Soil treatment system uses hot air instead of an open flame. Pascale Tholl reports
From a spill dating back to the 1970s and 1980s, Togiak Fisheries was faced with 70000 tons of diesel- and gasoline-contaminated soil on the shores of Togiak Bay, Alaska.
The remote fish-processing facility wanted to sell, but the plant was stuck with the price tag of US$12 million to clean up the contaminated site.
The cost was overwhelming, yet so were the challenges that go into cleaning a five-acre site this remote.
Without any roadways, all supplies and equipment had to be shipped in by barge or plane.
Brady Environmental was able to complete the project for US$4 million, dramatically lower than the US$12 million market rate due to its patented system using Leister hot-air tools.
So how did the brownfield redevelopment and consulting company do it?
Soil moisture
Geologist Patrick Brady, president and owner of Sisters, Ore-based Brady Environmental, found a better solution. He developed an Evaporative Desorption Thermal Soil Treatment System using hot air instead of an open flame - the traditional model - relying on high quality Leister heaters to evaporate soil moisture and contaminants.
The expensive, traditional method of soil treatment uses an open flame to boil off the water, which creates contaminates that must first be cleaned before being released into the air.
Plus, the operation, maintenance and fuel costs associated with an open flame technology greatly inflate the price of the cleaning process.
During the research and design stages for the Evaporative Desorption Thermal Soil Treatment System, Brady stumbled upon Assembly Supplies Co, a distributor of Leister Process Technologies hot-air tools, such as heaters, blowers and controllers, among others. He soon chose to use Leister tools in his innovative system.
"After meeting with Dennis Van Grol, owner of Assembly Supplies Co, and seeing other applications where the tool was used, I felt very comfortable with it," says Brady. "I wanted to make sure it could be operated continuously because we turn on the oven for five months and never turn it off."
And, indeed, the Leister products stood the test of time. Today, Brady Environmental incorporates 12 of the Leister LE 40,000 heaters - Leister's most powerful device with 39kw - to pump hot air into three of his soil ovens. Each heater is supplied with one Airpack blower.
The Leister tool regulates the heat. By monitoring the system to ensure the temperature hovers around 1000 degrees Fahrenheit, Brady can guarantee the air never reaches the oxidation temperature of 1300 degrees, which produces emissions.
"Leister heaters are an integral tool in our patented process and it doesn't produce the pollution that other systems produce doing the same thing," says Brady.
In 2001, Brady and his twin brother, John, filed a patent application for the Evaporative Desorption Thermal Soil Treatment System. The U.S. patent was issued in December 2004. This "soil oven" is a modular design in an airflow system. Vapours are extracted and the contaminants they contain are destroyed before being released into the air.
"Others can go in and it costs them US$250 to US$600 a ton to clean the remote Arctic site, but I can clean the soil for US$50 or US$150 a ton," says Brady. "My machine is much more portable, so I can fly it to a particular spot for US$150000, whereas the old technology would cost US$1.5 million to get it there by barge or truck.".
Cutting labour
As a result of the Evaporative Desorption Thermal Soil Treatment System, Brady was able to cut down his labour pool by a third. "That dramatically cuts down my cost," he says.
But to Brady, it's not only about the money he saves; it's about the communities he revives.
"The secondary effect this system has is it stimulates the local economy and produces hundreds of jobs in these areas. It makes for a better community ... it takes the smell away," says Brady. "Because the Leister tool is an integral part of the patent, it really does a lot of good beyond just saving me money. It's a thing called environmental justice."
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- Pascale Tholl is with Leister Process Technologies based in Kägiswil, Switzerland. www.leister.com