The Mennonite family of four and farm hand who were killed on their farm in Rockingham County in July died from hydrogen sulfide, not methane as originally thought. Hydrogen sulfide is a colorless gas that typically smells like rotten eggs and builds up in manure pits. Methane is an odorless gas that builds up in corn silos.
The tragic event occurred when Scott Showalter, 34, went into a manure holding tank to clear a clogged pipe. He passed out and the others died trying to rescue him: his wife Phyllis, 33, their daughters Shayla, 11, and Christina, 9; and farm worker Amous Stoltzfus, 24.
Sadly, this type of farm accident is not uncommon. Lives are lost because of the buildup of hydrogen sulfide in manure holding tanks, and each accident usually involves more than one person because rescuers try to help and are overcome by the extremely toxic gas. A couple of breaths can cause unconsciousness.
Also known as hydrosulfuric acid or sewer gas, hydrogen sulfide can cause eye irritation, headache, and fatigue; unconsciousness and death can occur after just a few breaths.
In the case of the Showalter accident hydrogen sulfide was caused by the breakdown of animal wastes but it can also occur in crude petroleum, natural gas, volcanic gases, hot springs, and the breakdown of human waste. Any manure holding tank is considered a hazardous confined space, and it is recommended that entry for whatever reason should be considered dangerous.
Manure holding tanks on farms are required under the Chespeake Bay Act that enacted numerous regulations to protect the Bay.