Addendum Regarding “Cancelled!” & Gas Leak at the House on Deer Park Prairie.

As previously posted, all activities on Deer Park Prairie has been cancelled until further notice.

IMG_1862crFor those curious, this is what happened: Gas was smelled near the shed in the side/backyard. Glenn Merkord called Centerpoint. The technician who came checked the house for gas and turned off the gas. When he determined there is no gas leak INSIDE the house, he turned the gas to the house back on. The leak was determined to be OUTSIDE in the Centerpoint gas line near the shed. The technician said that Centerpoint had 30 days allowed to fix it. When Glenn asked, if we needed to do anything, the technician said no.

About a week later, another Centerpoint technician again determined that the leak was outside near the shed, but he turned off the gas to the house and said that they will monitor the leak every 10-12 days until they have an opportunity to fix it. This time they recommended for full safety of any employees or volunteers that we need to stay off the property until it is fixed.

Based on the conflicting Centerpoint recommendations, NPAT decided to cancel activities until the gas leak is fixed.

The fact that Centerpoint is not fixing the leak immediately and the fact that the first technician turned the gas to the house back on says to me that Centerpoint’s assessment is there is no eminent danger of explosion, since there are other houses and a school nearby. I also heard that gas leaks outdoors dissipate into the atmosphere and generally do not explode.

I was puzzled; it is so well ingrained in all of us that gas leaks can explode with even the slightest ignition source. I was wondering why Centerpoint can wait up to 30 days to fix the leak.  I looked it up online. In short, apparently, when the leak is outside as this one is, the gas being lighter than air dissipates and generally does not built up to a concentration higher than the lower explosive limit. At a concentration below that limit, natural gas will not burn (or explode) even if an ignition source is present.

Since I learned something, I would like to share the sources of my information. Disclaimer: information in the above paragraph and in the paragraphs below are my interpretations based on what I found online. I know nothing about this field and each reader need to use his/her own judgement as to the validity of my interpretations.

When I googled “natural gas leaks outdoors” online, one article (source: The Spokesman Review, a newspaper) said “This year Spokane Valley Fire Department crews have responded to several broken natural gas lines, whether from some sort of construction work in the road or a homeowner who got careless with a pick ax. Spokane Valley Fire Battalion Chief Stan Cooke gave the same advice as Kolbet. It’s fine to stay in your home if you don’t smell anything [Lan’s note: implied is if you don’t smell anything inside the house], but you should leave if you smell the odor of rotten eggs, he said.

The reason is that once the gas is inside your home, it can’t be ventilated until the leak outside is stopped. It’s rare for explosions to occur with outside leaks, though firefighters recommend that if you are evacuated you do it on foot and not try to start a car.”

Also, Wikipedia (https://en.wikipedia.org/wiki/Gas_leak) described different grades of gas leaks. “A Grade 2 leak is a leak that is recognized as being non-hazardous at the time of detection, but justifies scheduled repair based on probable future hazard.”  I do not know what grade leak ours is, but apparently there are non-hazardous leaks. The article talked about 80% LEL or 40% LEL etc. Not knowing what LEL stands for, I looked it up.

LEL is lower explosive limit. “The lowest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in presence of an ignition source (arc, flame, heat)…At a concentration in air lower than the LEL, gas mixtures are “too lean” to burn. Methane gas has an LEL of 4.4%. If the atmosphere has less than 4.4% methane, an explosion cannot occur even if a source of ignition is present.
Percentage reading on combustible air monitors should not be confused with the LEL concentrations…A 5% displayed LEL reading for methane, for example, would be equivalent to 5% multiplied by 4.4%, or approximately 0.22% methane by volume at 20 degrees C. Control of the explosion hazard is usually achieved by sufficient natural or mechanical ventilation, to limit the concentration of flammable gases or vapors to a maximum level of 25% of their lower explosive or flammable limit.

So apparently when there is a slow leak of gas outdoors, the gas, being lighter than air, dissipates into the atmosphere and if the concentration of gas is lower than the LEL, the gas will not burn or explode regardless of whether there is an ignition source or not.

Then I had a question of what is the concentration of gas, when I can smell the gas and found this online: (http://www.rrc.state.tx.us/media/8553/chap4-leakdetection-natgas.pdf) “Gas is intentionally odorized so that the average person can perceive it at a concentration well below the explosive range.

Hence, gas leaks outdoors generally do not explode.  All that said, out of an abundance of caution, all activities on property has been cancelled until Centerpoint fixes the gas leak.

I still marvel at the information that can be found in minutes at 1:00 a.m. on the internet! I remember very well that not too long ago researching the above information would require many hours (at least) in the library – when it is open.

Lan Shen