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.
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.
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.
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 Impactreported 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
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/04/Screen-Shot-2019-04-22-at-10.18.42-AM-copy.jpg?fit=1500%2C966&ssl=19661500adminadmin2019-04-22 13:13:322019-04-22 13:14:10Tunneling: A Potentially Valuable Flood Mitigation Tool
On April 17th, the Texas House of Representatives Environmental Regulations committee heard testimony on a bill that would double fines for illegal sand mining, HB907. No illegal sand miners spoke against the bill, so this one has a pretty good chance of passing.
The bill’s author, State Representative Dan Huberty laid out the case for the bill starting at 9:29 into this recording. His main points: this bill does not penalize miners who have registered with the TCEQ, only those who have not. He reminded committee members how bad the problem of illegal sand mining was when his first sand mining bill was passed in 2011. Huberty said that he believes the problem of unregistered sand mining continues to this day. However, he said, the fines set in 2011, no longer make the same deterrent they did then. He said the increased fines would enable the TCEQ to increase oversight efforts.
Why This is Important
Illegal sand mining contributes disproportionately to the problem of sedimentation in the river. That’s because it often takes place in or on the banks of the river. The illegal miners make no attempt to control erosion or sediment. And the scars can last for decades.
Here is a satellite image from 1989 on the West Fork of a mining operation near a point bar. At this point in time, sand miners were not forced to register with the TCEQ.The same area almost 30 years later still bears the scars. Both photos courtesy of Google Earth.
Supported by Both TACA and Environmental Groups
At about 18 minutes into the recording, Rob Van Til, owner of River Aggregates, a registered sand mining company, spoke in favor of the bill. Speaking for himself as well as TACA, he said it would help deter “bad actors.”
Grant Dean, representing the Texas Environmental Coalition, from Marble Falls, also rose to speak in favor of the bill.
Not a “Christmas Tree”
Given the lack of opposition, Huberty then wrapped up testimony by moving for passage of he bill. He said that he would not allow the bill to become a “Christmas Tree” when it went to the House floor. A Christmas tree bill is a political term referring to a bill that attracts many, often unrelated, floor amendments that provide special benefits to various groups or interests.
While this is certainly not the most important piece of sand mining legislation, it will help in a limited way by plugging a legislative and enforcement gap. And because the extra revenue generated will pay for the enforcement, it is revenue neutral.
Status: Pending in Committee
To read the text of HB907, click here. Senator Brandon Creighton has introduced a companion bill in the Senate, SB2123. Both are still pending in committee.
A companion bill is a bill filed in one chamber that is identical or very similar to a bill filed in the opposite chamber. Companion bills are used to expedite passage as they provide a means for committee consideration of a measure to occur in both houses simultaneously. A companion bill that has passed one house can then be substituted for the companion bill in the second house.
How You Can Help
Both of these bills deserve the support of Lake Houston Area residents. To urge action, call or email the committee members. Here is contact info for:
Said Huberty at the end of the day, “It was quick, but we feel good about this!”
Posted by Bob Rehak on 4/20/2019
599 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/04/Environmental-Regulation.jpg?fit=1268%2C710&ssl=17101268adminadmin2019-04-19 20:22:102019-04-19 20:23:21Outlook Good for Bill That Would Double Fines for Illegal Sand Mining
As I’ve been posting a lot about sand mining legislation, a friend sent me this doc today about the reasons for Texas Parks & Wildlife Department’s (TPWD) permitting program. TPWD regulates mining in rivers; TCEQ regulates mining in flood plains.
Photo by Jim & Melissa Balcom of their son playing on the West Fork of the San Jacinto after Harvey.
Difference in Tax Rates Between Rivers and Flood Plains
Flood plain mining has a 2% tax rate; in-river mining 8%. This doc explains what the department does with that 8%. TPWD’s authority to regulate mining in rivers goes back more than 100 years.
TPWD says that:
Dredging of sand, gravel, and shell from rivers and bays can negatively impact fish and wildlife habitats. Habitat alteration is the primary cause of population declines, loss, and extinction of freshwater fishes, mussels, and other aquatic organisms. Habitat alteration is also one of the primary contributors to listing of fish and wildlife as threatened or endangered under the Federal Endangered Species Act.
Evolution of Mining Influenced
Because of the 4X difference in tax rates, and the fact that sand is a highly competitive undifferentiated commodity, sand from flood plains enjoys a huge cost advantage: 6%. As a result, comparatively little sand is taken from rivers today. In an average year, TPWD department says it brings in only $200,000 to $400,000 statewide. It comes mostly from small scale mining (less than 1000 cubic yards) by people who want to build roads or pipelines across streams.
Goals of Regulations
As the number of applications for permits has increased, TPWD has established project guidelines such as seasonal restrictions that avoid or minimize impacts to recreational users; site-specific provisions to ensure channel stability; and best management practices to control bank erosion, avoid land loss, and reduce downstream impacts.
Read Over Your Morning Cup
The entire document is 2-pages, well-written, and well-illustrated. It will give you a good understanding of why the state started regulating sand mining in rivers long ago…all during your morning cup of coffee or tea. Highly recommended easy reading!
Posted by Bob Rehak on 4/19/2019
598 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/04/image3-4.jpeg?fit=1200%2C900&ssl=19001200adminadmin2019-04-18 22:29:062019-04-18 22:35:49Texas Parks and Wildlife Sand and Gravel Permitting Program: History, Scope and Protections
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.
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.
Gravity-Driven Reliability
Once built, gravity drives the system during floods.
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
Outlook Good for Bill That Would Double Fines for Illegal Sand Mining
On April 17th, the Texas House of Representatives Environmental Regulations committee heard testimony on a bill that would double fines for illegal sand mining, HB907. No illegal sand miners spoke against the bill, so this one has a pretty good chance of passing.
Key Points in Huberty’s Testimony
The bill’s author, State Representative Dan Huberty laid out the case for the bill starting at 9:29 into this recording. His main points: this bill does not penalize miners who have registered with the TCEQ, only those who have not. He reminded committee members how bad the problem of illegal sand mining was when his first sand mining bill was passed in 2011. Huberty said that he believes the problem of unregistered sand mining continues to this day. However, he said, the fines set in 2011, no longer make the same deterrent they did then. He said the increased fines would enable the TCEQ to increase oversight efforts.
Why This is Important
Illegal sand mining contributes disproportionately to the problem of sedimentation in the river. That’s because it often takes place in or on the banks of the river. The illegal miners make no attempt to control erosion or sediment. And the scars can last for decades.
Supported by Both TACA and Environmental Groups
At about 18 minutes into the recording, Rob Van Til, owner of River Aggregates, a registered sand mining company, spoke in favor of the bill. Speaking for himself as well as TACA, he said it would help deter “bad actors.”
Grant Dean, representing the Texas Environmental Coalition, from Marble Falls, also rose to speak in favor of the bill.
Not a “Christmas Tree”
Given the lack of opposition, Huberty then wrapped up testimony by moving for passage of he bill. He said that he would not allow the bill to become a “Christmas Tree” when it went to the House floor. A Christmas tree bill is a political term referring to a bill that attracts many, often unrelated, floor amendments that provide special benefits to various groups or interests.
The testimony with questions from the committee members took about 15 minutes. In response to one of the questions, Huberty details all of the other flood mitigation legislation moving through the Legislature at this time. It’s definitely worth watching if you want a preview of how the political landscape could change for sand mining in coming years.
Revenue Neutral
While this is certainly not the most important piece of sand mining legislation, it will help in a limited way by plugging a legislative and enforcement gap. And because the extra revenue generated will pay for the enforcement, it is revenue neutral.
Status: Pending in Committee
To read the text of HB907, click here. Senator Brandon Creighton has introduced a companion bill in the Senate, SB2123. Both are still pending in committee.
Creighton’s SB2123 was referred to the Natural Resources & Economic Development Committee on March 21. The committee has not yet held hearings on it.
Reasoning Behind Companion Bills
A companion bill is a bill filed in one chamber that is identical or very similar to a bill filed in the opposite chamber. Companion bills are used to expedite passage as they provide a means for committee consideration of a measure to occur in both houses simultaneously. A companion bill that has passed one house can then be substituted for the companion bill in the second house.
How You Can Help
Both of these bills deserve the support of Lake Houston Area residents. To urge action, call or email the committee members. Here is contact info for:
Said Huberty at the end of the day, “It was quick, but we feel good about this!”
Posted by Bob Rehak on 4/20/2019
599 Days since Hurricane Harvey
Texas Parks and Wildlife Sand and Gravel Permitting Program: History, Scope and Protections
As I’ve been posting a lot about sand mining legislation, a friend sent me this doc today about the reasons for Texas Parks & Wildlife Department’s (TPWD) permitting program. TPWD regulates mining in rivers; TCEQ regulates mining in flood plains.
Difference in Tax Rates Between Rivers and Flood Plains
Flood plain mining has a 2% tax rate; in-river mining 8%. This doc explains what the department does with that 8%. TPWD’s authority to regulate mining in rivers goes back more than 100 years.
TPWD says that:
Evolution of Mining Influenced
Because of the 4X difference in tax rates, and the fact that sand is a highly competitive undifferentiated commodity, sand from flood plains enjoys a huge cost advantage: 6%. As a result, comparatively little sand is taken from rivers today. In an average year, TPWD department says it brings in only $200,000 to $400,000 statewide. It comes mostly from small scale mining (less than 1000 cubic yards) by people who want to build roads or pipelines across streams.
Goals of Regulations
As the number of applications for permits has increased, TPWD has established project guidelines such as seasonal restrictions that avoid or minimize impacts to recreational users; site-specific provisions to ensure channel stability; and best management practices to control bank erosion, avoid land loss, and reduce downstream impacts.
Read Over Your Morning Cup
The entire document is 2-pages, well-written, and well-illustrated. It will give you a good understanding of why the state started regulating sand mining in rivers long ago…all during your morning cup of coffee or tea. Highly recommended easy reading!
Posted by Bob Rehak on 4/19/2019
598 Days since Hurricane Harvey