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In the Search for Natural Treatment Methods for Urban Water Pollution, Expecting Existing Natural Areas to do the Job Can Be A Hard-Sell
Gentle Treatment
Cities Run Up Against Regulations in Attempt to Go Green
by Lisa Owens Viani
From Terrain Magazine, Summer 2008
http://ecologycenter.org/terrain/article.php?id=13649What to do with human waste isn't dinner-table conversation, and it hasn't been city hall's favorite topic either. Now, with energy and chemical costs rising and conventional sewage treatment plants needing refurbishing to continue doing their jobs, cities are hunting for a better way to handle sewage—and it's easy to see why wetlands treatment ponds jump to the top of the list. These wetland areas, in which sunlight, soil, plants, and bacteria help break down waste, are often used in combination with conventional treatment, but they are greener and cheaper than the usual method, and they attract wildlife. With its flocks of resident and migrant birds, the treatment wetland at Arcata Marsh has become a major tourist attraction. And treatment wetlands are doable—or at least they used to be.
Treatment wetlands need to be built near an existing plant to minimize pumping costs, close to a potential disposal or re-use site, and on relatively flat land, all of which narrow down a city's site choices. In some cases, there's another hurdle to pass: proposals to create treatment wetlands are getting the ax because the site is already in use & as another wetland. Recently, the North Coast Regional Water Board shot down several cities' proposals on the grounds that installing a treatment wetland could damage an existing wetland on the same site. The board is attempting to protect existing wetlands even if they are seasonal or already degraded by livestock grazing.
But if a little wetlands is good, isn't a whole lot of wetlands better? Does a seasonal horse pasture count as degraded land ripe for a wetlands, or is it a habitat to preserve? Everybody involved in these stand-offs is trying to do the right thing, and the clashes demonstrate the strains between environmentalists with different land-use priorities.
First, though, a word about waste: It's routine for most of us to flush a toilet and not give it a second thought. Unless you have a septic tank (and most urban users don't), the flush goes into a sewer pipe that connects to a wastewater treatment plant. The force of gravity helps carry waste to the plant, but if the plant is uphill, sewage has to be pumped. The plant is likely a large concrete building tucked out of sight, and the only clue you might have to its existence wafts your way when the breeze blows just right.
After the sewage arrives at the plant, large debris is screened out (you'd be surprised what ends up in sewer pipes), and then the sludge is aerated and mixed in large vats. Grease, plastics, and soap are skimmed off the top, and the wastewater is sent to more tanks where it is disinfected using chlorine and other chemicals. Solids are kept for days in large heated digesters where bacteria gobble up as much as they can; the remains are sent to a landfill or incinerator. Some plants make leftover solids into "cakes" or "pellets" to be sold as fertilizer. The disinfected wastewater is discharged—usually via a long pipe—as far out as possible into a nearby bay, river, or ocean. If you've ever been trapped in traffic in the MacArthur maze, you likely noticed that East Bay MUD's treatment plant is located nearby, with its discharge pipe into the bay.
In rural areas where land is still available, treatment wetlands offer a viable alternative. They mimic and function like natural wetlands, with plants, soils, algae, and bacteria filtering and taking up nutrients from the waste. These created wetlands usually work along with some traditional treatment but still greatly reduce the use of energy and hazardous chemicals, as well as maintenance costs. Martinez, Hayward, Palo Alto, and Los Gallinas in Marin County treat their waste with wetlands; Humboldt County's Arcata, Manila, and McKinleyville also use the system, and Petaluma is completing construction.
Treatment wetlands keep waste local: "The worst thing we can do is treat [waste] at the end of the pipe," says treatment wetland expert and Humboldt State environmental engineering professor Brad Finney. "Shipping it off to some place on the other side of the bay where some magical plant pops out a little brick—I'm not interested in that." One of the biggest benefits of treatment wetlands, say advocates, is that they provide much-needed wildlife habitat, helping replace wetlands that have been filled for big boxes or condos.
What about the witch's brew of chemicals that clogs our sewers these days? Finney, who helped write the US Environmental Protection Agency's manual on treatment wetlands, says wetlands probably do a better and safer job of tackling contaminants than traditional treatment. "Worries about toxins are real, but [many toxins] are not removed during conventional wastewater treatment," he says. "With treatment wetlands, you're tightly regulated—you're right there in front of everyone's face. If dioxins start showing up, we can control them, contain them in a treatment wetland. With traditional treatment you send it out there into the bay or ocean and hope for the best. If it shows up in fish in fifty years, it's too late."
Finney was part of a team that studied potential pollution bioaccumulation at Hayward Marsh's treatment wetlands. "It was a comprehensive study, and no significant problems were found with birds, mammals, or other organisms," Finney says. "In fact, we found that the wetland water and sediments were significantly better than the adjoining bay muds and waters. In wetlands, there's an incredibly diverse set of organisms, solar radiation, lots of oxidizing agents, and lots of time—thirty, forty, fifty days of contact [compared to the average three to six days at a traditional plant]. It's likely that that complex environment can handle being exposed to these toxic compounds and also attenuate them better than conventional treatment—it can't do any worse. The key is a lot of opportunities for organisms to naturally break things down."
The downside to treatment wetlands is that they take up more land than those concrete buildings—and some communities have identified sites for treatment wetlands that already contain seasonal wetlands used for grazing cattle or horses. That's how Ferndale and Willits ran afoul of the North Coast Regional Water Quality Control Board—and in the case of Willits, aroused the ire of environmentalists who might be expected to support this greener method of treating waste.
When a proposed site contains a wetland of any kind—or in any condition—state and federal laws designed to ensure no net loss of wetlands come into play, particularly since so many wetlands have been destroyed, and continue to be destroyed, by development. In California, wetlands fall under the jurisdiction of the US Army Corps of Engineers, the region's water board, the US Environmental Protection Agency, and the Department of Fish and Game. Explains North Coast Regional Water Quality Control Board's John Short, "Wetlands, riparian areas, and headwaters are shallow waters, which by their nature are affected most often and severely by filling and excavation." When regulatory agencies allow developers or others to fill or alter natural wetlands, those parties are required to mitigate by creating new wetlands on- or offsite.
In Willits, a long-planned proposal to build full-treatment wetlands on agricultural land that contained seasonal wetlands was turned down by the North Coast water board regulators. "We had the land purchased; we had the design for three levels of treatment," says Willits city manager Ross Walker. "We knew that the deep oxidation ponds [used for the first level of treatment] would have taken some area designated as jurisdictional wetlands, but the treatment wetlands were designed not as a detriment to wetlands but an enhancement."
That was not the view of the water board or the Army Corps of Engineers, says Walker. "Our question was, what was our impact going to be? I could see no rationale for [the board's position] because 'no net loss' made no sense in an area where there are hundreds of acres of wetlands. We never wanted to do anything that was not improving the environment; we felt like we were enhancing it." Walker says he understands and supports wetlands regulations and stresses that he is not a scientist. What he can't understand is the board's decision: "When you're taking a piece of hardened ranchland, you're not talking about a major detriment to a wetland."
The city could have mitigated off-site—but "the cost [to acquire land] is a big thing for a small city; we couldn't do it," says Walker. Willits is now trying to squeeze an upgraded facility onto the footprint of its current plant and build a much smaller treatment wetland in an upland area. Because of the delays, Willits must raise its sewage rates to pay for the new mechanical plant.
Regulators weren't the only problem in Willits, says Walker. "We didn't have the full backing of a very active environmental group here," he says. The Willits Environmental Center's Ellen Drell says her organization was disturbed both by the scale of the project—ponds with berms for primary treatment, and acres of treatment wetlands for secondary treatment and beyond—as well as the proposed location. "The fact that this valley is a seasonal wetland makes it even richer than a permanent wetland," she says. "It acts as a sponge to absorb excess runoff; it recharges groundwater, mitigates flooding, and supports a wide range of vegetation and critters. That there's not only water every winter, but grasses going to seed in other seasons, is one reason it supports so many species."
Drell says she felt the city leaders never understood the value of seasonal wetlands. "They thought, 'If a little bit of wet is good, then a whole lot is really good.' We disagreed." Drell says the seasonal wetlands flood in the winter and connect to local creeks that support runs of steelhead, and Chinook and coho salmon. That made her nervous about altering the existing hydrology. Drell says the sewage treatment wetlands, some of which would be surrounded by berms, would have blocked the flow of water into the creeks. Drell says she wouldn't have objected had the city put wetlands on the site of an auto wrecker or lumber yard, but she felt the proposed site—known by locals as Little Lake—was just the wrong spot. "They said, 'There's nothing there.' But there is something there."
Farther north, Ferndale also ran up against the North Coast Regional Board. Facing enforcement orders from the board to upgrade its existing plant, the city rallied the community around the idea of a treatment wetland. City councilmember and wetlands ecologist Ken Mierzwa says the treatment wetland had tremendous support from Main Street business owners. "A lot of them are elderly and conservative politically," says Mierzwa, "but they understood that birdwatchers would come to see the birds."
Ferndale's geography got in the way. Situated at the mouth of the Eel River, the city is surrounded on three sides by wetlands—the floodplain of the Eel. That meant that building a treatment wetland on open space anywhere close to town would have involved impacting a natural wetland, says John Short, even if those wetlands happen to be cow pastures. And that meant that Ferndale would have had to mitigate for those impacts—with the only space available for mitigation on an upland area, a less than ideal spot for creating a wetland.
Building a mitigation wetland upland probably has the "least likelihood" of success, says Mierzwa: "You'd be trying to force ecological processes to do something they don't naturally do." Finney, too, was frustrated by the outcome in Ferndale. "There's nothing wrong with the wetlands that exist in a cow pasture, but to say that the [treatment wetland] systems we're creating have less wetland value makes no scientific sense."
Short says, "No one technology fits every situation. Each community has its own unique set of issues. In my mind, certain wetland treatment advocates have done a disservice to small communities by pushing treatment wetlands as a solution to all wastewater problems, and unfortunately, that is not always the case. Our responsibility is to remove pollutants before the discharge reaches our wetlands and streams." The bottom line, says Short, is that if Ferndale had been able to do enough wetland mitigation, the Regional Board probably would have permitted their project. Instead, Ferndale, like Willits, will undertake an expensive major upgrade of its existing treatment plant.
It wasn't always this hard to build wetlands. In 1974, the Mt. View Sanitary District in Martinez became the first wastewater wetlands in the state, built on the site of a degraded natural wetland that had been diked off and used for agriculture. The site was located between the treatment plant and the Carquinez Strait, where the district discharged its wastewater. To adequately dilute its waste, the district needed to build a very long, expensive, deepwater outfall pipe, says Mt. View Sanitary District's Dave Contreras. Instead, the wetland helped Mt. View retain and treat its wastewater sufficiently so that it did not need to build the pipe. In the early '90s, the district upgraded its traditional plant to use UV disinfection and sand filtration to treat the wastewater before it enters the wetlands for final treatment.
In addition to an enthusiastic San Francisco Bay Regional Water Board, Mt. View had support from the Department of Fish and Game and the Audubon Society, says Contreras. Today, the marsh is promoted as Martinez's crown jewel. "We have over 120 species of birds and wildlife, deer, river otter, fox, and beaver in these wetlands," says Contreras. By switching to UV and sand filtration for primary and secondary treatment, and treatment wetlands for final treatment, Mt. View has been able to stop using chlorine gas, gaseous sulfur dioxide, sodium hydroxide, and anhydrous ammonia, says Contreras. "We eliminated the use of acutely hazardous materials. It's actually been a model for the Bay Area."
Steve Moore, an engineer who formerly worked for the bay's regional water board and is now with a private engineering firm, says he thinks Mt. View produced "a net environmental benefit of treating waste while providing 21 acres of habitat." But as he points out, making a decision isn't always easy. "From a regulatory perspective, you have to decide: How do you fairly account for that lost natural wetland versus the wastewater purification function on your balance sheet?" he asks. "It's different environmental values clashing. I think we have to take a more holistic perspective and realize that all of us are robbing the state's natural waters for drinking and farming. That water is unavailable for wetland habitat. As we try to make gains in wetland function and habitat, wastewater wetlands are a good tool. That's the perspective we're missing."
Since it's hard for regulators to decide whether building treatment wetlands is ultimately going to help or hurt the local environment, the decision process can be rife with contradictions and absurdities. The Arcata Marsh and Wildlife Sanctuary, a highly successful treatment wetland and a major tourist attraction, likely would not be permitted by the North Coast Regional Board today. Arcata Marsh was built on top of historic wetlands that had been filled and become degraded, says Finney. "Their functioning was extremely poor, but in today's regulatory environment, [some regulators] would have said they were jurisdictional wetlands."
Often where a treatment wetland can or cannot be built depends on the judgment of the individual regulator—and the regional board office—involved. Says Bob Bastian with the US EPA's Office of Wastewater Management, "It's not unusual to see varying interpretations and constraints being imposed by field offices. The same thing happens with the US Fish and Wildlife Service and endangered species. In one part of the country they are open and willing to work with [a private landowner or developer] on how to manage an area to protect endangered species. In another office, you just can't do anything. I think we're seeing some of the same thing happening when it comes to how to protect existing wetlands."
Finney points out that since we have paved over most of our historic wetlands, constructed wastewater wetlands help replace that loss. But, he says, "If you object to the notion of using a wetland for treating water—which is what wetlands have been doing since before man roamed the planet—that contains some human waste, then it will be increasingly difficult to find sites that can receive regulatory approval." The bottom line is treatment wetlands have to be done right and in the right place, says Finney. "I wouldn't want to convert a nice, beautiful existing wetland to a treatment wetland. But where there's an opportunity to create new beneficial uses and at the same time take care of a problem, I think we should do it."
