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The backyards of Swan Hills are doing just fine.

Delegates attending the Canadian Chemical Conference have the chance to visit a unique facility in Canada -- the Alberta Special Waste Treatment Centre in Swan Hills, about 200 km northwest of Edmonton. (The technical tour will take place Thursday, June 4.)

The Swan Hills centre is operated by Chem-Security Alberta Ltd., but owned by Bovar (formerly Bow Valley Resource Services) and the Alberta Special Waste Management Corp. (ASWMC) (a Crown corporation) through the Alberta Special Waste Management System (ASWMS). Bovar owns 60%. The vice-president, operations, for ASWMC, Mark Polet, said the organziation has a "classical" joint venture set-up. To some extent it is run like a utility; the government guarantees a certain rate of return. However, Polet expects the centre to be paying its own way by 1995.

Opened in 1987, the centre handles any hazardous waste of a chemical nature, excluding biomedical, biological and radioactive wastes. This still leaves quite a range of materials which need to be destroyed. Typical wastes include: * Solvents used for cleaning -- acetone, benzene, carbon tetrachloride, ethanol, isopropanol, kerosene, methyl chloride, toluene, trichlorethylene, varsol, white spirits; * Acids/alkalis used in rust removal, acid batteries, chemical manufacturing, lab experiments, printing -- ammonium hydroxide, hydrochloric, nitric, sulphuric and phosphoric acids, potassium hydroxide, sodium hydroxide; * Reactive wastes generated by chemical and metal manufacturing -- hypochlorites, organic peroxides, sodium perchlorate, potassium sulphide, sodium sulphide; * Ignitable wastes -- paint wastes, paint and varnish removers, paint brush cleaners, epoxy resins and adhesives; * Heavy metals found in paints, chemical manufacturing, labs, metal manufacturing and processes such as coating, engraving, heat treating and electroplating -- lead, mercury, cadmium, arsenic, barium, chromium, silver, selenium.

Other wastes treated include PCBs, a variety of PCB-contaminated soil, phenolic compounds, and TCDD (dioxins, furans)-contaminated waste.

The treatment processes break down the complex molecular structures into simpler, non-toxic compounds, or oxidize them completely to carbon dioxide, water or other non-toxic components.

The client group spans industries such as petrochemical, oil and gas, fertilizer and agrochemical all the way to schools and the public. The plant can treat 13,500 tonnes per year (t/y) of waste and is hoping to install another rotary kiln that will increase capacity by 40,000 t/y.

The centre uses three basic processes to dispose of the wastes it receives: incineration; physical/chemical treatment and stabilization. Before we detail the workings of the centre, a short history lesson will explain how the centre came to be built.

NIMBY not a factor

When plans are announced for a hazardous waste treatment centre, the community's general reaction usually ranges from "Get my gun!" to the more famous "Not in my backyard" or, as it's commonly known, NIMBY. How did the province and management avoid this?

Polet believes they were successful because of the way the site was chosen. The groundwork for the facility goes back to 1979 when the Alberta government formed a Hazardous Waste Management Committee. "We never imposed ourselves on a single community -- |Here we are with our toxic waste.' -- We offered to do a complete land capability study for any community interested. If, after the study, they felt that they didn't want us, fine, we shook hands and they kept the study, free."

The community had to show an interest in having the facility before the committee showed an interest in them. After the initial land studies, a group of communities was chosen. Again, they had the option to pull out if they didn't want to go ahead. It came down to three communities, but one decided against pursuing the matter. In March 1984, the Alberta cabinet then chose Swan Hills. The community that lost out, Ryley, near Edmonton and perhaps a better geographic location in terms of being closer to the major producers of waste, even took out newspaper ads decrying the decision -- NIMBY in reverse.

"What distinguished this process," Polet said, "was the volunteerism. We gave the communities all the data they could possibly ask for, and then some, and then we let them decide."

By truck only

Swan Hills handles waste produced in Alberta alone. A government decree forbids the centre from accepting waste produced outside the province. Special containment trucks transport the waste to Swan Hills. Bulk liquids are shipped in tanker or vacuum trucks, bulk solids in specially-designed dumptrucks, while smaller amounts are placed in 45-gal drums sealed inside marine-type containers.

Drivers are allowed on the road no more than two hours or 200 km before they must take a break and do a walkaround inspection of the vehicle. Transportation may only be done during the day. Drivers receive special training beyond the National Road Test. Polet proudly noted there has not been one traffic accident involving the centre's vehicles since start-up in 1987.

Waste may be taken directly to Swan Hills, or to a transfer station. When sufficient quantities are accumulated at a transfer station, the load is sent to Swan Hills.

Once at the facility, the laboratory becomes the most important part of the process. Headed by Roy Jones, it sees all that comes into the centre. "They get a lot of stuff thrown at them," said Polet, "and it's not your basic feedstock."

The lab also receives samples from any potential clients, to determine if Swan Hills can dispose of the waste. ASWMS has salesmen in the field selling its services, but because the facility is the only one of its kind, clients usually come knocking on ASWMS door first.

Testing is done on each load, so the lab can check that clients are not trying to slip anything in that shouldn't be there. There are over 6,000 waste profile sheets. Each has a specific waste treatment strategy. There is a burn co-ordinator who decides what, if any, materials can be mixed for disposal. "He tries to combine a high-heat load with a low-heat one to reduce the Btu level in the incinerator and thereby increase productivity," Polet explained. "It's quite an art to mingle the waste properly to maximize productivity.

Waste is streamed to the appropriate storage process or disposed of immediately. Polet noted that there is no long-term storage. As soon as a sufficient load for effective/efficient disposal is collected, it is destroyed.

The lab also does environmental/hygienic testing to ensure the disposal systems work and the area around the centre is not being contaminated by emissions. This is backed up by testing done by an independent lab.

Some like it hot

Incineration is the best known of the disposal processes. Swan Hills has two kilns -- a von Roll rocking kiln and a C-E Raymond rotary kiln. Each is a dual chamber design: a primary horizontal chamber and a secondary vertical chamber. Contaminant removal is 99.9999%. If supplementary fuel is needed, it is natural gas.

The incinerators are used for organic (hydrocarbon-based) wastes contained in liquids, sludges or solids. The hazardous materials are destroyed in a high-temperature (up to 1200 [degrees] C), oxygen-rich environment.

The recent emphasis on waste minimization has affected Swan Hills' operations. "With everyone trying to cut down waste, the loads are more concentrated now," said Polet. "If the heat loads are that much higher, we must burn them more slowly."

The feed system for the rocking kiln sends fibre drums of waste into the kiln. The rotary kiln is more robust. It can also handle steel drums. A shredder is used to mash the drums before they enter the kiln. As can be expected, the shredder wears out rapidly; it needs to be replaced every six months.

In the rotary kiln, retention time is typically 0.5 to 4 hours for two drums, depending on waste type characteristics such as moisture content, viscosity, heat value, etc. Some examples: * Gas plant filters -- 1 hour processing time, drum mass of 200 kg; * Organic sludges -- 2 to 4 hours processing time, drum mass of 180 to 200 kg.

N.B. All retention time ranges for the examples given (rotary and rocking kilns, phys/chem or stabilization are highly dependent upon the individual waste type characteristics. The typical situations cited are approximates only.

In the rocking kiln, retention time is 0.5 to 1.5 hours per drum depending on the heat value and other waste characteristics. For example, diaryl disulphide has a 0.5-to 1-hour processing time per drum with a drum mass of 200 kg.

"Classic schoolbook chemistry"

Inorganic liquids and solids are sent for physical/chemical treatment. This is a three-step process involving neutralization, precipitation and filtration. "Classic schoolbook chemistry," is the way Polet described it. Depending on the waste stream, oxidation/reduction is also used.

Retention time in phys/chem treatment is usually 2 to 3 hours per batch. The typical batch size is 400 to 500 litres (20 to 25 drums), but some waste types need as long as 16 hours of treatment. Some examples are: * Metals-contaminated acids and bases -- 2 to 3 hours per batch, drum mass of 200 to 400 kg; * Phenol-contaminated aqueous material -- 2 hours per batch, drum mass of 200 kg.

A stabilization unit also exists for pretreated (outside Swan Hills) solids and sludges and low-level contaminated solids such as soils. Bulk chemicals such as fly ash and lime may be added in a mixer to produce a solid, stable material suitable for the secure landfill. This unit may also receive treated residue from the kiln and phys/chem processes.

In stabilization, retention time is typically 1 to 2 hours per batch with each batch weighing 1500 to 2000 kg. * Metal-contaminated soil -- 1 to 2 hours processing time with a drum mass of 400 to 450 kg; * Spent catalysts -- also 1 to 2 hours processing, with a drum mass of 300 to 400 kg.

What happens to what's left over

The incinerators' stacks are equipped with pollution control devices such as ionization scrubbers and precipitators. Slag and ash pass through standard leachate tests and if they pass, are sent to the secure landfill on site. Failure means another pass through the incinerators or stabilization. Excess water from the precipitators is tested, sent for physical/chemical treatment if needed and then poured down the deep well, also on site.

Filter cake from the physical/chemical process is stabilized and sent to the secure landfill. The aim is to obtain "clean" water for the deep well.

What is the deep well? The residual liquids are pumped into a limestone foundation containing salt water more than 2,000 m below the surface. This is below any usable water sources. Pressure in the formation is tested regularly as is the well casing for leaks. No solids are pumped into the well.

Even storm and truck wash water are tested, treated if necessary, and sent down the well.

The secure landfill is a series of sealed cells. Only dry, inert solids are placed in them. Each cell is dug into a 15-m-deep layer of dense clay, lined with a thick plastic shield. When in use, the landfill is covered with a moveable building. When full, each cell is covered with clay and sealed with a leakproof cap. Monitoring wells have been dug around each cell to detect any leakage.

As mentioned, Swan Hills wants to expand, adding another rotary kiln. Cost of the expansion is forecast at $60 million. Polet said that the waste stream in Alberta has changed "significantly" since the facility first fired up its kilns. "We used to see more high-liquid loads, with low heat value. The forecasts for phys/chem treatment have been bang-on. However, once our clients saw how well the centre was working, they started going into their |back 40s' to see what was hidden back there."

Plenty, according to Polet. There are now 22,000 barrels of solids waiting for treatment. Polet estimates that before any new capacity can be added, another 50,000 barrels will be on hand.

The new kiln would treat more of the same -- incinerable solids. The proposed increase in capacity has groups opposed to the expansion concerned that the provincial government will amend the law and allow Swan Hills to treat outside wastes. Although that would be a political decision, Polet said that facility will have all it can handle with just Alberta wastes, especially with incinerable solids.

A coalition fighting the expansion, SHERC (Swan Hills Expansion Review Coalition), is also afraid that increasing capacity will encourage industry to continue to produce hazardous waste rather than developing means to reduce or eliminate it, or to re-use or recycle the waste.

The Treaty 8 natives, living about 100 km north of Swan Hills, are also concerned with the proposed expansion. They are concerned about possible effects that emissions from Swan Hills could have on their way of life, specifically if chemicals could find their way into the traditional foodstreams of the natives.

The final arguments in front of the Natural Resources Conservation Board (NRCB) have been delayed twice to allow the natives to prepare their cases. The final hearings were scheduled to be heard in late March.

Once the NRCB makes its decision, and if it gives the go-ahead for the expansion, Polet said there are many other environmental reviews which the ASWMS must pass. At best, Polet added, construction could begin in September.
COPYRIGHT 1992 Chemical Institute of Canada
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Copyright 1992 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Alberta Special Waste Treatment Centre
Author:Rodden, Graeme
Publication:Canadian Chemical News
Date:May 1, 1992
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