The northern section of Perry Homes’ Woodridge Village now has three detention ponds in various stages of completion. As of a week ago, on May 11, 2020, all three were capable of holding water and did during last weekend’s rains. That meant much rainfall that previously might have overwhelmed the two southern detention ponds had places to hold up instead of overflowing into Elm Grove and flooding residents.
No Record Rainfall, But No Flooding Either
Harris County’s Flood Warning System shows that the area received about two and a half inches of rain last weekend. A 2.5 inch rain is far from a record. But forecasters predicted much more. And some areas to the south and east of Lake Houston got more than 10 inches! So Elm Grove residents lucked out, but they were rightly worried.
In the end, whether it was the additional detention capacity or the lighter rain, no one flooded. And that’s what counts.
The Harris County Flood Warning System shows that the nearest official rain gage to Elm Grove is at West Lake Houston Parkway. It registered 2.52 inches of rain in 3 DAYS. 2.52 inches would have to fall in 3 HOURS to even make this chart, and then it would be something we could expect every year.Source: NOAA
Status of Detention Pond Construction
So what is the current status of construction? As of last Monday, the two ponds on the southern section (S1 and S2) were complete.
Of the three ponds on the northern section:
N1 was partially excavated, with most of the capacity in the “tail” leading south toward N2.
N2 was about 80% excavated. Workers were expanding the new section and deepening the old section, developed by Montgomery County many years ago.
N3 was approximately half complete.
Part of N1 Excavation as of May 11, 2020Massive N2 pond in southwest corner of northern section. Grassy portion was previously excavated by MoCo, but contractors are deepening it. Photo taken May 11, 2020.Looking south at Woodridge Village N3 detention pond photo from week ago, May 11, 2020.Elm Grove is out of sight beyond top of frame.
As last week wore on, each pond expanded compared to the three images you see above. Jeff Miller, an Elm Grove resident who lives near Woodridge Village, estimates that all three detention ponds on the northern section were about 80% excavated by the end of last week. However, he also noted that much work remains in terms of sloping the sides, stabilizing soil, building pilot channels and connecting ponds.
Barring further major rains and at the current rate, Miller estimates contractors could finish all three ponds in June.
How They Performed Last Weekend
N1
The first shot below shows the tail of N1. It was not yet connected to N2 so water could not drain out of it.
Photo of N1, looking north, by Jeff Miller on Saturday after rains stopped.
N2
I have no pictures showing how well N2 did at holding back rain, but neither Taylor Gully nor the southern detention ponds overflowed.
N3
Prior to the rain, this portion of N3 was deep enough to conceal all but the top of a large dump truck.N3 might have held approximately 5 feet of water according to Miller.
Additional Culverts for Connecting N1 and N3
Jeff Miller also photographed these 4×4 box culverts stacked up north of N3.
Note the concrete box culverts stacked up north of N3. Plans call for connecting N1 and N2 with such culverts.Also notice how land has been sloped from left to right to flow into N3.See water draining into N3 from a temporary ditch that cuts through the bottom of the image.
Layout and Capacity of All Ditches
Layout of detention ponds on Perry Homes’ Woodridge Village.This pie chart shows the relative capacity of Woodridge Village detention ponds. In the May flood last year, only the blue pond was complete. By the September flood, Perry had also completed the green pond. The three northern detention ponds hold 77% of planned storage capacity. None of those had even started.
Conclusion
Last week’s rains were a small test. But results showed the work already done has added to to detention capacity.
Miller says that water from the northern section did not appear to spill over into S2. His pictures also showed that S2 was only half full.
That meant the entire rain, with the help of new detention ponds, was able to drain out through a 3 foot corrugated pipe that connects Taylor Gully on either side of the county line, just like it used to.
This is welcome news for flood-weary Elm Grove and North Kingwood Forest residents who feared the worst.
No Progress to Report on the Political or Purchase Fronts
Even though the deadline for a Harris County purchase of Woodridge Village from Perry has passed, and even though Commissioners are not supposed to discuss the buyout in tomorrow’s Commissioner’s Court meeting, Precinct 4 Commissioner Jack Cagle says negotiations are ongoing.
The County made an offer to buy the land in order to build a regional flood detention facility. But the offer was contingent on the City of Houston donating $7 million worth of other property to the Flood Control District to help offset costs. The City also had to adopt County drainage criteria. It reportedly is more conservative than current City standards.
Posted by Bob Rehak on 5/18/2020 with photos and reporting from Jeff Miller
993 days since Hurricane Harvey and 242 since Imelda
The thoughts expressed in this post represent opinions on matters of public concern 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/2020/05/20200516-IMG_1440.jpg?fit=1200%2C900&ssl=19001200adminadmin2020-05-18 17:53:562020-05-18 18:23:32New Perry Detention Ponds Held Surprising Amount of Rain Last Weekend
Erosion can sometimes be sudden. It’s not always a slow process of water grinding away at dirt and dissolving it, or wearing down rocks. This post will examine several examples around us and look at their implications. I intend it as a continuation of yesterday’s post about ditch maintenance.
The Northpark Woods development (right) on the West Fork San Jacinto River (background)
Hydraulic action – When rapidly moving water churns against river banks and scours or undermines them.
Abrasion – Caused by small pebbles moving along a river bank or bed and knocking other particles loose. Think of sandpaper.
Attrition – When rocks carried by the river knock against each other. They break apart to become smaller and more rounded. This is how boulders turn into gravel.
Solution – When water dissolves certain types of rocks, for example limestone. We often see this in Florida, where sinkholes frequently develop.
Most of these processes happen slowly. But the first can be sudden. One storm. One flood. And boom. That river bank where you used to sit and quietly contemplate nature is gone.
Now You See It; Now You Don’t
Sometimes large slabs of a river bank or ditch suddenly slump into a river, almost like mini landslides. One flood expert commented on the picture above; he said “The owners of those new homes may suddenly find the ditch in their backyards.”
At other times, the size of a flood forces a river to widen. We saw this during Harvey and Imelda. The relentless pounding of flood waters carries away everything in their path. Cutbanks (the outside of a river bend) are especially vulnerable. Water slams directly into them like a firehose and washes them away. This action actually changes the course of a river over time.
Most of the time, it happens so slowly, we barely notice it. But during large floods, it’s sometimes sudden, large, and devastating to homeowners or businesses near rivers.
Three More Examples of Hydraulic Action
Example A: East End Park
East End Park in Kingwood. In 2019, the San Jacinto East Fork removed approximately 50-100 feet of river bank during Imelda,including this part of the Overlook Trail.
Example B: Balcom House and River Migration
Note a long peninsula south of the Balcom House on the San Jacinto West Fork before Hurricane Harvey.After one monster storm, the peninsula was gone. The Balcoms lost 175 feet of riverfront property.
Example C: River Aggregate Mine on West Fork in Porter
The third example comes from the abandoned River Aggregates sand mine beyond the new development in the first picture above. It’s a spectacular example of river migration.
In this case, the San Jacinto West Fork migrated 258 feet toward the mine’s dike in 23 years. When I first photographed the dike after Harvey, the river had eaten away an average of 12.4 feet per year. At the time, the dike was only 38 feet wide, and I predicted it could soon fail. It did. Within approximately a year.
Image taken on 9/14/2017, shortly after Hurricane Harvey. At the time, only 38 feet stood between the abandoned mine in the background that the San Jacinto west fork in the foreground.Note how the pond in the foreground disappeared when the river took the last 38 feet of river bank.
Wait a minute, you say! What happened to the pond. After the river bank collapsed, the pond drained, exposing sediment already within it. And the action of draining concentrated more sediment in it, like all the remnants of food trapped in your sink drain after you’re done washing dishes.
History of Pond
The missing, shallow pond in the foreground above used to be the settling pond for River Aggregates.
This satellite image from 2004 shows thatRiver Aggregates used the missing pond as a settling pond.This is how the mine looked in 2017 after River Aggregates abandoned it.Note river bank is still intact.This is how the abandoned mine looked in January of 2019. The river bank was gone. The pond had drained. And a steady stream of silty water from other ponds leaked into the West Fork.
Here’s how it looks today from a helicopter.
River Aggregates mine now leaks a steady stream of silty water into the West Fork San Jacinto.This is the same area as above, but from the reverse angle.
Lessons of Life Near a River
Most people never live long enough to see massive changes such as these in rivers. In most places, river change happens on a geologic time scale. But along the Gulf Coast, hurricanes can create floods that make rivers change on a human time scale, as these examples have shown.
What can we deduce from this?
Around here, we need to give rivers room to roam. Parks, green spaces, and golf courses, often represent the highest and best use of land near a river, bayou or ditch.
Building too close to rivers, bayous and drainage ditches can be costly. Disturbing wetlands and topsoil accelerates erosion. That, in turn, can threaten everything in its path. Be prepared to maintain anything you build near a watercourse, including the watercourse itself. And be prepared to fight what ultimately becomes a losing battle.
The thoughts expressed in this post represent opinions on matters of public concern 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/2019/10/EastForkByBoat_115.jpg?fit=1280%2C854&ssl=18541280adminadmin2020-05-18 09:09:122020-05-18 09:39:26Erosion: Sometimes Sudden
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.
New Perry Detention Ponds Held Surprising Amount of Rain Last Weekend
The northern section of Perry Homes’ Woodridge Village now has three detention ponds in various stages of completion. As of a week ago, on May 11, 2020, all three were capable of holding water and did during last weekend’s rains. That meant much rainfall that previously might have overwhelmed the two southern detention ponds had places to hold up instead of overflowing into Elm Grove and flooding residents.
No Record Rainfall, But No Flooding Either
Harris County’s Flood Warning System shows that the area received about two and a half inches of rain last weekend. A 2.5 inch rain is far from a record. But forecasters predicted much more. And some areas to the south and east of Lake Houston got more than 10 inches! So Elm Grove residents lucked out, but they were rightly worried.
In the end, whether it was the additional detention capacity or the lighter rain, no one flooded. And that’s what counts.
Status of Detention Pond Construction
So what is the current status of construction? As of last Monday, the two ponds on the southern section (S1 and S2) were complete.
Of the three ponds on the northern section:
As last week wore on, each pond expanded compared to the three images you see above. Jeff Miller, an Elm Grove resident who lives near Woodridge Village, estimates that all three detention ponds on the northern section were about 80% excavated by the end of last week. However, he also noted that much work remains in terms of sloping the sides, stabilizing soil, building pilot channels and connecting ponds.
How They Performed Last Weekend
N1
The first shot below shows the tail of N1. It was not yet connected to N2 so water could not drain out of it.
N2
I have no pictures showing how well N2 did at holding back rain, but neither Taylor Gully nor the southern detention ponds overflowed.
N3
Additional Culverts for Connecting N1 and N3
Jeff Miller also photographed these 4×4 box culverts stacked up north of N3.
Layout and Capacity of All Ditches
Conclusion
Last week’s rains were a small test. But results showed the work already done has added to to detention capacity.
That meant the entire rain, with the help of new detention ponds, was able to drain out through a 3 foot corrugated pipe that connects Taylor Gully on either side of the county line, just like it used to.
This is welcome news for flood-weary Elm Grove and North Kingwood Forest residents who feared the worst.
No Progress to Report on the Political or Purchase Fronts
Even though the deadline for a Harris County purchase of Woodridge Village from Perry has passed, and even though Commissioners are not supposed to discuss the buyout in tomorrow’s Commissioner’s Court meeting, Precinct 4 Commissioner Jack Cagle says negotiations are ongoing.
The County made an offer to buy the land in order to build a regional flood detention facility. But the offer was contingent on the City of Houston donating $7 million worth of other property to the Flood Control District to help offset costs. The City also had to adopt County drainage criteria. It reportedly is more conservative than current City standards.
Posted by Bob Rehak on 5/18/2020 with photos and reporting from Jeff Miller
993 days since Hurricane Harvey and 242 since Imelda
The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.
Erosion: Sometimes Sudden
Erosion can sometimes be sudden. It’s not always a slow process of water grinding away at dirt and dissolving it, or wearing down rocks. This post will examine several examples around us and look at their implications. I intend it as a continuation of yesterday’s post about ditch maintenance.
There are four main types of erosion.
Most of these processes happen slowly. But the first can be sudden. One storm. One flood. And boom. That river bank where you used to sit and quietly contemplate nature is gone.
Now You See It; Now You Don’t
Sometimes large slabs of a river bank or ditch suddenly slump into a river, almost like mini landslides. One flood expert commented on the picture above; he said “The owners of those new homes may suddenly find the ditch in their backyards.”
At other times, the size of a flood forces a river to widen. We saw this during Harvey and Imelda. The relentless pounding of flood waters carries away everything in their path. Cutbanks (the outside of a river bend) are especially vulnerable. Water slams directly into them like a firehose and washes them away. This action actually changes the course of a river over time.
Most of the time, it happens so slowly, we barely notice it. But during large floods, it’s sometimes sudden, large, and devastating to homeowners or businesses near rivers.
Three More Examples of Hydraulic Action
Example A: East End Park
Example B: Balcom House and River Migration
Example C: River Aggregate Mine on West Fork in Porter
The third example comes from the abandoned River Aggregates sand mine beyond the new development in the first picture above. It’s a spectacular example of river migration.
In this case, the San Jacinto West Fork migrated 258 feet toward the mine’s dike in 23 years. When I first photographed the dike after Harvey, the river had eaten away an average of 12.4 feet per year. At the time, the dike was only 38 feet wide, and I predicted it could soon fail. It did. Within approximately a year.
Wait a minute, you say! What happened to the pond. After the river bank collapsed, the pond drained, exposing sediment already within it. And the action of draining concentrated more sediment in it, like all the remnants of food trapped in your sink drain after you’re done washing dishes.
History of Pond
The missing, shallow pond in the foreground above used to be the settling pond for River Aggregates.
Here’s how it looks today from a helicopter.
Lessons of Life Near a River
Most people never live long enough to see massive changes such as these in rivers. In most places, river change happens on a geologic time scale. But along the Gulf Coast, hurricanes can create floods that make rivers change on a human time scale, as these examples have shown.
What can we deduce from this?
Here’s a current list of ditch maintenance projects in the Kingwood area.
Posted by Bob Rehak on 5/18/2020
993 Days since Hurricane Harvey
The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.
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
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.
Ditch maintenance includes erosion repairs, silt buildup removal, mowing, de-snagging (removing downed trees), and removing collapsed drainpipes.
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