Tag Archive for: Woodlands

New UH Study Finds Subsidence Increasing in Houston Suburbs

A hot-spot analysis of subsidence in the Houston metro area during the period from 2016 to 2020 revealed total subsidence of up to 9 centimeters in some areas. Rates of subsidence approached 2 cm per year. (Two centimeters equals 0.8 inches. Nine centimeters = 3.54 inches.)

The scientific study, named “Surface Deformation Analysis of the Houston Area Using Time Series Interferometry and Emerging Hot Spot Analysis” appeared in a scientific journal called Remote Sensing. Authors included Shuhab D. Khan, Otto C. A. Gadea, Alyssa Tello Alvarado and Osman A. Tirmizi from the Department of Earth and Atmospheric Sciences at the University of Houston.

Correlating InSAR Data with Well Data

The authors correlated observations of surface deformation using interferometric synthetic aperture radar (InSAR) data with an analysis of 71,000 water and and 5,000 oil-and-gas wells in the Houston area. They collected the InSAR data over 5 years and the well data going back 31 years.

USGS calls InSAR an effective way to measure changes in land-surface altitude. The images are compiled by using radar signals with a very high degree of resolution bounced off Earth from orbiting satellites. By measuring the time for the signals to travel to earth and back, researches can measure altitude. And by superimposing images taken at different times, researchers can measure changes in altitude over time.

Documenting Link between Subsidence and Groundwater Pumping

Khan and his team sought to determine how much groundwater pumping contributed to subsidence (sinking ground). They performed the same analysis for oil and gas pumping.

The researchers found the greatest subsidence – which had not been previously reported – in some of the region’s fast-growing suburbs – Katy, Spring, The Woodlands, Fresno and Mont Belvieu. They identified groundwater pumping as the primary cause in the first four, and oil and gas pumping as the primary cause in Mont Belvieu.

From the study published as an open access article and distributed under a Creative Commons Attribution License.

Otto Gadea, a graduate student from Khan’s team is quoted in Phys.org as saying, “We determined for the suburbs that excessive groundwater extraction appears to be the primary driver of subsidence.”

Population Growth Drives Groundwater Pumping

With population growth, groundwater extraction has become more prevalent in the Houston area. But subsidence is no longer substantial in areas that regulate it through entities such as the Harris-Galveston Subsidence District.

The Appearance of Regulation as Cover for Private Interests

Other counties have set up entities to regulate ground water withdrawal, such as the Lone Star Groundwater Conservation District (LSGCD) in Montgomery County. However, the elected board chose not to include a subsidence limit in its desired future conditions. Many of the board members were backed by money from Quadvest, the area’s largest private groundwater pumper.

Website’s such as StopOurSinking.com have long linked excessive groundwater pumping in Montgomery County with a host of issues ranging from subsidence, flooding, pavement breaks, and foundation shifting to pipeline problems. However, the LSGCD Board has cherry-picked scientific evidence that supports unlimited groundwater pumping.

This latest study by the UH team will make that harder. It validates many of the claims StopOurSinking has made for years. Khan’s team even concluded that subsidence may even cause fault movement in the area.

Link to Fault Movement, Too

“If current ground pumping trends continue, faults in Katy and The Woodlands will likely become reactivated and increase in activity over time,” the authors write. No seismic activity is reported along these faults yet they say. They believe the movement is happening by “aseismic creep.” However, Khan and his team found evidence of fault activity in “damages to roads, buildings and other infrastructure in the vicinity of these faults. Displacement along some is measured by up to 3 cm/year.”

Posted by Bob Rehak on 10/12/22

1870 Days since Hurricane Harvey

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.

MoCo Groundwater Group Defers Action on Subsidence…Again, Putting Residents at Risk

The Lone Star Groundwater Conservation District (LSGWCD) board once again deferred action on subsidence at its three-hour board meeting on 2/9/2021. The ostensible reason: public confusion on the issue, although that confusion may have been caused by the District’s own staff.

Several board members also launched ad hominem attacks against critics, alleging they were deliberately spreading misinformation about the board’s position on subsidence. They demanded public apologies from critics after the District’s own staff made misleading presentations.

Confusion Starts when General Manager, Counsel Fail to Articulate Real Issue

At about 59 minutes and 35 seconds into the video, Samantha Reiter, LSGWCD’s General Manager, summarizes consultant James Beach’s testimony to GMA-14. She did not explicitly mention the exact text of his statement about LSGWCD’s position on subsidence to GMA-14. Specifically he said, “At this time, we can’t support the use of DFCs for subsidence in Montgomery County.” 

Reiter’s lack of specificity teed up a wandering, confusing and mind-numbing 90-minute presentation by Stacy V. Reese, LSGWCD’s General Counsel.

She designed the presentation to address one of the criticisms leveled against the board by critics, i.e., that a potential violation of the Open Meetings Act had occurred. According to LSGWCD watchers, LSGWCD’s board never openly authorized Beach to make that statement, which seemed to state a conclusion the Board had reached. That raised the questions, “Who authorized the statement and when?” But those were not the questions Reese addressed.

Reese’s Presentation a Masterpiece of Misdirection

Without mentioning Beach’s statement upfront or accurately summarizing critics’ concerns, Reese then tried to show that LSGWCD had investigated subsidence since 2017. But everyone already knew that. And that made a presentation which took up about half the meeting largely irrelevant while the audience drifted away.

Instead of addressing who authorized Beach’s statement and when by reviewing the LSGWCD January 12th meeting and the GMA-14 January 20th meetings, Ms. Reese instead discussed other board meetings and presentations dating back to 2017. Repeatedly skipping forward and back in time and between LSGCD and GMA 14 meetings, her presentation included so much irrelevant information, it became impossible to determine the board’s position on subsidence. One understood only that they had previously discussed it.

Not until two hours and sixteen mininutes into the meeting does Ms. Reese allude to Mr. Beach’s statement to GMA-14 about rejecting subsidence as a metric in DFCs at the bottom of a slide with eight bullet points. But she summarizes the slide in one sentence: “We’re adapting to a subsidence statement.” In other words, she shows one thing and says another.

Then she claims at 2:17 that the board has not yet voted on a final position re: DFCs or subsidence.

If you didn’t know that the real issue was Beach’s statement, you might conclude from Reese’s presentation that the board was, in fact, supportive of including some sort of a subsidence statement in Desired Future Conditions. That’s the opposite of what Beach said.

Laying the Groundwork for Backpedaling?

Ms. Reese did, however, lay some groundwork for a possible reinterpretation of Beach’s statement. Although she didn’t say it outright, she implied that measuring subsidence was unnecessary because it varies with groundwater pumping rates. While a correlation does exist at times between the two variables, the assertion masks two important points:

  • First, without measuring subsidence, you cannot calibrate the accuracy of groundwater-pumping models.
  • Second, groundwater levels are reversible; subsidence is not.

The latter point deserves explanation.

Groundwater Levels Reversible; Subsidence Not

The amount of groundwater depletion depends on pumping and recharge rates. Those can vary annually depending on usage and rainfall.

But while water-well levels can rebound, subsidence cannot. Subsidence lasts forever. Once clay collapses, it stays compressed. It’s like trying to re-inflate a brownie that you’ve smashed with a sledgehammer.

Not Adopting a Subsidence Metric Would Allow Board to Defer Action on Groundwater Withdrawals for Decades

Putting these facts together, you can see how a LSGWCD board intent on unlimited pumping could cause lasting subsidence and severe damage to homes throughout the region. In a 70-year plan, they could argue through Year 60, for instance, that aquifer levels would bounce back. Without a subsidence metric in place as a check on pumping, they could continually kick the can down the road. They could say year after year that they will change regulations at some point before Year 70 to restore aquifer levels to their targets.

Mr. Beach stated this explicitly during the board meeting. At approximately 2:31 into the video, he says, “We can incorporate subsidence in the future…”

At 2:32, Jim Spigener, LSGCD’s Treasurer says it, too. “It feels like there is a rush to do something. But DFCs are a 70-year process. The danger is that we do something in the heat of a political storm and it’s the wrong thing. We’re not in any hurry to figure out how to do this right. We’re not going to figure this out in a month.”

Righto! Ms. Reese’s presentation must have put him to sleep, too. According to her, LSGWCD has worked on this since 2017.

Finally, at 2:34, someone makes a motion to table any action on desired future conditions. The motion passed. Neither did the board consider Phase Two of their subsidence study. See 2:49 of the video.

More Questions than Answers Come from 3-Hour Meeting

Reese’s inventory of subsidence discussions skips from LSGWCD board meetings in May and June of 2020 to the GMA-14 meeting on January 20, 2021, leaving a critical six month gap. (See 2:16 in video.)

Without speculating on the motives of individuals, I would point out that actions speak louder than words. The inability or unwillingness of highly intelligent people to clearly articulate issues and address them in a straightforward manner raises many questions.

  • Why?
  • Why delay?
  • Why defer action?
  • Why not clarify the differences between measuring aquifer depletion and subsidence?
  • Why not elaborate on Beach’s statement for video posterity?
  • Why spend 90 minutes rehashing old board meetings and not one minute articulating a clear subsidence goal?
  • Who does the LSGWCD board represent? Residents or Quadvest?

These are important questions. Much depends on them. Perhaps even billions of dollars in potential damages.

Types of Damage Subsidence Can Cause

Differential subsidence across a county can cause bowls to develop in the landscape, such as near Jersey Village, which increases flooding. (See subsidence map below.)

The subsidence map below also shows something else. At the rate LSGWCD wants to pump, it could cause southern MoCo and northern Harris Counties to sink two feet relative to the dam at Lake Houston. Picture tilting a full bathtub two feet. Something will get wet!

Models show that excessive groundwater pumping in MoCo could create 3 feet of subsidence in Kingwood compared to 1 foot at the Lake Houston Dam.

SMU also found that subsidence triggered geologic faults in Montgomery County that have damaged homes.

Insurance companies have also linked subsidence to:

  • Damage to infrastructure such as roads, sewers and buried utilities
  • Foundation, sidewalk, driveway, roof, and brickwork damage
  • Cracks in plaster, wallboard, flooring, ceilings, windows, and moldings
  • Doors and cabinets that refuse to open or shut properly

In some cases, homes may not even be repairable.

Slow Rate of Subsidence Masks Magnitude of Problem

The biggest problem with the subsidence problem? With a few exceptions, such as fault-line triggering, it happens over such a long period of time that many homeowners will never fully experience it.

Median duration of homeownership in the U.S. is 13 years. But in The Woodlands and Houston, owners typically stay in a home just 10 years.

National Association of Realtors

At that rate, most people might not notice subsidence. I’m an exception, I’ve lived in my house almost 40 years. Stick around that long and you get a true feeling for the cost of subsidence. I’ve had my foundation leveled twice; my driveway repaved twice; my sanitary sewer lines repaired twice; my doors and windows replaced once; and my walls, cabinets, and ceilings repaired multiple times.

You don’t need to remind me about the true cost of subsidence.

Posted by Bob Rehak on 2/10/2021

1261 Days since Hurricane Harvey and 510 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.

Expert Witnesses Model Surprising Flood Risks in Sand Mine Lawsuit

The case of Emil C. Shebelbon, II v. Upstream Holdings, LLC ET AL (Montgomery County Cause No. 15-10-10710) provides fascinating new insights into how sand mines can affect flooding. This case is NOT about broken dikes, unauthorized discharges of sediment-laden water, or mines inundated by super-storms such as Hurricane Harvey. It involves the opposite of all those things. Yet it still has implications for state regulations – or lack thereof. Specifically, I’m talking about setbacks of mines from rivers, lack of best management practices, reclamation of mines after the completion of mining and monitoring of floodway development.

All of the mines around Shebelbon’s property (bottom center) lie completely within the West Fork floodway (cross-hatched area). Development in floodways should not impede flow.

Defendants in this case appear to have filled in or walled off more than 200 acres of floodway property north of Shebelbon. That should have raised eyebrows from Washington to Conroe City Hall, but didn’t.

Two sand mines north of Shebelbon occupy more than 200 acres of floodway. The one closest to I-45 has been abandoned without remediation. Mining debris still litters the site. Shebelbon’s property lies immediately to the south, across the river.

Plaintiff’s Property Did Not Fill Floodway

The plaintiff in this case, Emil Shebelbon, purchased approximately 200 acres of land on the southwest corner of the San Jacinto West Fork and I-45 North about 20 years ago. He operates a motorsports facility there with dirt tracks and jumps for cyclists. Most of his land is in the floodway at the original level. He did not bring in fill. However, he did push some dirt into mounds to create the jumps. Very little impervious cover exists. It resembles a park. If you were going to build a business in the floodway, this is one of the few you might consider. It does not obstruct floodwater.

Increase in Flood Frequency, Depth and Erosion

When Shebelbon bought his land, everything north of him was farm, ranch or forest land. Then one mine came in and another. They expanded and started building up their property or walling it off from the floodway with dikes.

Shebelbon soon started to notice an increase in the depth and frequency of floods. He also started to lose land to erosion during statistically small floods.

Allegations in Lawsuit

Shebelbon’s lawsuit alleges that:

  • Mines blocked half of the floodway, forcing their flood water south onto his property, a violation of state law.
  • Cutting the floodway width in half forced floodwaters up to 3-4 feet higher on his property.
  • The increased flow in a smaller area increased the velocity of floodwaters.
  • That increased what hydrologists call “sheer stress,” the force necessary to start erosion.

Modeling showed shear stresses increased upwards of 0.5 pounds per square foot. The hydrologists claim that’s enough to cause substantial land and bank erosion near and within the Shebelbon Property. That, in turn, widened the river, eroding Shebelbon’s property, they say. Shebelbon estimates he lost seven acres due to erosion caused by constriction of the floodway (see photos below).

The mine north of Shebelbon’s property on the San Jacinto West Fork. Shebelbon’s property is out of frame to the right, underneath the nose of the helicopter. To visualize the height of the dikes, compare activity in the red circle with the following photo.
A dredging expert estimates that the height of the berm at this point is 50-60 feet based on the size of the dredge. Note: this photo and the one above were taken on April 21, 2020, more than a year after the hydrologist’s study. Dikes here are likely taller than 2018 LIDAR data in the study indicates.

Federal, state, county, and city regulations all prohibit restricting the conveyance of floodways. So how did this get permitted? That will be the subject of another post.

Court documents show that the mines deny any connection to Shebelbon’s damages. They issued simple, general denials and are fighting Shebelbon tooth and nail.

Surprising Expert Witness Testimony

Shebelbon, however, has produced hundreds of pages of expert witness testimony to support his claims. This 197-page document downloaded from the Montgomery County Clerk’s office contains the testimony of several experts. For this post, I’m focusing on Exhibit E-22: Flood Impacts from Surrounding Activities, prepared by Dr. David T. Williams and Dr. Gerald Blackler. Their testimony and credentials run from pages 19 to 101 of the PDF. (Caution: 19 mb download.)

Surprisingly, experts for the plaintiff found that the problem is most visible in smaller floods, i.e., less than 18-year floods. 100-year floods can overtop dikes and spread out. But smaller floods cannot.

Despite hundreds of posts on the relationship between sand mining and flooding, I have not previously focused on the phenomenon described by these experts. But every flood expert I talk to – at local, county and state levels – says their findings make perfect sense.

Looking west. Compare height of dikes on right with river bank on left by Shebelbon’s property. Photo 11/2/2020. Also note how little flood storage capacity is left in ponds.
This abandoned sand mine virtually blocks TxDoT’s auxiliary bridge on the north side of the river (upper right). TxDoT commonly uses such auxiliary bridges to convey water in floodplains. Photo 11/2/2020.

Public-Policy Concerns Raised by Shebelbon

Shebelbon’s case has not yet gone to trial. But I see similar situations every time I get in a helicopter. Together, they raise some disturbing public-policy issues. For instance:

  • Do we need greater setbacks of mines from rivers? Greater setbacks would allow greater expansion of floodwaters and help protect neighboring properties.
  • Do we need a comprehensive set of best management practices for sand mines that cover reclamation and abandonment? Restoring the natural floodplain instead of leaving an elevated mine next to the freeway might have prevented some of Mr. Shelbelbon’s damages.
  • What happens when local officials turn a blind eye to those apparently violating regulations? Is there a higher authority to enforce compliance – short of expensive lawsuits?

Hopefully, the TCEQ or State Legislature can address these questions. But it won’t happen without public pressure.

I would simply ask.

Why should miners’ property rights outweigh those of a neighboring business or resident?

Food for thought as we approach the upcoming legislative session!

Posted by Bob Rehak on 11/4/2020

1163 Days after Hurricane Harvey

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.