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Septage management is not going to get any easier,” says Tim Frank, president of Tim Frank Septic Tank Cleaning Co. in Huntsburg, OH. “In fact, it’s going to get worse. It has to.”
But is Frank on the money? And if so, why? The unavoidable facts are that more and more residential development in this country is occurring in non-sewered areas, that more and more agricultural land is being turned into subdivisions, some close to actively used septage disposal fields, and that the public is increasingly weighing in on it wants its waste handled.
In 1990, the US Census Bureau estimated that 24.6 million housing units in this country used septic tanks or cesspools to dispose of their waste, accounting for 5.5 billion gallons of septage generated annually. California, which expects to grow by 15 million within the next six years, has 1.2 million onsite wastewater treatment systems currently in use, and the State Water Resources Control Board has described septage disposal as “an issue of concern.”
Also in California, voters in largely agricultural Kern County recently passed Measure E, which prohibits land application of sewage sludge in unincorporated parts of the county. The midstate county had been receiving over a million tons of wet sewage a year from municipalities throughout California, including 500 tons of treated biosolids a day from the city of Los Angeles. The Kern County ordinance is a potentially onerous development in a state where 84% of septage is disposed of at sewage treatment plants.
No one remembers septage being implicated in a public health crisis on the scale of the typhoid and cholera epidemics that challenged public health resources in the early 20th century. But his hasn’t inhibited community activists and their allies in the environmental community from becoming increasingly vocal on the potential for septage-contaminated runoff and groundwater pollution to cause large-scale public health problems. Without being specific as to effects, backers of Kern County’s Measure E, for example, played on fears that toxics and pathogens from sewage sludge could “trickle down” through the soil to threaten the area’s underground drinking water supplies.
Remembering Things Past
The fact is that once disposing of septic tank septage did appear easy: Pump it, drive across to the field on the other side of the highway and dump it. In 1993 (more than half a century after the drinking water industry took steps to safeguard the public against water-borne disease), the United States Environmental Protection Agency (USEPA) issued regulations that governed septage land disposal. Suddenly, getting rid of the stuff got expensive. You either met the EPA’s land disposal standards or dumped your load at a sewage treatment plant. Except that reality hasn’t turned out to be that simple.
“Thirteen years after the EPA regs were established,” says Tom Ferrero, executive director of the National Association of Wastewater Transporters, “we still see a high percentage of noncompliant haulers and a fairly high percentage of lack of enforcement.” The situation has been complicated by the fact that sewage treatment plants have gotten wise to the stress septage puts on their systems and have begun to charge to cover their costs. Many municipal plants financed by the Clean Water Act have reached or are nearing the 20–30% hydraulic capacity that was built in to accommodate growth and aren’t equipped to handle more inflow.
Adding to the challenge is the changing nature of septage itself, which Bill Stuth Sr., president of Aqua Test Inc. in Kent, WA, worries could lead to as yet unrecognized public health issues. “If it was just human waste,” says Stuth, “there isn’t much public health risk. And it’s a lot easier to take care of. But once you start adding the household chemicals, the antibacterial this or that, and the cleaning solvents, you’ve got problems, the biggest one being we don’t know what the long-term effects of these chemicals will be.”
As Stuth points out, it is as much the chemicals as it is the pathogens that have some public health officials worried. Just this year the Orange County, CA, Sanitation District teamed up with the Los Angeles County Sanitation District and the city of Los Angeles to initiate a “No Drugs Down the Drain” campaign. The objective is an educational program produced in partnership with the California Pharmacists Association and the California Poison Control System to reduce the amount of drugs that are disposed of down the toilet. A similar but much less formal campaign in being considered across the country in rural Vermont to control potentially dangerous pharmaceuticals dumped into onsite systems.
At the New Hampshire Department of Environmental Services, Pat Hanon calls septage the state’s “silent problem.” As with a number of New England states, New Hampshire is experiencing a growth spurt as farmers cash out and developers move in. Some 80% of this growth is occurring in non-sewered areas, and New Hampshire is currently generating approximately 100 million gallons of septage each year, nearly 30% of which is disposed out of state. In Nevada, where, unlike New England, there is plenty of open land, half of the septage is land-applied, mixed with grease trap waste from the state’s hotels and casinos.
Even in states where it looks like there’s still enough room, negative public health affects are being linked to septage land disposal. USEPA Region 9 Biosolids Coordinator Lauren Fondahl cites reports of potential health problems associated with airborne dust from land-application sites. “In places like Riverside County in California and Mohave County in Arizona, where land-application sites are close to growing suburban communities, people talk about their eyes watering and their skin itching and about having trouble breathing. We have yet to have a doctor say he is completely convinced these problems result from sludge or septage application, but when a lot of people start complaining, irritation becomes less a nuisance and more a health problem. In California and Arizona it’s airborne dust and particles and volatile compounds with sulfide components like methyl and dimethyl disulphide that are causing the problems. Some of these have been proved to be human health risks at much higher concentrations, although not at the level where you’d detect a smell of sludge. And while they haven’t been shown to be a public health problem, they’re an irritation, especially in conjunction with dust and other airborne irritants.”
What We’re Dealing With
Officially, septage is defined as the combined liquid and solids pumped from a septic tank, cesspool or other treatment facility after having accumulated over a period of time. A septic tank will typically retain 60–70% of the solids, oil, and grease that enter it. Scum accumulates at the top and the solids settle at the bottom, where they usually account for 20–50% of the total septic tank volume. Because it’s concentrated, septage on average is 50–100 times stronger than sewage sludge. Factors that can affect its physical characteristics include tank size and design and pumping frequency, plus climate, homeowner habits, water supply characteristics, piping material and the household’s use of water-conservation fixtures, garbage disposals, household chemicals, and water softeners.
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| Plasma processing systems destroy material by subjecting it to superheated gas. |
Typically, septage contains significant levels of grease, grit, hair, and debris. But more important from a public health standpoint, septage is a host for disease-causing viruses, bacteria, and parasites. Treatment and disposal of domestic septage is currently governed by the US Code of Federal Regulations (40 CFR) Part 503, although municipalities are free to establish regulations for handling, treatment, and disposal in addition to existing state and federal regulations.
Although dry-weather California treats 11% of its septage in dewatering lagoons, and a number of independent septage treatment plants are beginning to surface around the country, the basic methods of treating and disposing of septage in this country remain land-application and treatment at wastewater treatment plants. Potential problems with odor or pathogens associated with land disposal can be solved by pretreating and stabilizing the septage, which decreases levels of disease-causing organisms. Commonly used stabilization options include lime (adding lime slurry or other alkaline material to the pumping truck or as part of the dewatering process for a minimum of 30 minutes to raise the pH to 12.0) and composting. “Properly managed” land application is favored by the EPA as “simple and cost-effective” and because it uses minimal energy and recycles organic material and nutrients to the land while decreasing reliance on petroleum-based fertilizers.
Disposal at a wastewater treatment plant can involve: directing the entire wastestream into an upstream sewer manhole, which may allow for substantial dilution of the septage before it reaches the plant; directing the wastestream to plant headworks immediately upstream of screening and grit-removal processes; or directing the wastestream to sludge-managing processes after pretreatment in a receiving station. Alternately, a wastewater treatment plant can receive filtrate from solids dewatering into the plant’s liquid stream.
Treatment at facilities designed specifically to handle septage can include stabilization lagoons (a maximum of 6 feet deep, with the septage placed in small, incremental lifts of 15–30 cm with no infiltration), chlorine oxidation, and aerobic and anaerobic digestion. Septage treatment facilities typically use multi-unit processes to handle both liquid and solids. Many use lime for conditioning and stabilization before the septage is dewatered. The liquid residual can undergo further treatment and be used for spray irrigation or discharged into a wastewater treatment plant. Solids can be sent to a landfill, incinerated, land-applied, or composted. Processes used to dewater include screw presses, plate and frame presses, belt presses, rotary vacuum filters, gravity and vacuum-assisted drying beds, and sand drying beds.
Landfill disposal is also an option, although EPA regs stipulate that septage cannot be disposed of at any site that receives over 90 cm of rainfall annually or that is not equipped with leachate-prevention and control facilities or that does not have isolated underlying rock. An area that is filled with septage must be covered with 15 cm of soil each day and 2 feet of final cover within one week after the placement of the final lift.
Expanding Options
According to Hanon, New Hampshire’s No. 1 priority is to create enough instate septage disposal capacity to make the state self-sufficient today and in the future. “We understand that middle- and low-income families might defer pumping until their system fails, which can mean surface or groundwater contamination,” says Hanon. “So simply developing capacity is not enough; it has to be capacity that’s affordable to everyone.”
To get the ball rolling in the right direction, New Hampshire has initiated a program of private-public partnerships that includes grants to municipalities who commit to upgrading their wastewater treatment plants. The public partner is eligible for a grant of up to 50% of the cost of a plant upgrade if they create more capacity for septage disposal. The job of the private sector partner is to provide the technology. Recently the small community of Pittsfield, NH, took up the challenge. Joe Ducharme, president of Concord, NH-based TTG Environmental Consultants LLC, which assisted in the design of the septage management program, tells the story.
“Pittsfield has an aerated-lagoon treatment system, which the state doesn’t normally recommend for septage. But onsite service operator Bill Gosse had a piece of land in the town where he had established septage holding lagoons that were reaching the end of their design life. After two years of pilot testing, we arrived at a system that takes standard wastewater industry equipment and arranges it into a pretreatment process so septage could be disposed of in the town’s small sewage treatment plant. The sequence begins with flow measurement off the truck, then screening for organics and grit removal. Lime is then added for pH adjustment, then ferric chloride to bind phosphorus to the solid particles, because we wanted to get the phosphorus below 2.0 mg/L for algae control. Finally, a polymer is added to coagulate the solids together. From there it’s into a dewatering system—which right now is a gravity dewatering system where the solids get trapped in screens and the liquid presses out between the screens and the walls of the box—then eventually into the sewage treatment plant’s raw sewage influent line after pH and phosphorus have been checked.”
Meanwhile, the dewatered solids are transferred to a holding area inside the treatment plant grounds, where typically they will be blended with wood ash, along with a small amount of sand and leaf and yard waste to make compost. Through the two years of the pilot project and one year of interim operation, Ducharme says the operation has been producing class-A compost by allowing the dewatered septage to sit through the frost cycle and then the summer sun, turning it regularly. Currently the town is thinking of bringing its compost up to exceptional quality standards so it will be able to sell it to residents. As designed, the system can handle 5 million gallons per year (it’s currently handling 3 million). The system is designed so the town can charge haulers an average tipping fee for the area and so it can be easily duplicated in New Hampshire’s 75 other small-capacity treatment plants.
According to John Durhan, president of Atlantic DeWatering Services LLC, which supplied the Pittsfield project, an important consideration in building these types of pretreatment systems is to align each with the material it will handle, such as whether it will be treating grease trap waste like the Pat Jackson/Tri-City Septic treatment facility in Belgrade, ME.
Gene Dube started in the onsite service business almost 50 years ago, pumping septic tanks with his father. In the late 1980s the company saw the handwriting on the wall when wastewater treatment plants in Maine began limiting the amount of septage they would receive. “We began to look around for a place where we could actually process the septage,” says Dube, “taking the water out of it, composting the biosolids and either spray irrigation or sewer-line connection for the filtrate.” Today the facility handles 14 million gallons of septage a year (reportedly 20% of Maine’s total) and sells almost 5,000 yards of compost annually—and Dube serves on the faculty of the Maine Composting School.
The treatment plant Dube operates is based on the same principle as Pittsfield’s pretreatment plant, except that it takes the material to the next step and disposes of both biosolids and filtrate. “When we first built our treatment plant,” says Dube, “we did have land disposal. I still have a couple of licenses, but I don’t use them anymore.
“We are using a belt press and two dewatering boxes, one from Green Mountain [now Atlantic Dewatering] and one we built ourselves. A belt press will typically give you 19–25% solids if everything is running perfectly. A dewatering box will give you between 12 and 20%, depending on how well your polymers are working. He disposes of the filtrate in a sewer line that takes it directly to a treatment plant at $7 per thousand gallons, an option he considers less expensive than cleaning up the filtrate for spray irrigation. Along with septage, Dube takes grease from sewer traps wherever New Hampshire treatment plants don’t want it.
Across the country in Ohio, Frank decided to handle his own septage when operators at the Cleveland sewage treatment plant he was using asked him to decrease his loads. “I was just at the point where I was about to buy a semi and two trailers to shuttle back and forth,” says Frank. “Instead, I went to New Jersey and found the kind of press I wanted, put it on a semi trailer right next to one of my lagoons, and my son and I worked it in the afternoon and evening. It’s taken me 30 years and $1 million to build this facility, but I never took another load to a treatment plant.”
The 20 million gallons a day Frank’s facility handles is first screened to remove trash; from there the material goes to a series of lagoons, where the solids are separated from the water. When the solids are suitability dewatered, either lime or polymers are added before the solids pass through the plate and frame press. “If you have it conditioned right,” says Frank, “it will adhere to the claws in the plates. What we’re left with is a very dry waffle, 3-feet wide by 3-feet high by an inch-and-a-half thick of exceptional quality solids—no pathogens or viruses.” Currently, Frank either sells the waffles to farms or takes them to a landfill at $33 per ton. The filtrate passes out of the lagoons through four large artificial wetlands, where it’s naturally cleaned and treated. From there it goes into a holding pond to be tested for nitrogen and phosphorous then used for spray irrigation on Frank’s 100 acres.
Frank thinks independent treatment facilities like his are the future. Ferrero, himself a pumper who runs three septage treatment facilities, agrees. “This actually goes back to the beginning, when pumpers took charge of septage disposal by applying it to the land,” says Ferraro. “Maybe you start first with some lagooning, then maybe some spray irrigation or treating the filtrate well enough that you can put into a waste treatment plant. We have people who truck what they pump 60–100 miles to our Indiana facility. The solids from what we treat there go into a landfill, and I’d like to be greener than that. In Orlando the solids are land-applied, and at our Canadian facility they go to a third-party composter, and then it’s applied to the land.”
Good intentions aside, Franks and Ferrero are ahead of their time, just as the East appears to be ahead of the West. According to Bruce Holmgren, staff engineer for the Nevada Department of Environmental Protection, the 50% of the state’s septage that’s land-applied is not dewatered or subjected to any pretreatment but is instead mixed with grease trap waste, three parts septage with one part grease. Nevada has no septage regulations and falls back on the federal 503 rules. “The only pretreatment we require is screening to remove debris,” says Holmgren. “And we caution the operators that they have to incorporate what they apply into the soil within six hours for odor and vector control. Additionally, as required by the federal regs, all septage treatment and disposal facilities must be fenced and posted and maintain the required setback from public roads and wells.”
But Nevada is already experiencing a hint of things to come. Wastewater treatment plants are beginning to refuse septage, especially in the rural areas, where state regulators spend time working with pumpers to assure that they abide by regulations and not dump illegally. And Holmgren admits that although Nevada is not heavily populated, development is starting to close in on land used for septage disposal. Holmgren says he knows of only one facility that is composting septage.
In Washington state, no permits are required for land application. Most of the septage in steep western Washington, where watersheds drain into Puget Sound, goes to sewage treatment plants. But in the east, land application is prevalent for the same reason as in rural Nevada. Kyle Dorsey, formerly with the state Department of Ecology and now with Tenelco Inc. in Lake Stevens, WA, worries that the state doesn’t even require screening of septage applied to the land.
“A pump company proprietor could go out and pump 300,000 gallons of septage a day, put on a splash plate or a spreader bar, land-apply the material to 35 or 40 acres, potentially without screening it, and do the same thing day after day. If you set aside the question of whether pumpers do a good job with what they do, the question is: Does it make sense to allow that kind of activity without requiring a permit?”
So what’s up for the future? Dorsey thinks as technology gets better there will be more operations like the one Tenelco runs to treat onsite system waste. In the meantime, Washington will move toward permits and there will be requirements to pretreat the septage before it is land-applied. Right now, Tenelco handles about 10 million gallons of septage a year; it’s screened, dewatered to about 20% solids, and applied in what Dorsey calls a “properly permitted” site. The next step is to treat the solids to exceptional quality the same way Dube is doing in Maine.
The Future is Now
More advanced technology for handling septage may well come from outside the onsite wastewater industry. One of New Hampshire’s potential public-private partnerships is with Wilton, CT-based Startech Environmental Corp., which is marketing a plasma processing system for waste disposal. The system uses closed-loop elemental recycling to irreversibly destroy everything from municipal solid waste to medical and chemical industry waste. Most of the installations now in development will process a combination of household waste (garbage, septage, sludge) in combination with hazardous waste to produce electricity and a synthetic gas plus small amounts of methanol and hydrogen.
The system destroys the material it’s fed by subjecting it to superheated, ionized gases (the plasma). At temperatures that run as high as 30,000°F, chemical bonds are broken, leaving behind the basic chemical elements.
In contrast, the Central Vermont Solid Waste Management District (CVSWMD) is urging a low-tech approach to managing septage from the 55% of residences that currently use onsite systems. Instead of dismissing land disposal as an option, the Vermonters actually want to increase the availability of land disposal by increasing demand among farmers for septage while simultaneously promoting public acceptance of this means of disposal. To accomplish this, the district aims to produce a cleaner product straight out of the tank.
So far the program is in the research-and-planning stage. Recommendations for action include developing a public outreach and education program to reduce the amount of household chemicals in residential wastewater, developing a system of collection for pharmaceuticals, encouraging composting as a substitute for garbage disposals (to keep nutrients and organic matter of the wastewater stream), encouraging nutrient-recycling wastewater treatment systems in pubic buildings as well as private homes, promoting the use of black water and urine diversion (leading ultimately to recycling to agriculture), and a better onsite system management program that includes pumping on an as-needed basis, thereby reducing the amount of septage generated at the source.
“There are a lot of people around the country looking at ways to relocalize many functions like this,” says Carl Etnier, project scientist for Stone Environmental Inc. in Montpelier, VT, who has been working with CVSWMD.
According to data included in a 1997 EPA report to Congress, onsite and decentralized wastewater treatment systems have become a permanent part of the nation’s infrastructure, and their numbers are increasing annually, both absolutely and as a percentage of homes served. It seems logical to assume, as Tim Frank has noted, that the challenges associated with septage management and disposal are going to become more widespread and complicated before resolution is achieved. In southern California, the Orange and Riverside county sanitation districts will soon be sending their sewage sludge to a facility in Rialto, CA, built by Enertech Environmental Inc., of Atlanta, GA. The sludge will be subject to both heat and pressure to produce a product that will be marketed as a fossil-fuel supplement. Enertech marketing manager Brian Dooley explains that the company’s SlurryCarb technology mechanically dewaters the material to greater than 50% solids, and this in turn allows the residual to be dried at much less total energy. Dooley reports that the southern California facility will be taking in 675 wet tons of regional waste daily when it becomes fully operational in 2008. The municipalities will pay a tipping fee, and the “E-fuel” will be used to fire a local cement kiln.
Also in southern California, the USEPA is soliciting public comment on a plan put forward by the city of Los Angeles to inject sludge into the ground beneath the city’s Terminal Island sewage treatment plant in Los Angeles Harbor. The proposed permit would allow the city to drill three wells, one for sludge injection and two to monitor the effectiveness of injecting up to 400 tons of biosolids a day, supposedly without impacting drinking water supplies. The project is designed to provide an alternative to the city’s practice of applying its treatment plant biosolids on nonfood crops grown on land it owns in Kern County—a practice now prohibited by Measure E.
Like the Vermonters who think the chemical and biological contaminates in septage are not well characterized and may represent persistent, accumulative toxins that will remain in the soil for an undetermined amount of time (with unknown effects on public health), Stuth thinks the big picture of onsite waste disposal is significantly more dangerous than it used to be. “I own a lab, and we do a lot or research, so we know what’s really going on. One thing that will have to happen in the future is that we’re going to have to start listing household products that are dangerous.
“I’ve been looking into septic tanks for 50 years now, and they’re not the same. They used to be a lot more predictable. The way it works now, we identify a product on the market that could cause a problem, and everyone attacks it.
“But it isn’t one product, it’s the accumulation of all the chemicals we’re putting into these systems. If the environmentalists really wanted to do something, they’d look at that end of the horse.”
PENELOPE GRENOBLE O'MALLEY specializes in environmental topics.
OW - July/August 2006 |
