The Genius of Jean Pain

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[2] Shredding: Since the underbrush that's collected may reach diameters of up to four inches, relatively heavy-duty machinery is necessary to shred the wood. Jean prefers a cutter that produces slivers rather than chips . . . since water penetrates the surface of along thin fragment more easily than it does blocky chunks. Though the shavings may be as much as an inch long, the ideal thickness is about 1/16 of an inch.

[3] Saturation: M. Pain claims that a cubic yard of brush can—under ideal conditions—absorb and retain about 140 gallons of water . . . if the pile is progressively stacked and soaked over the course of three days. Water must be added to the layers at least once every 4 inches, but watering at 2-1/2-inch intervals will give the best results. In addition, since a certain amount of liquid will filter through the stack, a trough must be built to collect all the excess moisture so that it can be sprayed back onto the heap.

OPERATION

Any thermal compost pile—Jean explained—can be sized according to the demand for heat that is anticipated. We'll discuss, then, a heap built from about 16 tons of clippings. This happens to be equivalent to the amount of brush that can be removed from an average acre of timber during a year of normal stewardship . . . and such a pile also produces the right amount of humus to add to an acre of land that's to be used for growing cereal grains.

After the twigs from such an area have been shredded, they'll form a mound about 10 feet wide, 10 feet high, and 15 feet long . . . with an average density of about 20 pounds per cubic foot. However, the process of saturation may bring the poundage up to nearly 60, and the final density will still be in the range of 40 pounds per cubic foot. (Jean has found that the piles usually finish decomposing by the eighteenth month . . . but he tests the materialby crushing a chip between his fingers-to be sure the compost is ready for field and garden use at that time.)

While composting goes on, the bacterial activity within a pile produces a considerable amount of heat . . . averaging about 140°F in most instances. Thus it is possible to tap a significant source of thermal energy by intertwining heat-exchanging pipes throughout the interior of the stack.

Jean's early research consisted of laying 1" black polyethylene semirigid pipe in a serpentine pattern within the rectangular heaps . . . in either a vertical or horizontal array. While the horizontal arrangement proved to be easier to assemble, the vertical approach was considerably easier to take apart once decomposition was complete. Of course, in either case the connections in the plastic pipe must be secure . . . since a leak will be hard to notice within the heap, and even more difficult to repair . . . without completely disassembling the pile.

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