River migration can imperil sand-mine dikes and that can imperil people downstream.
In the case presented below, the San Jacinto river migrated 258 feet toward a dike in only 23 years and now threatens it. The river has eaten away at a dike by migrating an average of 12.4 feet per year. The dike is now only 38 feet wide. This a textbook case for why we need greater separation between mines and the San Jacinto river. Another dike failure could exacerbate downstream sedimentation and flooding, as it has before.
River Migration Raises Questions about Setbacks and Abandonment
This example of river migration raises serious questions about the lack of setback requirements for Texas sand mines. As rivers migrate toward mines, they can breach dikes and increase the risk of future breaches. Sediment then sent downstream can block rivers and streams, and contribute to worse flooding.
In some cases, mining companies may still be around to repair breaches. But what happens when the mine is played out and no one is there to repair the dike? Hundreds of acres of silt could suddenly be exposed to river currents and washed downstream. As more and more mines on the West Fork approach the end of their lives, this is becoming a huge concern.
Before Sand Mines
This series of satellite images from Google Earth starts in 1995, before there were any sand mines on either side of the river at this location. I created the red line in a separate layer above the satellite images. As we move forward in time, the location of the line will NOT change; but the location of the river WILL.
1/18/1995 before sand mining in this area of the West Fork
By 12/31/2001, the river had shifted slightly. We now have a sand mine on the east side of the river. Note the width of the dike and the road on top of it.
By 1/25/2004, the river had eaten away at the dike and threatened the road.
1/14/2006: The river has almost completely shifted from its original bed and wiped out a large part of the road
1/8/2008: The dike has become dangerously thin, and the road has completely disappeared.
3/14/2014: The mining company has shored up the road by adding fill to both sides of the dike, increasing sedimentation in the river.
On 5/31/2015, the Memorial Day Flood inundated the mine and wiped out the road again. Note the large body of water at the far left. This was a new pit started on the west side of the river that year. Notice how the dike on the left has been breached and silt from the mine is flowing directly into the river.
7/31/2015: The dike on the left remains open and erosion from the Memorial Day flood has eaten the road on the right dike. Twenty years after the start of this sequence, the river has now completely migrated from its original path.
Then along came the Tax Day Flood of 2016.
By 1/23/17, we see sediment building up at the south end of the both pits from the storm during the previous year. This shows that the current was strong enough to move sand within the pits, something the miners say is impossible.
By 8/30/17, the entire area was inundated. Peak flow during Harvey actually happened the day before this photo was taken. It was four times greater than what you see above.
On 10/28/17, two months after Harvey, the dike on the right has almost disappeared. It is now a mere 38 feet wide. The red line, which represents the original riverbed, no longer overlaps the current river bed. The pond next to the G in Google has almost completely filled in, more evidence of sediment migration within the pit.
This series of river migration images shows the relentless forces of erosion. Mining in the floodway so close to the river increases sedimentation, and as a consequence, the risk of flooding.
We’re already spending tens of millions of public tax dollars to dredge the San Jacinto and restore its carrying capacity. Sediment clogged it, in large part, because sand mine dikes have failed repeatedly to protect the mines from floods.
At what point does the honorable pursuit of profit become reckless endangerment? At what point does hope that the dikes will hold become willful blindness? Since when does one man’s unfettered right to mine sand give him the right to damage others and imperil public safety? Why do legislators allow business practices that endanger neighboring communities? When will regulators see the partial truths spread by TACA for what they are – an deceptive attempt to escape liability for egregious business practices? And above all, what happens when miners walk away from the property but floods continue as they always have.
Property Rights Vs. Public Safety
Miners claim they have the right to do what they want on their property. But not at the expense of public safety. Should the owners of commercial buildings be allowed to operate without fire alarms, sprinkler systems and safety exits just because it’s their property?
Miners have choices. They don’t need to compromise safety. The meander belt of the San Jacinto stretches for miles. There’s plenty of sand out of the floodway to mine.
At the current rate, without human intervention, river migration should capture the mine on the right side of these photos in about three years. It won’t be the first time something like this has happened.
To prevent such disasters in the making and protect public water sources, other states and countries have established setback regulations from rivers. Texas should do the same.
Posted on August 29, 2018 by Bob Rehak
365 Days since Hurricane Harvey flooded the Lake Houston Area
As always this is my opinion on a matter of public policy and is protected by the First Amendment of the United States Constitution and the Anti-SLAPP statutes of the Great State of Texas.