The sign outside the abandoned Texas Concrete Sand and Gravel Mine in Plum Grove tells readers that an RV resort is coming soon. They might want to rethink that concept. Yesterday, rampaging floodwaters destroyed most of the mine except for a small area near the entry on FM1010.
Classic Example of Pit Capture
The East Fork rerouted itself right through the heart of the mine, sweeping away almost everything in its path. The river swelled to more than half a mile wide and ruptured dikes in at least four places when the river rose 10 feet in 24-hours.
This is a classic example of what geologists call pit or river capture. The East Fork entered the northern side of the mine and exited at multiple points on the south. Current coming out of the mine exceeded that in the river itself, carrying mud and muck downstream.
Flooding Based on Less than 10-Year Rain
The gage at this location indicated Plum Grove received only 3.36 inches of rain over a three-day period. However, up to 8 inches fell upstream from here, primarily during a two-day period. Jeff Lindner, Harris County’s meteorologist characterized the rains that produced the flood as, “Generally less than a 10-year event for the 48-hour time period.”
Pictures Taken on 5/3/2021
I took all of the shots below on 5/3/2021, three days after the major portion of the rain fell on April 30.
Danger of 2090 Washout in Next Big Flood?
Unless someone reroutes the river back to its original course and fixes the dikes, the current through the mine will continue to erode the banks of the roadway at the top of the image above.
These images dramatize the need for real sand-mining reform in Texas. There’s some evidence that Imelda did the same thing to this mine two years ago. But the TCEQ forced the company to repair the dikes. Now that the miners are gone, who will do that?
Plum Grove was lucky that upstream rains only amounted to a ten-year event. A larger storm could have cut the City and Colony Ridge off from the only viable evacuation route. More than 20,000 people would have been affected.
Posted by Bob Rehak on 5/3/2021
1343 Days since Hurricane Harvey and 592 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.