Sand Mining Best Management Practices: Vegetation

Sand mining best practices throughout the country and the world urge operators to leave vegetation in place until they are ready to mine an area. The reason: to reduce erosion. However, approximately 60 acres of the sand mine below on the East Fork of the San Jacinto where it meets Caney Creek and White Oak Creek was cleared but not mined – just in time for two 500-year floods.

Approximately 65 acres of this mine were cleared before two five-hundred year floods, contributing to downstream sedimentation in the East Fork, even though only about three acres of the area was mined.

Removing Vegetation Risks Sedimentation Downstream

The cleared area lies totally in the 100-year flood plain and was inundated. Satellite images of the area downstream from the cleared land show a sudden buildup of sand. While the sand did not all come from the cleared area, one wonders how much sedimentation could have been prevented by following best practices.

The following sequence of images shows the rapid removal of vegetation.

The white outlined area will be totally cleared before Harvey. On April 8, 2014, it was all dense forest. 

By March 3, 2016, most of the area was cleared.

By January 23, 2017, just before Harvey, the area was entirely cleared.

Risk from Flooding

This FEMA flood hazard map shows that the entire area lies within with 100-year flood plain (aqua) and adjacent to the floodway (cross-hatched area).

Before and After: Results

This image from 2014 shows the area in question when it was still forested. Note how little sand is in the river downstream from the mine.

Here’s the same view after vegetationwas cleared and the area was inundated by Harvey in 2017. Note all the sediment in the river downstream.

Much of the sand and sediment washed downstream is invisible to satellite photos because it’s under dense forest canopy. This area (downstream the sand mine being discussed) was once wetlands. A boardwalk through those wetlands had to be excavated from several feet of sand after Harvey.

Here’s what part of the same trail looked like before it was excavated. Approximately 30 acres of the park were blanketed with dunes up to 10 feet tall after Harvey. Every trail in the park required repairs. Total cost: approximately $200,000 to Kingwood residents.

A bird’s nest that was ten feet up in a tree is now knee high. Many of the trees along the Eagle Point trail in East End Park are buried under so much sand that they are dying. 

An Ounce of Prevention

It’s impossible to tell how much of the sand above resulted from the removal of vegetation?  Previous posts showed how the mines stockpile also eroded. The river itself contributed sediment. However, if the mine were not in the flood plain and if the miners had not removed so much vegetation so far in advance of mining, we wouldn’t be having this discussion.

So why do miners favor the floodplains and floodways? Why to they remove vegetation years before it will be mined? Is it all about the relentless pursuit of efficiency at the expense of safety?

Tomorrow, we will look at economics, taxation and how some well-intentioned laws passed in the late seventies to protect family farms helped fuel a boom in sand mining.

Posted September 24, 2018

391 Days since Hurricane Harvey