SJRA directors will consider accepting grant funding for three flood-mitigation studies at their board meeting on Thursday, 7/22/21. The studies include:
A joint reservoir operations study between Lake Conroe and Lake Houston
An upper San Jacinto Watershed regional sedimentation study
A conceptual engineering feasibility study for flood-control dams in the Spring Creek Watershed
The board will also consider executing escrow agreements related to each grant. TWDB grants work on a reimbursement basis. At the start of the project, TWDB puts the grant money into an escrow account. Then funds are drawn down as vendors submit invoices and TWDB approves them.
I posted previously about grant applications for these projects. Now that the grants have been approved, work can actually begin once the board agrees to accept the money. See details below about each project.
Joint Reservoir Operations Study
The addition of 1000-feet of crest gates to the Lake Houston Dam is a game changer for the way reservoirs on the San Jacinto work together. Right now, the gates on Lake Houston have a discharge capacity of only 10,000 cubic feet per second (CFS). The discharge capacity of the crest gates would increase that by more than 4X to 45,000 cfs. It’s still not the 150,000 CFS of Lake Conroe gates, but percentage-wise it’s much closer.
Thus, operators need to re-examine how best to synchronize their operations and plans. For instance, pre-releasing water in advance of a storm might be more viable now as a flood-mitigation strategy.
Another element of this study is a “flow forecasting tool.” It would predict rises in Lake Houston depending on the flow rates in tributaries during major storms. Matt Barrett, SJRA’s flood-mitigation director, says this tool could be useful for flood warnings and evacuations. If you knew that lake water would rise X feet in Y hours, and that your slab was a foot below X, you’d know exactly how much time you had to pack up your valuables and get out.
This study is being conducted with help from the Cities of Houston and Humble.
Upper San Jacinto Basin Sedimentation Study
The upper basin of the San Jacinto River includes everything above Lake Houston. This study has three goals:
Understand where the sediment is coming from
Learn where it ends up
Develop a management plan to handle it.
For the record, here is the scope of work. Note that stakeholder input and public meetings will be a big component of this project (Task 2). Tasks 3 and 6 include evaluation of sand mines. And Task 7 includes “Sand and Gravel Mining Best Management Practices.”
The San Jacinto West Fork has more than 20-square miles of sand mines in the 20-mile stretch between I-69 and I-45, exposing a swath of sediment averaging a mile wide.
The sedimentation study is being conducted with financial help from the Cities of Houston and Humble, and the Harris County Flood Control District.
A related sand-trap study is nearly complete. The SJRA should release it next month for public input.
Spring Creek Flood Control Dam Feasibility Study
About a year ago, SJRA applied for a TWDB grant to study the feasibility of building two flood control dams in the upper Spring Creek Watershed. The partners identified two preferred locations from a previous siting study that considered dozens. The two included Walnut and Birch Creek tributaries.
The objective now: to see whether the benefits justify the costs. Said another way, will the dams reduce flooding and protect enough structures to make the cost of building them worthwhile?
Together, they would have a combined capacity of 20,000 acre feet. That’s significant. But it would provide more benefit to people in the upper Spring Creek watershed than the Lake Houston Area.
The scope of work includes:
Environmental due diligence
Site investigations
Literature and mapping review
Permitting requirement investigations
Desktop surveys/assessments
Preliminary coordination with permitting agency
Conceptual design of dams to determine feasibility – geotechnical borings, alternative configurations development, H&H modeling analysis, etc.
Cost estimate development – dam construction costs, as well as costs related to land acquisition, utility conflicts and relocations, environmental mitigation, O&M, etc.
Update benefit/cost ratios (BCR) from SJRWMDP using data developed as part of this effort.
Partners in this effort include the SJRA, HCFCD, City of Humble, and five municipal utility districts. To learn more about these projects and others, consult pages 19 and 21 of this PDF.
To View or Participate in the Board Meeting
The SJRA board meeting starts at 8am.
If you choose to participate via webinar, register at this link and use webinar ID 950-202-179.
If you use the GoToWebinar App, you will have the opportunity to provide public comments.
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/2021/07/DJI_0724.jpg?fit=1200%2C900&ssl=19001200adminadmin2021-07-21 21:13:052021-07-21 21:36:38SJRA to Consider Three Flood-Mitigation Studies Thursday
Looking north across Woodridge Village toward Porter from over the Harris/Montgomery County line. The abandoned development currently has five detention ponds that will hold about 60% of the rain in an Atlas-14 100-year storm.
Currently, Idcus, Inc., an engineering company, has been contracted to look at:
Whether existing detention and proposed channel improvements would suffice to mitigate flooding
Whether expanding existing detention would eliminate the need for channel improvements
A combination of the two scenarios above – determining the amount of additional detention and channel improvements necessary to ensure no adverse impact all the way to Lake Houston.
Out-of-the-box alternatives that ensure no adverse impact while maximizing flood mitigation and minimizing construction costs.
The Idcus contract calls for the company to deliver channel and basin layouts for Taylor Gully no later than 300 days from the notice to proceed, which presumably was given in early July. However, excavation could start much sooner than that. (See below.)
Pieces of Puzzle Falling into Place
The no-cost contract with Sprint lets them set their own timetable as long as they complete improvements within three years. Sprint’s timetable will be driven by the company’s ability to sell the material they excavate; that forms their compensation.
The next step is for Harris County Flood Control District (HCFCD) to provide a grading plan to the contractor. While that will not happen tomorrow, the good news is that it won’t require waiting 300 days.
HCFCD can start excavating the retention pond before plans are finalized. After all, it’s not a problem if a detention pond holds more than the minimum required. It’s only a problem if it holds less. Engineers and contractors can adjust plans if necessary after excavation starts. This approach should minimize flood risk for worried Elm Grove and North Kingwood Forest residents.
All the pieces of the puzzle are starting to fall into place.
Posted by Bob Rehak on 7/21/2021
1422 Days since Hurricane Harvey
00adminadmin2021-07-21 12:14:542021-07-21 15:11:21Commissioners Approve Excavation Contract for Regional Detention Pond on Taylor Gully
Tuesday, 7.20.21, Harris County Commissioners will vote on a contract with Sprint Sand & Clay for excavation of a Woodridge Village detention basin. Item #21-3394 on the agenda is only for $1000, but it gives the contractor the right to enter the site and begin removing up to 500,000 cubic yards of dirt (at no cost to HCFCD) which it can then sell.
Backup provided to commissioners states that “This benefits the District because excavation and removal is always the highest cost of any stormwater detention basin that is constructed.”
Amount of excavation TBD – somewhere between 20,000 and 500,000 cubic yards, depending on plans that HCFCD will deliver to the contractor based on the outcome on an engineering study currently underway.
The contractor must properly dispose of the spoils, which it is allowed to sell to make its money on the contract.
Contractor is liable for any materials that are disposed of improperly, i.e., within Base Flood Elevation or the 500-year flood plain and must identify all disposal locations.
Time allowed: 3 years.
Termination of contract possible if contractor fails to excavate a minimum average of 5,000 cubic yards every month.
Contractor responsible for environmental mitigation if necessary, excluding wetlands.
The contractor must provide an approved Stormwater Pollution Prevention Plan and abide by it.
The contract outline contains the map above but does not specify the exact size, depth or location of the proposed work within the outlined area – just that it will occur in Montgomery County. Engineers will supply additional details at a later date.
Looking SE across Woodridge Village toward Elm Grove and North Kingwood Forest, areas where hundreds of homes flooded badly in 2019 – twice. Photo taken May 26, 2021.
Sprint Sand and Clay is a regular contractor for HCFCD. Currently, the company is excavating the massive Cutten Detention Basin near 290, Beltway 8 and Cutten Road.
Posted by Bob Rehak on 7/20/21
1421 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/07/20210526-RJR_8313.jpg?fit=1200%2C800&ssl=18001200adminadmin2021-07-19 21:34:452021-07-19 21:41:04Commissioners Vote Tuesday on Contract for Woodridge Village Detention Pond Excavation
SJRA to Consider Three Flood-Mitigation Studies Thursday
SJRA directors will consider accepting grant funding for three flood-mitigation studies at their board meeting on Thursday, 7/22/21. The studies include:
The board will also consider executing escrow agreements related to each grant. TWDB grants work on a reimbursement basis. At the start of the project, TWDB puts the grant money into an escrow account. Then funds are drawn down as vendors submit invoices and TWDB approves them.
I posted previously about grant applications for these projects. Now that the grants have been approved, work can actually begin once the board agrees to accept the money. See details below about each project.
Joint Reservoir Operations Study
The addition of 1000-feet of crest gates to the Lake Houston Dam is a game changer for the way reservoirs on the San Jacinto work together. Right now, the gates on Lake Houston have a discharge capacity of only 10,000 cubic feet per second (CFS). The discharge capacity of the crest gates would increase that by more than 4X to 45,000 cfs. It’s still not the 150,000 CFS of Lake Conroe gates, but percentage-wise it’s much closer.
Thus, operators need to re-examine how best to synchronize their operations and plans. For instance, pre-releasing water in advance of a storm might be more viable now as a flood-mitigation strategy.
Another element of this study is a “flow forecasting tool.” It would predict rises in Lake Houston depending on the flow rates in tributaries during major storms. Matt Barrett, SJRA’s flood-mitigation director, says this tool could be useful for flood warnings and evacuations. If you knew that lake water would rise X feet in Y hours, and that your slab was a foot below X, you’d know exactly how much time you had to pack up your valuables and get out.
This study is being conducted with help from the Cities of Houston and Humble.
Upper San Jacinto Basin Sedimentation Study
The upper basin of the San Jacinto River includes everything above Lake Houston. This study has three goals:
For the record, here is the scope of work. Note that stakeholder input and public meetings will be a big component of this project (Task 2). Tasks 3 and 6 include evaluation of sand mines. And Task 7 includes “Sand and Gravel Mining Best Management Practices.”
The sedimentation study is being conducted with financial help from the Cities of Houston and Humble, and the Harris County Flood Control District.
A related sand-trap study is nearly complete. The SJRA should release it next month for public input.
Spring Creek Flood Control Dam Feasibility Study
About a year ago, SJRA applied for a TWDB grant to study the feasibility of building two flood control dams in the upper Spring Creek Watershed. The partners identified two preferred locations from a previous siting study that considered dozens. The two included Walnut and Birch Creek tributaries.
The objective now: to see whether the benefits justify the costs. Said another way, will the dams reduce flooding and protect enough structures to make the cost of building them worthwhile?
Together, they would have a combined capacity of 20,000 acre feet. That’s significant. But it would provide more benefit to people in the upper Spring Creek watershed than the Lake Houston Area.
The scope of work includes:
Partners in this effort include the SJRA, HCFCD, City of Humble, and five municipal utility districts. To learn more about these projects and others, consult pages 19 and 21 of this PDF.
To View or Participate in the Board Meeting
The SJRA board meeting starts at 8am.
If you choose to participate via webinar, register at this link and use webinar ID 950-202-179.
If you use the GoToWebinar App, you will have the opportunity to provide public comments.
To view the Agenda, visit SJRA’s website at: 07-22-21 Agenda and Coversheets.
Posted by Bob Rehak on 7/22/21
1423 Days after 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.
Commissioners Approve Excavation Contract for Regional Detention Pond on Taylor Gully
In yesterday’s Harris County Commissioners Court meeting, commissioners unanimously approved a contract with Spring Sand & Clay LLC for excavation of a regional detention pond on Taylor Gully in Montgomery County at the Woodridge Village site.
Preliminary Engineering Began in Early July
Earlier this year, Harris County purchased Woodridge Village from Perry Homes for this purpose. Currently, engineers are examining several Taylor Gully alternatives.
Currently, Idcus, Inc., an engineering company, has been contracted to look at:
The Idcus contract calls for the company to deliver channel and basin layouts for Taylor Gully no later than 300 days from the notice to proceed, which presumably was given in early July. However, excavation could start much sooner than that. (See below.)
Pieces of Puzzle Falling into Place
The no-cost contract with Sprint lets them set their own timetable as long as they complete improvements within three years. Sprint’s timetable will be driven by the company’s ability to sell the material they excavate; that forms their compensation.
The next step is for Harris County Flood Control District (HCFCD) to provide a grading plan to the contractor. While that will not happen tomorrow, the good news is that it won’t require waiting 300 days.
HCFCD can start excavating the retention pond before plans are finalized. After all, it’s not a problem if a detention pond holds more than the minimum required. It’s only a problem if it holds less. Engineers and contractors can adjust plans if necessary after excavation starts. This approach should minimize flood risk for worried Elm Grove and North Kingwood Forest residents.
All the pieces of the puzzle are starting to fall into place.
Posted by Bob Rehak on 7/21/2021
1422 Days since Hurricane Harvey
Commissioners Vote Tuesday on Contract for Woodridge Village Detention Pond Excavation
Tuesday, 7.20.21, Harris County Commissioners will vote on a contract with Sprint Sand & Clay for excavation of a Woodridge Village detention basin. Item #21-3394 on the agenda is only for $1000, but it gives the contractor the right to enter the site and begin removing up to 500,000 cubic yards of dirt (at no cost to HCFCD) which it can then sell.
Backup provided to commissioners states that “This benefits the District because excavation and removal is always the highest cost of any stormwater detention basin that is constructed.”
Details of Proposed Contract
Here is the full text of the proposed agreement. Highlights include:
The contract outline contains the map above but does not specify the exact size, depth or location of the proposed work within the outlined area – just that it will occur in Montgomery County. Engineers will supply additional details at a later date.
Making up for the 60% Solution
Assuming commissioners approve this, it is good news for the people who live who live in Elm Grove and North Kingwood Forest – indeed, for everyone who lives along Taylor Gully. The detention ponds installed by Perry Homes before they sold the land to Harris County were based on old rainfall statistics and will only hold about 60% of a new 100-year rain defined in Atlas-14.
Sprint Sand and Clay is a regular contractor for HCFCD. Currently, the company is excavating the massive Cutten Detention Basin near 290, Beltway 8 and Cutten Road.
Posted by Bob Rehak on 7/20/21
1421 Days since Hurricane Harvey