9/25/23 – Approximately 425,000 people live in the 204 square mile Cypress Creek watershed which has severe repetitive flooding. At a press conference this morning, County, State and Federal officials announced $50 million in funding for a massive complex of stormwater detention basins on Cypress Creek at T.C. Jester Blvd. to help protect those people.
The basins will span approximately 150 acres on both sides of T.C. Jester and include 1200-acre feet of planned stormwater detention capacity, wet bottoms, and recreational trails.
Approximate boundaries of three detention basins – one will go west of TC Jester and two more east.White area is existing basin.
Altogether, the stormwater detention capacity in this area will increase approximately 75X.
Google Earth calculation of existing and planned ponds
The existing pond covers approximately 2 acres and the new areas will cover more than 150.
Looking E over T.C. Jester. Existing 2-acre basin in foreground was site of press conference. Wooded area beyond will become two new detention basins.
Thanks to County, State and Federal Governments
The $50 million will come from three primary sources:
State Representative Sam Harless secured $12 million in State of Texas funding.
Harris County Flood Control District Executive Director Tina Petersen also reminded everyone of the money designated for Cypress Creek in the Flood Bond, which was considerable.
The GLO/HUD money has been requested but not yet confirmed although all indications are positive at this time. GLO Commissioner Dawn Buckingham has committed to making sure that people in all parts of Harris County benefit from the $750 million.
Timetable and Project Scope
HCFCD Director Dr. Petersen addressed the next steps in the projects. “A portion of the projects on the east side of T.C. Jester will start construction in the next 6 to 9 months. The remainder should go into construction no later than the end of 2024. So we’re going to see these projects move quickly. This type of progress would not have been possible without the critical funding that our Congressman and Representative secured “
The overall project includes three stormwater detention basins within a broader footprint. Two basin compartments are on the east side of T.C. Jester Boulevard and another is on the west side.
Excavation of the west side basin (see below) has already begun under an E&R (Excavation and Removal) Contract. A private contractor is removing the dirt, almost free of charge, then selling it at market rates to recoup costs and make a profit. An estimated 120,000 cubic yards of material has already been excavated to date.
Work to date on basin west of T.C. Jester. Looking N toward Cypresswood Drive.
The contractor began removing dirt in the general area to get a head start on construction, even before final design of the basin. The final design will begin soon.
Each basin will have a wet-bottom with maintenance berms, side slopes and high banks along the outside.
Construction for all basins should begin no later than Q4 2024. They have estimated 8-month construction timelines.
Extent of Benefits
The three stormwater detention basins will work together – taking stormwater from the main stem of Cypress Creek and holding it until water levels recede on the main stem.
The projects will also have recreational benefits such as hike and bike trails.
Director Petersen stated that the projects will primarily benefit the local area, i.e., benefits will not extend very far downstream. The 1200 acre feet will likely take several thousand homes out of the floodplain.
Even though those homes will be in the Cypress Creek area, 1200 acre feet being held back upstream is 1200 acre feet that won’t be in the living rooms of Lake Houston Area residents during the next big flood.
More to Come
Ramsey also pointed to more projects to come, though he didn’t elaborate. He said, “This is $50 million of the $100 million that will be spent over the coming months in the Cypress watershed. So hold on. We’re getting started. This isn’t the end. This is the beginning.”
Speakers at T.C. Jester Detention Basin Press Conference included U.S. Representative Dan Crenshaw, State Representative Sam Harless, Harris County Precinct 3 Commissioner Tom Ramsey P.E., and HCFCD Executive Director Dr. Tina Petersen.
Posted by Bob Rehak on 9/25/2023
2218 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/09/20230925-RJR_2415.jpg?fit=1100%2C733&ssl=17331100adminadmin2023-09-25 17:58:212023-09-25 22:11:13Funding Announced for Massive Detention-Basin Complex on Cypress Creek
The book is primarily targeted to flood-project managers and city officials. However, the informative illustrations and easy-to-understand writing make it a useful primer for anyone who wants to become more knowledgeable about flooding.
The World Bank bills the handbook as a “roadmap for conducting an urban flood risk assessment in any city in the world.”
What will the average person get from it? The ability to understand flood professionals, the issues they face, and how they evaluate problems/solutions.
It also made me realize that Harris County’s equity framework, which the county uses to allocate flood-mitigation funds, fails to incorporate many factors recommended by the Department of Homeland Security and others.
Outline of Handbook
The book contains five chapters.
Chapters cover the following sub-topics.
Intro and Chapter 1: Defining Risk
Much of the book has a checklist quality to it. For instance, what should professionals quantify when defining flood risk?
Hazards and their probabilities
Exposure – an inventory of elements and activities affected by hazards, for instance:
The population and its assets such as homes and belongings, private businesses, and industrial assets
Infrastructure such as roads, drinking water, sanitation, drainage, and flood protection infrastructure
Public infrastructure like health care and school facilities
Environmental and cultural assets
Economic activities.
Vulnerability – the degree to which people, property and infrastructure can be adversely affected
Here, for instance, I was surprised to learn that Harris County’s equity framework considered some, but not all of the factors that make areas vulnerable. For instance, it doesn’t really incorporate infrastructure!
Chapter Two: Hazard Assessment
The chapter on Hazard Assessment begins with a list of “boundary conditions” typically used within a flood model.
Five conditions typically include: (1) rainfall, (2) infiltration, (3) flow, (4) water levels and waves, and (5) pumps and flow control structures.
But just measuring rainfall can be difficult depending on the number and types of gages in use. “Most meteorological services only provide daily values (mostly from manual gauges), which provide part of the overall rainfall characteristics. However, the distribution and intensity within a single day are essential,” say the authors.
Automated gages that can measure short (sub-daily) periods are critical in informing regulations that affect the design of infrastructure. Short, high-intensity bursts are a significant factor in urban flooding. However, many areas have gages measured manually once per day. (The Flood Control District’s are all automated.)
As I scanned the text of this chapter, flashbacks from Harvey kept recurring. When I read this sentence, I thought of the Lake Conroe discharge designed to prevent the flooding of Lake Conroe homes. “Discharge rates from control gates normally relate to both upstream and downstream water levels…” [Emphasis added.] Did the dam operators consider downstream water levels at the time? The case is still pending in the courts.
In chapter 2, I also found the most illuminating discussion of differences between 1D, 2D and 3D modeling that I have ever read.
Ditto for a description of Manning’s Coefficient, which is used to estimate the impact of friction on the speed of water, which in turn affects the rate of accumulation and flood height.
Illustration of Mannings Roughness Coefficient and friction’s impact on speed of floodwater.
Trees and buildings create friction for floodwater that slows it down. But concrete and clear-cutting speed it up.
Such information is used to quantify the potential consequences of flooding to homes, businesses, and people across an area.
Chapter 3: Risk Assessment
Chapter 3 focuses on Risk Assessment and lists types of infrastructure that the Department of Homeland Security defines as “critical sectors.”
Again, Harris County’s Equity Framework (used to distribute flood-mitigation funds) considers none of these.
Chapter 4: Interventions
Chapter 4 discusses types of interventions (solutions to flooding). They fall into three main categories.
The chapter then addresses the limitations, applicability, costs, benefits, and environmental/social impacts of each.
It’s too complicated to summarize here. But it’s fascinating to see how flood professionals evaluate the range of options.
Conclusion
The last chapter addresses the business side of flood mitigation, i.e., bidding jobs. I’ll skip that here and close by saying this. Even after studying flooding for six years, I felt lights turning on almost every time I turned a page in this book.
I had a high level understanding of most of the concepts. But this gave me a much fuller understanding. I found myself constantly thinking, “Aha, so that’s how that fits in.”
Social media has been abuzz this week about the Northpark Drive entry to Kingwood. As contractors removed trees from the north side of the road to make room for a detention pond, many people complained.
But it’s important to remember why we’re improving Northpark: to accommodate increased traffic and to create a reliable, all-weather evacuation route. In that regard, the Lake Houston Redevelopment Authority (LHRA) must balance three conflicting needs: flood mitigation, saving trees and cost. Let’s look at how each relates to the objectives.
Reliable, All-Weather Evacuation Route
During Harvey, Hamblen Road, Kingwood Drive and Northpark were all blocked by rising floodwaters. That forced many people to try to snake out of Kingwood through Porter…if they could get there. Many couldn’t.
For decades, we’ve also worried about the possibility of a train disaster that could block off Kingwood’s exits. The longer trains that Union Pacific runs now can block multiple exits simultaneously. The longest trains stretch for more than three miles. And if there were a derailment or toxic spill, it would be difficult getting people to safety.
Raising the elevation of Northpark between Bens Branch and the Kingwood Diversion Ditch eliminates the first problem. And building the bridge over the tracks at 494 eliminates the second.
Finally, widening the road will enable more vehicles to evacuate faster.
Flood-Mitigation Enhancements
All that extra concrete to expand the road, however, reduces rainwater infiltration and increases runoff. To keep the road from flooding, engineers calculated they needed 22 acre feet of stormwater detention capacity near US59.
The solution: build two permanent ponds, one each on the north and south sides of 59 where the groves of trees were. TxDoT already owned the land. So it was available at no cost.
Looking N toward Kroger Center. Clearing for N pond completed. Clearing for S pond (bottom right) begins next week.
Water will permanently fill the ponds, just like those at Kingwood Drive. The difference between the normal water surface elevation and the lip of the ponds will equal 22 acre feet. The size of the ponds will keep that gap at an aesthetically pleasing level.
Looking S. Note the protective fencing around the remaining trees. Additional trees may be stored temporarily in the foreground.
Said another way, the ponds will look like decorative enhancements but serve a vital purpose that few realize.
The outline you see in the photo below will match the perimeter of the pond.
No more trees will be cut for this pond. The area cleared represents the final outline of the pond.
The layout below shows how the ponds should look when completed.
According to Ralph De Leon, project manager, “Enough trees will remain to form a pleasing backdrop for the pond, screen the visually noisy area behind them, and create a good first impression for visitors.”
From 30 feet, you can barely see the shopping center behind the trees. From ground level, it will be completely screened.
It’s important to remember that when KSA revised the Kingwood entries after TxDoT widened 59, many people wanted ponds at Northpark. They complained that KSA was neglecting Northpark compared to Kingwood Drive.
Many trees are being transplanted. But that’s an expensive proposition; the trees have grown since LHRA first prepared estimates two years ago.
“We’ve already identified the trees that will be saved,” De Leon continued. “Some will move to their permanent location immediately. Others will be stored temporarily at staging locations until the road construction gets further along. Then they’ll be moved to their permanent positions.”
The landscape architects, contractor, and LHRA are evaluating each tree individually. Their objective is to save as many as possible. But dollars pose a constraint.
Cost Limitations
De Leon also says “The cost to move each tree is roughly $11,000. We can’t afford to move the truly huge trees. They cost up to $100,000 per tree. And we just don’t have a budget for those.”
Machines like these will move trees that range from 4″ to 17″ in diameter.Photo courtesy of Davey Tree Company.
To maximize aesthetics, the Redevelopment Authority will relocate a mix of trees, such as oaks and pines.
The trees that will move have already been inventoried and tagged.
Update on Water-Line and Utility Conflicts
In my last Northpark post, I pointed out two conflicts holding up construction of the median farther east – one with a water line to a new church near Russell-Palmer Road and a second with CenterPoint.
The City of Houston has agreed to let the Redevelopment Authority’s contractor design a workaround for the water line that interfered with the placement of box culverts. Contractors left a gap big enough for two sections of culvert and a coffer dam to keep dirt from collapsing into the hole.
Because the culvert is tongue-in-groove, contractors also left enough room for a collar. That will allow the two new sections to slide into place. It will also prevent leaks in any gap that remains.
Regarding the CenterPoint gas line running down the center of the ditch at different depths, CenterPoint decided to move the whole line out of the culvert to the south side of the road. Inbound drivers may notice long lengths of welded blue pipe stacked up between Russell-Palmer and Kings Mill. That’s what that is for.
Next Steps
Contractors will start removing trees for the south entry pond at 59 during the week of 9/24/23. Here is the latest revised schedule. Check back often for more updates as they happen.
Funding Announced for Massive Detention-Basin Complex on Cypress Creek
9/25/23 – Approximately 425,000 people live in the 204 square mile Cypress Creek watershed which has severe repetitive flooding. At a press conference this morning, County, State and Federal officials announced $50 million in funding for a massive complex of stormwater detention basins on Cypress Creek at T.C. Jester Blvd. to help protect those people.
The basins will span approximately 150 acres on both sides of T.C. Jester and include 1200-acre feet of planned stormwater detention capacity, wet bottoms, and recreational trails.
The existing pond covers approximately 2 acres and the new areas will cover more than 150.
Thanks to County, State and Federal Governments
The $50 million will come from three primary sources:
Harris County Flood Control District Executive Director Tina Petersen also reminded everyone of the money designated for Cypress Creek in the Flood Bond, which was considerable.
The GLO/HUD money has been requested but not yet confirmed although all indications are positive at this time. GLO Commissioner Dawn Buckingham has committed to making sure that people in all parts of Harris County benefit from the $750 million.
Timetable and Project Scope
HCFCD Director Dr. Petersen addressed the next steps in the projects. “A portion of the projects on the east side of T.C. Jester will start construction in the next 6 to 9 months. The remainder should go into construction no later than the end of 2024. So we’re going to see these projects move quickly. This type of progress would not have been possible without the critical funding that our Congressman and Representative secured “
The overall project includes three stormwater detention basins within a broader footprint. Two basin compartments are on the east side of T.C. Jester Boulevard and another is on the west side.
Excavation of the west side basin (see below) has already begun under an E&R (Excavation and Removal) Contract. A private contractor is removing the dirt, almost free of charge, then selling it at market rates to recoup costs and make a profit. An estimated 120,000 cubic yards of material has already been excavated to date.
The contractor began removing dirt in the general area to get a head start on construction, even before final design of the basin. The final design will begin soon.
Each basin will have a wet-bottom with maintenance berms, side slopes and high banks along the outside.
Construction for all basins should begin no later than Q4 2024. They have estimated 8-month construction timelines.
Extent of Benefits
The three stormwater detention basins will work together – taking stormwater from the main stem of Cypress Creek and holding it until water levels recede on the main stem.
The projects will also have recreational benefits such as hike and bike trails.
Director Petersen stated that the projects will primarily benefit the local area, i.e., benefits will not extend very far downstream. The 1200 acre feet will likely take several thousand homes out of the floodplain.
Even though those homes will be in the Cypress Creek area, 1200 acre feet being held back upstream is 1200 acre feet that won’t be in the living rooms of Lake Houston Area residents during the next big flood.
More to Come
Ramsey also pointed to more projects to come, though he didn’t elaborate. He said, “This is $50 million of the $100 million that will be spent over the coming months in the Cypress watershed. So hold on. We’re getting started. This isn’t the end. This is the beginning.”
Posted by Bob Rehak on 9/25/2023
2218 Days since Hurricane Harvey
Review: Urban Flood Risk Handbook
The World Bank recently published the 177-page Urban Flood Risk Handbook: Assessing and Identifying Interventions by Scott Ferguson, Mathijs van Ledden, Steven Rubinyi, Ana Campos, and Tess Doeffinger.
The book is primarily targeted to flood-project managers and city officials. However, the informative illustrations and easy-to-understand writing make it a useful primer for anyone who wants to become more knowledgeable about flooding.
The World Bank bills the handbook as a “roadmap for conducting an urban flood risk assessment in any city in the world.”
What will the average person get from it? The ability to understand flood professionals, the issues they face, and how they evaluate problems/solutions.
It also made me realize that Harris County’s equity framework, which the county uses to allocate flood-mitigation funds, fails to incorporate many factors recommended by the Department of Homeland Security and others.
Outline of Handbook
The book contains five chapters.
Chapters cover the following sub-topics.
Intro and Chapter 1: Defining Risk
Much of the book has a checklist quality to it. For instance, what should professionals quantify when defining flood risk?
Here, for instance, I was surprised to learn that Harris County’s equity framework considered some, but not all of the factors that make areas vulnerable. For instance, it doesn’t really incorporate infrastructure!
Chapter Two: Hazard Assessment
The chapter on Hazard Assessment begins with a list of “boundary conditions” typically used within a flood model.
Five conditions typically include: (1) rainfall, (2) infiltration, (3) flow, (4) water levels and waves, and (5) pumps and flow control structures.
But just measuring rainfall can be difficult depending on the number and types of gages in use. “Most meteorological services only provide daily values (mostly from manual gauges), which provide part of the overall rainfall characteristics. However, the distribution and intensity within a single day are essential,” say the authors.
Automated gages that can measure short (sub-daily) periods are critical in informing regulations that affect the design of infrastructure. Short, high-intensity bursts are a significant factor in urban flooding. However, many areas have gages measured manually once per day. (The Flood Control District’s are all automated.)
As I scanned the text of this chapter, flashbacks from Harvey kept recurring. When I read this sentence, I thought of the Lake Conroe discharge designed to prevent the flooding of Lake Conroe homes. “Discharge rates from control gates normally relate to both upstream and downstream water levels…” [Emphasis added.] Did the dam operators consider downstream water levels at the time? The case is still pending in the courts.
In chapter 2, I also found the most illuminating discussion of differences between 1D, 2D and 3D modeling that I have ever read.
Ditto for a description of Manning’s Coefficient, which is used to estimate the impact of friction on the speed of water, which in turn affects the rate of accumulation and flood height.
Trees and buildings create friction for floodwater that slows it down. But concrete and clear-cutting speed it up.
Such information is used to quantify the potential consequences of flooding to homes, businesses, and people across an area.
Chapter 3: Risk Assessment
Chapter 3 focuses on Risk Assessment and lists types of infrastructure that the Department of Homeland Security defines as “critical sectors.”
Again, Harris County’s Equity Framework (used to distribute flood-mitigation funds) considers none of these.
Chapter 4: Interventions
Chapter 4 discusses types of interventions (solutions to flooding). They fall into three main categories.
The chapter then addresses the limitations, applicability, costs, benefits, and environmental/social impacts of each.
It’s too complicated to summarize here. But it’s fascinating to see how flood professionals evaluate the range of options.
Conclusion
The last chapter addresses the business side of flood mitigation, i.e., bidding jobs. I’ll skip that here and close by saying this. Even after studying flooding for six years, I felt lights turning on almost every time I turned a page in this book.
I had a high level understanding of most of the concepts. But this gave me a much fuller understanding. I found myself constantly thinking, “Aha, so that’s how that fits in.”
And it’s a free download!
Kudos to the World Bank and the authors. They have provided a valuable addition to the literature.
Posted by Bob Rehak on 9/24/23
2217 Days since Hurricane Harvey
Used with permission of World Bank
Northpark Entry Plan Balances Flood Mitigation, Saving Trees, Cost
Social media has been abuzz this week about the Northpark Drive entry to Kingwood. As contractors removed trees from the north side of the road to make room for a detention pond, many people complained.
But it’s important to remember why we’re improving Northpark: to accommodate increased traffic and to create a reliable, all-weather evacuation route. In that regard, the Lake Houston Redevelopment Authority (LHRA) must balance three conflicting needs: flood mitigation, saving trees and cost. Let’s look at how each relates to the objectives.
Reliable, All-Weather Evacuation Route
During Harvey, Hamblen Road, Kingwood Drive and Northpark were all blocked by rising floodwaters. That forced many people to try to snake out of Kingwood through Porter…if they could get there. Many couldn’t.
For decades, we’ve also worried about the possibility of a train disaster that could block off Kingwood’s exits. The longer trains that Union Pacific runs now can block multiple exits simultaneously. The longest trains stretch for more than three miles. And if there were a derailment or toxic spill, it would be difficult getting people to safety.
Raising the elevation of Northpark between Bens Branch and the Kingwood Diversion Ditch eliminates the first problem. And building the bridge over the tracks at 494 eliminates the second.
Finally, widening the road will enable more vehicles to evacuate faster.
Flood-Mitigation Enhancements
All that extra concrete to expand the road, however, reduces rainwater infiltration and increases runoff. To keep the road from flooding, engineers calculated they needed 22 acre feet of stormwater detention capacity near US59.
The solution: build two permanent ponds, one each on the north and south sides of 59 where the groves of trees were. TxDoT already owned the land. So it was available at no cost.
Water will permanently fill the ponds, just like those at Kingwood Drive. The difference between the normal water surface elevation and the lip of the ponds will equal 22 acre feet. The size of the ponds will keep that gap at an aesthetically pleasing level.
Said another way, the ponds will look like decorative enhancements but serve a vital purpose that few realize.
The outline you see in the photo below will match the perimeter of the pond.
The layout below shows how the ponds should look when completed.
Saving Trees
According to Ralph De Leon, project manager, “Enough trees will remain to form a pleasing backdrop for the pond, screen the visually noisy area behind them, and create a good first impression for visitors.”
It’s important to remember that when KSA revised the Kingwood entries after TxDoT widened 59, many people wanted ponds at Northpark. They complained that KSA was neglecting Northpark compared to Kingwood Drive.
Many trees are being transplanted. But that’s an expensive proposition; the trees have grown since LHRA first prepared estimates two years ago.
“We’ve already identified the trees that will be saved,” De Leon continued. “Some will move to their permanent location immediately. Others will be stored temporarily at staging locations until the road construction gets further along. Then they’ll be moved to their permanent positions.”
The landscape architects, contractor, and LHRA are evaluating each tree individually. Their objective is to save as many as possible. But dollars pose a constraint.
Cost Limitations
De Leon also says “The cost to move each tree is roughly $11,000. We can’t afford to move the truly huge trees. They cost up to $100,000 per tree. And we just don’t have a budget for those.”
To maximize aesthetics, the Redevelopment Authority will relocate a mix of trees, such as oaks and pines.
Update on Water-Line and Utility Conflicts
In my last Northpark post, I pointed out two conflicts holding up construction of the median farther east – one with a water line to a new church near Russell-Palmer Road and a second with CenterPoint.
The City of Houston has agreed to let the Redevelopment Authority’s contractor design a workaround for the water line that interfered with the placement of box culverts. Contractors left a gap big enough for two sections of culvert and a coffer dam to keep dirt from collapsing into the hole.
Because the culvert is tongue-in-groove, contractors also left enough room for a collar. That will allow the two new sections to slide into place. It will also prevent leaks in any gap that remains.
Regarding the CenterPoint gas line running down the center of the ditch at different depths, CenterPoint decided to move the whole line out of the culvert to the south side of the road. Inbound drivers may notice long lengths of welded blue pipe stacked up between Russell-Palmer and Kings Mill. That’s what that is for.
Next Steps
Contractors will start removing trees for the south entry pond at 59 during the week of 9/24/23. Here is the latest revised schedule. Check back often for more updates as they happen.
Posted by Bob Rehak on 9/23/23
2216 Days since Hurricane Harvey