Growing green

By CHUCK POULSEN 2008-05-17 Kelowna Courier
It looks like a witch‘s brew and it works like magic. Here is the recipe: Mix wood chips with “biosolids” (human waste). Pump air through the pile and let it heat up to 75 C through decomposition. Cook for two or three weeks and let stand for awhile longer. Serve up the nutrient-rich soil supplement to lawns, flowers and vegetables. The Ogogrow operation at Predator Ridge near Vernon is the biggest go-green business in the Okanagan. It opened 18 months ago after it became clear that people wanted the Ogogrow mulch, as well as its cousin, Glenmore Grow. And, as expensive as it is to operate, the process is cheaper than the alternative. “It‘s also the green thing to do,” said Gord Light, manager of the Glenmore Landfill. The plant is run by Kelowna, with costs split two-thirds to Kelowna and one-third to Vernon. It‘s also the source for Natures (CCT) Gold, a product that is further refined by its Lake Country company and sold through the province. Natures Gold buys more than half of the Ogogrow crop. Ogogrow gained some stature among gardeners five years ago when Kelowna won the Composting Council of Canada‘s annual great pumpkin growing contest. The Ogogrow-fed 407-pounder from the Glenmore Landfill outweighed the second-place finisher by 61 pounds.

The biosolids come from the wastewater treatment plants in Vernon and Kelowna. They are mixed with the ground-up wood waste – including beetle-killed trees – and piled into rows where perforated pipes attached to blowers distribute air to promote decomposition. The microbes do their job for up to 21 days. The pile is then stirred up and left to continue composting for another 60 to 90 days. As the compost matures, it gets darker and takes on an earthy smell. The compost is then screened to remove excess pieces of wood, which are reused. The plant opened in the fall of 2006 at a cost of $7.6 million. Last year, the two cities sold 44,000 cubic yards of material for $460,000. Three large loaders run all day at a cost of $1.2 million per year. “We don‘t make money, but the alternative would cost way more,” said Light. “Landfilling alone would cost about $1 million a year, and then there would be no chance of revenue.”

The solid waste, looking as you might expect – like mud – is trucked in from Kelowna and Vernon treatment plants. The recipe calls for about 35 parts wood to one part biosolids. Glenmore Grow is composted wood waste, including leaves and needles, without the biosolids. Both are available at Glenmore, although Natures Gold is sold throughout the Okanagan. The high temperatures in the pile kill the bacteria and also aids in the decomposition. “The little microbes divide every 20 minutes,” said Light. “They multiply very quickly. “The byproducts are heat, moisture and carbon dioxide.” Light said the heat isn‘t captured for use – yet. “It‘s something we are aware of,” he said. “There could be a use, especially if we had a greenhouse located here. The piles give off carbon dioxide, which is another valuable gas for greenhouse plants. “I‘m not sure it will happen here because we‘re kind of constrained. But we‘re already talking to the parks department about doing that at the Glenmore site.” The plant is installing its own lab to do testing that‘s needed on a daily basis, but the rest is sent out to an independent lab. Testing is done for pathogens, nutrient value, moisture, PH and metals content. Test results have to be approved by the Environment Ministry. Light said the aerobic system is low on odours, but a bio-filter was installed to further reduce the smell. “The bio-filters have made a tremendous difference,” said Light. The hog fuel has come from Tolko and other mills, but that basic feed stock is becoming more difficult to acquire with the forest industry slowdown. The operators are substituting ground-up dimension lumber that is thrown away at Glenmore. “The feed stocks are rich in carbon and the biosolids are rich in nitrogen,” said Light. “To get a good composting mix, we need a good carbon to nitrogen ratio.” Water is also in the mix. “The bacteria live on a thin layer of water on every particle of wood,” said Light. “Without that home to live in, we wouldn‘t be composting here.” Air is blown into the piles through perforated pipes. When the temperature at the top gets warmer than the bottom, the air is then drawn down to keep the heat uniform within the pile. Thermo probes measure the temperature and send the data to a computer. The large hunks of wood that are screened out are also necessary to the process because they allow the air to circulate through the pile. The leachate from the piles is chlorinated and ends up in the North Okanagan McKay Reservoir, where it‘s diluted further. That‘s used for irrigation water. “We have a closed loop system,” said Light. “We‘re quite proud of what we do, but we want to do better. We want to reduce the time of the process and control the odours better. You can get a whiff of odour, and, although it‘s not terribly excruciating, we don‘t want any odour at all.”