GARSON, Man. – A Manitoba engineering firm may have found a way to keep a lid on the problem of malodorous manure stored in lagoons.
More than 50 hog farmers and industry representatives showed up at the farm of John and Leanne Van Aert recently to check out a black, tarp-like cover over a lagoon.
DGH Engineering is testing the cover with $50,000 in funding from three groups concerned with hog manure strategies.
Weeping tile surrounds the lagoon and a sheet of sunlight-resistant, reinforced polyethylene covers it, anchored by sandbags and gravel. The material is often used as a liner for lagoons, dugouts and ponds in golf courses.
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A small half-horsepower fan at one corner of the lagoon sucks air from under the plastic, explained engineer Doug Small, creating a vacuum equivalent to about six pounds of pressure per square foot.
This pressure prevents the plastic from blowing off the 5,880-square-metre lagoon used to store manure from the Van Aerts’s 800-head sow barn and 200-head finishing barn.
“I’m quite impressed with what I’ve seen so far,” said Van Aert, explaining there is no odor from the pit, even downwind.
The materials and labor for the cover cost about $20,000, and the cover should last three to five years. Power may cost about 60 cents a day.
The cover has nylon rope sewn along each side. It was pulled over the lagoon by a tractor on either side, and went “just as slick as you could imagine,” said Small. When Van Aert decides to pump out the lagoon, the cover will be lifted the same way.
Small said the cost should be comparable to spreading barley straw over lagoons, a common way to reduce odors.
Straw works, but can cause problems when farmers agitate and pump out the lagoons. It also allows rainwater into lagoons, which adds costs for farmers.
Small does not expect water from melting snow on top of the cover to cause problems. In fact, it will help anchor the plastic, he said.
After six weeks, pockets of methane puffed up the cover in places. Small said he thinks the bubbles will eventually move to the edge of the lagoon, then escape into the weeping tile and through the fan.
If that creates odors, Small plans to run exhaust from the fan through a filter of peat and straw.
Some mice have already found homes underneath the tarp. Small said a few mice shouldn’t cause problems, although he is worried about deer running onto the cover and puncturing holes.
Small will monitor wear and tear closely for a year to see if the concept works. The company also may experiment with other colors and types of plastic.
In the past, some research has been done on air-inflated covers over lagoons, said Small, but they were too expensive, and hard to keep in place in the wind.
This demonstration project is funded by the Canadian Pork Council, the Triple S Community Futures Development Corp. and the Manitoba Livestock Manure Management Initiative.
It is one of the simpler projects receiving funding in the province from the manure management initiative, said chair Garland Laliberte.
“It’s so simple that it could just work,” said Laliberte.
“We maybe have a winner going here.”
