To reduce the risk of future flooding and the need for future dredging, we need to reduce the amount of sand coming downstream to our area. But how? I have two modest proposals that I would like to suggest. They may go too far for some people and not far enough for others. However, these proposals are a reasonable start to a conversation that we can no longer avoid. Let’s start by looking at where the sand comes from.
Two sources of sand
For the sake of discussion, let’s divide sand sources into two broad categories: natural and sand mines. We can’t really do much about the sand coming at us from natural sources, such as Spring and Cypress Creeks.
However, sand mines are different. Upstream from Kingwood on the West Fork, we have more than a dozen sand mines. They comprise 20 square miles of loose, exposed sand surface between US59 and I-45. When these areas flood, sand comes downstream at us in larger-than-normal volumes. Historical satellite imagery shows that the large build-up of sand between Humble and Kingwood has coincided with the growth of sand mining during the last three decades. So the question is really, “How do we reduce the volume of sand escaping from the mines?”
The two major problems with sand mines
From a helicopter, I observed that:
- The mines are built right up to the edge of the river. Their dikes leave no room for the river to expand in a flood.
- When miners finish working an area, they generally don’t replant grass or trees that could reduce erosion. I saw NO areas that had been remediated.
These two observations are the key to understanding the proposals below.
Two modest proposals
After carefully studying thousands of satellite images, aerial photos and ground-level photos taken after Harvey, I have two modest proposals to reduce the amount of sand coming downstream from sand mines.
- Push the mines back from river approximately 150 yards.
- Get them to replant areas that they no longer actively mine, including the 150-yard buffer.
Why 150 yards?
Harvey carried sand about 150 yards inland from the main river channel in numerous places before the deposits tapered off to zero (see River Grove photo below). I deduce, therefore, that at that distance from the main channel, the current during Harvey was also too weak to pick up sand in the mines and transport it downstream. So 150 yards should serve as a good buffer. It’s certainly better than nothing.
A 150-yard buffer zone will also give the river more room to expand during floods (300 yards across). That should reduce pressure on the dikes and therefore reduce the chances of dike failure, which could release untreated effluent into the river.
Why replant areas no longer being actively mined, including the 150-yard buffer?
To stabilize soil. To resist erosion. To minimize the acreage of loose sand exposed to flood waters. And to trap sand.
What will it take?
In announcing its emergency dredging project, the U.S. Army Corps of Engineers stated, “Excessive debris from Hurricane Harvey is exacerbating and impeding the free flow of water…”
We can’t control nature. But sand mines are a different story. Hopefully, getting the sand mines to become part of the solution will be based on willing cooperation.
Given the billions of dollars in damages and remediation costs being born by the public, these modest proposals seem like a small price for sand miners to pay.
I welcome opposing points of view from the industry. If miners have a better, different, or less expensive way to reduce risk, please share it.
Posted by Bob Rehak, May 4, 2018
248 days since Hurricane Harvey