Note to readers, attached is the complete final report for FNE93-019.
Ara Lynn raises chickens. She had the idea of building a biogas digester on her farm as a way of disposing of manure, and at the same time generating heat with which to warm her hatchery. Toward this end Ms. Lynn had a pit excavated under the floor of her barn. It would have been preferable to line the pit with poured concrete, but because of the close quarters it was not possible to bring in concrete forms. She lined the pit with concrete blocks instead; next followed a layer of styrofoam insulation, and finally a fabric liner. The latter consisted of many pieces joined with multiple seams which, unfortunately, developed multiple leaks. Ms. Lynn spent a lot of time patching these leaks but never was able to obtain a good seal, and on this the project foundered.
Ms. Lynn offers this advice to others who may have similar designs: 1) choose a site that has easy access for heavy machinery, so that the pit may be properly excavated and prepared, 2) use poured concrete, 3) be sure of the material for the inner liner, that it has a minimum of seams and makes a complete seal, 4) secure the digester cover with stainless steel lag bolts, to avoid corrosion, 5) make sure of a good fit between the liner and the cover, 6) use plastic lumber, because it doesn’t shrink and swell, and 7) keep it simple.