While far from complete, Humble ISD contractors have made steady progress with the construction of the new Kingwood Middle School (KMS), despite heavy and steady rains in May, June and July. Back in late March, I reported that steel was going up. Since then, the contractors have finished erecting steel on 80-90% of the new KMS building.
I took all the photos below on 7/10/2021.
Overview of campus, looking south. Woodland Hills Blvd on right. The white area in the foreground appears to be roofing.
The new KMS is being built on the site of the old athletic fields. When complete, the old school will be demolished and the athletic fields will be relocated there.
A prominent feature of the new construction is a temporary detention pond (foreground) to reduce flood risk for neighbors. Looking NNW. Note the concrete slab between the detention pond and the crane, where contractors have not yet started erecting steel.The new building will be much taller and “airier” than the old one which had solid brick walls over most of the exterior.Portions will be 3-stories tall, letting more students learn on a smaller footprint. Looking north across old KMS campus toward new construction shows the variation in the respective footprints.
When demolition of the old KMS has finished, the temporary detention pond will reportedly turn into a permanent one near the location of the semi-circular drop off zone above.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/07/20210710-DJI_0038.jpg?fit=1200%2C799&ssl=17991200adminadmin2021-07-10 20:33:522021-07-10 20:33:56Contractors Almost Finished with Framing New KMS, Starting on Roof
At one of the first large public meetings since Covid began, several hundred people crowded into the Kingwood Community Center last night. They came to see the City unveil floodgate and dredging plans for Lake Houston. Stephen Costello, PE, the City’s Chief Recovery Officer, addressed dredging. And Chris Mueller, PhD, PE, of engineering firm Black & Veatch discussed adding more floodgates to the Lake Houston Dam. Mayor Pro Tem Dave Martin coordinated the meeting.
In late 2019, the Army Corps finished hydraulic dredging in the area south of the West Fork mouth bar. Then in early 2020, the City of Houston began mechanical dredging to extend the effort. In terms of the estimated dollars designated for dredging, the effort is about halfway done.
The first four rows on this chart are done or almost done. They total $114 million out of a projected total of $222 million.
Scope of Long-Range Dredging Plan Still in Development
A long-range dredging plan for Lake Houston is critical. We must understand where the sediment comes from, how fast it builds up, where it builds up, and the consequences of not removing it periodically.
The numbered dots in the photo above show channels south of the East and West Forks draining into Lake Houston where sediment can also build up.
Costello says the City is currently working with affected homeowner associations to discuss cost-sharing arrangements.
He also says that the City must identify a long-range site for depositing the spoils that is suitable for hydraulic dredging. He called the mechanical dredging now in progress “not sustainable.” Currently, the City is using Berry Madden’s property on the West Fork south of Kingwood’s River Grove Park to deposit the mechanical dredging spoils. That’s a long haul for barges on the East Fork.
Next Dredging Steps: Channel to East Fork and East Fork Itself
Contractors must next deepen the channel between the West and East Forks of the San Jacinto to move dredging equipment and spoils back and forth (see below).
Current location of dredging is near yellow dot.
From there, dredgers will move slightly north of where Luce Bayou (far right) enters the East Fork and begin dredging the East Fork mouth bar. See large circle above. The map shows that area grew shallower by up to nine feet between 2011 and 2018. Imelda, in September 2019, made it grow even shallower. Note the fresh deposits of sand in the photo below now poking up above the water.
Growth of East Fork Mouth Bar after Imelda in September 2019. Photo taken in November 2019.
Additional Floodgates for Lake Houston Dam
Chris Mueller of Black & Veatch then discussed the reasons for adding additional floodgates to Lake Houston, preliminary engineering findings, and an implementation schedule.
The primary objective: to increase the outflow capacity of the dam to reduce the risk of future flooding. However, he emphasized that reducing the risk for people upstream of the dam cannot have an adverse impact on people below it. See below.
He emphasized that Lake Houston is, first and foremost, a drinking water reservoir. He also emphasized that the dam is almost seventy years old and near the end of its useful life. Significant safety issues exist in working with such old concrete.
Calculating the Benefit/Cost Ratio of Additional Floodgates
Mueller then explained how FEMA calculates the benefit/cost ratio of additional floodgates.
On the benefit side, it considers: the reduction in water surface level; how many buildings and streets that will prevent from flooding; reduced societal impacts; and reduced impacts to business revenues. These are primarily damage costs avoided.
On the cost side of the equation, FEMA factors in construction costs and annual operation and maintenance costs.
To win project approval, the City must show that the benefits of additional floodgates exceed the costs in a 100-year storm, similar to Imelda. Such a storm elevates the lake 10 feet.
The peak inflow to Lake Houston in a 100-year storm: 286,000 cubic feet per second (CFS), enough to fill the Astrodome in 3 minutes! However, during Harvey, SJRA estimated the peak inflow at 400,000 cfs.
Proposed Alternative Produces 11-Inch Benefit Nearest Dam
A hydrologic and hydraulic analysis conducted by Black & Veatch will help prove up the benefit/cost analysis. The San Jacinto Watershed (including Buffalo Bayou) includes flow from eight counties.
In evaluating about ten alternatives for adding floodgates, Black & Veatch considered both cost and non-cost factors listed below.
The company’s first choice was to install additional gates on the earthen portion of the dam on the east side. But environmental considerations there would have delayed the project by a decade or more.
So they decided to recommend a 1,000 feet of crest gates on the west side of the spillway instead. See example of crest gates in operation below.
An air bladder near a bottom hinge raises or lowers the floodgatesto let water in/out
Such gates would increase the discharge capacity to 45,000 cfs, more than four times the current capacity of 10,000 cfs. That’s still only about a third of the discharge capacity of the floodgates on Lake Conroe. But according to Martin, that would still be enough to lower the level of the lake 4 feet in 24 hours.
However, before floodgate construction can begin, engineers must evaluate:
Downstream impacts and how to mitigate them
Impact to the stability of the existing concrete dam
Back in the 1950s when the Lake Houston dam was built, engineers did not use rebar. So this will be a delicate operation. Contractors must cut 6 feet into the existing spillway; cap the remaining concrete with a slab; and install the crest gates on top of the slab.
Black & Veatch must also develop an operations protocol for new floodgates that maximizes upstream benefits and limits downstream impacts. Mueller shared this schedule with attendees.
Best-Case Project Timeline Shows Completion in 2024
Schedule as of 7/8/2021.Detailed engineering could take another year.
A best-case scenario shows construction starting at the end of 2022 and finishing before the start of hurricane season in 2024. So, at least three more hurricane seasons to get through before seeing any benefit from additional gates.
After writing about flooding daily for nearly four years, I have developed some beliefs about how to reduce future flooding. In the last 20+ years, Harris County has spent more than $2.6 billion on flood mitigation. And I know one engineer who claims it could take another $50-60 billion to fix all of the County’s flooding problems. That raises the question, “Why aren’t we focusing more on preventing them in the first place?”
Changing Landscape of Flood Mitigation
Flood-mitigation projects alone can’t prevent future flooding because the landscape constantly changes. As population density increases, so does housing density, impervious cover, and runoff. As areas build out and land prices escalate, people often build homes in places they shouldn’t (floodways and floodplains). That puts others at risk. But the allure of having a water view, dazzles potential buyers who may not understand the risk of future flooding.
I once bought a new house on Spring Creek in a Dallas suburb. The home was supposed to be two feet above the hundred-year floodplain. It looked out over the Richardson golf course. My wife and I were ecstatic…until pickup trucks started floating down the creek on minor rains.
I managed to get a three-city commission started to look into the causes. The City Engineers from Garland, Richardson and Plano petitioned the Army Corps to re-survey the creek. They found that…
Instead of being 2 feet above the hundred-year floodplain, we were now 10 feet below it.
They pointed to Plano upstream from us. It was the fastest growing city in America at the time. They also pointed to the development of an 80-acre shopping mall just upstream from us.
With two small babies at the time, we decided that the beauty of the location no longer justified the risk. We put the home on the market, disclosed the flood problems, took a $35,000 hit on the sale (about 20% of the purchase price in those days), and moved to (please don’t laugh) Houston!
Urban Sprawl Increases Future Flood Risk For People in Center
Houston has grown even faster than Dallas. We are now completing the third ring of highways around the City. Just as development of areas around Beltway 8 contributed to flooding woes inside Loop 610, now, the Grand Parkway will contribute to flooding woes farther out.
Grand Parkway extension in Liberty County, photographed May 26, 2019.A magnet for future development.
Look Outward, Not Just Inward, to Reduce Future Flooding
This continued expansion demands that we look outward, not just inward to reduce future flooding. The counties around Harris have an opportunity now encourage development practices that respect the property rights of others. Those include, but are not limited to:
Preservation of green space and wetlands, nature’s sponges.
Adequately sized detention and retention ponds
Lining channels with grass to reduce erosion and sediment deposition downstream
Control of housing density
Use of green technologies in home building
If every new home and development “retained its rain,” no one downstream would face increased flood risk.
The mantra of floodplain managers
But, alas, that costs money. And for every ten thousand dollars that you increase the price of a home, you also price X number of people out of the market. Not just the home buying market, but the Houston market.
Cost of Land Can Be 40% of New Home’s Cost
According to one homebuilder, land now accounts for 40% of the cost of a new home. So, we constantly see pushback from developers who hire engineers willing to find a way to make questionable projects happen. And that’s how we get places like Colony Ridge – a development that didn’t exist 10 years ago that is now larger than any city in Liberty County – built on wetlands.
A small part of the Colony Ridge expansion now underway. Photo taken at end of June, 2021.
Ironically, Colony Ridge is just upstream from Luce Bayou which has received the least flood-mitigation funding since 2000.
Pay Now or Pay Later
Harris County Flood Control Capital Improvement Spending since 2000.
The Colony Ridge expansion area above will drain into Luce which runs through Huffman downstream. One can only guess how long it take for flooding to strike there and how long it will take to find a solution now that a developer has permanently altered the landscape and destroying even more wetlands.
Sensible regulation and enforcement could reduce future flooding risk at no cost to the public. But upstream county commissioners are eager to experience the financial freedom that a larger tax base will bring. And their residents aren’t eager to pay for someone else’s flood mitigation.
And that is why fighting future flooding will always be a two-front war.
Posted by Bob Rehak on 7/8/2021
1409 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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/06/20210303-RJR_5778.jpg?fit=1200%2C800&ssl=18001200adminadmin2021-07-08 14:52:052021-07-08 14:52:08To Reduce Future Flooding, We Need to Focus on BOTH Mitigation AND Root Causes
Contractors Almost Finished with Framing New KMS, Starting on Roof
While far from complete, Humble ISD contractors have made steady progress with the construction of the new Kingwood Middle School (KMS), despite heavy and steady rains in May, June and July. Back in late March, I reported that steel was going up. Since then, the contractors have finished erecting steel on 80-90% of the new KMS building.
I took all the photos below on 7/10/2021.
The new KMS is being built on the site of the old athletic fields. When complete, the old school will be demolished and the athletic fields will be relocated there.
When demolition of the old KMS has finished, the temporary detention pond will reportedly turn into a permanent one near the location of the semi-circular drop off zone above.
Humble ISD expects the school to open for the 2022 school year. For more information about the plans for the building, see the District’s web site. Find updates on other new construction from the 2018 bond here.
Posted by Bob Rehak on 7/10/21
1411 Days since Hurricane Harvey
Floodgate, Dredging Plans Unveiled
At one of the first large public meetings since Covid began, several hundred people crowded into the Kingwood Community Center last night. They came to see the City unveil floodgate and dredging plans for Lake Houston. Stephen Costello, PE, the City’s Chief Recovery Officer, addressed dredging. And Chris Mueller, PhD, PE, of engineering firm Black & Veatch discussed adding more floodgates to the Lake Houston Dam. Mayor Pro Tem Dave Martin coordinated the meeting.
To see both presentations, click here. Or see the summaries below.
Dredging: About Half Done
In late 2019, the Army Corps finished hydraulic dredging in the area south of the West Fork mouth bar. Then in early 2020, the City of Houston began mechanical dredging to extend the effort. In terms of the estimated dollars designated for dredging, the effort is about halfway done.
The last two rows on the chart above are estimates because they depend on bids currently in progress and a long-range plan not yet complete. The need for a long-term plan and maintenance dredging were identified early on by the Army Corps so that any benefits of dredging were not immediately wiped out by future sedimentation.
Scope of Long-Range Dredging Plan Still in Development
A long-range dredging plan for Lake Houston is critical. We must understand where the sediment comes from, how fast it builds up, where it builds up, and the consequences of not removing it periodically.
Costello says the City is currently working with affected homeowner associations to discuss cost-sharing arrangements.
He also says that the City must identify a long-range site for depositing the spoils that is suitable for hydraulic dredging. He called the mechanical dredging now in progress “not sustainable.” Currently, the City is using Berry Madden’s property on the West Fork south of Kingwood’s River Grove Park to deposit the mechanical dredging spoils. That’s a long haul for barges on the East Fork.
Next Dredging Steps: Channel to East Fork and East Fork Itself
Contractors must next deepen the channel between the West and East Forks of the San Jacinto to move dredging equipment and spoils back and forth (see below).
From there, dredgers will move slightly north of where Luce Bayou (far right) enters the East Fork and begin dredging the East Fork mouth bar. See large circle above. The map shows that area grew shallower by up to nine feet between 2011 and 2018. Imelda, in September 2019, made it grow even shallower. Note the fresh deposits of sand in the photo below now poking up above the water.
Additional Floodgates for Lake Houston Dam
Chris Mueller of Black & Veatch then discussed the reasons for adding additional floodgates to Lake Houston, preliminary engineering findings, and an implementation schedule.
The primary objective: to increase the outflow capacity of the dam to reduce the risk of future flooding. However, he emphasized that reducing the risk for people upstream of the dam cannot have an adverse impact on people below it. See below.
He emphasized that Lake Houston is, first and foremost, a drinking water reservoir. He also emphasized that the dam is almost seventy years old and near the end of its useful life. Significant safety issues exist in working with such old concrete.
Calculating the Benefit/Cost Ratio of Additional Floodgates
Mueller then explained how FEMA calculates the benefit/cost ratio of additional floodgates.
The peak inflow to Lake Houston in a 100-year storm: 286,000 cubic feet per second (CFS), enough to fill the Astrodome in 3 minutes! However, during Harvey, SJRA estimated the peak inflow at 400,000 cfs.
Proposed Alternative Produces 11-Inch Benefit Nearest Dam
A hydrologic and hydraulic analysis conducted by Black & Veatch will help prove up the benefit/cost analysis. The San Jacinto Watershed (including Buffalo Bayou) includes flow from eight counties.
In evaluating about ten alternatives for adding floodgates, Black & Veatch considered both cost and non-cost factors listed below.
The company’s first choice was to install additional gates on the earthen portion of the dam on the east side. But environmental considerations there would have delayed the project by a decade or more.
So they decided to recommend a 1,000 feet of crest gates on the west side of the spillway instead. See example of crest gates in operation below.
Such gates would increase the discharge capacity to 45,000 cfs, more than four times the current capacity of 10,000 cfs. That’s still only about a third of the discharge capacity of the floodgates on Lake Conroe. But according to Martin, that would still be enough to lower the level of the lake 4 feet in 24 hours.
However, before floodgate construction can begin, engineers must evaluate:
Back in the 1950s when the Lake Houston dam was built, engineers did not use rebar. So this will be a delicate operation. Contractors must cut 6 feet into the existing spillway; cap the remaining concrete with a slab; and install the crest gates on top of the slab.
Black & Veatch must also develop an operations protocol for new floodgates that maximizes upstream benefits and limits downstream impacts. Mueller shared this schedule with attendees.
Best-Case Project Timeline Shows Completion in 2024
A best-case scenario shows construction starting at the end of 2022 and finishing before the start of hurricane season in 2024. So, at least three more hurricane seasons to get through before seeing any benefit from additional gates.
Posted by Bob Rehak on 7/9/2021
1410 Days since Hurricane Harvey
To Reduce Future Flooding, We Need to Focus on BOTH Mitigation AND Root Causes
After writing about flooding daily for nearly four years, I have developed some beliefs about how to reduce future flooding. In the last 20+ years, Harris County has spent more than $2.6 billion on flood mitigation. And I know one engineer who claims it could take another $50-60 billion to fix all of the County’s flooding problems. That raises the question, “Why aren’t we focusing more on preventing them in the first place?”
Changing Landscape of Flood Mitigation
Flood-mitigation projects alone can’t prevent future flooding because the landscape constantly changes. As population density increases, so does housing density, impervious cover, and runoff. As areas build out and land prices escalate, people often build homes in places they shouldn’t (floodways and floodplains). That puts others at risk. But the allure of having a water view, dazzles potential buyers who may not understand the risk of future flooding.
When neighborhoods flood, community groups demand action. Someone commissions an engineering study. Years later, the engineers quote an often astronomical cost for flood-mitigation projects. Finding the money can take years longer. Or lead to a frustrating dead end and repeat flooding.
Unwitting Flood Victim: A Personal Story
I once bought a new house on Spring Creek in a Dallas suburb. The home was supposed to be two feet above the hundred-year floodplain. It looked out over the Richardson golf course. My wife and I were ecstatic…until pickup trucks started floating down the creek on minor rains.
I managed to get a three-city commission started to look into the causes. The City Engineers from Garland, Richardson and Plano petitioned the Army Corps to re-survey the creek. They found that…
They pointed to Plano upstream from us. It was the fastest growing city in America at the time. They also pointed to the development of an 80-acre shopping mall just upstream from us.
With two small babies at the time, we decided that the beauty of the location no longer justified the risk. We put the home on the market, disclosed the flood problems, took a $35,000 hit on the sale (about 20% of the purchase price in those days), and moved to (please don’t laugh) Houston!
Urban Sprawl Increases Future Flood Risk For People in Center
Houston has grown even faster than Dallas. We are now completing the third ring of highways around the City. Just as development of areas around Beltway 8 contributed to flooding woes inside Loop 610, now, the Grand Parkway will contribute to flooding woes farther out.
Look Outward, Not Just Inward, to Reduce Future Flooding
This continued expansion demands that we look outward, not just inward to reduce future flooding. The counties around Harris have an opportunity now encourage development practices that respect the property rights of others. Those include, but are not limited to:
But, alas, that costs money. And for every ten thousand dollars that you increase the price of a home, you also price X number of people out of the market. Not just the home buying market, but the Houston market.
Cost of Land Can Be 40% of New Home’s Cost
According to one homebuilder, land now accounts for 40% of the cost of a new home. So, we constantly see pushback from developers who hire engineers willing to find a way to make questionable projects happen. And that’s how we get places like Colony Ridge – a development that didn’t exist 10 years ago that is now larger than any city in Liberty County – built on wetlands.
Ironically, Colony Ridge is just upstream from Luce Bayou which has received the least flood-mitigation funding since 2000.
Pay Now or Pay Later
The Colony Ridge expansion area above will drain into Luce which runs through Huffman downstream. One can only guess how long it take for flooding to strike there and how long it will take to find a solution now that a developer has permanently altered the landscape and destroying even more wetlands.
Sensible regulation and enforcement could reduce future flooding risk at no cost to the public. But upstream county commissioners are eager to experience the financial freedom that a larger tax base will bring. And their residents aren’t eager to pay for someone else’s flood mitigation.
And that is why fighting future flooding will always be a two-front war.
Posted by Bob Rehak on 7/8/2021
1409 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.