kingwood area drainage analysis Archives

Preliminary Engineering Contracts Approved for Two Kingwood Drainage Improvements

On June 29, 2021, Harris County Commissioners approved two contracts for preliminary engineering on Taylor Gully and the Kingwood Diversion Ditch. The Taylor Gully project includes looking at Woodridge Village in Montgomery County to possibly expand detention-pond capacity there. See more below.

Taylor Gully Project

Harris County Flood Control District (HCFCD) awarded Idcus, Inc. a $180,555 preliminary engineering contract to develop up to five conceptual alternative scenarios for modifying Taylor Gully. HCFCD and Idcus will then select three scenarios for more detailed analysis. Idcus must perform the work within 300 days of the Notice to Proceed.

The alternative modeling scenarios may include:

Preferred Channel Alternative: This would look at improving the slope, width and lining of channel in conjunction with the existing detention on the Woodridge Village site. This purpose: to determine if the existing detention and proposed channel improvements suffice to mitigate flooding.
Expanded Detention: This would look at expanding the existing stormwater detention on the Woodridge Village site so that no channel improvements are necessary.
Alternative Channel/Detention: This would look at a combination of the two scenarios above. It would determine the amount of additional detention and channel improvements necessary to ensure no adverse impact all the way to Lake Houston.
Optimization Alternative: Building on the alternatives above, this effort would examine additional alternatives to produce a no-adverse-impact solution while maximizing the flood mitigation and minimizing construction costs.

Deliverables for the alternatives include:

Channel and basin layouts
Estimates of benefits for various levels of storms (100-year, etc.)
Right-of-way requirements
Cost estimates for right-of-way acquisition, engineering and construction management.
Performance metrics, i.e., estimated acreage of land inundation, number of structures in floodplain, number of structures flooded and miles of inundated roadway.
A scoring matrix to rank the alternatives.

The scope also includes, when necessary:

Hydrologic and hydraulic analysis
Surveying
Soil sampling
Environmental site assessment
Subsurface utility exploration
Landscape architecture

Finally, Idcus will hold two public engagement meetings near the beginning and end of the project and consult with community groups such as KSA.

*Geographic scope includes the Woodridge Village property in MoCo plus the Taylor Gully channel in Harris County.*

Kingwood Diversion Ditch

HCFCD entered into a contract with Neel-Schaffer, Inc. for $437,685 for preliminary engineering on the Kingwood Diversion Ditch. Within 300 days,Neel-Schaffer must:

Evaluate existing site conditions, previous studies, other projects that could affect this one, topography, rights-of-way, utilities, and soil surveys.
Evaluate existing bridges
Conduct and H&H analysis to assess existing and proposed conditions (from 2-year to 500-year storms).
Analyze Channel Improvements including the:
- Impact of TIRZ #10’s latest design to replace the Northpark Bridge
- Diversion structure at the confluence of Bens Branch and the Diversion Channel
- Drop structures in lieu of a concrete lined channel to minimize high velocities due to the steep grade between
  Walnut Lane and Deer Ridge Estates Blvd.
Develop phased construction plans based on available funding, potential impacts and benefits.
Conduct two public engagement meetings and coordinate with community groups.

HCFCD may also require Neel-Schaffer to provide addition services when necessary, such as:

Surveys
Geotechnical investigations, i.e., bridge borings
Environmental assessment
“Jurisdictional” determination. Does this channel fall under the jurisdiction of the Army Corps? If so, channel design may need to be altered.
Determination of detention pond requirements
Exploration for subsurface utilities
Obtaining permits from the Corps
Providing Landscape Architect services

Extent of Kingwood Diversion Ditch. It runs from the new St. Martha Catholic Church north of Northpark to the fire station on Kingwood Drive. Then it runs down to Deer Ridge Park where it makes a turn and enters the West Fork at River Grove Park.

For Complete Text of Contracts…

The first half of each link below contains contract details such as compensation. The second half contains the scope of work.

They were items 146 and 147 respectively on the agenda for the 6/29/21 Commissioner’s Court meeting.

Next Steps

In general, the critical path for each of these projects will follow the project-lifecycle pattern of all HCFCD projects.

*Typical steps for new projects constructed under the 2018 bond program.*

HCFCD will:

Conduct public meeting
Develop, review and prioritize alternative designs
Commissioner’s court reviews and votes on recommendation
Move to final design of selected alternative with same company
Engineering company develops construction specs
Bid
Award
Build

These were two of many such contracts approved in the last Commissioners Court meeting.

Both came out of the Kingwood Drainage analysis. More on projects affecting other parts of the Lake Houston Area in future posts.

Posted by Bob Rehak on 7/3/2021

1404 Days after Hurricane Harvey

HCFCD Taylor Gully Repair Project Approximately One-Third Complete

On January 19, I posted about Harris County Flood Control District’s (HCFCD) second major repair project on Taylor Gully since 2019. Thirty-nine days later, HCFCD has completed about one third of the project. They have now started on the downstream side of the Maple Bend Bridge in Kingwood’s Woodstream Village.

Pictures of Work to Date

Here are pictures of the Taylor Gully repairs taken today, 2/28/2021.

*Looking upstream from Maple Bend Bridge at completed portion. Compare how this looks to a little more than a month ago.*

*Reverse angle, looking downstream from start of repairs toward Maple Bend Bridge.*

*Look at the size of that new storm drain. That should get water to the ditch in a hurry.*

*There’s another new, huge pipe downstream from the bridge. Compare the size of the old one on the opposite side of the creek.*

Purpose of Project

The purpose of the project: to repair erosion and side-slope failures; repair or replace outfalls; rectify flowlines; and rehabilitate existing backslope swale systems.

Erosion repairs include the placement of fill material, placement of 3″x5″ granular fill and the placement of grade #1 riprap.
Channel cross sections will be restored to the original design where feasible.
The oldest recorded drawing on file is for the proposed channels from Elm Grove Village to White Oak Creek completed in March 1982. Record drawings typically show a 6-foot wide channel bottom with 3:1 side slopes.

Separate From Preliminary Engineering Study Approved on 2/5

Before HCFCD leaves a project, they will establish grass on the side slopes to prevent erosion and more downstream sedimentation.

This project is separate from a Taylor Gully preliminary engineering study for capital improvements that was approved by Harris County Commissioner’s Court at its last meeting. The capital improvements could include more upstream detention on the Perry Homes Woodridge Village Property, which is still pending purchase 1.5 years after Imelda.

A previous study, the Kingwood Area Drainage Analysis, proposed improvements to Taylor Gully in October 2020.

Posted by Bob Rehak on 2/28/2021

1279 Days since Hurricane Harvey

HCFCD Recommends Expanding Diversion Ditch as First Priority in Kingwood

At the Harris County Flood Control District’s (HCFCD) Kingwood Area Drainage Analysis meeting tonight, HCFCD recommended that expansion of the Kingwood Diversion Ditch should be the community’s highest priority.

The Diversion Ditch project would help address several potential problems. Expanding it would remove 62 structures from inundation areas and another 586 structures would benefit from improved local drainage. In addition, the project:

Can divert floodwater from Ben’s Branch, which will be a much more complicated project, taking more time.
Has a 300-foot right-of-way, of which only half is being used
Has bridges that already span the entire 300 feet.
Will help carry floodwaters from rapidly growing south Montgomery County.

History of Diversion Ditch

In the early days of Kingwood, Friendswood Development Company built the Diversion Ditch to reduce water flowing into Ben’s Branch. But since then, upstream development and larger rains have stressed the capacity of both Ben’s Branch AND the Diversion Ditch. Engineers estimate that peak flows have doubled since 1985.

Most of Ben’s Branch is Natural Channel

Ben’s Branch cuts diagonally through the heart of Kingwood. See red lines below. More than half its length – between Woodland Hills and Rocky Woods Drive is natural channel. Widening it will be complicated and take much time.

*Red Line indicates approximate path of Ben’s Branch through Kingwood.*

Ben’s Branch Now at 2-Year Level of Service

However, areas on both sides of Ben’s Branch are threatened by flooding as you can see in the image below from FEMA’s Flood Hazard Viewer.

Ben’s Branch once had a 100-year level of service, meaning it had enough carrying capacity to prevent homes from flooding in everything but a 100-year rain. Models based on new Atlas-14 rainfall probability frequencies indicate that the channel’s capacity is now down to a 2-year level of service. That means it will flood in minor rains, exactly as St. Martha School did last year.

Worse yet, Ben’s Branch has decreased to a 2-year level of service throughout its length.
HCFCD Kingwood Area Drainage Analysis

*Source: Fema’s Flood Hazard Layer Viewer. Cross-hatched equals floodway, aqua = 100 year floodplain, brown = 500-year floodplain.* *Floodplains shown above are based on pre-Atlas-14 rainfall probability statistics. An Atlas-14 hundred-year rain is about 30-40% higher than the old hundred-year rain.*

When flood maps are updated based on Atlas-14 statistics, those floodplains will likely expand…unless we do something to handle more floodwater before then.

However, Ben’s Branch will not move to preliminary engineering right away.

How to Protect Against Bigger Rains and More Upstream Development

The Kingwood Area Drainage Analysis sought to understand what we need to do to restore a 100-year level of service to all ditches and streams based on Atlas 14. Of the 19 ditches and streams studied, nine need improvement. The level of service for some, including Ben’s Branch, has been reduced to 2 years.

Expanding the Diversion Ditch is the fastest way to take pressure off of Ben’s Branch.

The Diversion Ditch intersects Ben’s Branch at the new St. Martha Church. It then flows south to Deer Ridge Park and then winds through River Grove Park. See the white line below.

*Kingwood Diversion ditch (white line) intersects Ben’s Branch near the new St. Martha Church.*

Expansion Capacity Already Built into Diversion Ditch

Engineers foresaw the day when Kingwood would need more drainage capacity due to upstream development in Montgomery County. They built the Kingwood Diversion Ditch to handle the extra stormwater. They also made the bridges over the diversion ditch wider than they needed at the time. Finally, they dedicated a flood easement on both sides of the ditch that was wider than they needed, so they could expand the ditch later without encroaching on neighboring properties. Here’s how it looks from the air.

Looking north across Northpark Drive toward Bens Branch, which cuts diagonally from left to right through the middle of the frame. Note the ample clearance under the bridge and the wide shoulders of the ditch. St. Martha Church is in the upper left.

*Looking south toward Kingwood Drive at the Diversion Ditch. King’s Mill is on right in foreground.*

Both Kings Mill and Kings Manor now drain into the Diversion Ditch. But they came long AFTER Diversion Ditch construction. Other new upstream developments that drain into the Diversion Ditch and Ben’s Branch include Brooklyn Trails and Woodridge Forest, both in Montgomery County.

As a result, the Diversion Ditch itself has decreased to a 2- to a 25-year level of service in places. However, it still offers a 100-year level of service in others.

Looking NE toward Deer Ridge Park from over Hamblen Road. A corner of Deer Ridge Estates is on the left. The diversion ditch cuts in front of the park (upper left to lower right) and goes into an area largely undeveloped on its way to the river (out of frame to the right).

Impact on River Grove Park

Once the Diversion Ditch passes through the area shown in the photo above, it enters wetlands and winds through River Grove Park. Two questions arise. How do we protect, from additional flow:

The park?
People downstream on the West Fork?

The first question is simple: split the flow in two. Take part through the undeveloped area west of the park. See the green below.

*Green Line represents one possible route for diversion of the diversion ditch.*

The second question is more complicated. We need a retention basin to hold the extra stormwater until the peak of any flood passes on the West Fork. But where? The closer you get to the river, the lower the elevation. Because of that, the basin could fill with floodwater from the river before it fills with floodwater from upstream. Fortunately, some large tracts of land exist on higher ground that could be purchased. HCFCD estimates the need at 1248 acre-feet. Preliminary engineering should start soon to address these issues.

Upstream Development Not Addressed by Analysis

Unfortunately the Kingwood Area Drainage Analysis did not address upstream development issues in Montgomery County. That was beyond the scope of work. Regardless, such issues must be addressed somehow, someday soon. Otherwise, even the improvements we invest in today could soon be overwhelmed by additional floodwaters.

In that sense, these channel improvements represent a stopgap measure. The real solution lies in making everyone in the region realize that we are all in this together.

Additional Resources

If you missed the presentation, you can view it on YouTube.

Here is a PDF that contains the District’s summary of the Kingwood Study. It includes a spreadsheet comparing the improvements plus data sheets on the nine recommended projects.

The ten remaining channels/streams already offer a 100-year level of service. Therefore, no improvements are needed. HCFCD felt Taylor Gully should be the next priority after the Diversion Ditch. But the possible purchase of Woodridge Village may require re-thinking project requirements. Specifically, if Woodridge turns into a giant detention basin, the channel may not need as much deepening or widening.

Posted by Bob Rehak on 10/20/2020

1148 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:

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

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

Save the Date: Kingwood Area Drainage Analysis

Harris County Flood Control District (HCFCD) will hold a Virtual Community-Engagement Meeting for the Kingwood Area Drainage Analysis project: 10/20 at 6:30 PM.

Study Purpose

The purpose: to inform residents about the status of the project and share findings to date.

The Kingwood Area Drainage Analysis focuses on “evaluating the existing drainage level of service for the 32.3-mile open channel network within the greater Kingwood area and identifying the drainage infrastructure which will improve the network’s level of service.”

What That Means

The San Jacinto River Master Drainage Study examined the major streams around Kingwood. But this study examined every stream and ditch within Kingwood. From Taylor Gully, Ben’s Branch and the Diversion Ditch on down to the smallest ones.

When originally constructed, engineers designed ditches to convey a 100-year rain without flooding homes or businesses. However, over time, many have filled in with sediment – often so gradually, the process is invisible. Such ditches may need cleaning out. See below.

*Ditch between Valley Manor and Twin Grove where it goes under Kingwood Drive. Capacity dramatically reduced by sedimentation and vegetation. Photo courtesy of Chris Bloch.*

Also, new upstream development, such as Woodridge Forest and Woodridge Village, may be contributing additional stormwater to ditches during heavy rains. So those ditches may need expansion.

Instead of being able to safely convey a 100-year rain, ditches now might only be able to convey, for example, a 25- or 50-year rain because of such factors.

“Identifying drainage infrastructure which will improve the network’s level of service” means “figuring out what it will take to make them safely convey a 100-year rain again.”

Partially Funded by Lake Houston Redevelopment Authority

The Flood Control District has entered an interlocal agreement with the Lake Houston Redevelopment Authority (TIRZ 10) to partially fund this drainage study. Bonds approved by Harris County voters on August 25, 2018, have funded the rest.

Public Participation Important

Community engagement is an important component of the Bond Program. You live here. You know where the problems are and how high water gets. Your participation is necessary to ensure your safety. Speak up now BEFORE HCFCD begins implementing the program.

If you know of a problem HCFCD is not addressing, you need to tell them.

The virtual Community-Engagement Meeting will be held on:

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

Meeting Format and Other Details

The meeting will begin with a brief presentation to share project updates, followed by a moderated Q&A session with Flood Control District team members.

You can submit questions and comments throughout the presentation. Any comments not addressed during the Q&A session will receive a response after the event.

A recorded version of the meeting will be available on the Flood Control District’s website and YouTube channel after the event.

Meeting accommodations can be made for those with disabilities. If needed, please contact 346-286-4152 at least 48 hours prior to the meeting.

The Kingwood Area Drainage Analysis Technical Report Executive Summary will be available online prior to the October 20, 2020, Community Engagement Meeting at www.hcfcd.org/F14.

For questions, please contact the Flood Control District at 346-286-4000, or fill out the comment form online at www.hcfcd.org/F14.

Posted by Bob Rehak on 10/7/2020

1135 Days after Hurricane Harvey

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