Disclaimer: I spent the better part of a day driving down every street that borders Ben’s Branch. I saw damage clustered in three areas. It’s possible other areas were affected but the City had removed trash before I got there.
At least two schools, 7 homes, and one business flooded along Ben’s Branch in Kingwood during Imelda. All were located near choke points along the creek. And massive recent upstream development likely played a role in each case. That new development also played a role in eroding the margin of safety between floodwaters and foundations all along the creek – even for homes and businesses that did not flood. Total damages will likely exceed $3 million along Ben’s Branch in Kingwood.
Ben’s Branch Now and 10 Years Ago: Influence of Upstream Development
Imelda Tested Design Limits of Drainage Systems
Most drainage systems are designed to protect homes and businesses from a hundred-year flood. Imelda was a hundred year flood. The storm tested the design limits of flood infrastructure everywhere along Ben’s Branch in Kingwood.
Based on its peak intensity of 4.56 inches in one hour (as measured at the US59/West Fork gage), Imelda qualified as a 100-year storm. Streets, storm drains and ditches are designed to handle that much as an upper limit. And for the most part they did. Especially because builders usually elevate most structures at least two feet above the hundred-year flood plain.
Those extra two feet act as a margin of safety and as a hedge against future upstream development.
Limits Exceeded in Several Places During Imelda
In each case where homes, businesses or schools flooded along Ben’s Branch, unique circumstances eliminated that margin of error and resulted in flooded structures.
With the exception of one low-lying home I found in Hunter’s Ridge very close to the creek, all of the structural damage took place at three choke points along the creek.
Choke Point #1: Northpark and Ben’s Branch
Where Ben’s Branch crosses under Northpark Drive, two things happen. A ditch from the new Woodridge Forest subdivision joins it. And then all that water is forced into a culvert that crosses under Northpark Drive.
To my knowledge, no one has ever upgraded that culvert despite significant upstream development. It backs water up for several blocks during heavy rains and forces water OVER Northpark Drive. This caused at least six homes near Aspen Glade west of Hidden Pines to flood.
When water backed up and flowed over Northpark, it cut off both inbound and outbound traffic. It also broke through the fences of homes that back up to Northpark.
Impact of New Development
Net: the flooding of homes on Aspen Glade was likely caused by an undersized culvert at North Park that could not convey all the water coming from hundreds of acres of new development. When the water backed up, it rushed over North Park for approximately two blocks. Eyewitness reports and FaceBook videos peg the height at a foot above the roadway.
Much of the drainage from the new development joined Ben’s Branch just before it reached the culverts.
Choke Point #2: Woodland Hills Drive and Ben’s Branch
About two or three blocks east of the culverts under Northpark, between St. Martha Catholic School and Kids in Action, Ben’s Branch narrows down again. It quickly funnels from a wide, excavated ditch to a narrow stream cutting through dense forest. See photo below.
At this choke point, both the school and Kids in Action, flooded. Repairing the school after the May flood cost St. Martha $900,000. Repairing Kids in Action cost $500,000. This time it will cost each even more.
The results were costly. St. Martha’s lost two classroom buildings plus its playground.
Until the school buildings can be dried, disinfected and rebuilt, classes are being held on upper floors and in other parish buildings. No children were ever endangered by the flood. Parish personnel started evacuations to higher buildings as soon was water started coming into the parking lot, the lowest point on the campus.
Across the creek, Kids in Action, one of Kingwood’s most popular day care and after school facilities, had its own problems.
Haven’s spent $500,000 repairing her facilities after the May 7th flood. That’s a lot for a small business. She’s determined to weather this storm, too. But she worries that some of her clients may grow impatient in the inconvenience during repairs.
Choke Point #3: Kingwood Drive and Ben’s Branch
As Ben’s Branch approaches Kingwood Drive from the northwest, it spreads out into a 100+ acre forested area that includes the Creekwood Nature Center. But just before it crosses under Kingwood Drive, Ben’s Branch’s flood plain funnels down between Kingwood High School and the old H-E-B shopping center. At that point, a second branch of the stream joins it from the north. After crossing under Kingwood Drive, it is further constricted on the east side by commercial development. This represents another choke point.
The Kingwood High School gym and natatorium took on several inches of water during Imelda when drains and/or Ben’s Branch backed up. Merchants in the old H-E-B shopping center also report being stranded in their stores for two hours at the peak of Imelda as water from Ben’s Branch raced through the parking lot. Merchants said the water was inches from coming in their stores.
While many of the businesses south of Kingwood Drive in Town Center and Kings Harbor reported having water lapping at their foundations, I found none that reported flood damage.
No Simple Fix
I can’t think of a simple fix to all of three of these problems. Fixing one could compound the others. For instance, it would be simple to replace the culverts under Northpark with a bridge when the street is widened. However, that would just increase the volume of water backing up where the creek narrows between St. Martha’s School and Kids in Action. That would likely flood them even worse.
Channelizing the creek all the way to Kingwood Drive would likely be unpalatable from a political point of view. Four reasons: Few people in that area were affected. They all love their greenbelts. And the costs would be high. That would make the Benefit/Cost ratio of the project a non-starter.
One Possible Solution
One possible solution: convert the unused land around St. Martha’s new church north of Northpark Drive to additional detention. That’s valuable land and detention is expensive, but it may be a better alternative than losing the school which was just expanded in 2008. Father TJ Dolce is pitching that idea and hopes the Archdiocese would approve the use of their vacant land for detention. The big question: Would it be enough to make a difference.
Drainage Study Already Under Way
Thankfully, Harris County Flood Control is conducting a Kingwood-wide drainage study right now. They are studying Ben’s Branch. Hopefully, their talented engineers will be able to find the optimum solution that protects everyone. I sure hope they find it soon because these people are every bit as desperate as the people who flooded twice in Elm Grove and North Kingwood Forest.
Ben’s Branch may affect fewer structures. But it probably affects more people when you add up enrolled students and their families.
Posted by Bob Rehak on 10/1/2019 with help from Father TJ Dolce, Diane Havens, Lela Yorba, Daryl Palmer and National Helicopter Service.
763 Days since Hurricane Harvey and 12 since Imelda