Pigeons often hang out in this area, contaminating the treated recycled water.

Illegality aside, animal rights groups such as the National Audubon Society also argue that killing the birds wouldn’t do much good anyway since new birds will just fly into the site. They’re looking for water and shade, which would make wastewater plants a prime location for birds looking for a break.

Birds often congregate in the marsh habitat where the San Jose-Santa Clara Regional Wastewater Facility discharges its treated effluent, Loft says. The water, in this case, is used to sustain this marsh habitat and is environmentally beneficial for the herons, geese, and animals that call the marsh home.

But birds aren’t exactly picky about where they nest. At the Dublin San Ramon Services District’s sludge ponds, geese and ducks build nests and lay eggs in the tall grass around the sludge that is injected at the last stages of wastewater treatment, Fuller says.

For the most part, the birds and the wastewater employees don’t get in each others’ way at these ponds. Contamination is certainly not a problem when you consider that the pond contains treated fecal matter.

But, Fuller says there have been times when the department has to delay cutting the grass to prep for tilling the ponds prior to injection because the birds are still nesting. He says they have to wait until the chicks have left the nests and can fend for themselves before the mowers are called in.

Bird droppings cover pipes above water being treated at the Dublin San Ramon Services District’s wastewater plant in Pleasanton, CA.

Credit: MEREDITH RUTLAND BAUER
Bird droppings cover pipes above water being treated at the Dublin San Ramon Services District’s wastewater plant in Pleasanton, CA.

Nesting season presents an additional challenge at sludge ponds since the mother geese can be territorial. If an unaware employee gets too close to newborn chicks, they can end up being chased by a squawking goose—and possibly left with a few pecks, too.

“The birds can get pretty aggressive if you get too close to their nests,” says Fuller.

Nests themselves can cause an issue if birds get into enclosed structures in wastewater sites. For years, pigeons roosted in the enclosed room where the sludge thickener process occurs, Fuller says. Because this process happens with waste rather than water that will be reused or reintroduced to the environment, it means the birds’ droppings aren’t a bacterial issue, but they still create other problems.

The birds’ nests sometimes fell from the rafters, and the birds themselves would fly into employees. Bird poop covered just about every surface, which was an issue for the employees who have to grab onto railings to keep their balance on walkways.

The Dublin San Ramon Services District experimented with slotted hanging flaps on the open door to keep the birds out, but the pigeons found their way inside. Now, a metal door keeps birds outside and away from the sludge.

Fuller walked down the metal walkway into the middle of the circular room. Metal sliding doors covered the entire floor—a rotating mix of treated solids constantly moving under his feet.

The work is hard enough without pigeons running into your head or slipping on bird droppings. Plus, annoyances aside, that presents a workplace safety hazard and a concern for employees’ health. Bird droppings are known to carry disease.

“We had probably 30 or so pigeons at all times, and their nests were all over,” says Fuller. “It’s not very sanitary.”

While the industry’s best practice appears to be enclosing as much of a wastewater treatment facility as possible, other amusing—but less effective—techniques are employed by residents looking to keep birds out of their gardens or boaters who want to avoid scrubbing the deck of white splotches.

Sheepdogs are among the newest bird deterrents since the dogs will chase and bark at the birds, and it might even have some fun while doing it, according to Avian Control, Inc., a company that sells a liquid bird deterrent. Cats are also recommended for boats and docks. Vineyards often use shiny metallic strips to confuse birds, as well as netting to physically separate them from the trees of plump fruit.

Then there’s the old gardening standby: fake predators. To be even slightly effective, plastic owls, coyotes, and hawks have to be moved at least once a week, or else the birds will wise up to the modern scarecrow.

Driving along the sludge ponds at the Dublin San Ramon Services District, Fuller looks over at a gaggle of geese and ducks that appear to be sunbathing on a walkway between two ponds.

There are some challenges he expected when his time in the Navy was over. Water treatment equipment wasn’t too difficult for him to manage. He was prepared for the busy days and the public education and the endless challenges that come with managing employees. He expected the monotony that comes with some days and the annoyances arising when treatment plants have to adjust to customers tossing non-organic garbage down the drain like “flushable” wipes and feminine sanitary products.

But birds were never on his radar.

He says his staff deals with the birds pretty well. It’s rare that the district has to pump out and retreat water as a result of their unexpected gifts. And, he says there’s a good deal of discussion within the industry about ways to build enclosures for treated wastewater basins, both physically and fiscally.

In the meantime, Fuller says, the facility will deal with the cards it has been dealt. But sometimes it feels like a wild goose chase. WE_bug_web

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