Don’t Dig Near Pipelines: A TACA Safety Moment
The Texas Aggregate and Concrete Association (TACA) brags that its members uphold the industry’s highest standards for safety. Or did they mean daring? Let’s have a safety moment.
Myth Meets Reality on the West Fork
To shine a light on the difference between the myth and reality, I’ve taken up a new hobby: sand-mine photography from a helicopter. On my December flight up the West Fork of the San Jacinto, I flew over this mine. Note the wetlands and utility corridor in the middle. Also note the trench leading through the trees on the right to that open gap in the tree line along the utility corridor.
I was curious about that gap. So I asked the pilot to go closer and got the photo below. How strange, I thought! The pipeline corridor has washed out, like at the Triple PG Mine. But this was a little different. The mine appeared to be draining the wetlands. Note the river of muck in the photo below.
Enlargement Shows Makeshift Supports
Someone had rigged “supports” under five pipelines. See the enlargement below. I put supports in quotes because they don’t seem to be working very well; note the sagging. Some look more like clotheslines than pipelines under pressure.
Pipelines Carry Highly Volatile Liquids
Investigation showed this is the SAME utility corridor bisecting the Triple PG mine miles to the southeast in Porter. These are the same five pipelines carrying highly volatile liquids (HVL). This mine, however, lies on the West Fork of the San Jacinto in Conroe near 242.
The channel under the five pipelines is up to a 100 feet wide.
Historical Images in Google Earth Show How This Happened
An investigation of historical satellite images in Google Earth shows that erosion has been a problem in this area at least since 1995 – the date of the earliest available image. Water overflowing the wetlands tried to make its way to the river on the other side of the utility corridor. The problem was manageable, however, as long as the land was flat. That was until 2014.
In 2014, two things happened. The mine started excavating right up to the edge of the pipelines (just as Triple PG did).
Next, three back-to-back-to-back monster storms in 2015, 2016 and 2017. They were “perfect storms” where the right combination of circumstances came together: Heavy rain. Exposed, loose soil. Steeper gradient.
How “Headward Erosion” Happens
The fact that miners had excavated up to the pipeline corridor with some very deep pits created a steep drop at the edge of the pipelines. That meant water crossing the corridor tended to accelerate and erode the sandy soil beneath the pipelines faster. The soil then sagged into the pit, much as you see in the pictures above. This process is well documented and has a name: headward erosion.
Here’s an illustration of how the process of headward erosion works
Here’s a 43-second YouTube video showing the process in action in a table-top flume experiment.
Makeshift Repairs Not Working All That Well
Trying to make the best of a bad situation, it appears that either the miners or the pipeliners tried to shore up their pipelines with supports. But it’s not working. They keep trying to plant grass. They keep using erosion control blankets. The supports keep sinking. And the pipelines keep sagging. Here’s an even bigger blowup.
It looks as if some of these supports are anchored in quicksand. Notice the extreme difference in their heights. The cross braces supporting the weight may be adjusted as the supports sink. But not on this day.
Another factor here: What if a tree washes down this chute during a torrential rain? It happens. Regularly.
I have a hard time imagining the stress on these pipelines. An engineer calculated a range of weights for me. He made some assumptions about the thickness of the pipes and the weight of liquids inside them. Then he calculated the weight of 100 feet. The range: 20,000 to 30,000 pounds. No wonder they’re sagging. That’s more than I weigh after a dinner at Carrabbas!
Probably No Imminent Danger, But Just in Case…
They’re probably not an imminent danger. But what happens in the next big storm? We’re overdue. It’s been more than two months!
Hundreds of thousands of gallons of flammable liquids. Under high-voltage electric lines. Pipes under stress. Erosion that widens with every storm. This should be a wake up call. But…
TACA has resisted all attempts at sensible regulation. They don’t even want to define and publish best practices. And it has long been known that you can’t legislate common sense. So I guess we are just stuck living on the edge with connoisseurs of edge work.
Where to File Complaints
If you would like to complain to someone, these people may be willing to listen.
Mine Safety and Health Administration (this puts miners at risk)
Texas Railroad Commission (responsible for pipelines in Texas)
US Pipeline and Hazardous Materials Safety Administration
Location of exposed pipelines: 30º11’56.63″N, -95º21’57.78″W
Office on 18214 East River Road in Conroe, TX
Highly Volatile Liquid (HVL) Pipelines Involved:
- Plains Pipeline – Red Oak Pipeline (20”) moving crude
- Enterprise Products Operating – Chapparral System (12.75”) – HVL Liquid (probably crude)
- Mustang Pipeline – GLPL System (6”) – HVL Liquid
- Enterprise Products Operating – Texas Express Pipeline System (20”) – HVL Liquid
- Phillips 66 Pipeline LLC – 8″ Products Pipeline
That concludes our safety moment.
Posted by Bob Rehak on 12/9/2019 with help from Josh Alberson
832 Days after Hurricane Harvey and 80 since Imelda
The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.
