When considering property tax implications of the proposed $2.5 billion flood bond, start with how much you currently pay in Harris County Flood Control District (HCFCD) taxes. Hint: It’s very little.
Only about 1.4% of Typical Property Tax Bill Currently Goes to Flood Control
Only about 1.4% of the average annual property tax bill now goes to Flood Control. The rest funds schools, cities, hospitals, law enforcement, etc. How much you currently pay each year in flood control taxes depends on your home’s value and your exemptions. See some representative costs below.
What homes assessed at representative price points will pay in additional taxes if the Harris County Flood Control Bond passes.
Amount Will Vary Depending on Age, Assessment and Exemptions
If your home is assessed at $200,000 and you are under 65, you pay only $45 annually for flood control. If over 65 in that same home, you pay no flood control taxes.
In a worst-case scenario, Harris County says the flood-control portionof your taxes would double. Would doubling one of the numbers above create a hardship for you? Or would it help you sleep better?
Remember, any increase applies only to the flood control portion of your tax bill, not the entire bill.
Less than Cost of Flood Insurance
Any increase would be gradual. Bonds are only sold when projects are ready to start. Harris County expects no increase at all until 2020 at the earliest.
Flood Control improvements cost much less than flood insurance. And unlike flood insurance, they might actually prevent your home from being damaged.
Protecting Home and Community Values
Once implemented, the flood mitigation measures in the bond package will help make our entire community more resistant to flooding. That’s important. It helps protect your home’s value, your schools, businesses, roads, bridges and other infrastructure. That helps keep your community growing and makes it attractive for people looking to relocate. In the long run, rising home values will pay you back many times over for your investment in flood control. So send a signal to the world that we’re willing to invest in our future.
How to Check Your Current Assessed Value
To see how much you pay right now, go to hcad.org, click on “Property Search”, then “Real Property” followed by “Search by Address.”
Posted by Bill Fowler on July 29, 2018
334 Days since Hurricane Harvey
00adminadmin2018-07-27 22:21:572018-07-29 10:26:43How Much Would the Flood Bond Cost You?
The U.S. Army Corps of Engineers originally solicited bids to dredge the West Fork of the San Jacinto from 59 to Lake Houston, a distance of 8 miles. At some point in the project, the Corps limited the scope to 2.1 miles – from River Grove Park to the West Lake Houston Parkway bridge – for reasons never made clear. Perhaps they ran out of money when they had to double the volume they were dredging in that 2.1 miles. Regardless, that meant leaving a huge sandbar in place at the mouth of the river (see below).
I have been concerned about that bar ever since they excluded it from the scope. I wasn’t the only one. Two retired geologists, Tim Garfield and R.D. Kissling, approached me after my post about reduced scope. They have more than 50 years of experience with one of the world’s most successful oil companies. Both are experts in river morphology and sedimentation.
They compiled this fascinating 28-page report about the mouth bar, which I helped them edit. It explains how the river is changing, why it’s crucial to remove the mouth bar, and what will likely happen if we don’t.
The goal of this presentation was to get the Corps to expand the scope of their current dredging project to include the bar. Why? Approximately half of all the damage that occurred in Kingwood occurred BEYOND where the Corp intends to stop dredging. If not removed, everything behind the mouth bar for miles upstream will be at greater risk of flooding.
Major Concerns From a Geologist’s Perspective
If this blockage is left in place, it will, say Garfield and Kissling:
Cause the river to run UPHILL
Create, in effect, a partial dam
Slow water down, back it up and elevate the water surface
Increase flooding upstream
Increase the rate of sedimentation behind it
Cause the river to escape its banks, flood neighborhoods and damage or destroy infrastructure
How the River Is Changing
Since the late 1970s, a delta has been forming within the river and advancing toward where the river meets the lake. You can see the 2-mile advance most clearly in this summary slide that shows Kingwood in 1977 and 2017.
Evolution of mouth bar over 40 years. The full presentation contains many intermediate images.
When Friendswood designed Kingwood’s drainage, it was based on a different reality. Note, for instance, what happened east of the West Lake Houston Parkway Bridge. A huge area has filled in, reducing the conveyance of the river.
The chart below shows the increasing rate of change in the Stream Mouth Bar (SMB) at the right in the photo above (the area outlined in white with the red arrow pointing to it).
Sudden exponential growth in mouth bar volume tells geologists that it has reached critical mass and is likely contributing in a major way to upstream flooding.
How Our Mouth Bar Contributes to Upstream Flooding
This next series of slides shows how and why the West Fork mouth bar affects flooding.
Before the Lake Houston Dam was built, water in the river dropped steadily in elevation from the site of today’s Grand Parkway all the way to the coast.
Since the construction of the Lake Houston Dam, water continues to drop to US59, but then it levels out. That’s because the dam backs up water that far.
A huge mouth bar grew up where the river enters the lake. As water slowed down and spread out, it deposits sediment. When the river is flowing at normal levels, water can find its way around the blockage without threatening neighborhoods.
However, during floods, the mouth bar acts as a partial dam. It creates a hydraulic jump that begins to back water up behind it. Note how the orange bar is higher on the left than on the right, relative to the blue line. That’s because the stream mouth bar increases the height of water behind it during a flood.
If the mouth bar were removed, water would no longer back up behind it. The river could flow freely in a flood. The dotted line represents an estimate of how much a flood like Harvey could be lowered. If the reduction were four to six feet, that could make the difference between major and minor flooding.
In this profile, the horizontal scale is less compressed than in the charts above it, so you can visualize more easily how water is forced to flow uphill as it approaches the mouth bar. This forces water to flow uphill and the water surface to elevate behind the mouth bar, contributing to upstream flooding.
Options Going Forward
Ignoring the mouth bar and hoping it will go away is not an option.
It has nearly doubled in size in the last three years. It will force the river to flood more frequently and more extensively, causing more damage to houses and infrastructure.
I suspect that the reason the Corps did not handle this in the first place is because they were constrained by budget. So removing the mouth bar as part of a change order is not an option either.
It will likely cost far more to remove the mouth bar than it does to clear the 2.1 miles upstream.
That leaves two options recommended by the Army Corps’ Deputy District Engineer for Programs and Project Management, Dr. Ed Russo (plus another that he didn’t recommend).
Option 1: Russo helped draft a proposal request for consideration under Section 7001 of the Water Resources and Reform Development Act of 2014. The proposal requires a local, county, or state agency to put up a match for federal funds. Deadline is August 20. If approved by Congress this fall, the mouth bar could potentially be removed while Great Lakes still has dredging equipment on the river, saving the cost of another mobilization.
Option 2: Similar to 1, but without cost sharing. A partnership of local, county, state, or federal agencies can hire the Corps to be their public engineer and constructor for the project under an Interagency Agreement . This requires 100% funding by the Federal, state, county, or local agency. There is no cost share. Hmmmm. County Bond Referendum? The State’s rainy day fund? Lots of possibilities. But they would probably take longer to work out.
Option 3: Go it alone.
Benefits of Removing the Mouth Bar
The Lower West Fork delta of the San Jacinto River is advancing development in size and shape. The West Fork mouth bar and surrounding shoal sediments are constraining in-bank flow conveyance capacity.
With no action to restore flow conveyance capacity within the river’s banks, the evolving conditions will cause the river to rise out of its banks and extensively flood properties and critical infrastructure in the region. If addressed, flood risks to developments will be reduced and the river will have the conveyance capacity to pass flood flows and flush sediment that would otherwise reduce conveyance capacity.
Removing the mouth bar would reduce flood damages to properties regionally and provide for increased resilience to flooding of properties, transportation systems, water treatment systems, public/private utilities, emergency response facilities, petrochemical industries, and other critical infrastructure, in the West Fork, San Jacinto River Watershed, Harris, Montgomery, and Liberty Counties,TX, on the order of $200 Billion.
Given that petrochemical industries in the region produce a significant amount of the Nation’s petroleum based energy products, reducing flood risks of these plants and its workers who reside in flood-prone areas, and providing for greater resiliency, is a National security benefit. The environmental benefit of providing for this project is reduced risks of water treatment plant and chemical spills due to flooding, which is a threat to human and environmental health and safety. The non-monetary benefits would include reduce risks to loss of life due to regional flooding, especially to residents with insufficient means.
Posted by Bob Rehak, R.D. Kissling and Tim Garfield on July 27, 2018
332 Days since Hurricane Harvey
00adminadmin2018-07-27 17:56:072018-07-28 07:14:48Why We Must Remove Mouth Bar on West Fork of San Jacinto
This is what East End Park used to look like – a natural gem within the nation’s fourth largest city, an urban refuge for wildlife on the East Fork, and an island of quiet enjoyed by more than 80,000 visitors per year.
Then Things Changed
After Harvey, sand and gravel dunes covered 30 acres (about 20 percent of the park’s 150 acres). The sand destroyed wetlands. Look at the wetland image three rows up in the center of the poster. Now look below. They’re the same area!
This bridge had to be excavated from several feet of sand after Harvey. It used to cross wetlands shown in the poster above.
Here’s what the trail looked like in the opposite direction before excavation.
Standing on five feet of sand deposited in East End Park wetlands
A bird’s nest ten feet up in a tree is now knee high because sand raised the ground elevation so much.
Natural or man-made disaster?
So I asked myself, where did all this sand come from? Was this just something that you have to accept when you live near a river? To find answers, I rented a helicopter and flew up the East Fork. Opposite East End Park, I saw this giant dune below, one of several along the way.
A new dune deposited during Harvey now blocks half of the East Fork opposite East End Park (upper right).
From ground level (below), you can see how tall it is – 10 to 12 feet. Some people who have climbed this dune tell me that it gets even higher back in the trees.
This new sand dune, created during Harvey is twice the height of the average human. A geologist told me that he doesn’t usually see changes this dramatic on a human time scale.
Farther up the river, I started to see what the problem might be.
A 750 acre sand mine hugs the banks of Caney Creek. Note how another giant sand bar adjacent to the mine again chokes off 50 percent of Caney Creek. Such blockages are now common.
As I flew around the northern part of the mine and started looking south, I saw large areas that are not being actively mined, yet are un-vegetated. This makes sand more susceptible to erosion in floods.
Flying closer to the giant stockpile, I noted its height relative to trees around it. Those trees typically grow up to 100 feet tall. That water tower in the background is on Kingwood Drive.
As I got closer to the stockpile, I noted ripples/wave forms in the lower part on the left and the remnants of heavy erosion from rainfall on the right. These are signs that water had been moving through the interior of this mine pretty quickly and that the dikes around them were no barrier to erosion.
Below, note how the road that comes up from the bottom left washed out inside of the mine.
Satellite imagery in Google Earth shows that the washout most likely happened during Harvey. It first shows up in satellite photos on 9/1/17.
I reviewed other areas within this mine in Google Earth. The mine measures more than 750 acres. The stockpile alone comprises 34 acres. The image below from 9/1/17 reveals severe erosion of this massive stockpile as Harvey’s floodwater’s receded.
Erosion in East Fork sand mine stockpile as Harvey’s floodwater’s receded.
Evidence Mounts: Clearer Picture Emerges
Satellite imagery below shows that no other sand mines are visible on the East Fork or its tributaries for miles around. None of the rivers or streams in this area seem to produce much. And all of those monster sand bars appear downstream. Hmmmm! Had we found the source of all that sand?
No other sand mines exist on Caney Creek. No huge sand bars show up above the mine; all appear below. Note that the sand bars represent only a tiny portion of the sand carried downstream; as in East End Park, huge volumes were deposited beneath the forest canopy and are not visible in satellite imagery.
Half of this mine lies in two floodways as shown in this USGS flood hazard viewer. The part of the stockpile that eroded most is in the the 100 year floodplain (aqua). See right side of circle. Brown represents the 500 year flood plain and the cross-hatched area represents the floodway, which is defined as the main current of the river during a 100-year flood.
According to Harris County Flood Control on page 12 of their final report, more than 20,000 cubic feet of water per second came down Caney Creek. And the Flood Control District has no gauges on White Oak Creek, the tributary that comes from the west, so the real flow total was higher. I can’t imagine how water would “back up” into this particular mine during an event like Harvey, especially during the early stages when everything was rushing downstream fast enough to wash out a road and erode a mountain of sand.
But still, those TACA guys are the experts, right?
I needed a way of showing exactly how fast the water was flowing through this area. Since there are no gages, I looked at particle sizes deposited downstream. Science tells us that rivers pick up particles in a particular order as flow increases and accelerates.
Erosion and Deposition of Various Particle Sizes at Different Velocities.
Among the new sand dunes at East End Park, I found gravel…lots of it.
Dunes of gravel or small pebbles were also found in East End Park.
If the current during Harvey was strong enough to pick up 2.5 centimeter pebbles like the one below, it was definitely strong enough to pick up sand. You can even see sand mixed in with the pebbles if you look closely.
Pebble found at top of ten-foot mound in East End Park. It measures about 2.5 centimeters.
To deposit gravel this size, the river was moving at about 150 cm/second – fast enough to pick up EVERYTHING smaller, including clay, silt, sand, gravel and pebbles (items listed below the horizontal axis on the chart above). The flow rate was high enough to move every type of material found in the mine.
While the sand miners claim the river wasn’t moving fast enough to carry sand out of the mines, the physical evidence suggests a different story.
Sand deposits reach high up on trees and are killing many smaller trees. The sand came from somewhere. There’s one likely culprit in my opinion.
1290 structures in Huffman and Kingwood flooded on the sand-clogged East Fork. See the purple and green totals right of the black line that bisects the purple. Those represent damaged structures in the East Fork watershed.
Harvey damaged 1290 Harris County structures in the East Fork watershed. Assuming an average loss of $250,000 for each structure and its contents, damage would total about $350,000,000 – one third of a billion dollars.
Recommended Next Steps
Even though no sedimentation surveys have yet been completed on the East Fork that could definitively link this sand to subsequent flooding, the Army Corps of Engineers has confirmed that similar sand blockages have contributed to flooding on the West Fork. (The Corps is currently embarking on a $70 million dredging project there…at taxpayer expense.)
My findings suggest that such a study should be done on the East Fork. Further, I believe that we need to:
Debate whether to allow sand mining in floodways, especially so close to the source of drinking water for 2 million people; sediment is rapidly filling the lake at an accelerating rate.
Strengthen permitting requirements, setbacks and best management practices
Enforce them by imposing prohibitive fines for violations.
Need to Strengthen TCEQ
Regarding the last point, in the five years from 2013 to 2017, the TCEQ found 619 violations at sand mining operations throughout Texas, but assessed only $506,151 in penalties. That’s about $101,000 per year and works out to an average of $817.69 per fine.
I know Texas is a business-friendly state; that’s why I moved here 40 years ago. But really! This is like the Legislature giving the Domino’s guy a license to speed 90mph through school zones so he can make more tips.
Those are my opinions on matters of public policy protected under the first amendment of the U.S. Constitution and the Anti-SLAPP statutes of the great State of Texas. I sincerely hope that TACA can come to the table and help structure sensible mining regulations that protect the public, not just the profits of miners. I’ll talk more about what those might be in subsequent posts.
That would make Harvey a 33-year event in this area. Impossible, you say! The flow measured upstream from the mine was only the fourth highest on record.
Posted by Bob Rehak on 7/25/18
331 Days since Hurricane Harvey
00adminadmin2018-07-25 22:23:362018-07-26 07:31:17A Closer Look at Sand Issues on the East Fork of the San Jacinto
How Much Would the Flood Bond Cost You?
When considering property tax implications of the proposed $2.5 billion flood bond, start with how much you currently pay in Harris County Flood Control District (HCFCD) taxes. Hint: It’s very little.
Only about 1.4% of Typical Property Tax Bill Currently Goes to Flood Control
Only about 1.4% of the average annual property tax bill now goes to Flood Control. The rest funds schools, cities, hospitals, law enforcement, etc. How much you currently pay each year in flood control taxes depends on your home’s value and your exemptions. See some representative costs below.
What homes assessed at representative price points will pay in additional taxes if the Harris County Flood Control Bond passes.
Amount Will Vary Depending on Age, Assessment and Exemptions
If your home is assessed at $200,000 and you are under 65, you pay only $45 annually for flood control. If over 65 in that same home, you pay no flood control taxes.
In a worst-case scenario, Harris County says the flood-control portionof your taxes would double. Would doubling one of the numbers above create a hardship for you? Or would it help you sleep better?
Less than Cost of Flood Insurance
Any increase would be gradual. Bonds are only sold when projects are ready to start. Harris County expects no increase at all until 2020 at the earliest.
Flood Control improvements cost much less than flood insurance. And unlike flood insurance, they might actually prevent your home from being damaged.
Protecting Home and Community Values
Once implemented, the flood mitigation measures in the bond package will help make our entire community more resistant to flooding. That’s important. It helps protect your home’s value, your schools, businesses, roads, bridges and other infrastructure. That helps keep your community growing and makes it attractive for people looking to relocate. In the long run, rising home values will pay you back many times over for your investment in flood control. So send a signal to the world that we’re willing to invest in our future.
How to Check Your Current Assessed Value
To see how much you pay right now, go to hcad.org, click on “Property Search”, then “Real Property” followed by “Search by Address.”
Posted by Bill Fowler on July 29, 2018
334 Days since Hurricane Harvey
Why We Must Remove Mouth Bar on West Fork of San Jacinto
The U.S. Army Corps of Engineers originally solicited bids to dredge the West Fork of the San Jacinto from 59 to Lake Houston, a distance of 8 miles. At some point in the project, the Corps limited the scope to 2.1 miles – from River Grove Park to the West Lake Houston Parkway bridge – for reasons never made clear. Perhaps they ran out of money when they had to double the volume they were dredging in that 2.1 miles. Regardless, that meant leaving a huge sandbar in place at the mouth of the river (see below).
I have been concerned about that bar ever since they excluded it from the scope. I wasn’t the only one. Two retired geologists, Tim Garfield and R.D. Kissling, approached me after my post about reduced scope. They have more than 50 years of experience with one of the world’s most successful oil companies. Both are experts in river morphology and sedimentation.
They compiled this fascinating 28-page report about the mouth bar, which I helped them edit. It explains how the river is changing, why it’s crucial to remove the mouth bar, and what will likely happen if we don’t.
The goal of this presentation was to get the Corps to expand the scope of their current dredging project to include the bar. Why? Approximately half of all the damage that occurred in Kingwood occurred BEYOND where the Corp intends to stop dredging. If not removed, everything behind the mouth bar for miles upstream will be at greater risk of flooding.
Major Concerns From a Geologist’s Perspective
If this blockage is left in place, it will, say Garfield and Kissling:
How the River Is Changing
Since the late 1970s, a delta has been forming within the river and advancing toward where the river meets the lake. You can see the 2-mile advance most clearly in this summary slide that shows Kingwood in 1977 and 2017.
Evolution of mouth bar over 40 years. The full presentation contains many intermediate images.
When Friendswood designed Kingwood’s drainage, it was based on a different reality. Note, for instance, what happened east of the West Lake Houston Parkway Bridge. A huge area has filled in, reducing the conveyance of the river.
The chart below shows the increasing rate of change in the Stream Mouth Bar (SMB) at the right in the photo above (the area outlined in white with the red arrow pointing to it).
Sudden exponential growth in mouth bar volume tells geologists that it has reached critical mass and is likely contributing in a major way to upstream flooding.
How Our Mouth Bar Contributes to Upstream Flooding
This next series of slides shows how and why the West Fork mouth bar affects flooding.
Before the Lake Houston Dam was built, water in the river dropped steadily in elevation from the site of today’s Grand Parkway all the way to the coast.
Since the construction of the Lake Houston Dam, water continues to drop to US59, but then it levels out. That’s because the dam backs up water that far.
A huge mouth bar grew up where the river enters the lake. As water slowed down and spread out, it deposits sediment. When the river is flowing at normal levels, water can find its way around the blockage without threatening neighborhoods.
However, during floods, the mouth bar acts as a partial dam. It creates a hydraulic jump that begins to back water up behind it. Note how the orange bar is higher on the left than on the right, relative to the blue line. That’s because the stream mouth bar increases the height of water behind it during a flood.
If the mouth bar were removed, water would no longer back up behind it. The river could flow freely in a flood. The dotted line represents an estimate of how much a flood like Harvey could be lowered. If the reduction were four to six feet, that could make the difference between major and minor flooding.
In this profile, the horizontal scale is less compressed than in the charts above it, so you can visualize more easily how water is forced to flow uphill as it approaches the mouth bar. This forces water to flow uphill and the water surface to elevate behind the mouth bar, contributing to upstream flooding.
Options Going Forward
Ignoring the mouth bar and hoping it will go away is not an option.
I suspect that the reason the Corps did not handle this in the first place is because they were constrained by budget. So removing the mouth bar as part of a change order is not an option either.
It will likely cost far more to remove the mouth bar than it does to clear the 2.1 miles upstream.
That leaves two options recommended by the Army Corps’ Deputy District Engineer for Programs and Project Management, Dr. Ed Russo (plus another that he didn’t recommend).
Benefits of Removing the Mouth Bar
The Lower West Fork delta of the San Jacinto River is advancing development in size and shape. The West Fork mouth bar and surrounding shoal sediments are constraining in-bank flow conveyance capacity.
Removing the mouth bar would reduce flood damages to properties regionally and provide for increased resilience to flooding of properties, transportation systems, water treatment systems, public/private utilities, emergency response facilities, petrochemical industries, and other critical infrastructure, in the West Fork, San Jacinto River Watershed, Harris, Montgomery, and Liberty Counties,TX, on the order of $200 Billion.
Given that petrochemical industries in the region produce a significant amount of the Nation’s petroleum based energy products, reducing flood risks of these plants and its workers who reside in flood-prone areas, and providing for greater resiliency, is a National security benefit. The environmental benefit of providing for this project is reduced risks of water treatment plant and chemical spills due to flooding, which is a threat to human and environmental health and safety. The non-monetary benefits would include reduce risks to loss of life due to regional flooding, especially to residents with insufficient means.
Posted by Bob Rehak, R.D. Kissling and Tim Garfield on July 27, 2018
332 Days since Hurricane Harvey
A Closer Look at Sand Issues on the East Fork of the San Jacinto
This is what East End Park used to look like – a natural gem within the nation’s fourth largest city, an urban refuge for wildlife on the East Fork, and an island of quiet enjoyed by more than 80,000 visitors per year.
Then Things Changed
After Harvey, sand and gravel dunes covered 30 acres (about 20 percent of the park’s 150 acres). The sand destroyed wetlands. Look at the wetland image three rows up in the center of the poster. Now look below. They’re the same area!
This bridge had to be excavated from several feet of sand after Harvey. It used to cross wetlands shown in the poster above.
Here’s what the trail looked like in the opposite direction before excavation.
Standing on five feet of sand deposited in East End Park wetlands
A bird’s nest ten feet up in a tree is now knee high because sand raised the ground elevation so much.
Natural or man-made disaster?
So I asked myself, where did all this sand come from? Was this just something that you have to accept when you live near a river? To find answers, I rented a helicopter and flew up the East Fork. Opposite East End Park, I saw this giant dune below, one of several along the way.
A new dune deposited during Harvey now blocks half of the East Fork opposite East End Park (upper right).
From ground level (below), you can see how tall it is – 10 to 12 feet. Some people who have climbed this dune tell me that it gets even higher back in the trees.
This new sand dune, created during Harvey is twice the height of the average human. A geologist told me that he doesn’t usually see changes this dramatic on a human time scale.
Farther up the river, I started to see what the problem might be.
A 750 acre sand mine hugs the banks of Caney Creek. Note how another giant sand bar adjacent to the mine again chokes off 50 percent of Caney Creek. Such blockages are now common.
Flying closer to the giant stockpile, I noted its height relative to trees around it. Those trees typically grow up to 100 feet tall. That water tower in the background is on Kingwood Drive.
Below, note how the road that comes up from the bottom left washed out inside of the mine.
I reviewed other areas within this mine in Google Earth. The mine measures more than 750 acres. The stockpile alone comprises 34 acres. The image below from 9/1/17 reveals severe erosion of this massive stockpile as Harvey’s floodwater’s receded.
Erosion in East Fork sand mine stockpile as Harvey’s floodwater’s receded.
Evidence Mounts: Clearer Picture Emerges
Satellite imagery below shows that no other sand mines are visible on the East Fork or its tributaries for miles around. None of the rivers or streams in this area seem to produce much. And all of those monster sand bars appear downstream. Hmmmm! Had we found the source of all that sand?
No other sand mines exist on Caney Creek. No huge sand bars show up above the mine; all appear below. Note that the sand bars represent only a tiny portion of the sand carried downstream; as in East End Park, huge volumes were deposited beneath the forest canopy and are not visible in satellite imagery.
Mine Located in Two Floodways; Living Dangerously
At this point, I had my suspicions. But TACA claims that “when rivers back up into a mine during floods” they slow down and drop their sediment in the pits. I puzzled over the phrase “back up,” especially because this mine, like virtually all others in the area, sits in a floodway. Actually, this one sits in TWO.
Half of this mine lies in two floodways as shown in this USGS flood hazard viewer. The part of the stockpile that eroded most is in the the 100 year floodplain (aqua). See right side of circle. Brown represents the 500 year flood plain and the cross-hatched area represents the floodway, which is defined as the main current of the river during a 100-year flood.
According to Harris County Flood Control on page 12 of their final report, more than 20,000 cubic feet of water per second came down Caney Creek. And the Flood Control District has no gauges on White Oak Creek, the tributary that comes from the west, so the real flow total was higher. I can’t imagine how water would “back up” into this particular mine during an event like Harvey, especially during the early stages when everything was rushing downstream fast enough to wash out a road and erode a mountain of sand.
But still, those TACA guys are the experts, right?
I needed a way of showing exactly how fast the water was flowing through this area. Since there are no gages, I looked at particle sizes deposited downstream. Science tells us that rivers pick up particles in a particular order as flow increases and accelerates.
Erosion and Deposition of Various Particle Sizes at Different Velocities.
Among the new sand dunes at East End Park, I found gravel…lots of it.
Dunes of gravel or small pebbles were also found in East End Park.
If the current during Harvey was strong enough to pick up 2.5 centimeter pebbles like the one below, it was definitely strong enough to pick up sand. You can even see sand mixed in with the pebbles if you look closely.
Pebble found at top of ten-foot mound in East End Park. It measures about 2.5 centimeters.
To deposit gravel this size, the river was moving at about 150 cm/second – fast enough to pick up EVERYTHING smaller, including clay, silt, sand, gravel and pebbles (items listed below the horizontal axis on the chart above). The flow rate was high enough to move every type of material found in the mine.
While the sand miners claim the river wasn’t moving fast enough to carry sand out of the mines, the physical evidence suggests a different story.
Sand deposits reach high up on trees and are killing many smaller trees. The sand came from somewhere. There’s one likely culprit in my opinion.
Homes Flooded on East Fork, Too
This entire sequence shows the risk of locating mines in floodways. Not just because of damage to nature, but because of danger to homes. Harris County Flood Control compiled this damage map.
1290 structures in Huffman and Kingwood flooded on the sand-clogged East Fork. See the purple and green totals right of the black line that bisects the purple. Those represent damaged structures in the East Fork watershed.
Harvey damaged 1290 Harris County structures in the East Fork watershed. Assuming an average loss of $250,000 for each structure and its contents, damage would total about $350,000,000 – one third of a billion dollars.
Recommended Next Steps
Even though no sedimentation surveys have yet been completed on the East Fork that could definitively link this sand to subsequent flooding, the Army Corps of Engineers has confirmed that similar sand blockages have contributed to flooding on the West Fork. (The Corps is currently embarking on a $70 million dredging project there…at taxpayer expense.)
My findings suggest that such a study should be done on the East Fork. Further, I believe that we need to:
Need to Strengthen TCEQ
Regarding the last point, in the five years from 2013 to 2017, the TCEQ found 619 violations at sand mining operations throughout Texas, but assessed only $506,151 in penalties. That’s about $101,000 per year and works out to an average of $817.69 per fine.
Those are my opinions on matters of public policy protected under the first amendment of the U.S. Constitution and the Anti-SLAPP statutes of the great State of Texas. I sincerely hope that TACA can come to the table and help structure sensible mining regulations that protect the public, not just the profits of miners. I’ll talk more about what those might be in subsequent posts.
Urgency also Needed
It’s important that we start this dialog now. If the new USGS data is correct, Harvey was not a 1000-year event; USGS estimated that the flow on Caney Creek, upstream from the mine, had an annual exceedance probability of 3.3. See Page 9, Table 3, Line 32 for Gage #08070500 in their report titled “Characterization of Peak Streamflows and Flood Inundation of Selected Areas in Southeastern Texas and Southwestern Louisiana from the August and September 2017 Flood Resulting from Hurricane Harvey.” The report was produced in cooperation with FEMA.
That would make Harvey a 33-year event in this area. Impossible, you say! The flow measured upstream from the mine was only the fourth highest on record.
Posted by Bob Rehak on 7/25/18
331 Days since Hurricane Harvey