Tonight, the Lake Houston area is under yet another flash flood watch. Residents of North Kingwood Forest and Elm Grove are wondering whether a new detention pond in Woodridge Village will be enough to protect them.
Another 1-4 Inches of Rain Possible
We may get another chance to test the engineering on the detention ponds in that new Woodridge Village under development in Montgomery County. Our area received 1-3″ of rain today and more is on the way tonight. The area remains under a flash flood watch until 7a.m. Monday morning.
Heavy rainfall and severe thunderstorms will be possible tonight into early Monday.
Jeff Lindner, Harris County Meteorologist warned at 8:30 p.m. Sunday night that, “Numerous thunderstorms are in progress over portions of Liberty, Harris, and Montgomery Counties. Heavy rainfall is the main threat with these cells with recent HCFCD gages in SE Montgomery County recording 2.60 inches in 1 hour. Additional rainfall amounts tonight of 1-2 inches with isolated totals of up to 4 inches are possible.”
The storms appear to be fast moving so the higher totals are less likely than in early May when approximately 200 homes flooded in Elm Grove and North Kingwood Forest just south and east of the area that Woodridge contractors had clearcut.
Role of Detention Pond in Reducing Flood Potential
Had the Woodridge Village S2 Detention Pond been excavated before May 7, it might have prevented much of the flooding. But despite the land being cleared for approximately six months, the pond had not yet been built. LJA Engineers designed the pond to hold 50 acre-feet of runoff. What does that mean?
How Much is An Acre Foot?
One acre foot would cover an entire acre to a depth of one foot. An acre is about the size of a football field. That means 50 acre feet would cover:
One football field to a depth of 50 feet
50 football fields to a depth of one foot
Or, in the case, of this pond, about 3.5 acres to a depth of about 15 feet.
The pictures below show what it looks like today. Very little of this area was excavated on May 7.
S2 has the shape of a hockey stick. Here’s the “face” of the stick. It took a 14mm super-wide-angle lens to get the width of this pond in the frame.This conveys its width but does not adequately convey its depth.This panoramic image was stitched together in Photoshop from seven still images taken with a normal focal length lens. It more accurately conveys the height of the sides. But there’s still nothing in the frame to communicate scale.Although the sides don’t look tall in the previous photo, this is what they look like when you turn and face them. This shot was taken while standing near the bottom. My eye level is more than six feet high and didn’t come halfway up the slope.This notch in the wall of the pond allows water from the ditch behind the grass to overflow into the pond instead of flooding North Kingwood Forest (behind the tree line. That’s the theory anyway … if the calculations are correct.The red circle shows the location of the notch between the pond and drainage ditch beyond it.
Hopefully, the amount of detention in place tonight is enough to handle the rain we get.
Posted by Bob Rehak on 6/16/2019
656 Days after Hurricane Harvey
Thoughts expressed in this post represent my opinions on matters of public policy 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/2019/06/Woodridge6.17.19_01_01.jpg?fit=1500%2C1000&ssl=110001500adminadmin2019-06-16 22:40:432019-06-16 22:43:09Flash Flood Watch in Effect Until 7 a.m. Monday; Luckily, Woodridge Detention Pond Nearing Completion
Officials close to the project say actual dredging could start as early as next week. Dredgers only need more 24″ pipe to pump the sediment 10 miles back upstream to placement area #2, an old sand pit near Kingwood College. However, the City and Corps are still debating the volume deposited by Harvey. The Corps has not yet divulged where it plans to start dredging, what its objectives are for this phase of the project, or what the contributions of other partners will be.
New Drone Video of Mouth Bar by Jim Zura of Zura Productions
New drone footage of the West Fork mouth bar shows just how much the mouth bar has grown since Harvey. I took the still shot immediately below from a helicopter two weeks after Harvey. To see what it looks like today, scroll down. Kingwood-based Jim Zura of Zura Productions shot two new drone videos this morning. They show what the mouth bar looks like 22 months later. As you watch the videos shot from different elevations, consider the immensity of the bar compared to the dredge at the tail end of each video.
Five hundred thousand cubic yards will not come close to restoring the full conveyance of the West Fork. How does 500,000 cubic yards compare with what NEEDS to be dredged?
Let’s start by looking at the channel that the Corps is dredging upriver and assume that they will extend that between the mouth bar and Atascocita Point. That strategy follows the relict channel. The relict channel is also the path with the least sediment at the moment. So that would make the most efficient use of funds.
Let’s also assume that the channel needs to be dredged an average of five yards (15 feet) deeper than its current depth along that path in order to match the profile below.
Endpoint of current dredge program shows channel 22.5′ deep by 400′ wide..
A “budget” of 500,000 cubic yards would allow you to dredge a channel 133 yards (400 feet) wide 5 yards deeper and 752 yards long. That equals 500,080 cubic yards. But 752 linear yards is only about one-fourth of the 3,000+ yards to the FM1960 bridge. And we haven’t even touched the mouth bar!
West Fork Map shows difference in sedimentation between 2010 and 2017. Note the white and violet areas near the FM1960 bridge. Red/orange/yellow/green areas represent decreases in sediment. Blue, violet and white represent increases.
Clearly, dredging the rest of the way to the bridge will require more money from the State, County and/or City. Thankfully for the Lake Houston Area, all of those entities have already allocated funds.
Details Yet to Work Out
However, the City, Harris County, and State of Texas have even more hurdles to clear beyond the volume debate.
They must find a suitable storage site that can accommodate all the sediment they hope to dredge. The storage site represents the biggest obstacle at the moment and a limiting factor.
The Corps would prefer a below ground site, i.e., an abandoned sand pit. That would reduce the risk of future floods carrying sediment back into the river. Also, it would NOT encroach on the flood plain.
Finally, the closer the site is to the dredging, the faster and cheaper the project. Long pipelines lead to more breakdowns. And each additional booster pump uses 1000 gallons of diesel per day.
Latest on Madden Property
The largest property evaluated so far is a 4000-acre site owned by Berry Madden of Humble. Madden’s property is close – half the distance of the sand mine on Sorters Road. It is also large enough to accommodate all the sediment people want to remove – including sediment from maintenance dredging down the road. Permitting one property instead of several would save lots of time (perhaps years).
But storage on Madden’s property would be above ground. Until someone builds on it, that introduces an element of risk that below-ground storage does not have. Madden has conducted an environmental survey of his property and is now conducting an archeological survey required for a storage permit. The Corps has not yet approved his property.
A source close to negotiations says the Corps is considering approving half of the Madden site for now while it performs additional evaluations of the rest of the site. That might be enough to accommodate immediate needs, reduce the cost of pumping sediment ten miles upstream, and provide storage room for future maintenance dredging.
80,000 CY More Sediment Deposited Since Last Survey
Meanwhile, time and sediment march on. Sources say the Corps recently found another 80,000 cubic yards of sediment deposited in the mouth bar area since the last survey after Harvey.
This supports the theory of two top local geologists, RD Kissling and Tim Garfield, who predicted that the mouth bar would form a dam that accelerated sedimentation. That theory also explains why the mouth bar must be removed, or at least why we must dredge a channel around it ASAP.
Posted by Bob Rehak on 6/18/2019with drone footage courtesy of Jim Zura, Zura Productions
658 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/06/FirstDroneVideo.jpg?fit=1500%2C839&ssl=18391500adminadmin2019-06-16 12:55:552019-06-18 17:39:41Dredge Finally Reaches Mouth Bar
When Elm Grove and North Kingwood Forest flooded on May 7, the Woodridge Village contractor had cleared most of the 268 acres of land north and west of them. The contractor also had sloped the drainage toward those subdivisions without first installing a critical 50 acre-foot detention pond to intercept runoff. Tonight after months of delays, and the flooding of almost 200 homes, work on that pond is almost complete.
S2 Pond Finally Connected to Drainage Ditch Today
Regular readers may remember plans call for a 15-foot deep detention pond shaped somewhat like a hockey stick (see below). The area circled in red is the channel that will connect the pond to the drainage ditch that runs down the east side of the property. Today, some workers excavated that channel while others deepened the pond.
Circled in red: the channel excavated today that will connect the drainage ditch with the detention pond.
Not Much Excavated on May 9
Back on May 9, about a month ago, very little of the pond was excavated when local videographer, Jim Zura, captured this image from his drone. Only a small ditch connected a pond north of Sherwood Trails to the box culvert seen below. The white outline indicates how much of the pond had yet to be excavated.
Almost nothing had been excavatedshortly after the May 7 flood.White outline shows the approximate intended dimension of the pond.
Despite the heavy rains in early May and early June, the contractor now has most of the pond excavated. See the video that Jeff Miller shot this afternoon.
Since the flood, the pond has been widened and deepened. Rebel Contractors is now approaching the pond’s final dimensions and target depth of 15 feet, according to Miller. However, Miller was even more excited about the excavation of the channel connecting the drainage ditch running down the east side of the property to the detention pond. “I’ll be able to sleep with both eyes closed tonight,” he said.
In the future, when runoff drains from the northern part of the property to the southern, it will overflow from the ditch into the pond, rather than into neighbors’ houses.
Recent Excavation Despite Heavy Rains Last Week
The next two shots show what the connecting channel looks like from the ground.
Previously, water in the ditch had to funnel down into the 3′ black culvert (bottom left). This caused the ditch to overflow into surrounding neighborhoods when the ditch got full.Now, however, this channel connects ditch (foreground) and pond (upper left). It will allow runoff to overflow into pond instead of neighbors’ homes.
Bill King Visits Elm Grove Again, Meets Texas Monthly Writer
But that wasn’t the only good news, today. Houston mayoral candidate Bill King visited Elm Grove for the third time in a month and toured the area with Mark Dent, who is covering the story for Texas Monthly.
Bill King (left) and Mark Dent talk about flood mitigation strategies with Taylor Gulley in the background.
King emphasized several needs to Dent. They included:
Greater clarity and accuracy of flood maps, so that people can realistically assess their flood risk
Safer construction practices that better protect downstream residents
Preservation of natural wetlands, buffers and drainage features like those that previously existed on the Woodridge site, and that had protected Elm Grove since it was built.
King emphasized that preserving such natural areas and the wetlands on them can provide both recreation and protection against flooding. Finally, he advocated using buyouts to build more and bigger detention ponds, and also to create more green space.
It’s good to know that King is taking Kingwood issues seriously. He’s making them a centerpiece of his campaign and using them to shine a spotlight on development practices that need improvement in my opinion.
Posted by Bob Rehak on 6/14/2019with help from Jeff Miller
654 Days since Hurricane Harvey, 5 weeks since the Elm Grove Flood, and 4 Months Until the Election
Thoughts expressed in this post represent my opinions on matters of public interest 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/2019/06/Swale_01.jpg?fit=1500%2C1000&ssl=110001500adminadmin2019-06-14 19:41:442019-06-14 19:50:21Critical Woodridge S2 Detention Pond Approaching Final Dimensions
Flash Flood Watch in Effect Until 7 a.m. Monday; Luckily, Woodridge Detention Pond Nearing Completion
Tonight, the Lake Houston area is under yet another flash flood watch. Residents of North Kingwood Forest and Elm Grove are wondering whether a new detention pond in Woodridge Village will be enough to protect them.
Another 1-4 Inches of Rain Possible
We may get another chance to test the engineering on the detention ponds in that new Woodridge Village under development in Montgomery County. Our area received 1-3″ of rain today and more is on the way tonight. The area remains under a flash flood watch until 7a.m. Monday morning.
Jeff Lindner, Harris County Meteorologist warned at 8:30 p.m. Sunday night that, “Numerous thunderstorms are in progress over portions of Liberty, Harris, and Montgomery Counties. Heavy rainfall is the main threat with these cells with recent HCFCD gages in SE Montgomery County recording 2.60 inches in 1 hour. Additional rainfall amounts tonight of 1-2 inches with isolated totals of up to 4 inches are possible.”
The storms appear to be fast moving so the higher totals are less likely than in early May when approximately 200 homes flooded in Elm Grove and North Kingwood Forest just south and east of the area that Woodridge contractors had clearcut.
Role of Detention Pond in Reducing Flood Potential
Had the Woodridge Village S2 Detention Pond been excavated before May 7, it might have prevented much of the flooding. But despite the land being cleared for approximately six months, the pond had not yet been built. LJA Engineers designed the pond to hold 50 acre-feet of runoff. What does that mean?
How Much is An Acre Foot?
One acre foot would cover an entire acre to a depth of one foot. An acre is about the size of a football field. That means 50 acre feet would cover:
The pictures below show what it looks like today. Very little of this area was excavated on May 7.
Hopefully, the amount of detention in place tonight is enough to handle the rain we get.
Posted by Bob Rehak on 6/16/2019
656 Days after Hurricane Harvey
Thoughts expressed in this post represent my opinions on matters of public policy and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP statute of the Great State of Texas.
Dredge Finally Reaches Mouth Bar
The Army Corps of Engineers announced last week that it had received a mission assignment from FEMA to dredge 500,000 cubic yards in the area of the mouth bar of the San Jacinto West Fork. This week, the dredge operated by Great Lakes was sighted within 200 yards of the bar. (See videos below.)
Dredging Could Start Next Week
Officials close to the project say actual dredging could start as early as next week. Dredgers only need more 24″ pipe to pump the sediment 10 miles back upstream to placement area #2, an old sand pit near Kingwood College. However, the City and Corps are still debating the volume deposited by Harvey. The Corps has not yet divulged where it plans to start dredging, what its objectives are for this phase of the project, or what the contributions of other partners will be.
More Meetings Needed to Finalize Volume
All parties will meet in the coming days to finalize the volume and a plan. The City of Houston and Army Corps are still 900,000 cubic yards apart in their estimates of the amount of sediment deposited by Harvey. The City hopes to get the Corps to increase its estimate of 500,000 cubic yards. However, that hasn’t happened so far. Meanwhile everyone wants to reduce flood risk by removing as much sediment as possible before the peak of hurricane season.
New Drone Video of Mouth Bar by Jim Zura of Zura Productions
New drone footage of the West Fork mouth bar shows just how much the mouth bar has grown since Harvey. I took the still shot immediately below from a helicopter two weeks after Harvey. To see what it looks like today, scroll down. Kingwood-based Jim Zura of Zura Productions shot two new drone videos this morning. They show what the mouth bar looks like 22 months later. As you watch the videos shot from different elevations, consider the immensity of the bar compared to the dredge at the tail end of each video.
How Far Would 500,000 Cubic Yards Get Us?
Five hundred thousand cubic yards will not come close to restoring the full conveyance of the West Fork. How does 500,000 cubic yards compare with what NEEDS to be dredged?
Let’s start by looking at the channel that the Corps is dredging upriver and assume that they will extend that between the mouth bar and Atascocita Point. That strategy follows the relict channel. The relict channel is also the path with the least sediment at the moment. So that would make the most efficient use of funds.
Let’s also assume that the channel needs to be dredged an average of five yards (15 feet) deeper than its current depth along that path in order to match the profile below.
Extending the channel through the bridge is important because of the sediment built up behind it.
Clearly, dredging the rest of the way to the bridge will require more money from the State, County and/or City. Thankfully for the Lake Houston Area, all of those entities have already allocated funds.
Details Yet to Work Out
However, the City, Harris County, and State of Texas have even more hurdles to clear beyond the volume debate.
The Corps would prefer a below ground site, i.e., an abandoned sand pit. That would reduce the risk of future floods carrying sediment back into the river. Also, it would NOT encroach on the flood plain.
Finally, the closer the site is to the dredging, the faster and cheaper the project. Long pipelines lead to more breakdowns. And each additional booster pump uses 1000 gallons of diesel per day.
Latest on Madden Property
The largest property evaluated so far is a 4000-acre site owned by Berry Madden of Humble. Madden’s property is close – half the distance of the sand mine on Sorters Road. It is also large enough to accommodate all the sediment people want to remove – including sediment from maintenance dredging down the road. Permitting one property instead of several would save lots of time (perhaps years).
But storage on Madden’s property would be above ground. Until someone builds on it, that introduces an element of risk that below-ground storage does not have. Madden has conducted an environmental survey of his property and is now conducting an archeological survey required for a storage permit. The Corps has not yet approved his property.
A source close to negotiations says the Corps is considering approving half of the Madden site for now while it performs additional evaluations of the rest of the site. That might be enough to accommodate immediate needs, reduce the cost of pumping sediment ten miles upstream, and provide storage room for future maintenance dredging.
80,000 CY More Sediment Deposited Since Last Survey
Meanwhile, time and sediment march on. Sources say the Corps recently found another 80,000 cubic yards of sediment deposited in the mouth bar area since the last survey after Harvey.
This supports the theory of two top local geologists, RD Kissling and Tim Garfield, who predicted that the mouth bar would form a dam that accelerated sedimentation. That theory also explains why the mouth bar must be removed, or at least why we must dredge a channel around it ASAP.
Posted by Bob Rehak on 6/18/2019 with drone footage courtesy of Jim Zura, Zura Productions
658 Days since Hurricane Harvey
Critical Woodridge S2 Detention Pond Approaching Final Dimensions
When Elm Grove and North Kingwood Forest flooded on May 7, the Woodridge Village contractor had cleared most of the 268 acres of land north and west of them. The contractor also had sloped the drainage toward those subdivisions without first installing a critical 50 acre-foot detention pond to intercept runoff. Tonight after months of delays, and the flooding of almost 200 homes, work on that pond is almost complete.
S2 Pond Finally Connected to Drainage Ditch Today
Regular readers may remember plans call for a 15-foot deep detention pond shaped somewhat like a hockey stick (see below). The area circled in red is the channel that will connect the pond to the drainage ditch that runs down the east side of the property. Today, some workers excavated that channel while others deepened the pond.
Not Much Excavated on May 9
Back on May 9, about a month ago, very little of the pond was excavated when local videographer, Jim Zura, captured this image from his drone. Only a small ditch connected a pond north of Sherwood Trails to the box culvert seen below. The white outline indicates how much of the pond had yet to be excavated.
Despite the heavy rains in early May and early June, the contractor now has most of the pond excavated. See the video that Jeff Miller shot this afternoon.
Since the flood, the pond has been widened and deepened. Rebel Contractors is now approaching the pond’s final dimensions and target depth of 15 feet, according to Miller. However, Miller was even more excited about the excavation of the channel connecting the drainage ditch running down the east side of the property to the detention pond. “I’ll be able to sleep with both eyes closed tonight,” he said.
Recent Excavation Despite Heavy Rains Last Week
The next two shots show what the connecting channel looks like from the ground.
Bill King Visits Elm Grove Again, Meets Texas Monthly Writer
But that wasn’t the only good news, today. Houston mayoral candidate Bill King visited Elm Grove for the third time in a month and toured the area with Mark Dent, who is covering the story for Texas Monthly.
King emphasized several needs to Dent. They included:
King emphasized that preserving such natural areas and the wetlands on them can provide both recreation and protection against flooding. Finally, he advocated using buyouts to build more and bigger detention ponds, and also to create more green space.
It’s good to know that King is taking Kingwood issues seriously. He’s making them a centerpiece of his campaign and using them to shine a spotlight on development practices that need improvement in my opinion.
Posted by Bob Rehak on 6/14/2019 with help from Jeff Miller
654 Days since Hurricane Harvey, 5 weeks since the Elm Grove Flood, and 4 Months Until the Election
Thoughts expressed in this post represent my opinions on matters of public interest and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP statute of the great State of Texas.