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HCFCD Will Begin More Work on Ben’s Branch Starting January 19

Harris County Flood Control District (HCFCD) will begin repairing the next section of Ben’s Branch on January 19. The repairs will take place in the channel between Kingwood Drive and the natural portion of Ben’s Branch at the end of Rocky Woods Drive.

Project limits for next phase of Ben’s Branch clean out. Kingwood High School in lower center of frame.

Project Purpose

Jose Predraza of Stuart Consulting is coordinating the project. He said, “The purpose of this project is to restore the conveyance of Ben’s Branch. It has been reduced over the years due to erosion and sedimentation. The project will include implementing erosion repairs, repairing side slope failures, repairing or replacing outfalls, rectifying flow lines, and removing excess sediment.”

Contractors will remove approximately 22,000 cubic yards of sediment deposited by floods over the years.

Continual cycles of deposition and erosion have clogged, deformed and narrowed the creek.

The Kingwood Area Drainage Analysis showed that Ben’s Branch had been reduced to a 2-year level of service in places. That means, it will flood in a 2-year rain.

The analysis did not specify whether this was one of those places, but outside the natural portion of the stream, this is currently the most constricted part. Other parts of the channel have already been restored, i.e., from Woodland Hills Drive to Northpark Drive and south of Kingwood Drive to the YMCA.

Red lines represent approximate outlines of original high banks near Rocky Woods. Area between red lines has filled with sediment and then the creek has eroded down through it again repeatedly. Photo 1/8/2021.

“Erosion repairs include the placement of fill material, placement of 3”x5” granular fill, and the placement of grade #1 riprap,” continued Pedraza. “Channel cross sections will be reconstructed with a maximum 5:1 (H:V) slope where necessary. This project will be conducted wholly within the existing channel right-of-way.”

Schedule

Pedraza estimates construction will last 145 days – not quite five months. If weather cooperates, contractors should complete the work in early June.

The project originally was scheduled to start in October 2020. But several delays occurred.

  • Initially, rain delayed completion of the survey.
  • Then, geotechnical investigations led to additional design time.
  • Finally, getting approval to cross CenterPoint’s power-line easement took additional time.

Access Routes

Trucks do not have enough room to turn around within the work area, so one-way traffic will be the rule. Trucks will enter the work area by coming up Woods Estates Drive to Cedar Knolls and entering the greenbelt from there. They will then follow the Centerpoint easement to the work area. Finally, they will exit by going south toward Kingwood Drive, cutting across the ditch, and coming out behind the old H-E-B.

Contractors will then haul the excavated dirt to nearby TCEQ-approved landfill sites outside of the .02% annual chance (500-year) flood plain.

Daily schedules are being coordinated with Kingwood High School start/stop times to reduce traffic congestion and improve safety.

Benefitting Residents, Schools and Businesses

When complete, the creek will be able to handle much more water than before without coming out of its banks…as much as it could when Friendswood originally excavated it.

This will be a vast improvement, especially for those who live near the creek in Kings Forest and Bear Branch, many of whom flooded during Harvey.

The work should reduce the flood risk for Kingwood High School also. The school first flooded in 1994. During Harvey, the building flooded to the second floor. It suffered $67 million dollars in damages and lost another $10 million in contents. The Humble ISD had to close Kingwood High for seven months and bus kids to another high school where they alternated “shifts” with the students from that high school.

Kingwood High also flooded during Imelda, but had less damage.

Finally, the work will also benefit the shopping center on the northwest corner of Kingwood Drive and West Lake Houston Parkway. Every store in the center flooded badly during Harvey. Many businesses still have not returned. The center nearly flooded again during Imelda. Water flowed through the parking lot and was inches from coming into stores.

Paths along the high banks represent the original edges of the channel. Everything between them has filled in over time, reducing conveyance. Photo 1/8/2021.

Funding

The Ben’s Branch project will be funded through the HCFCD maintenance budget and a grant from USDA Natural Resources Conservation Service (NRCS).

Posted by Bob Rehak on 1/9/2021

1229 Days since Hurricane Harvey

Sneak Peak at Results of Kingwood Area Drainage Analysis; Review Before Meeting Tuesday Night

The Harris County Flood Control District has released a Report Summary of results from the 600-page Kingwood Area Drainage Analysis. HCFCD will hold an online community meeting Tuesday night to discuss the results. It may help to review this summary or HCFCD’s before the meeting.

Objective: Protect Homes/Businesses from Bigger Rains

The objective of the Kingwood Area Drainage Analysis: to provide the knowledge needed to protect homes and businesses from flooding in a 100-year (1% chance) rain as defined by the new, higher Atlas-14 Rainfall Probability Statistics. Said another way, the engineers want to make sure that if you bought a home outside the 100-year flood plain, that you STILL won’t be flooded in a 100-year rain. Engineers call that “the 100-year Level of Service (LOS).”

Steams, ditches and channels evaluated as part of the Kingwood Area Drainage Analysis. Please note ditch numbers for any comments you make as the flood control district identifies them by that number. It will help communication.

What Study Included

To accomplish their objectives, engineers:

  • Evaluated historical floods and mapped flood damage
  • Created hydrologic and hydraulic models to quantify flooding risks along streams, channels and open ditches
  • Identified drainage issues associated with storm sewers and streets
  • Performed an overland flow analysis
  • Used LiDAR, record drawings, previous surveys and data collected in the field
  • Incorporated the impact of potential storm sewer improvements on channel capacity
  • Quantified detention capacity needed to prevent increasing flows into Lake Houston
  • Determined how many structures would benefit from each improvement (or planned future improvement)
  • Researched rights-of-way and flowage easements
  • Recommended channel-capacity improvements
  • Recommended bridge and culvert improvements
  • Developed preliminary cost estimates
  • Recommended construction sequencing

In places where ditches provide less than a 100-year level of service, storm sewers cannot empty into them during a 100-year rain. When that happens, water backs up into streets and can flood homes. So engineers are looking at the performance of the drainage system from end to end in conjunction with the City of Houston.

Limitations: What Study Does NOT Include

The study does NOT:

  • Include new topographic surveys
  • Evaluate improvements for greater than 100-year events
  • Examine Montgomery County issues except for North Park Drive
  • Identify sites for detention basins
  • Duplicate the San Jacinto River Basin Master Drainage Plan or associated sedimentation and sand trap studies

No construction is included as part of this project. This project will only lay the groundwork for subsequent construction projects.

Study Identified Nine Channels That Need Improvement

Not surprisingly, the Kingwood Area Drainage Analysis found that many channels do not need improvements. Said another way, they already provide the required level of service. However, engineers identified nine channels that DO need improvement to protect homes and businesses.

Six of those nine have rights-of-way controlled by HCFCD. They include:

  1. Bens Branch – G-103-33-00
  2. Kings Crossing Ditch – G103-33-04
  3. Kingwood Diversion Ditch – G103-38-00
  4. No Name – G103-38-01
  5. No Name – G103-38-01.1
  6. Taylor Gully – G-103-80-03.1

Other entities control the rights-of-way for the three remaining ditches/streams that need improvements:

  1. Bear Branch – G103-36–00
  2. No Name – G103-36-03
  3. No Name – G103-46-01

For summary sheets of each recommended Kingwood Area Drainage Analysis project, click on the associated links. The Taylor Gully project will need to be re-analyzed if the Woodridge Village purchase goes through; that area could turn into a regional detention facility.

This table contains a summary of streams, channel types, ownership, current level of service, improvements, rights of way needed, cost estimates and detention estimates for all the projects considered in the Kingwood area.

Two Projects Recommended Immediately

Based on the results of the Kingwood Area Drainage Analysis, HCFCD recommends two projects: G103-38-00 (Kingwood Diversion Ditch) and G103-80-03.1B (Taylor Gully) move to the next phase: engineering design. Additionally, HCFCD recommends the Taylor Gully project be reanalyzed to determine how the use of Woodridge Village for detention could modify the recommended plan.

These two projects were chosen because:

  • They help the largest number of people.
  • HCFCD owns land to expand and deepen the Diversion Ditch.
  • Diversion Ditch enhancement will immediately take pressure off Ben’s Branch, and help flooding there.

Thus, these two projects address the three biggest needs. The remainder will have to wait for Capital Improvement funds.

First Step of Many

The Kingwood Area Drainage Analysis is a feasibility study that helped identify the problem areas. As you can see from the lifecycle diagram below, it represents the first step of several. The Flood Control District included $10 million in the bond fund (See F14) for Kingwood projects. That can be local-match seed money for attracting state and federal grants.

Source: Harris County Flood Control. After completion of the feasibility study comes preliminary engineering.

Online Meeting Details Tuesday Night

HCFCD will hold an online meeting Tuesday night. Engineers will describe the project and recommendations in more detail. You will also have a chance to interact with team members, make suggestions, and ask questions.

Tuesday, October 20, 2020

6:30 p.m. to 7:30 p.m.

 Join online at PublicInput.com/Kingwood

Or by phone at 855-925-2801 with Meeting Code: 9541

Please login a few minutes early. The Flood Control District has a brief survey on the login page that will help them track your concerns.

What the Flood Control District Needs from You

The Flood Control District needs to know about local issues that they may NOT have identified near you.

For example, culverts under Kingwood Drive for a ditch near me are almost totally blocked by sediment. That could have affected their analysis. And the stream may have correctable issues that could easily prevent future flooding.

Another example. The recommendations include taking out the low water crossing near Bear Branch Elementary School. Many kids use that to walk or bicycle to school. Removal without replacement would create a major inconvenience. It might also negatively affect downstream bridges damaged in previous storms.

A final example: the study did not recommend any changes to the bridge over Taylor Gully at Rustling Elms. However, many Elm Grove residents identified that as a major issue in two floods last year.

The Rustling Elms Bridge is a road over twin culverts, not a true open bridge like the one farther downstream in the background.

Please join the meeting Tuesday night and be prepared to discuss such issues. Volunteer your local knowledge. Speak up now or live with the results.

Credits

The Kingwood Area Drainage analysis cost $700,000. Funds from the 2018 Harris County Flood Bond and TIRZ 10 paid for this study.

Posted by Bob Rehak on 10/19/2020

1147 Days since Hurricane Harvey

HCFCD to Begin Next Phase of Ben’s Branch Clean Out in October

Harris County Flood Control District (HCFCD) and its contractors met today with representatives of Kings Forest, the Bear Branch Trail Association and Kingwood Service Association to discuss the next phase of the Ben’s Branch clean out. On the south, the project lies entirely within the Creekwood Nature Area between Kingwood High School and the old H-E-B shopping center. Rocky Woods Drive forms the northern extent of the project. This will extend northward the work already completed south of Kingwood Drive.

Project extent outlined in red. Kingwood High School is at bottom center; Town Center on right; Kings Forest on left and Bear Branch at top of frame.

Maintenance Objective: Restore Conveyance

The objective: to restore conveyance of Ben’s Branch and reduce potential for flooding in Kings Forest, Bear Branch, the Kingwood High School, and Kingwood Town Center.

The ground these men are standing on is all deposited sediment that needs removal to restore conveyance. The original channel bank is the higher slope behind them. The other side has a similar problem.

Sediment has restricted the flow of the channel gradually during the last three decades. It now contributes to flooding.

Tucked into the tree line on either side of Bens Branch, you can see the maintenance roads that formed the top of the original banks.

During Harvey, many homes on both sides of the stream flooded. Many also flooded again during Imelda.

Walking along the creek today, the first thing one notices is a craggy channel with sides that seem to have slumped into the stream. Flood control surveys, however, show that is not the case. The channel filled with sediment. Then the stream eroded down again through the accumulated sediment.

Continual cycles of deposition and erosion have clogged, deformed and narrowed the creek.

Approximately 15,000 Cubic Yards of Sediment To Be Removed

Getting the channel back to its original state will require removal of approximately 15,000 cubic yards of sediment. However, engineers have not yet determined the exact number.

The scope of work will include replacement of damaged drain pipes that carry water to the ditch.

The job is still in its planning stages. Actual dirt work should begin sometime in October.

Funded with Help from USDA NRCS

A grant from the USDA Natural Resources Conservation Service (NRCS) will help HCFCD fund the project. Contractors will haul the excavated dirt to nearby TCEQ-approved landfill sites outside of the .02% annual chance (500-year) flood plain.

Looking north. The project will NOT extend into the natural portion of Ben’s Branch at the top of the frame, near Rocky Woods Drive. It will affect only the man-made portion of the channel.

Downstream, the project will stop at Kingwood Drive. Note below how the channel under the Kingwood Drive bridge is virtually twice as large as the channel in the foreground.

Looking south over Ben’s Branch toward Kingwood Drive and the portion of Ben’s Branch restored earlier this year. Note how constricted the channel in the foreground is.

When complete, this project should make the channel north of Kingwood Drive as wide as it is south of Kingwood Drive. It’s all about getting the channel back to its designed carrying capacity.

An exact timetable for the project is not yet available, but it will take several months.

Posted by Bob Rehak on 9/4/2020

1102 Days after Hurricane Harvey