Tag Archive for: Diversion Ditch

Deeper Dive into Northpark Expansion, Drainage Plans

On 7/27/23, I interviewed Ralph De Leon, Northpark project coordinator for the Lake Houston Redevelopment Authority (TIRZ 10) and Kevin Perkins, a project manager for HNTB, one of the contractors on the job. The discussion covered both the eastern and western phases of the project from Woodland Hills Drive on the east to US59 and beyond on the west.

Since Tuesday, the contractors have made visible progress. Let’s cover that first. Then I’ll cover some surprising facts I learned about the project, including flood-mitigation plans; why the project has taken so long; how it will expand to 10 lanes near the railroad and Loop 494; parts of the project that will be elevated; bridge reconstruction; Atlas-14 conflicts; and more.

Box Culverts Arrive

By mid-day today, contractors had box culverts stacked several blocks in the median between Russell-Palmer Road and Flowers of Kingwood. They also had three excavators working Thursday, compared to one on Tuesday. And they were cutting concrete in the cross-overs.

Looking west from the diversion ditch (foreground). Only the 66″ round concrete pipe by the first excavator was there on Tuesday.
Looking east down the Northpark Drive median in opposite direction. Those rectangular culverts measure 6’x8′.
Note men cutting concrete in the median between Flowers of Kingwood (upper left) and the fireworks stand (out of frame, lower right).

The 6×8 box culverts stacked in the distance will extend under the cross-over and connect to the round concrete pipe using the junction box stacked in front of the four round pipes. See below.

Box culverts were stacked up to the red rib truck in the background.

The box culverts will convey 35 square feet of stormwater compared to slightly fewer square feet for the round pipe.

That “step-down” as stormwater moves toward the diversion ditch will provide inline detention.

Also note that the existing culverts under the crossovers provide even less conveyance/storage than the new pipe. The old pipes were much smaller and frequently become clogged with weeds and grass due to long maintenance intervals.

According to Perkins, the new pipe/culvert solution offers less friction from end-to-end. The pipes shouldn’t become clogged like the old pipes did because grass and weeds won’t grow in them. Also, their consistent dimensions under the cross-overs should let more water pass through faster.

To make sure water can get into the culverts quickly during heavy rains, contractors will use extra large inlets, similar in size to those used on freeways.

Why Project Has Taken So Long

De Leon and Perkins discussed approval delays at length, mostly related to multiple groups giving input and approvals.

  • The project goes into, out of and back into the City of Houston.
  • It straddles two counties, each with different leadership and regulations.
  • A TIRZ, several MUDs, homeowner associations, commercial associations, KSA and Lone Star College are also involved.
  • Harris County Flood Control District is reviewing all the plans and approvals.
  • TxDoT has final say over design criteria.
  • Funding will come from State, Federal, and local authorities.
  • The Union Pacific (UP) Railroad has had multiple changes in leadership since the project started.
  • Gaining utility easements and rights of way has taken much longer than expected. For instance, Entergy wants 50 months to move a SINGLE transformer, almost half again as long as it will take to build the ENTIRE bridge over 494 and the UP railroad tracks.

Getting all those dominos to line up has challenged everyone involved.

Project Will Expand to 10 Lanes Near Loop 494

Where the western phase of the project crosses Loop 494 and the UP railroad tracks, traffic surveys indicate that 80% of the traffic will go over the bridge. Regardless, TxDoT requires two lanes of feeder road in each direction to handle local traffic not going over the bridge. Six lanes of bridge and four lanes of feeder will require some property acquisition still to be completed. Not all of the expansion will fit over the center ditch.

Pedestrian Underpass

The eastern phase of the project will contain a pedestrian underpass similar to others found throughout Kingwood. Engineers hope to keep water out by making the entrances higher than surrounding areas so water drains away. The tunnel will be 10 feet wide to accommodate special extra-wide wheelchairs for people with curved spines. Ten feet will accommodate two such wheelchairs moving in opposite directions.

Elevated Roadway with Cheek Walls

In certain areas that experience repetitive flooding, especially east of the drainage ditch where Bens Branch cuts under Northpark Drive, the road will be elevated. Feathering out the bed toward the sides would require killing hundreds, if not thousands of trees. So instead, contractors will elevate the road using “cheek walls.” Highway 59 makes extensive use of cheek walls for the same reason – to conserve space and allow trees to grow.

Two 10-Foot Sidewalks to Lone Star College

West of 59, contractors will build two 10-foot sidewalks along Rock Creek south of Northpark. The sidewalks will help cash-starved Lone Star College students ride bicycles to class when weather permits. Katherine Perrson, now retired head of the college, made the request.

Leaving Room for Diversion Ditch Expansion

The City has hired a contractor called NBG Constructors to clean out the diversion ditch under both Northpark Drive bridges and return the channel to its original as-designed capacity. Over the years, sedimentation has constricted the flow as you can see below.

Note accumulated sediment constricting flow under bridge.

Eventually, Harris County will widen the diversion ditch. HCFCD rated it one of the two most important projects in Kingwood. As part of the Northpark Expansion project, both bridges will be rebuilt, but with enough width to accommodate eventual expansion of the ditch.

Meets Harris County Atlas-14 Requirements

When complete, the project will meet Harris County Atlas-14 requirements for 77339 which are more stringent (about 40% higher) than Montgomery County’s. That’s because virtually all of the water associated with this project will drain into Harris county. MoCo standards are lower because Montgomery averages requirements across the entire county. Rainfall drops off with distance from the Gulf.

Detention Basins and 59 Entry

To reduce the chance of flooding near 59, contractors will build two detention basins on either side of Northpark at 59. They will connect with each other underground and also connect with another basin and channel north of Northpark via an 8 foot pipe.

Timetable

All this won’t happen overnight. De Leon is working on updating the timetable and will post it with a new project website that gives Kingwood and Porter residents weekly or bi-weekly updates. More news to follow, including a deeper dive into the drainage analysis and how some water will be diverted around Northpark.

Posted by Bob Rehak on 7/27/23

2158 Days since Hurricane Harvey

CoH Excavating Silt from Diversion Ditch at Kingwood Drive

After finishing excavating silt from under the Kingwood Drive Bridge over Ben’s Branch, City crews are now doing the same under the bridge over the Diversion Ditch near the fire station on Kingwood Drive.

Before excavation began. Looking south at the Kingwood Drive Bridge over the Diversion Ditch in August.

Bridges are often chokepoints during floods because of their supports that reduce and sometimes slow the flow of water and contribute to sediment buildup.

Closer shot of same bridge, still looking south. Note sediment buildup. Also note how bridge supports catch debris.

The City of Houston is responsible for excavation under the bridges because the bridges are City property.

On Ben’s Branch, Harris County Flood Control District (HCFCD) had excavated both north and south of the bridge at Kingwood Drive. Then the City did its part.

Pictures of Work in Progress At Kingwood Drive.

However, at the Diversion Ditch Bridge, HCFCD has not yet begun excavation. CoH went first.

Dan Monks, a Kingwood resident, captured work in progress last week and gave ReduceFlooding.com permission to use his photos.

Photo By Dan Monks shows excavation in progress under east side of Kingwood Drive Bridge over Diversion Ditch.
The City is stacking the dirt on the bank, letting it drain and then hauling it off. Another shot courtesy of Dan Monks.
There’s still more work to do on the western side, but that should happen soon. Photo courtesy of Dan Monks.

The Second of Many Such Projects

According to Mayor Pro Tem Dave Martin’s office, the City’s Public Works Department will also be investigating other bridges in the Kingwood area to see if they too need to have silt removed from under them. These projects aren’t glamorous, but they are necessary to restore conveyance of area ditches. HCFCD’s Kingwood Area Drainage Analysis showed that some area ditches were down to a 2-year level of service. That means they were so constricted that they would flood in a two-year rain.

Bridges along Kingwood Drive and Northpark Drive can least afford flooding. They are vital links in crucial evacuation routes.

Thanks to the folks in the District E Council Office and the Public Works Department for addressing these issues.

It’s not yet clear when HCFCD plans to start excavation of the Diversion Ditch in this area.

If you have photos you would like to share with the public, please submit them through the Submissions Page of this website.

Posted by Bob Rehak on 10/10/21

1503 Days since Hurricane Harvey

Woodridge Village Purchase and Two More Kingwood Flood Control Measures APPROVED by Harris County Commissioners Today

Today, at 5:52PM, Harris County Commissioners Court unanimously approved three flood-control measures affecting Kingwood. The measures included approval to negotiate engineering contracts for improvements to the Kingwood Diversion Ditch and Taylor Gully. The third approval involved purchase of Woodridge Village from Perry Homes to build a regional floodwater detention facility in Montgomery County.

Woodridge Village Purchase Finally Approved

The latter has ranked high on the community’s agenda ever since sheet flow from Woodridge Village contributed to flooding hundreds of homes in Elm Grove and North Kingwood Villages twice in 2019.

Woodridge Village photographed one year after Imelda, when sheet flow flooded approximately 600 homes at the top of the frame.

Since then, Perry has completed the planned detention ponds on the property. However, the amount of detention still falls 40% of that needed under the new Atlas-14 standards.

The City of Houston will purchase 77 acres of the property outright for a wastewater treatment facility. The City will then pay for its half of the remaining Woodridge property by trading land that the Flood Control District can use to reduce the cost of flood mitigation projects elsewhere.

Neither the City nor County have yet announced a closing date for the Woodridge purchase.

The City and HCFCD will work with the community as plans for the property and Taylor Gully are developed by IDCUS Inc.

Kudos to County and City

Seventeen months after Imelda, families in Elm Grove and North Kingwood Village will sleep easier tonight, knowing they are one HUGE step closer to safety.

Thanks to all four Harris County Commissioners, especially Precinct 4 Commissioner Jack Cagle, and Harris County Judge Lina Hildaldo. Thanks also to Houston Mayor Pro Tem Dave Martin who helped overcome objections raised at several stages in the Woodridge purchase process.

Posted by Bob Rehak on 2/9/2021

1260 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

HCFCD Begins Kingwood Diversion Ditch Repairs

Last week, while driving through Forest Cove, I noticed construction activity and Harris County Flood Control District signs at the Kingwood Diversion Ditch near Walnut Lane. The area downstream from the bridge has some of the worst erosion of any ditch in Kingwood.

Area Now Under Repair As It Looked in 2009

Kingwood Diversion Ditch in 2009. Looking south from Walnut Lane. Forest Cove on right.

Erosion was bad for years and only got worse during major storms in 2015, 2016, and 2017. Massive slabs of the banks broke off in chunks, threatening trails and adjacent homes.

Since the picture above in 2009, the ditch has eroded both down and outward to increase its conveyance as new subdivisions upstream scabbed off of Kingwood’s infrastructure.

Pictures of Work in Progress Today

Oh, what a difference a decade makes! Note the exposed storm drains in the pictures below that you cannot see in the picture above.

Looking south from Walnut Lane Bridge. Exposed, elevated and crushed storm drains due to erosion.

The erosion left storm drains elevated and exposed to the ravages of floodwaters. Some were crushed, causing water to back up into streets and drainage ditches during heavy rains.

The area that collapsed circa 2009 above is the same area shown under construction today.

The velocity of water through this ditch during floods has earned it the nickname “Kingwood Rapids” from white-water enthusiasts.

Storm drains left exposed and elevated as the ditch widened and deepened itself to accommodate upstream development such as Woodridge Forest.
HCFCD works to restore and stabilize banks, and repair damaged storm drains.
Crumpled drains being removed by excavator.

How the Diversion Ditch Got Its Name

The Kingwood Diversion Ditch got its name when Friendswood realized that Ben’s Branch could not hold all the water being brought to it by adjacent subdivisions.

So Friendswood literally built a ditch that diverts a portion of the water coming down Ben’s Branch from Montgomery County just above Northpark Drive.

The point of diversion. Believe it or not, that’s Ben’s Branch flowing from bottom to top. As Ben’s Branch squeezes down, it forces water into the diversion ditch, which splits off to the right, just south of the new St. Martha’s Catholic Church.
From there, the ditch goes under Northpark Drive, past Woodland Hills, and south to the river.

Luckily, Friendswood designed the bridges over the Diversion Ditch to accommodate expansion of the ditch. HCFCD is studying that possibility now as part of the Kingwood Area Drainage Analysis. Results of the study should be published this fall.

Posted by Bob Rehak on 6/5/2020

1011 Days after Harvey

HCFCD Begins New Kingwood Drainage Ditch Repairs

Harris County Flood Control District has quietly started repairs to two more Kingwood Drainage Ditches. The first is G103-33-01, the ditch between Fosters Mill and Kings Point that enters the river near the mouth bar at Scenic Shores. The second is the Kingwood Diversion Ditch, G-103-38-00. It runs down the west side of Woodland Hills, crosses Kingwood Drive by the fire station, then descends to the lake between Trailwood Village and Forest Cove.

Work In Progress as of Monday 5/11/2020

Erosion on the ditch between Fosters Mill and Kings Point that enters Lake Houston near the mouth bar (background) undergoes repair.
Turbulence downstream of weirs, bottom left, commonly results in erosion.
Here’s what the erosion looked like before repairs started. Picture taken in 2018 courtesy of HCFCD.
Close up of eroded drain pipe near weir.

Work on Diversion Ditch Expected to Start This Week

According to Beth Walters of Harris County Flood Control, work on the Diversion Ditch should start this week. Below are several pictures taken of severe erosion that threatens homes and trails.

Looking west at Property in Deer Ridge Estates threatened by erosion of Kingwood Diversion Ditch. Looking west. Picture taken Jan. 2019.
Looking south at the Kingwood Diversion Ditch erosion just south of Walnut Lane. This area is a perennial problem. Photo taken in 2009. Kayakers have dubbed this area the Kingwood rapids. During floods, it offers the only white water experience in Kingwood.

Ditch maintenance includes erosion repairs, silt buildup removal, mowing, de-snagging (removing downed trees), and removing collapsed drainpipes.

Erosion in Kingwood Diversion Ditch near fire station on Kingwood Drive.

Additional details are not yet available on the length of time repairs will take.

Left unrepaired, such erosion can destroy property and trails. These repairs are part of HCFCD’s ongoing maintenance efforts.

Here’s a list of planned maintenance projects on other ditches around the Kingwood area.

Posted by Bob Rehak on 5/17/2020

992 Days after Hurricane Harvey

HCFCD Crews Work on Thanksgiving Day to Clear Ben’s Branch

Earlier this week, I reported an improbable meeting in Huffman on the eve of Thanksgiving that showed promise to increase conveyance on Luce Bayou. This story is even more amazing holiday miracle. Harris County Flood Control District (HCFCD) crews worked on Thanksgiving Day to clear trees blocking Ben’s Branch.

HCFCD has a right to cut trees 50 feet on either side of the centerline of the Ben’s Branch and clearing started Thanksgiving week. Photo courtesy of Thomas Blailock.

I did not personally see them but received an email with images from Thomas Blailock Thursday. Blailock says, “The contractor is UFLGC from Ackerman, MS. They had 7 trucks and around 20 employees clearing on Thanksgiving Day. They have been here for 4-5 days.”

I saw evidence of their work at Tree Lane. The areas on either side of Bens Branch look like they got a haircut.

Such clearing reduces the chances that trees will fall into the creek during storms, get hung up on other trees and form “beaver dams” that back water up into neighborhoods.

Result of One Year of Negotiation

The clearing follows a year of negotiation between HCFCD, Friendswood and Bear Branch Trail Association. The Association owns the greenbelt, but Friendswood still exercises deed restrictions.

The Community had mixed reaction to news of the agreement. Many were thankful for progress. Others felt the agreement didn’t go far enough. Many, like Blailock, hoped the creek could be widened or straightened.

Judging by how difficult it was to work out terms of this compromise, widening or straightening won’t happen any time soon – even as upstream development continues to dump more water faster into the creek.

An Alternative That Could Help

I have heard, however, that HCFCD has examined the possibility of widening the Kingwood Diversion ditch that runs down the western side of Woodland Hills and crosses under Kingwood Drive near the fire station. Preliminary reports from HCFCD indicate that a) their easement includes enough room to widen the ditch, b) no bridges would have to be widened (they were built with enough room under them to widen the ditch), and c) that could divert water from Ben’s Branch that would help reduce flooding along the creek.

Looking south down the diversion ditch from over Northpark Drive. That’s Woodland Hills on the left and Kings Mill on the right.
Looking north along the diversion ditch toward where it intersects with Ben’s Branch in front of the new St. Martha Church. That’s Ben’s Branch crossing left to right, parallel with the power lines.
HCFCD’s easement and the bridges are wide enough to widen the ditch without rebuilding the bridges. Note the extra room under the bridges on the right of the water.

Nothing is final yet. The Kingwood Area Drainage Assessment is not yet complete. So things could change. But don’t be surprised if you see this as a future recommendation.

For a full review of issues along Ben’s Branch from Kingwood Drive north past Northpark Drive and St. Martha’s new church, check out this thorough, thought-provoking presentation by Chris Bloch. It underscores the need to use all means possible to improve conveyance.

For more information about HCFCD work in the Kingwood Area, see this page on their new, updated website.

Posted by Bob Rehak on 11/30/2019 with help from Thomas Blailock and Chris Bloch

824 Days after Hurricane Harvey and 72 after Imelda