The Hazmat of Pre-Refined Gas and a House Explosion

Map of oil and gas wells in Colorado. Click on the map to link to the interactive map. From the Denver Post.

Pre-refined gas is a mixture of methane and propane that comes from natural gas wells. Pre-refined means that it hasn’t yet been refined into natural gas for energy. It is an extremely flammable gas and a hazard that is managed in the oil and gas industry. It’s not something you should have to worry about blowing up your home. Unfortunately a pipeline leaked this gas into a house in Firestone, CO. The house was built only a few hundred feet from a natural gas well. The leaking gas ignited in the house and the explosion killed 2 people. You can read more about this tragedy here. I’ve been asked about this several times since it happened. Therefore, here’s the basic how and why.

How did this happen?

This is the technical, hazmat part. Methane is an odorless, colorless, flammable gas, which is lighter than air. Propane is also odorless, colorless, and flammable, but it is heavier than air. Each of those characteristics are important. For example, natural gas has an odor added to it (ethyl mercaptan) that gives it that distinct “I smell gas” smell. The methane and propane in pre-refined gas are odorless. Although methane is lighter than air, propane is heavier than air. I don’t know the exact mixture in this gas, but a combination of methane and propane can be heavier than air. That means if this leaks near your house it would accumulate in low lying areas. An undetectable, heavy gas accumulating in your basement is not a good condition. Add an ignition source and you have an explosion.

Why did this happen?

D-J Basin. By Daniel H. Knepper, Jr. (editor), US Geological Survey –

This was the imperfect combination of several factors: a natural gas boom in Colorado that kicked off around 2007, plus a population boom along the Colorado Front Range a the same time, both of which partly occurred over the Denver-Julesburg Basin. The D-J Basin is a productive oil and natural gas reservoir right under Denver, Fort Collins, and much of the Front Range plain and eastern Colorado. The last decade has seen a land use “battle” between housing developments and production wells. State and local governments, fracking controversies, oil and gas jobs and their tax money, home owner tax…whew. It’s one of the difficult land use issues facing the mountain west.

In this instance, a housing development was built close to a natural gas well. A pipeline from that well leaked; the leak wasn’t detected; and the worst happened.

For more thoughtful reading on the topic, here’s an interesting USGS circular from 2002 foreseeing all of this. Planning for the Conservation and Development of Infrastructure Resources in Urban Areas—Colorado Front Range Urban Corridor.

Did you find your house on the above map? Are you a bit close to an active natural gas well? Then share this with your neighbors.