Foaming manure in hog barn manure pits could pose a fatal hazard for people and animals, warns the Ontario Ministry of Agriculture and Food (OMAF).

The foaming manure is a combination of gas, methane bubbles, a surfactant, soap and a stabiliser: filamentous methanogens bacteria. One possible cause is the use of dried distillers grains with solubles (DDGS) for feed.

“The issue is more prevalent among finishing hogs than piglets because of the feed but the risk is always there,” says Terrence Sauvé, a farmstead optimisation and safety engineer with OMAF and a co-author of a new fact sheet on the hazard.

If you encounter foaming manure

Some amount of foaming may be typical in manure storage, says the University of Minnesota Extension. Of particular concern is a type of foam that is persistent, has a mucus-like texture, and occasionally grows very fast.

OMAF’s fact sheet advises against using aggressive agitation or pressure washing to break up the foam. Otherwise, the sudden release of methane — 50 to 70 per cent of the total volume — could overwhelm the barn’s ventilation system, putting workers and animals at risk of explosion, fire or asphyxiation. Instead, ventilate thoroughly.

Methane is lighter than air, so it rises up and collects in storage headspace and unvented areas. In these areas, ignition sources such as a switch, motor, welder, grinder or pilot light could set off an explosion or fire. Even without an ignition source, high enough concentrations of methane, which is odourless and colourless, could asphyxiate the unwary.

Take preventive measures

“If you have a hog barn,” says Mr Sauvé, “please consult the fact sheet, 'Methane Gas in Hog Barns'.

“The extent of the hazard really depends on how you store or move the manure. The plain and simple thing to do is ventilate all areas of the barn, including individual rooms.”

Follow the recommended guidelines for air turnover rates in your type of barn, and ensure all storage and transfer pits are vented to the exterior so that methane is removed as it is being produced. Proper ventilation will eliminate hazards to your workers and animals, and maximise the animals’ well-being and productivity.

Also recently published by OMAF: Hazardous Gases on Agricultural Operations.

This article first appeared in WSPS Network News: Agricultural Industrial Sector, a newsletter published by Workplace Safety & Prevention Services.

March 2014