Tag Archive for: cypress creek

Batches 1 and 2 of Cypress Creek Major-Maintenance Projects Completed, More to Come

Harris County Flood Control District (HCFCD) has essentially completed Batches 1 and 2 of Cypress Creek major maintenance projects, according to District spokesperson Karen Hastings. On 9/12/22, I photographed the freshly repaired and reseeded channel K131-00-00 (Spring Gully) at Cypresswood Drive, one of the last projects in Batch #1. See the pictures below.

Looking NW at K131-00-00 (Spring Gully) across Cypresswood Drive in foreground. Location is about a block west of TC Jester.

Such projects typically involve desilting. That involves removing accumulated sediment that reduces the conveyance of the channel.

Same tributary from a vantage point a little farther upstream. Looking NW.
At the split, you can see that repairs extend farther upstream. Spring Gully goes toward the right; Theiss Gully to the left.

Even though maintenance on Spring Gully may be complete for the time being, additional projects are in the works to provide even more flood relief to the area.

TC Jester Stormwater Detention Basin

Among them is the capital improvement project below. Note the two red ovals in the photo. They loosely represent the locations of what will become two large detention basins on either side of TC Jester.

Looking SE across Cypresswood Drive. TC Jester cuts across Cypresswood in the upper left and continues S between the circles.

Looking SE toward TC Jester in upper left. HCFCD has a head start on a detention basin thanks to an E&R Contract.

E&R Contract

E&R stands for Excavation and Removal. HCFCD has owned this property and the property across TC Jester for years. Knowing that someday a detention pond would be built here, HCFCD entered into an E&R contract with a dirt company. Such contracts give dirt companies the right to excavate the dirt and haul it away for pennies a truckload. The company then makes its money by selling the dirt at market rates.

Such contracts also create a quadruple-win situation.

  • Taxpayers get dirt removed virtually for free.
  • HCFCD gets a head start on excavation.
  • The hauling company reduces its costs.
  • Home- and road-builders reduce their costs.

The main restriction: excavated dirt must be taken outside of the floodplain.

The main drawback: If the market slows, so does excavation.

This contract is very similar, if not identical to the one with Sprint Sand & Clay on the Woodridge Village property in Montgomery County. There, HCFCD hopes to more than double the stormwater detention capacity on the site.

Crenshaw Earmark Will Accelerate Construction

U.S. Congressman Dan Crenshaw obtained a $9.9 million earmark earlier this year to help build a stormwater detention basin near TC Jester.

Crenshaw is also seeking another $15 million next year to expand stormwater detention basin capacity in the area.

Area shown in photo above with E&R contract is approximately 40 acres. HCAD has owned this since 2003.
Area east of TC Jester is almost 100 acres. HCAD has owned this since 2015. First phase of expansion will include light blue area.

Together, the projects will mitigate the risk of future riverine flooding by providing a safe place to temporarily store stormwater runoff. That will reduce both the size of the floodplain and the water level within it.

Every cubic yard of dirt removed creates room for a cubic yard of stormwater runoff.

Crenshaw and HCFCD say that approximately 2689 structures are located nearby in the existing 100-year floodplain. The proposed detention basin east of TC Jester could reduce stormwater elevations in a 100-year storm by half a foot. The first phase will remove 87 structures from the 100-year floodplain. When complete, the full detention basin will remove 271 structures from the existing floodplain. 

Spending this money now should save money in the long run – money that would otherwise go to more costly post-disaster recovery programs. 

Looking east over TC Jester toward area where HCFCD will build first phase of first detention basin. Photo taken 7/24/21.

More Major Maintenance and Capital Items

In addition to that, HCFCD just started its third batch of major maintenance projects in the Cypress Creek Watershed. HCFCD also expects a fourth and fifth batch. Altogether, HCFCD built $60 million into the 2018 flood bond for Cypress Creek maintenance projects. (See Project CI-012).

Separately, Crenshaw has also requested another $8.25 million to begin building the planned Westador Stormwater Detention Basin farther east along Cypress Creek at Ella Blvd.

None of these projects will provide an instant fix for the entire Cypress Creek watershed. But together they will reduce risk in areas along it.

Posted by Bob Rehak on 9/15/22

1843 Days since Hurricane Harvey

Coastal Prairie Conservancy Plan Shows How Preservation Can Help Reduce Flooding

The Katy Prairie Conservancy (now the Coastal Prairie Conservancy) has preserved prairies for more than 25 years to slow down and reduce floodwaters.

Tall-grass prairies and wetlands soak up, store and slow runoff from heavy rains, all of which decrease flooding for residents downstream.

The three main dimensions of natural flood reduction.

But how does that work in practice in specific locations? How MUCH do nature-based initiatives reduce flooding? And how can they complement traditional engineered solutions?

Multifaceted Plan Could Hold Back Harvey’s Excess Floodwater

Working with the SSPEED Center at Rice University, the Conservancy produced this brochure. It outlines a plan to expand currently protected lands to 50,000 acres and restore 21,000 of those.

Source: Katy Prairie Conservancy and Rice University SSPEED Center

The plan would absorb, slow, and store water in the Upper Cypress Creek Watershed. It also recommends detaining water near Cypress Creek by creating shallow detention on private lands with the help of willing landowners.

Likewise, by constructing retention and detention ponds in the Upper Addicks Watershed, even more floodwater could be stored and slowed down. The plan also includes the creation of retention corridors along Bear and South Mayde creeks. The retention corridors would serve as a buffer for floodwaters that threaten communities along the creeks. These projects will store up to 110,000 acre-feet of floodwater.

That’s the equivalent of a foot of rain falling over 172 square miles! And that’s 10% of Harris County!

Expand Addicks Reservoir Storage through Excavation

Addicks and Barker Reservoirs are valuable assets that need to be restored and enhanced. Storing additional floodwaters in Addicks Reservoir can keep homes upstream safe and prevent extreme releases that destroy downstream properties, according to the Conservancy and SSPEED.

Addicks Reservoir on May 20, 2021. Looking NW.

Put all these solutions together and the results look like the bar graph above.

The recommendations could easily hold back more water than Addicks had to release during Harvey.

Benefits Extend to Multiple Watersheds

During Harvey, so much water accumulated in the Cypress Creek watershed that it overflowed into the Addicks watershed. So, these recommendations could help reduce flood risk in superstorms along multiple streams, including Buffalo Bayou and Cypress Creek.

Plan includes excavation of additional capacity within Addicks with a goal of enhancing natural environment.

Other Interesting Statistics

The brochure also cites interesting statistics from other groups that touch on the plan. For instance, the Natural Resources Defense Council estimates that every 1% increase in soil organic matter results in the soil holding an additional 20,000 gallons of water per acre.

No One Solution

After studying flood reduction for almost five years now, I’ve concluded there is no silver bullet. No one solution will work for all situations. But every little bit helps. Multifaceted recommendations like these can ultimately reduce costs and increase effectiveness by harnessing the power of nature.

Natural solutions also provide numerous other benefits such as recreation and wildlife habitat.

Posted by Bob Rehak on 5/16/2022

1721 Days since Hurricane Harvey

Reality Check: Easy Way to Learn About Flood-Mitigation Projects in Your Area

It’s time for a reality check, folks. I meet regularly with Harris County residents from almost every watershed. Virtually all of them have one thing in common. Rich and poor alike see NO Harris County Flood Control District (HCFCD) projects in their watersheds. Yet as of the end of the first quarter, out of 181 total 2018 Bond Projects, 19 were completed, 141 were active, and only 21 had not been initiated.

Gap Between Perception, Reality

So what accounts for the gap between perception and reality?

  • Most projects are practically invisible from streets. They’re “hidden” behind fence lines, tree lines, gates, or often, under forest canopies.
  • They’re scattered over dozens to hundreds of square miles. Often, they happen outside of residents’ normal traffic patterns in unfamiliar neighborhoods.
  • Most people have only a sketchy idea of which watershed they live in.
  • People could drive by projects and not realize they were flood-control construction as opposed to some other kind.
  • The projects are often disguised as parks, wetlands or natural areas when finished.

I lunched last week with three people from Cypress Creek who swore that nothing was happening in their 205-square-mile watershed. But actually, within the watershed, HCFCD has spent:

  • $260 million since 2000, the fourth most of any watershed in Harris County.
  • $169 million since Harvey – more than any other watershed – period – since Harvey.

Simple, Three-Step Reality Check

So where did all the money go? Here’s an easy, three-step way to learn…that applies to any watershed in Harris County:

  1. Go to www.HCFCD.org
  2. If you know your watershed, select it from the list. If not, type your address in the search bar just above the list.
  3. You’ll be taken to a page that lists recent, current and planned projects in your watershed. Click through them and start digging down several levels to learn more about the status of each.

Want to verify the information? Make a list and get in your car. I did that this morning and checked out four Cypress Creek projects between the Katy Prairie and I-45.

It took an hour of planning, three hours of driving, and another 3 hours for drone photography. The hardest part was finding favorable drone launch sites near the projects. But sure enough, all the projects existed. Here’s what I found.

Katy-Hockley Wetlands Mitigation Bank

The Katy-Hockley Wetlands Mitigation Bank. 152 acres that will be part of a 440-acre tract set aside for wetlands mitigation. Note additional wetlands in the upper right and below.
Detail from upper left of first photo. At same site.

The property will remain protected under a conservation easement with the Katy Prairie Conservancy. The wetlands may be used in the future to offset unavoidable wetland impacts caused by other federally permitted projects.

T.C. Jester Stormwater Detention Basin

South of Cypresswood Drive, HCFCD has 171.5 acres of land split by T.C. Jester. Eventually, this whole area could become one large detention pond. The east side of TC Jester is still undergoing a preliminary engineering review, but excavation has already started on the west side.

East of T.C. Jester at Cypress Creek (foreground).
West side of T.C. Jester where excavation has already begun.
Start of excavation on west side of T.C. Jester.

The purpose of these projects: to construct stormwater detention on the main stem of Cypress Creek, which will work to reduce flood risks and damages during heavy rains.

A regional drainage study for the watershed found that flooding along tributaries of Cypress Creek is predominately caused by stormwater from a rising Cypress Creek backing up into tributaries. Stormwater detention basins could reduce that backwater.

The study recommends nearly 25,000 acre-feet of additional stormwater detention in the watershed. This one area could go a long way toward meeting that goal.

Cypress Creek Tributary K-163 Conveyance Improvements

At Timberlake Drive and Cypress North Houston Road, HCFCD is replacing a shallow, silted-in ditch with 8’x6′ reinforced concrete box culverts. Depending on the location along Timberlake, there are either two or three such box culverts side by side.

The project is replacing a portion of an existing earthen channel with 4,750 linear feet of boxed culverts, including inlets, junction boxes and tie-ins with subdivision outfalls.

This ditch was down to a two-year level of service and had flooded neighborhoods on both sides on multiple occasions.

The project will also include the installation of approximately 1,200 linear feet of erosion control for the channel downstream nearer the confluence with Cypress Creek in the distance.

Ridge Top Channel Improvements

Another ditch (K129-00-00) farther east parallels Ridge Top Drive in the Ponderosa Forest area of northwest Harris County.

Here, HCFCD replaced the concrete lining in the entire channel. That included about 3,800 linear feet from Saddlecreek Drive to Cypress Creek. The project also repaired multiple sinkholes or voids that had developed in some areas as a result of stormwater undermining the original channel lining. 

Major Maintenance by HCFCD on K129, a Cypress Creek Tributary
Early stages in the design of this project took place prior to the 2018 Bond Election. Construction began in October 2018 and was completed in January 2020.

More than Cypress Creek Projects in the Works

Altogether, I counted more than 20 projects in Cypress Creek at various stages of development. They included:

  • Swales for extreme rainfall events
  • Right-of-way acquisitions and floodplain preservation
  • Buyouts
  • Neighborhood projects
  • Stormwater detention basins in various stages of planning and construction
  • Channel conveyance restorations
  • Major maintenance projects

Knowing that improvements are happening sure beats living in fear that they aren’t. So do a reality check of the watershed around you.

Posted by Bob Rehak on 7/24/2021

1425 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.

I-45 Feeder Over Cypress Creek Is Cattywumpus

Ever since Harvey, Cypress Creek residents near I-45 have been caterwauling that the southbound feeder road is cattywumpus. For those who may not speak fluent Texan, that first word means “screaming” and the second means “skewed” or “out of alignment.”

So on my latest helicopter flight, I flew over the bridge to see what was up. Or down. Actually, the road bed appears level. And nothing has yet fallen into the creek.

However, aerial photos indicate that the bridge panels are indeed cattywumpus. Note how the side guardrails seem to be out of alignment. Also note uneven gaps in the bridge panels (tight on one side, wide on the other). Finally note the vegetation growing or stuck in the cracks, and the un-level bridge support – at bottom of center oval in row of three.

This image taken on 5/26/2021 and cropped from image below.
I-45 Southbound Feeder Road at Cypress Creek

For now, the bridge seems to be holding. But I’m not sure I would want to be the first one to drive over this after the next big flood.

During Harvey, residents say, this bridge went completely underwater. It appears that the force of the water lifted and twisted the bridge panels as much as 6 to 10 inches. However, TxDoT, the responsible authority in this case, has not yet fixed the issue.

Repairs Delayed

According to resident Frank Adamek, TxDoT originally said it would fix the bridge in 2020. Now, says Adamek, TxDoT says they hope to bid the job by the end of 2021 and start construction in March of 2022.

The bridge has other issues, too. Adamek says, the supports under the main lanes are 110 feet across. That allows trees swept downstream in floodwaters to pass through. However, the supports under the southbound feeder road are only 26 feet apart. Adamek says that they have caught trees and backed water up toward homes in the area.

Extreme events, such as Harvey, tend to reveal problems we didn’t even realize existed. Once you see them, though, they’re hard to forget. I, for one, intend to stay off that feeder road.

Posted by Bob Rehak on 6/2/2021

1373 Days since Hurricane Harvey

TWDB To Vote on Financial Assistance for Improving Taylor Gully Level of Service from 10 to 100 Years

In its May 6 board meeting tomorrow, the Texas Water Development Board will vote on whether to approve financial assistance from the Texas Flood Infrastructure Fund to widen and deepen Taylor Gully. That would increase the “level of service” from 10 to 100 years.

The channel would then be able to handle a 100-year rain without flooding instead of just a 10-year rain as it does now. And that would benefit more than 400 homes.

To put a ten-year rainfall into perspective, the eight inches received in two days last week by areas northwest of Lake Houston qualified as a ten-year year event. Luckily, the rain that fell over the Taylor Gully watershed only qualified as a 1- to 2-year rain.

Taylor Gully is the channel below Woodridge Village that experienced disastrous flooding twice in 2019 on May 7th and September 19th (during Imelda).

Explanation of Partnerships and Financing

The City of Houston has requested a $10.1 million loan for construction of the Taylor Gully project. The financial assistance that the TWDB will vote on would take the form of a purchase of City of Houston bonds.

Harris County Flood Control District (HCFCD) would lead the project all the way through construction. The Flood Control District (and hopefully, federal money) will provide the balance of project funds up to $20.2 million out of Bond Project ID F-14 and a Community Project Funding request by US Congressman Dan Crenshaw.

The project will require a considerable amount of upfront work that includes engineering, design, surveying, geotechnical work, environmental permitting and more. The project won’t be ready for actual construction for at least a year. And the City cannot tap into a construction loan until construction starts.

Therefore, the Harris County Flood Control District (HCFCD) will use County money to cover those upfront costs, according to Alan Black, Director of Operations for HCFCD. Some land acquisition may also be necessary, though that has not been fully investigated yet.

Congressman Dan Crenshaw has requested federal dollars to help supplement HCFCD funds for the Taylor Gully and Kingwood Diversion Ditch improvements identified in the Kingwood Area Drainage Analysis. Federal dollars could help stretch local dollars to help develop more projects. (See below about Cypress Creek projects.)

Crucial TWDB to Vote Tomorrow

But everything hinges on the City’s application for a loan from the Texas Flood Infrastructure fund. The City’s request will be #6 on the TWDB meeting agenda. Here is the packet for the board that explains the proposal. It includes cost breakdowns and a timetable, which will likely be accelerated according to project insiders.

The TWDB staff has recommended that the board approve the project.


The Taylor Gully watershed currently has a 10-year level of service because the area upstream has undergone significant development with limited flood mitigation or detention.

Elm Grove debris pile from Imelda flood. This is one of hundreds of homes that flooded near Taylor Gully.

The proposed project includes improvements along the Taylor Gully channel to upgrade the conveyance capacity to provide a 100-year level of service. The improvements include channel widening, deepening, and lining. The project will benefit more than 400 structures. 387 will see direct benefit during 100-year inundations. An additional 62 structures benefit indirectly.

How to Attend the TWDB Meeting

The Texas Water Development Board (TWDB) meeting to consider approving financial assistance for Flood Infrastructure Fund projects will be held on Thursday, May 6, at 9:30 a.m. There are two ways that the public and interested stakeholders may attend the Board meeting:  

  1. Via GoToWebinar 
  2. Via AdminMonitor.

A recording of the meeting will also be available.

If you wish to address the Board, please fill out the visitor registration form and send it to Cheryl.Arredondo@twdb.texas.gov no later than 8:00 a.m. on May 6. For more information, please visit the TWDB’s website.

This link explains how the TWDB closing process works on loans.


State Senator Brandon Creighton sponsored the bill that created the state’s Flood Infrastructure Fund in the 2019 legislature. This link tracks expenditures from the Flood Infrastructure Fund. To date, the TWDB has committed almost $200 million from the fund.

The TWDB has recognized the importance of the project. The City of Houston is putting up the lion’s share of the money for the project. HCFCD is fronting the upfront costs and half of construction dollars. And Congressman Dan Crenshaw is helping to stretch local dollars by supplementing them with federal funds.

HCFCD, Crenshaw Also Working on Cypress Creek Improvements

Crenshaw’s funding request would also help fund the Westador and TC Jester Detention Basins on Cypress Creek. Those are two large basins being planned by HCFCD. Together they would hold about 1,600 acre-feet of stormwater.

To put that in perspective, 1,600 acre feet is enough to contain a foot of rain falling over 2.4 square miles. That could provide benefits both upstream and down. More news to follow on those projects.

Posted by Bob Rehak on May 5, 2021

1345 Days since Hurricane Harvey and 594 since Imelda

West Fork Still Running Siltier Than Spring Creek

After 3.5 years since Harvey and dozens of helicopter flights up and down the West Fork of the San Jacinto, it never ceases to amaze me. Despite sediment gage readings that say more silt is coming from Spring and Cypress Creeks than the West Fork, the West Fork appears siltier the vast majority of the time.

Misleading Data Used to Kill Meaningful Legislation

Here’s what the West Fork looked like today. Definitely siltier.

West Fork comes down from top of frame, Spring and Cypress Creeks from right. Photo taken 3/3/2021 from near US59 bridge, looking north.

Approximately 20 squares miles of sand mines line the West Fork. Problem is, the one sediment gage on the West Fork is upstream from virtually all of the mines. But most people don’t understand that. And that lack of understanding has allowed the mines to claim for decades that they are not the dominant source of sediment.

I’ve even heard miners testify on multiple occasions in the state legislature to that effect. That’s how they managed to kill best-practices legislation and minimum setbacks in the legislature in 2019.

When Brown & Root, the SJRA, City of Houston, Montgomery County, and Harris County Flood Control all cite the same misleading statistics, what’s an ordinary citizen to do?

Only a Sediment Gage Below Sand Mines Will Tell Whether This is Serious

To be fair, the engineers and hydrologists point out that the silt you see above and below may float out into Galveston Bay.

But I would also point out that:

  • The giant sand bar above didn’t exist before Harvey.
  • Neither did the multiple sand bars blocking the West Fork up to 90% (according to the Army Corps) after Harvey.
  • A misrepresentative gage placement, no matter how many times you repeat the sample in different studies, will always yield the same sampling error.
  • Most sediment moves during floods and far more sand is exposed to floodwater on the West Fork.

Finally, I would point out that the dikes of sand mines routinely breach and many mines routinely pump sediment laden water into the West Fork.

The point is: we will never really know what’s going on here until we get a gage downstream from the sand mines.

Photos of same location taken from different angles in previous months. In each case, the West Fork is siltier.

Time Of Essence

When I pointed out the data error caused by a misrepresentative gage location, the partners in the San Jacinto River Basin Master Drainage Study promised to re-evaluate claims they made based on the gage. The originally found, as did Brown & Root, that the vast majority of the sediment is coming from Spring and Cypress Creeks – based on the gage upstream of the sand mines. They also promised to consider installing a new gage downstream from the mines. But nothing has happened yet. And we’re already well into this legislative session.

Until changes are actually made to the study and a new gage is added, I fear the same miners may again repeat the same self-serving and misleading statistics in the legislature. That’s how they have killed bills that could help clean up our water more than once.

We’re now into the third month of the legislative session. And until the San Jacinto Master Drainage Plan consultants modify their findings, we’re all at risk. People will likely reference that study for another two decades, just as they have referenced Brown & Root’s. So this is important. Tick tock.

Posted by Bob Rehak on 3/3/2021

1282 Days since Hurricane Harvey

Developing Problem

A Guest Post by Paul Eschenfelder and George Peckham of CyCreekStopTheFlooding.com

It’s the heart of the storm season.  It’s going to be an interesting next several weeks as we look toward the sea.  Buy flood insurance.  ANY place in Harris County can flood, don’t be another surprised flooding victim.  “I’ve never flooded before” will not get you much sympathy anymore, we have heard it too much.  

Rice U Assesses Cypress Creek Situation

In 1984 Dr. Phil Bedient, of Rice University, wrote his first research paper on flooding along Cypress Creek.  At the time he said the cause was too much development with no place for the water to go.  In 2018 Dr. Bedient, as head of Rice’s Severe Storms Center, wrote another paper on flooding on Cypress Creek.  

He said the cause was too much development with no place for the water to go – too much run off.  

One of his co-authors told us that even if a dam was erected on the creek at 290, and another dam erected at the junction with Little Cypress Creek, the main stem of the creek would still flood.  Too much run off, no place for the water to go.  And too much unbridled development.

We all bewailed the Arizona developer who brought eight (8) feet of fill onto the 50 acres at the Vintage, on Vintage Preserve Pkwy., to build apartments.  He installed detention to capture the run off on that 50 acres, but what of the water that used to pool there during floods, where does it go?  He produced an engineering study saying “no adverse impact”, but where does that water go?

Rebuilding Next to Buyouts!

We recently visited a Harris County home buy out focus site in Saracen Park on Cypress Creek.  There were several vacant lots where residents had sold out to FEMA to escape repeated flooding.  Immediately adjacent to these properties, which were purchased with federal tax dollars, was a new home being constructed.  It was a spec home being erected by a builder – “for sale by owner”.  The County verified that the builder had the proper permits to build in the floodway.  Not flood plain, floodway – the stream channel.  

Is There No Other Land?

Harris County allows building in the stream channel.  Why?  Is there no other land?  Or is this land just really cheap because it’s in the floodway?  Why spend tax dollars to buy out properties and, in turn, allow more properties to be built there?  What sense does this make?  Who are the stewards of our tax money?  

Harris County is one of the few places in the country which allows building in the floodway.  As one of our state representatives told us, it is difficult to obtain state funding for flood mitigation in Harris County when other representatives from around the state ask: “Well, why ya’ll allow building in the flood plain, anyhow?”  How does one answer that?

Fill Without Permit and Slap-on-Wrist Fine

At the corner of Cypresswood Drive and Champions Forest Drive a developer, Don Hand, recently brought in 5-6 feet of fill to build up his lot for a construction project.  

He didn’t bother to obtain a permit.  There was no detention built and no consideration for his neighbors.  

If a tropical storm had arrived, the water would have cascaded off that lot into the Chase branch bank, crossed the street into the Mormon Temple, flooded the Conservatory parking lot, inundated Cypresswood Drive and perhaps entered the Kroger, again.  Citizen outrage caused the County to ‘red flag’ his construction.  

The County was required to go to court to obtain an injunction to stop this developer and require the fill to be removed.  It was a pyritic victory.  The penalty assessed under the law against this type of dangerous develop is $100/day.  Little wonder the dirt is still there – it’s cheaper to pay the fine than remove it.  

3600 Building Permits Issued Along Cypress Creek Since 1997

Development continues apace along Cypress Creek.  Community Impact’s investigation into development along the creek indicates that since the 1997 county standards were adopted, there have been over 3,600 new building permits issued along the creek.  More impervious surface, less room for the water.  

Subsidizing Developers with Taxpayer Dollars

The Greater Houston Flood Consortium’s 2017 report on flooding and building standards recited that “…not requiring new development to fully mitigate its impacts would essentially be a subsidy for that development, reducing the cost of building but ultimately requiring taxpayers to pay for more new flood mitigation infrastructure and saddling downstream residents with flood-related property damages.”

The Politics of Development

How did we get so far out of balance?  For a century builders & developers have had a powerful hold on Houston and Harris County.  Recall the 1960s mayor of Houston, Louie Welch, and his statement: “The business of Houston is business”.  No zoning, weak regulation.  

Another reason is money.  County regulations are approved by Commissioner’s Court.  In 2018 a Houston Chronicle investigative report indicated that all four commissioners received at least 80% of their re-election funds from builders/developers/engineering firms.  While all the commissioners deny that these election contributions have any impact on their decisions, you can bet the donors get their phone calls returned.  

Luck Not a Strategy

Thus far in this very active hurricane season we have been lucky and dodged all the storms.  In flood mitigation, luck is not a strategy.  We must have flood infrastructure.  Three years after Harvey, four years after Tax Day, not a shovel of dirt has turned on Cypress Creek.  But we must also have reasonable rules which look after not only developer profits, but public safety and security.  Tell your friends, tell you neighbors, tell your elected representatives.  Let’s start that conversation.

By Paul Eschenfelder and George Peckham of cycreekstoptheflooding.com

1105 Days after 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