Mid-February Update on Lake Houston Gate Project

The preliminary engineering phase of the project to add more gates to Lake Houston is rapidly drawing to a close. Engineers should complete their final (preliminary) report on the Spillway Improvement project next month.

At the Coastal Water Authority board meeting on 2/10/21, Chris Mueller, PhD, PE, gave an update on the preliminary engineering report being prepared by Black & Veatch (BV) on the Lake Houston Spillway Improvement Project. Because the report is still in draft form, I won’t reproduce every slide here. Nor will I list exact flood-reduction benefits, which are still being refined. I will simply summarize some of the key points which seem unlikely to change at this point.

The final preliminary engineering report should be released next month. Before then, BV and subcontractors need to finish environmental surveys and their drainage analysis. They also need to put a sharper pencil to the Benefit/Cost Analysis, and prepare scope, schedule, and budget proposals for detailed engineering. The board will consider authorizing the next steps in its March 10 meeting.

Lake Houston Spillway photographed 1/1/2021.

Top-Ranked Alternatives to Date

BV’s top ranked alternatives to date include adding (in order of preference):

  1. 1000 feet of crest gates on the Spillway (see foreground in picture above).
  2. 1200 feet of crest gates on the Spillway.
  3. 6 new tainter gates to the existing gate structure.

In evaluating alternatives, BV had to balance competing priorities. They go beyond just reducing upstream flood-reduction benefits and downstream impacts. They include all the factors shown below.

From BV presentation to CWA on 2/10/2021

Metrics that engineers and partners will use to evaluate alternatives and success include:

From 2/10/2021 presentation to CWA Board. U/S and D/S stand for upstream and downstream.

According to the BV presentation, some positive benefit revealed by the work to date include:

Benefits Revealed To Date

  • Engineers found that the peak of floods from Buffalo Bayou would arrive downstream much faster than water from the Upper San Jacinto Watershed above the Lake Houston Spillway. This means the peaks would not arrive on top of each other. That’s good. It helps mitigate downstream impacts.
  • The recommended alternative would reveal a positive benefit/cost ratio and not adversely affect downstream structures.
  • The recommended alternative could turn a 100-year flood into a 25-year flood.

Engineers based the flood reduction benefits on a 100-year flood, not another Harvey.

How Final Decision Be Made

The engineers and partners will consider both cost and non-cost factors in making final recommendations.

Type of Crest Gate Recommended

BV is recommending an Obermeyer gate, though they have not detailed how it would be installed. Water Power and Dam Construction Magazine says, “The Obermeyer spillway gate system is most simply described as a row of steel gate panels supported on their downstream side by inflatable air bladders.” The air level in the bladders control water levels by raising or lowering the bottom-hinged steel panels.

This one-minute video shows how Obermeyer gates work.

Gate Project in Context

After Harvey, Lake Houston Area leaders recommended three main types of projects to reduce flooding. They included:

  • More upstream detention to reduce the amount of water coming downstream during floods.
  • Sediment removal/dredging to restore throughput and conveyance.
  • More gates on the dam to speed up output.

For the October 2020 update on this project, see this post.

Posted by Bob Rehak on 2/12/2021

1263 Days since Hurricane Harvey

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.

Woodridge Village Purchase and Two More Kingwood Flood Control Measures APPROVED by Harris County Commissioners Today

Today, at 5:52PM, Harris County Commissioners Court unanimously approved three flood-control measures affecting Kingwood. The measures included approval to negotiate engineering contracts for improvements to the Kingwood Diversion Ditch and Taylor Gully. The third approval involved purchase of Woodridge Village from Perry Homes to build a regional floodwater detention facility in Montgomery County.

Woodridge Village Purchase Finally Approved

The latter has ranked high on the community’s agenda ever since sheet flow from Woodridge Village contributed to flooding hundreds of homes in Elm Grove and North Kingwood Villages twice in 2019.

Woodridge Village photographed one year after Imelda, when sheet flow flooded approximately 600 homes at the top of the frame.

Since then, Perry has completed the planned detention ponds on the property. However, the amount of detention still falls 40% of that needed under the new Atlas-14 standards.

The City of Houston will purchase 77 acres of the property outright for a wastewater treatment facility. The City will then pay for its half of the remaining Woodridge property by trading land that the Flood Control District can use to reduce the cost of flood mitigation projects elsewhere.

Neither the City nor County have yet announced a closing date for the Woodridge purchase.

The City and HCFCD will work with the community as plans for the property and Taylor Gully are developed by IDCUS Inc.

Kudos to County and City

Seventeen months after Imelda, families in Elm Grove and North Kingwood Village will sleep easier tonight, knowing they are one HUGE step closer to safety.

Thanks to all four Harris County Commissioners, especially Precinct 4 Commissioner Jack Cagle, and Harris County Judge Lina Hildaldo. Thanks also to Houston Mayor Pro Tem Dave Martin who helped overcome objections raised at several stages in the Woodridge purchase process.

Posted by Bob Rehak on 2/9/2021

1260 Days since Hurricane Harvey