Tag Archive for: detention

Key Woodridge Detention Pond Missing, Only Small Percent of Total Detention Developed Before Elm Grove Flooded

On the plans, LJA Engineers calls it S2 – the second detention pond in the southern portion of the new Woodridge development north of Elm Grove. Even though all drainage on the 268 clearcut acres slopes toward S2, the developer did not start building this crucial pond before the May 7 storm that flooded Elm Grove and North Kingwood Forest. The pond will ultimately hold 49.4 acre feet of water during a storm, but holds something less now because Rebel Contractors has not yet fully excavated it. Further, it appears that less than 10% of the site’s required detention was fully excavated when May storms struck.

Rebel Contractors Starts Expanding S2 After Flood

At the time of the May 7 flood, it appears that Rebel Contractors had not yet begun excavating the largest part of S2. I could see only a ditch connecting S1 with the large box culvert at the entry to Taylor Gully.

Photo taken on May 11, four days after Elm Grove Flood, shows extent of excavation for crucial S2 detention pond. Only this ditch connected S1 pond with Taylor Gully. Photo looks northeast, where giant pond should extend almost to tree line on both sides of image.

In the last seven days, however, Rebel has roughed out the pond. You can see it starting to assume its final shape, though it has not yet reached its final size or depth. See pictures below.

On Friday, May 24, I observed a steady parade of haulers moving earth from the future detention pond, S2. The contractor is using the excavated material to raise the height of streets and home pads elsewhere on the property in a process called “cut and fill.”

According to numerous residents that I have talked to, much of this area once consisted of wetlands. To develop such property, contractors use a process called “cut and fill.” They build up one area, by excavating another.

S2 pond in early stages of development. Plans show this should ultimately cover more than three acres and be 15 feet deep. Photo taken 5/25/19 looking west from Taylor Gully toward Woodland Hills Drive.
Plans for Woodridge Village show five detention ponds. Before the May 7 storm, it appears that only S1 was in place though even it was not finished. This raises the question, “Why did the developer focus on clearcutting the northern section before finishing crucial detention ponds on the southern section, where all the water from the north would flow?”

Only S1 Pond Fully Excavated at Time of Storm

Houston City Council Member Dave Martin investigating job site shortly after the May 7 flood on May 9. Shown here: The area that will become detention pond S1. It appeared to be the only semi-functioning detention pond on the entire 268 acres. This photo shows it almost fully excavated but not fully finished. Contractor will eventually slope right side to create more detention capacity and vegetate both sides to reduce erosion.

91% of Detention Capacity Not Completed at Time of Storm

Ultimately, the 268 acre site should hold five detention ponds with a total of 292.3 acre feet of storage. An acre foot would cover one acre to a depth of one foot. The bullet points below summarize the total storage of each pond in the map above.

  • N1 = 16.9 acre feet (not started)
  • N2 = 143.3 acre feet (started, but does not appear complete)
  • N3 = 56.4 acre feet (does not appear to be started)
  • S1 = 26.3 acre feet (mostly functioning, but not finished)
  • S2 = 49.4 acre feet (not exacted at time of May 7 storm)
  • Total = 292.3 acre feet
  • Not Started or Incomplete on May 7 = 91%
People in construction often use the term “substantially complete” to mean functional, but not fully finished.

The developer, Figure Four Partners, LTD, a subsidiary of Perry Homes and PSWA, Inc., issued a statement after the flood claiming that: “… many of the detention ponds are COMPLETE.” (Emphasis added.) Many appears to be 1 out of 5. And not even that one appeared complete. Complete, as their own engineer LJA pointed out, would have entailed sloping the sides and planting vegetation. See photo above; not even S1 was fully complete at the time of the flood.

The Figure Four Partners statement also claimed they had “improved drainage to the area that did not previously exist.” Residents say their contractor filled in existing streams on the property. Yet residents that did NOT flood during Harvey DID FLOOD after the so-called “improvements.”

How Detention Ponds Work

Detention ponds collect runoff during a heavy rain. Then they release it at a slow, controlled rate that drainage ditches like Taylor Gully can handle without flooding people downstream. That’s the theory anyway. They do this by restricting the outflow compared to inflow. However, to function, they have to be BUILT.

How Much Rain Detention Ponds Should Have Held vs How Much Fell

Had all five ponds been complete on May 7, the entire site should have detained 1.1 feet of rain, a little more than 13 inches. However, we received less than 8 inches.

Jeff Lindner, the Harris County meteorologist, issued a statement on May 13 summarizing the storm that flooded Elm Grove and North Kingwood Forest. In it, he said, “A 30-min rate of 2.9 inches was recorded at US 59 and the West Fork of the San Jacinto River and a 1 hour rate of 4.0 inches. A 6-hr rainfall rate of 7.9 inches was recorded at the East Fork of the San Jacinto River and FM 1485. Rainfall rates between the 15-min and 6-hr time periods on Tuesday afternoon and evening averaged between a 2-yr and 50-yr frequency over the extreme northeast portions of Harris into southeast Montgomery Counties.”

Questions Owners and Contractors Need to Answer

In the last four years, we received three so-called 500-year storms. Two happened in the spring.

  • Knowing that, why did Rebel Contractors wait six months after clearing to begin excavating S2, the detention pond adjacent to areas that flooded?
  • Why did Rebel grade the rest of the site to funnel water toward Elm Grove before detention was in place?
  • Did economics factors push Rebel Contractors to clearcut the entire site before constructing detention that could control the runoff?
  • Why did Rebel Contractors fill in existing drainage features that could have helped reduce flooding before starting work on S2?
  • Why did Figure Four Partners claim that many of the detention ponds were complete?
  • If Figure Four improved drainage, why did homes flood that never flooded before?
  • Silt fences were supposed to be put up before any land was cleared. However, they were not put up until AFTER the flood on May 7. Why?
  • The plans required an onsite engineer to ensure compliance with permit provisions. Who was that engineer? How could he/she have possibly missed glaring deficiencies?
  • Stormwater Pollution Prevention Permits were supposed to be posted at all job site entrances. They were not. Why? And why did the contractor put them up the day before LJA Engineers inspected the site for Montgomery County and the TCEQ?

I hope I live long enough to learn the answers! I hope officials care enough to look for the answers! Tens of thousands of Kingwood homes did NOT flood during the May 7th storm; 196 homes next to this development did. They deserve answers.

All thoughts in this post are my opinions on matters of public policy and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

Posted by Bob Rehak on 5/26/2019

635 Days after Hurricane Harvey

Impervious Clay in Clear-Cut Area Accelerated Runoff Toward Elm Grove Before Detention Fully Developed

Hundreds of residents in Elm Grove and North Kingwood Forest, south of the new Woodridge Village development, flooded last week. Everyone says they never flooded before the contractor started clearcutting and grading the property. So what changed? Clearcutting removed all the plants and ponds that slowed the water’s velocity. It also exposed a highly impervious clay soil base, so slick when wet, that it offered very little resistance to flow. That accelerated stormwaters toward Elm Grove, where detention ponds had yet to be built and, according to residents, the developer had filled in natural drainage features.

Geologist Finds Impervious Clay

I asked a retired top geologist from one of the world’s largest oil companies to describe the soil composition. The answer? At least 50% clay. “Because clay grains are very small (<2 microns), plate shaped and tightly bonded, water does not easily or quickly move through or into clay-dominant sediments without the help of plant roots.” Thus, there’s much more runoff than absorption, especially after clearcutting and grading.

To check that assumption, he dug a hole and filled it with water from a bucket.

The water took 15 minutes to go down one-half inch.

Absorption rate indicates low permeability and high runoff rates. Note the ponding water halfway up the stake, still sitting on the surface from week-old rains.

Still Had Standing Water Eight Days after Rain

He continued. “The presence of many puddles of standing water from week-old rains indicate that clay-dominant sediment like I sampled is wide spread across the site as it is throughout our fluvial flood plain setting – except locally where sandy channel fills are also present.”

Standing water remained on the site, days after the last rain, indicating a high clay content.

What a Photo Can Tell: Decoding Erosion Patterns

I also asked him to analyze this photo below and tell me whether it changed his opinion of soil composition. The photo was taken directly north of the box culvert installed by the developer near Taylor Gulley. The area was several blocks from where he sampled soil.

Several days after this photo was taken the contractor excavated this area to form a retention pond that should have been there before the flood.

When the geologist saw the photo above, he said:

  1. The erosion itself indicates a high rate of water runoff and minimal absorption. 
  2. Steep edges imply cohesion typically associated with clay. Sand or less cohesive soils would slump.
  3. Standing water proves low percolation rate. Only clay rich sediments would hold water like that for more than a few hours.

What Contractor Should Have Known

The contractor developing the site had to know the soil was impervious. They had worked it for a year or more and had to see standing water on numerous occasions that reportedly caused delays. Still, they did several things that increased flood risk for downstream residents – before they completed site detention. For instance, they:

Basically, they increased the slope of land, reduced the friction that vegetation provides, and accelerated runoff toward an area that they knew could flood, across soil that they knew was impervious…before finishing the detention work.

Photo by Jeff Miller on 5/16/2019, more than a week after the Elm Grove flood, shows developer starting to excavate the detention pond near the portion of Elm Grove and North Kingwood Forest that Flooded.

Had all the detention been installed before the storm hit, Elm Grove and surrounding areas should not have flooded.

Hydrologist’s Claims at Odds with Performance

The hydrologist’s conclusion (see page 3 of the 59 page report) states that on-site detention should hold up to a hundred-year rain. But the Harris County meteorologist estimates that on the day Elm Grove flooded, the area received at most a 50-year rain. Maybe everything wasn’t working as planned after all. Maybe the developer should have changed its approach too construction. Developing detention sooner could have reduced flood risk.

Posted by Bob Rehak with help from Jeff Miller on 5/20/2019

629 Days since Hurricane Harvey

Tunneling: A Potentially Valuable Flood Mitigation Tool

Engineering firm Freese & Nichols claims that “Incorporating tunneling into Houston’s stormwater portfolio could significantly reduce flood damages and improve the reliability of existing conveyance and detention infrastructure.” Tunneling technology, the firm says, has improved dramatically in the last 30 years, making projects possible that were once deemed impossible.

Rapid Growth Limits Mitigation Possibilities

Houston’s exponential population growth (16X during the last 100 years) has made both flooding and flood mitigation more difficult to deal with. However, tunneling, says Freese & Nichols bypasses the urban sprawl issue – especially in dense neighborhoods, such as those inside Beltway 8. Tunneling’s low-impact can move stormwater with very little effect on the surface, benefiting communities and addressing environmental concerns.

Tunnels Expand Both Conveyance and Storage

Tunnels, they point out, expand conveyance capacity within a watershed. They can also store stormwater during floods. A 30-50 foot tunnel can store 50 to 150 acre-feet of storm water per mile. More important, it can convey 10,000 to 15,000 cubic feet of water per second. To put that in perspective, that’s about 40-60% of the flow coming from Cypress Creek during Harvey. Or almost 20% of the flow coming from the Lake Conroe Dam.

San Jacinto River Watershed Flow Rates
During Harvey, an estimated 24,100 cfs came from Cypress Creek.

Thus, tunneling could significantly reduce total flow coming down rivers and streams during floods by providing an alternative means of conveyance.

How Tunnels Are Built

This detailed video shows how a modern tunneling machine works. It can construct up to 350 meters of tunnel in a week. That’s between a fifth and a quarter of a mile per week. The machine continuously cases the hole with precision, pre-caste, concrete segments as it excavates through loose sandy soil. It also dynamically balances pressure in the tunnel along the cutting head face to prevent cave ins. Working a hundred feet or more below the surface, it can even evacuate ground water.

Machine used to build subways and storm tunnels. See fascinating 14 minute video.

Editor’s note: This 13-minute industrial video is among the best-produced videos of its kind that I have ever seen. It should satisfy professionals as well as non-technical types. If you have students who lean toward science and engineering, make sure they see this; it shows how human ingenuity can fill the gap between problem and solution.

Gravity-Driven Reliability

Once built, gravity drives the system during floods.

Diagram courtesy of Freese & Nichols. Reproduced with permission. Note that this diagram shows the start point within a detention basin. Starting within a detention basin helps reduce sediment accumulation in tunnels.

Success Stories in Other Parts of Texas

Here in Texas, engineers have used the technology successfully to reduce flooding potential in Dallas, San Antonio and Austin. As urban centers grow, the need to move infrastructure underground grows with them. Disruption to life and the environment on the surface are simply too costly otherwise.

This presentation gives an overview of the technologies involved several case studies in Texas and the U.S. Here’s a shorter two-page summary. And a link to the Freese & Nichols blog that provides a more detailed discussion of the possibilities.

Weighing Expense Against Flood Cost

Because of the expense, tunneling isn’t the first technology you would consider for flood mitigation. But it can be a valuable addition to the tool chest…especially when weighed against the $125 billion that Harvey cost Houston residents.

Numerous discussions have been held at the county, state and federal levels re: the potential applications of this technology.

Community Impact reported last week that Brian Gettinger—tunneling services leader with Freese & Nichols —said he thinks the concept could work on Cypress Creek.

The newspaper said that Gettinger pitched the tunnel system to the Cypress Creek Flood Control Coalition in March. He said if the tunnel becomes a reality, it could cost $2 billion-$3 billion, would take years to build, and would require federal support because of the high price tag.

Feasibility and Alignment Studies

Harris County Flood Control should soon begin Phase 1 of a $400,000 study. Once started, it could take four months to confirm whether tunneling is feasible in this area. Future phases of the study will dig deeper into specific alignments (Buffalo, Brays, Cypress, etc.), evaluating inflow and outflow points, and specific routes.

Posted by Bob Rehak on 4/22/2019 (Earth Day)

601 Days since Hurricane Harvey

Why You Should Be Concerned About Sediment and Sand Mines

For readers new to the site, I’d like to explain why I frequently mention sand mines in posts.

Bright, White Trail of Sand from the Mines

Shortly after Harvey, I became alarmed by the huge buildups of sand and sediment along the banks of the San Jacinto and in the river itself. I rented a helicopter to see if I could determine where it came from. It didn’t take long. I found bright, white trails of sand and monstrous dunes leading from sand mines on the East and West Forks of the San Jacinto all the way downstream to Lake Houston. I posted four hundred and fifty photos that I took that day (9/14/17) in the gallery section of this web site. See for yourself.

A six foot high dune – not present before Harvey – now virtually blocks the West Fork just south of the Kingwood Country Club.

Possible Sources

TACA claims that all the sand came from somewhere else, a contention that I have always found self serving and hard to believe. Miners exposed approximately twenty square miles of sand surface  to 131,000 cubic feet of water per second at the height of Harvey. As one of the world’s leading hydrologists told me, “The miner’s claims don’t appear plausible.”

Sand certainly came from other sources. But I believe my own eyes. Review the photos and Google Earth for yourself. You can see far more sand in the river and on the banks now than before. It had to come from somewhere.

Harvey deposited sand four to five feet deep along both shores of the San Jacinto for miles.

Sand now reaches into the tree tops at the West Lake Houston Parkway Bridge and blocks water from flowing under it.

The problem comes in determining how much came from different sources: Spring Creek, Cypress Creek, West Fork, Peach Creek, Caney Creek, East Fork, channel scouring, channel widening, sand mines, sand stockpiles, urbanization, etc. The short answer: some came from all of the above. How much came from each source? I personally can’t say with certainty.

So why should you worry about sand mines then?

Restoring Channel Conveyance is Costly

The U.S. Army Corps of Engineers is currently trying to remove 1.8 million cubic yards of sediment from a 2-mile stretch of the West Fork. Their objective: restore channel conveyance to the river between River Grove Park and King’s Harbor. Cost: Approximately $70 million.

That project will NOT include the “mouth bar” between King’s Point and Atascocita Point. Estimated cost of that project: another $100 million…if it happens. And we have not yet even estimated the cost of dredging the remainder of the West Fork, the East Fork, and channels down through the FM1960 bridge.

Other Concerns

HGAC has discovered alarming levels of bacteria in both forks of the San Jacinto and linked the levels to sedimentation.

The capacity of Lake Houston is rapidly decreasing at a time when the City of Houston plans to radically increase the number of people using its water.

River migration could soon capture a number of abandoned sand pits, increasing levels of sediment in the river.

It could be years before land for additional upstream detention is identified and purchased. Harris County and the SJRA are still awaiting funding from FEMA for the study that will help identify the best locations. FEMA has studied the study since April.

Stephen Costello, the City’s flood czar, told a meeting of residents at the Kingwood Community Center in October that additional flood gates for Lake Houston could take 5-10 years.

It’s Time for Progress, Not Promises

The next legislative session starts in less than two months. Two things we can focus on NOW: strengthening sand mine regulation and putting some teeth in the TCEQ. Let’s get the sand mines out of floodways. Let’s establish an erosion hazard zone like they have on the Brazos.

Other mitigation projects to reduce flood risk are far off. And if the mouth bar project is delayed, any additional sediment coming downstream will likely be deposited behind the bar in the heavily populated Humble/Kingwood/Atascocita corridor again.

The risk of a future flood could be catastrophic to the community. Dozens of people I have interviewed have told me that they are rebuilding now based on the Mayor’s assurances of additional dredging, upstream detention and flood gates. However, they say they will never rebuild again if flooded a second time.

It’s been 448 days since Hurricane Harvey. We need progress, not promises.

As always, these are my opinions on matters of public policy. They are protected by the First Amendment of the United States Constitution and the Anti-SLAPP statute of the great State of Texas.

Posted by Bob Rehak on November 19, 2018

448 days since Hurricane Harvey

 

Harris County Flood Control Updates Project List for Flood Bond

The Harris County Flood Control District has updated the project list for the upcoming flood bond referendum. This will be the last update before early voting starts on August 8.

Location of proposed projects in San Jacinto Watershed

There are several earlier versions of this list that do not include all of the most recent projects that have been added for the Lake Houston area. Make sure you review the most current list before voting.

The Lake Houston Area Chamber and the Lake Houston Area Grassroots Flood Prevention Initiative lobbied long and hard to get items on this list including additional:

  • Upstream detention
  • Dredging of the East and West Forks
  • Floodgates for the Lake Houston Dam

These three items comprised the so-called Plea for DDG (detention, dredging and gates). They have been added to the project list and will be in the bond proposal that people vote on. To review all projects that could affect you, make sure you also look upstream in the Spring and Cypress Creek Watersheds.

Early voting starts August 8 and the Kingwood Community Center. Here is the complete list of early voting hours and dates.

Wednesday, August 8, 8:00 a.m. to 4:30 p.m.
Thursday, August 9, 8:00 a.m. to 4:30 p.m.
Friday, August 10, 8:00 a.m. to 4:30 p.m.
Monday, August 13, 8:00 a.m. to 4:30 p.m.
Tuesday, August 14, 8:00 a.m. to 4:30 p.m.
Wednesday, August 15, 7:00 a.m. to 7:00 p.m.
Thursday, August 16, 7:00 a.m. to 7:00 p.m.
Friday, August 17, 7:00 a.m. to 7:00 p.m.
Saturday, August 18, 7:00 a.m. to 7:00 p.m.
Sunday, August 19, 1:00 p.m. to 6:00 p.m.
Monday, August 20, 7:00 a.m. to 7:00 p.m.
Tuesday, August 21, 7:00 a.m. to 7:00 p.m.

The final day for voting is August 25 at your normal polling place. To find your polling place, follow this link.

The August 1 list includes partnership projects that could bring in additional funds through matching grants. They could potentially total another $3.1 billion.

For complete details on the bond proposal, visit the Harris County Flood Control District website and click on Bond.

This list must be approved by Commissioner’s Court. Their next meeting is August 14.

Posted by Bob Rehak on August 4, 2018

340 Days since Hurricane Harvey

County Position on More Detention, Dredging and Gates for Flood Bond

Today, I received feedback from Harris County on adding “more detention, dredging and gates” (Plea for DDG) to the upcoming flood bond referendum. The good news: Additional dredging, detention and gates will be achievable within the bond. The bad news: based on the feedback, there is still one hurdle to clear: finding partners to share dredging costs.

The mouth bar where the West Fork meets Lake Houston. Fosters Mill and King’s Point are in the background.

Background on Plea for DDG: Detention, Dredging and Gates

You may recall that RecoverLakeHouston, the Lake Houston Area Chamber, and the Lake Houston Area Grass Roots Flood Prevention Initiative (as well as I) all lined up to support the Plea for DDG. The idea: during floods, more detention, dredging and gates would reduce input, increase throughput and speed up output.

Giant Turnout

The community turned out in force to support the initiative. The response literally overwhelmed county officials at the meeting. Seven to eight hundred people attended, making it the most attended of all the watershed meetings to date. Typically, meetings have been drawing one to two hundred people according to those who have attended multiple meetings.

Because of the large number of attendees in Kingwood and the open house format, many people felt the meeting was somewhat chaotic. Worse, some attendees received feedback from a small number of the county employees who mistakenly told them that dredging was NOT possible under the bond.

Clearing up the Confusion

I received this email from the county today. It clarifies their position on all three requests:

Thank you for your input in support of #PleaForDDG for the San Jacinto River watershed.  Your submission has been recorded and considered by the Harris County Flood Control District staff.

With regard to drainage improvements for the the San Jacinto River watershed, the Flood Control District is partnering with Montgomery County, the City of Houston and the San Jacinto River Authority to determine short-term and long-term improvements, such as:

  • Expanding the Flood Warning System (http://www.harriscountyfws.org) into Montgomery County to include new rainfall and stream level gages
  • Improved coordination between the two county Offices of Emergency Management during disasters
  • A vegetation and sediment management plan with the goal to reduce the amount of silt and sand eroding into the river
  • Regional mitigation projects such as river dredging, buyouts and detention basins

Dredging to restore the San Jacinto River and Lake Houston

On July 6, 2018, the US Army Corps of Engineers awarded a contract to Great Lakes Dredge and Dock, in the amount of $69,814,060 to remove sediment and debris resulting from Hurricane Harvey from the West Fork of the San Jacinto River. The Bond Program does include funding that could provide a portion of the cost share for any future dredging work on the East Fork/West Fork/Lake Houston area. Any future dredging project would have to be a collaborative effort between the City of Houston, the Coastal Water Authority, and possibly the State of Texas. At this time, no details have been worked out on future dredging. The Flood Control District will update the Bond Program maps to indicate another Partnership Project (green cross symbol) within the San Jacinto River watershed exhibit noting East Fork/West Fork/Lake Houston Dredging. The description will be “Potential Partnership Project with the City of Houston, Coastal Water Authority, and the State of Texas to permit, design, and complete dredging of the East Fork/West Fork/Lake Houston area waterways to reduce flooding risks.” The dollar amount will be shown as $50M from Harris County Flood Control District and TBD (to be determined) for the City of Houston, the Coastal Water Authority, and the State of Texas. The Flood Control District cannot commit nor obligate other agencies to allocate funding due to the fact that there is no agreement in place for the dredging project.

Detention/Sediment Basins West and North of Highway 59

These improvements are included in the list of potential projects within the bond program (see local projects F-88, F-14, and F-15 which will be used for Planning, Right-Of-Way Acquisition, Design and Construction of General Drainage Improvement along the San Jacinto River and Cypress Creek west of Highway 59). For drainage improvements north of Highway 59, the Flood Control District is coordinating with Montgomery County on a watershed study to investigate flooding problems and identify where detention basins could best serve to reduce flooding risks along the San Jacinto River.

Tainter Gates on Lake Houston Dam

On July 10, 2018, as a result of the community input process, the Flood Control District has added a Partnership Project (green cross symbol) to the list of potential projects within the bond program for the design and construction of additional gates. The partners would be the City of Houston and the Coastal Water Authority since they are the entities that have jurisdiction over the lake and the dam structure; our agency does not. The Bond Program could, however, provide partial funding of up to $20M for this effort.

When considering project ideas suggested by the community, the Flood Control District will prioritize projects that meet its mission to provide flood damage reduction projects that work, with appropriate regard for community and natural values. You can learn more about the project ranking criteria on our website: https://www.hcfcd.org/bond-program/community-input/

Thank you again for sharing your input. The bond election will be held on August 25 with early voting on August 8.

After reading this, I emailed Harris County Flood Control for one more clarification. Was spending $50 million on dredging contingent upon finding partners to share the cost? The answer: Yes. Fifty million, they say, is not sufficient by itself to do the dredging necessary.

So Where Does that Leave Us?

Additional gates for Lake Houston seem to be within scope and well supported.

More upstream detention seems to be within scope and also well supported. However, before any action can take place, the San Jacinto Watershed study must be completed. It is rumored to cost around $2 million and has been awaiting funding since late March. Presumably, the County’s share of the funding would come from this bond if it passes. The study would take a year or more to complete.

No one can say at this time what the study’s recommendations would be. So there is some uncertainty surrounding the request for more upstream detention. Please note, however, that other groups further upstream, for instance on Cypress Creek, are also requesting more upstream detention. My feeling? If the bond passes, more upstream detention is very likely. However, of all the projects, detention would take the longest to complete because it involves identifying and acquiring land.

Finally, additional dredging is also within scope and well supported. However, dredging has the highest degree of uncertainty associated with it because it will require partners who have not been approached and who have not committed any dollars.

To reduce uncertainty surrounding dredging before the bond, we would likely have to obtain commitments from one or more other stakeholders who are mentioned in the email above.

Recommended Next Steps

Before the bond referendum, area leaders need to actively seek support from those other stakeholders and communicate the outcome so that voters can make informed decisions about their votes. Of all three measures, dredging could be implemented the quickest.

In the meantime, residents should continue to submit their requests for more detention, dredging and gates. A groundswell of support will help send a message to the county’s potential partners.

Posted July 17, 2018 by Bob Rehak

322 Days since Hurricane Harvey

Lake Houston Chamber Launches Plea for DDG

The Lake Houston Chamber has launched its latest campaign in a series of flood mitigation efforts. Called the “Plea for DDG,” it is designed to:

  • Help educate residents and business owners about three key proposals that could address the root causes of flooding in the Lake Houston Area
  • Help turn out a crowd at Harris County’s flood bond meeting on July 10, 6 p.m., at Kingwood Park High School.

Purpose of Flood Bond Meeting

The purpose of the flood bond meeting is to solicit input from residents on the things that they believe will best help the largest numbers of people.

DDG: More Detention, Dredging and Gates

DDG stands for more Detention, Dredging and Gates, three proposals that will reduce flooding here.

The U.S. Army Corps of Engineers is NOT addressing this giant sand bar in its dredging project – a big reason why we need to get the County to address additional dredging in its flood bond package. 

Harvey taught us that we had vulnerabilities. We had more water coming downstream than the San Jacinto’s current channel and the Lake Houston Dam could handle in a timely way. We need to fix those problems so residents know that a 1% storm will leave a home above the 100-year flood plain high and dry. Likewise for a 500-year flood. To do that:

Less input. More throughput. Faster output.

It’s simple. Logical. Achievable. And should restore drainage to original design assumptions.

Now we just need to get enough people to show up and request these things at the bond meeting for the county to include them in the bond package.

Drag your friends, relatives and neighbors to this meeting…especially the ones that didn’t flood.

Remind them that the flood affected this entire community. Tell them why more detention, dredging and gates are so important.

Get them to request more dredging, detention and gates from the County. These three measures could help virtually everyone who lives in the area.

DDG: A two step process

We have to make sure we get the right measures into the bond package. Then we have to get people to vote for it.

Right now, nothing is more important to the future of this area.

This bond package will be used to:

  • Pay for capital projects outright
  • Qualify us for federal matching grants that could triple the amount of dollars available to us (beyond the amount voters approve).
  • Free up money in the Flood Control District’s current capital budget so that the Distict can step up maintenance on ditches (which we also desperately need).

So tell everyone you know to “Plea for DDG” – more detention, dredging and gates – at the bond meeting on July 10, 2018, 6-8 p.m., at Kingwood Park High School.

For more information about the Chamber’s campaign, see recoverLakeHouston.com.

Posted 7/2/2018 by Bob Rehak

308 days since Hurricane Harvey

Lake Houston Area’s Most Pressing Needs for Flood Bond Referendum

On August 25, Harris County residents will vote on a historic flood bond proposal. Everyone asks, “Will the bond include projects that help this area?”

That of course, raises the question, “What does the Lake Houston Area need?”

We Must Address Root Causes of Flooding HERE

Several factors make flooding here different from other parts of the region. Since Harvey, I’ve corresponded almost daily with experts in geology, hydrology, sedimentation, meteorology, city planning, engineering, mining, and disaster relief. The goal: to identify root causes of flooding in THIS area. They fall into three main “buckets”:

  • Sedimentation. Sand and silt clog the San Jacinto everywhere. The Army Corps’ emergency dredging project will remove only part of the sand from a 2.1 mile stretch of the West Fork, and not even touch the East Fork. One of the largest blockages at the mouth of the West Fork will remain. And the Corps will only restore the areas it dredges to pre-Harvey conditions, not pre-1994 conditions.
  • Releases from the dam at Lake Conroe can increase the volume of water flowing between Humble and Kingwood by ONE-THIRD. Of the roughly 240,000 cubic feet per second flowing down the west fork, 80,000 cubic feet of water per second came from the Lake Conroe dam. Many Lake Houston area residents say the onset of flooding coincided with release from Lake Conroe.
  • We have a bottleneck at Lake Houston. In a flood, much more water converges on Lake Houston than Lake Conroe. At the peak of Harvey, Lake Houston took in 492,000 cubic feet per second whileLake Conroe took in only 130,000 CFS. Seven different watersheds converge on Lake Houston. Yet until water reaches the spillway of the dam, our floodgates have one-tenth the discharge capacity of Lake Conroe’s. This effectively eliminates pre-release as a mitigation strategy.

We Need Specific Solutions, Not Generic

True solutions to flooding in the Lake Houston area must address these unique challenges. Generic solutions, such as buyouts with bond money  will help, but won’t affect many people. Pushing new development further away from rivers will help, but will not restore the carrying capacity of the San Jacinto, increase the discharge rate of the Lake Houston dam, or offset discharges from Lake Conroe.

We Need: Dredging, Detention, More Gates

The objective of the Lake Houston Area’s flood mitigation efforts should be, in my opinion and the opinion of many engineers, to restore our drainage systems to their original design capacity. Homes located outside of the 1% (100-year) risk area should not flood until we get a 1% flood. The same goes for the .02% level (500-year flood).

Experts generally focus on three categories of solutions that will help achieve those objectives: dredging, detention and greater discharge capacity for the dam, i.e., adding more gates. We need all three. No one solution will do the job by itself.

Additional DREDGING can remove sediment, restore carrying capacity, eliminate water backing up, and get us back to level of the original design assumptions.

Additional  DETENTION on the West Fork will help offset discharges from the Lake Conroe dam, which affected the heavily populated area between Humble and Kingwood, where the worst and most damage took place.

Additional GATES on Lake Houston will help relieve the bottleneck created by the different discharge rates between Lake Conroe and Lake Houston.

Here’s a diagram that shows what we need in the flood bond, where we need it, and why.

Reduce flooding in the Lake Houston Area with additional dredging, detention and drainage.

Of the three types of projects, dredging is the easiest and fastest to implement. It can buy us time while we build additional dams and gates. That could take years.

More Explanation to Follow

I will elaborate on each of these in coming days.

Harris County Commissioners and executives from the Flood Control District will hold a meeting in Kingwood on July 10 to solicit input from the community on the flood bond.

Hopefully, this series of posts will help focus discussion on the things that will do the most good for the largest number of people at the lowest cost.

Mark Your Calendars for July 10

In the meantime, mark your calendars for July 10. The County wants your input. Get your friends and neighbors to do the same. If you want peace of mind, we need to restore our ditches, rivers, and drainage systems to their original design capacity.

The location of the bond meeting may change because of the expected turnout and need for parking. So check back often.

Posted June 26, 2018, by Bob Rehak, 14 days before the flood bond meeting and…

301 days since Hurricane Harvey.

Top Priorities for Lake Houston Area Flood Mitigation

The fast-approaching Harris County Flood Bond referendum on August 25 is forcing people to focus on their top mitigation priorities.

Harris County Flood Control Bond Page at https://www.hcfcd.org/bond-program/.

Here is the current list of projects included in the Bond Proposal. Scroll down to page 7 to see those associated with the San Jacinto Watershed as of 6/1/18. Only one item from MY top four is currently on the County’s priority list.

Here are four things that I think would make the biggest impact for this area. Do you agree?

Top Priorities

  1. More river dredging. We must restore the velocity and carrying capacity of the entire river, not just a small portion of the West Fork and not just to pre-Harvey conditions.  The Army Corps of Engineers is restoring a 2-mile stretch to pre-Harvey conditions. But we need to dredge deeper and further. And we need to do it on a regular basis. In 2000, Brown & Root recommended dredging and periodic maintenance as the best option they examined to mitigate flooding. Neither was ever done. That’s a huge part of the reason why we face increased flood risk today. Personally, I’d like to see the East and West Forks restored to their 2000 condition.
  2. More floodgates on Lake Houston. Freese and Nichols found that 14 additional gates could have lowered the flood level during Harvey by up to 1.9 feet. That could help reduce flooding both upstream and downstream from the dam. It could also help reduce flooding downstream. By releasing water before a storm hits in a gradual, controlled fashion, you can create more capacity within the lake so you can discharge water at a lower rate as the reservoir fills back up.
  3. More upstream detention. Offset Lake Conroe releases by capturing and holding water elsewhere. Everybody from here to Waller County seems to be lobbying for this. Small dams along the streams and bayous could temporarily hold back flood waters before they reach highly populated areas. Spring and Cypress Creeks are popular candidates. Lake Creek has also been mentioned. Finally, TACA pointed out that sand mines could make excellent detention ponds – my favorite alternative.
  4. Better ditch maintenance. Before Harvey, many of our drainage ditches became silted and clogged with fallen trees. Some, like Ben’s Branch, near the public library, still have islands and standing water in them. Keeping these ditches clear and free flowing should be a high priority at all times to eliminate internal flooding.

Consensus Starting to Emerge

Monday, at separate meetings of the Lake Houston Area Grass Roots Flood Prevention Initiative and the Recover Lake Houston Task Fork, I saw consensus emerging around these flood mitigation measures. Together, these top priorities seem to have the best chance of actually reducing flooding in the Lake Houston area.

What are your top priorities? Whether you agree or disagree with these, please communicate your thoughts to Harris County Flood Control ASAP. The County is actively soliciting ideas for the bond proposal right now.

According to Community Impact, Judge Ed Emmett said the county hopes to have a final list of projects to share with the public by Aug. 1. Early voting will begin on Aug. 8. Thus, we have only six weeks to influence the project list.

Leveraging Local Dollars

County bond money can be used to leverage Federal matching funds from FEMA and HUD grants. These grants usually operate on a 75/25 or 90/10 basis, returning $3 to $9 for every dollar put up. If voters approve the$2.5 billion referendum, it could potentially bring in tens of billions of additional dollars. This flow chart explains how the Flood Control District’s funding works.

Federal dollars for Harvey flood mitigation efforts are available now, but may go elsewhere if we don’t act. So it’s important that we:

  • Make sure the language in the proposed bond accommodates our needs
  • Pass the bond
  • Focus the money where it will do the most good

Here is where the proposed bond language stands as of this date. See BondLanguageAsOf6.13.18.  It will most likely be modified before voting begins, based on what officials hear from citizens at a series of meetings being held in all 22 watersheds throughout Harris County.

Give the County Your Thoughts

Remember, according the Greater Houston Flood Mitigation Consortium, the Lake Houston area historically has received 0% of the region’s flood mitigation dollars, but sustained 14% of the region’s damage during Harvey. Let’s make sure we get our fair share of flood control dollars this time around.

Call 713-684-4107 or mail comments to 9900 Northwest Freeway, Houston, Texas 77092, ATTN: Bond Program Communications.

Come to the meeting with Judge Ed Emmett at the Kingwood Community Center on July 10 from 6 to 8 pm. Learn more about bond proposal and give the Judge your feedback directly.

Posted by Bob Rehak 6/13/2018

288 days since Hurricane Harvey