Pictures taken of a new Huffman development after a 3.75-inch, 2-year rain last week illustrate why flood risk increases during construction compared to other phases of a project.
Aerial images taken over Sila, west of the Huffman-Cleveland Road, show:
Cleared land that accelerates runoff and decreases infiltration
Partially constructed stormwater detention basins
Trenches not yet consistently sloped
Rampant erosion
Workers pumping water out of one flooded area under construction only to flood another
Friendswood took more precautions with the 553-acre Sila than most developers take with their projects.
Regardless, despite their best intentions, a 2-year rain still overwhelmed them in places. Let’s look at examples of each point above.
Accelerating Runoff, Decreasing Infiltration
Natural ground cover slows the rate of runoff. Removing the ground cover lets stormwater flow faster.
Contractors also grade the land to create consistent slopes for roads and storms drains. That can eliminate little ponds, pockets of wetlands, and other natural catchments that slow water down.
First phase of Friendswood’s Sila Development in Huffman. Looking east toward St. Tropez at top of frame across Huffman-Cleveland Road.
I took these pictures just hours after the rain stopped. Notice how fast the runoff accumulated, even without storm drains.
Reverse angle looking west. Note water rapidly collecting and running off cleared area compared to forested area.
Partially Constructed Mitigation Facilities
Stormwater detention basins collect accumulated runoff and later release it at slower pre-development rates. Thus post-development runoff rates equal pre-development rates. At least if everything is done correctly.
But what happens when a large rain slams you before you complete the detention basins?
Partially completed Sila detention basin.
Trenches Not Yet Consistently Sloped
During work in progress, like this, trenches may not be consistently sloped. In the picture below, water flowed downhill from left to right. A swale caught most of the runoff. And a silt fence backstopped it. Regardless…
Because the swale was not consistently sloped toward the top of the frame, stormwater overflowed onto a neighbor’s property.
Rampant Erosion
Backslope interceptor systems that reduce erosion on the sides of ditches and basins have not yet been built here. Neither has grass been planted on the side slopes of those ditches and basins. The result: rampant erosion that can clog ditches and streams, and reduce the capacity of basins.
Note silt in stormwater detention basin.
Workers Saving One Area Only to Endanger Another
The first three shots below show the partially completed detention basin and workers scrambling to expel the rapidly accumulating runoff.
Workers pump water out of the pond into a ditch.Note the pumps washing dirt into the ditch.
From there, water raced downslope toward the East Fork of the San Jacinto.
But the high flow from the pumped water found a way around one set of rock gabions and destroyed another.
That turned the outfall for a neighboring ditch (right of greenish pond above) into a mass of muck. From there, the muck flowed toward the river.
Muck moves toward East Fork San Jacinto beyond top of frame.
Could Have Been Worse
I didn’t see any homes that flooded on this day. Muck did flow into a few yards and across roads. And the outfall to a neighborhood drainage ditch, which was just cleaned out, will have to be cleaned out again.
But no doubt, it could have been much worse. See below.
Contractors created a slight depression to keep water from rushing downhill into neighboring homes (top of frame).
It’s also worth noting that runoff from Sila must go through more than a half mile of forested wetlands before reaching the East Fork. That will slow the water down, capture some of the erosion before it reaches the river, and keep the sediment from reducing the conveyance of the river channel.
Construction always entails flood risk, especially large scale construction that can take years. But with the right precautions, large rains don’t have to spell disaster.
Posted by Bob Rehak on 4/14/2024
2420 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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2024/04/20240410-DJI_20240410115705_0181_D.jpg?fit=1100%2C619&ssl=16191100adminadmin2024-04-14 16:41:232024-04-14 16:59:55Why Flood Risk Increases During Construction
The persistent after-hours pumping of silty stormwater from the Trammell Crow construction site into the street drains has been reported to Harris County Engineering for several months now. Despite warnings, the practice continues. The danger: accumulated silt in drain pipes and the river can reduce their conveyance, back water up in heavy rains, and lead to flooding.
One small development won’t be catastrophic. But the cumulative impact of hundreds could be.
For all those reasons, construction permits come with instructions to use things that retain and filter silty water such as berms, sediment basins and semi-permeable fencing.
Repeat Offender
In January 2024, contractors began clearing Phase II of an apartment complex on West Lake Houston Parkway without any of these safeguards. Because the complex lies just outside the City limits, Harris County Engineering is responsible for inspections.
They have visited the site numerous times and cautioned contractors about discharges of silty stormwater. At different times, the contractors installed silt fences and erected berms. They also built sediment basins and channeled excess stormwater to them.
On April 10th, the area received approximately 2 inches of rain. And yesterday, April 11, the contractors were pumping water back into the street THROUGH A PILE OF MUD. After quitting time. When inspectors wouldn’t be around. Again!!!
Caught on Camera
Michelle Chavez, a nearby resident, caught the action on camera.
39 second video by Michelle Chavez showing extent and source of pumping
Chavez also took several still photos.
Silty stormwater being pumped through open gate washing out drivewayNote mud on right being washed into street.Pumping took place near sunset, around 8PM when County inspectors were unlikely to be present.They appeared to be pumping water from unfinished, underground storm drains, but pumped it through mud. Photo by BR taken around 7PM on 4/11/24.
At least one local resident concerned about flooding reported the pumping to Harris County Engineering. He was told that Engineering would send an inspector out.
Sending Wrong Message: Will Sixth Time be the Charm?
This is the sixth story I have posted about stormwater-control issues at this construction site. See the previous five.
One wonders when the county will level a stiff fine or shut down this site. At this point the Harris County Engineering Department also has its reputation on the line. Tolerating such behavior sends a message to other developers that may be unsafe in the long run.
Posted by Bob Rehak on 4/12/24
2418 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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2024/04/434446698_733173785641283_9042163331193754798_n-scaled.jpg?fit=2560%2C1920&ssl=119202560adminadmin2024-04-12 17:28:372024-04-12 17:28:38Trammell Crow Contractors Still Pumping Silty Stormwater into Street
The April 10th storm that swept through Houston during the early morning hours dumped amazing amounts of rainfall just east of here.
A report received today from Harris County Meteorologist Jeff Lindner says that the April 10th storm dumped 12-17 inches of rain in a 12 hour period in a swatch across East Texas. The result: widespread, catastrophic flooding in parts of Newton, Jasper, Hardin, and Tyler Counties.
A peak total of 17.68 inches was recorded near Kirbyville, TX. Lindner characterized the totals as “insanely high.” In fact, NOAA’s Atlas 14 rainfall chart for Kirbyville lists a 12-hour/17-inch rainfall as a 1000-year event.
Late yesterday morning, Weather.com reported that a Disaster Declaration had been issued for Jasper County, Texas. Officials there said that multiple people were rescued from both homes and vehicles due to flooding in the area. “The city of Kirbyville remains underwater.”
April 10th Storm Rivaled Tax Day Storm
The squall line which started near the Rio Grande around 9:30 pm Monday evening traveled some 800 miles reaching the FL panhandle producing wind damage and tornadoes along much of the path.
According to Lindner, “This should serve as a reminder that when the flash flood ingredients are in place around here, it can rain, and rain a lot, in a very short period of time.”
Some 12-hour rainfall totals were near those of the April 2016 (Tax Day) Storm. It is worth noting that yesterday’s event took place at nearly the same time of year.
The flash flooding developed along a stalled low-level convergence boundary. An influx of tropical moisture and repeat cell training anchored on the boundary for much of the night fed the high totals.
“This was a classic meso-scale flash-flood event common along the Gulf coast,” said Lindner.
High resolution computer models suggested the heaviest rainfall would occur over central Louisiana. So this caught many forecasters off guard.
Tornadoes, Too
The April 10th storm also produced several tornados including one that briefly touched down south of the Katy Freeway inside of SH99.
EF-1 tornado with maximum wind speeds of 90mph touched down around 2:45 am just west of Mason Rd south of Kingsland. It tracked generally eastward toward Fry Rd.
Damage along the east side of Mason Rd was consistent with low-end EF-1 rating. It included lifting and movement of vehicles in a parking lot, the complete failure and collapse of a Tire Shop, blow-out of windows, and failure of roofing on a nearby strip center.
The storm also lofted a commercial AC unit on the top of the strip center and dumped it in the parking lot.
Wind damage continued eastward along and south of Cimarron Pkwy toward Fry Rd.
The wind snapped and uprooted numerous trees through this area and blew down several fences. A corridor of damage continued eastward, but there was little evidence of a full fledged tornado at that point.
Winds estimates in the residential areas between Mason and Fry Rd were on the order of 65-75mph – an EF-0 rating.
Lindner says that these types of tornadoes are common along the leading edge of intense squall lines. Bows or “kinks” develop in the line, enhancing low-level rotation, which results in quick, short-lived, weak tornados.
The path lasted 1.7 miles and width ranged from 300 to 400 yards.
The maximum intensity reached EF-1 (90mph) on east side of Mason Road.
Maximum Winds
High winds were reported in numerous places through the Houston/Galveston area.
62 MPH at Hooks Airport in Tomball
55-59 MPH in Galveston, Pearland, Palacios and Fulshear
2.16 inches at West Lake Houston Parkway and the West Fork.
3.00 inches in Huffman
4.92 inches farther east along Luce Bayou at 321.
Notice the trend as you move farther east?
All things considered, the Lake Houston Area lucked out. We got enough rain to green up the grass, but not so much that people flooded.
Posted by Bob Rehak on 4/11/2024
2418 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2024/04/20240411-Atlas-14-Stats-for-Kirbyville-TX.jpg?fit=1100%2C931&ssl=19311100adminadmin2024-04-11 18:19:522024-04-11 18:19:54April 10th Storm Dumps 12-17 Inches in 12 Hours East of Houston
Why Flood Risk Increases During Construction
Pictures taken of a new Huffman development after a 3.75-inch, 2-year rain last week illustrate why flood risk increases during construction compared to other phases of a project.
Aerial images taken over Sila, west of the Huffman-Cleveland Road, show:
Friendswood took more precautions with the 553-acre Sila than most developers take with their projects.
Regardless, despite their best intentions, a 2-year rain still overwhelmed them in places. Let’s look at examples of each point above.
Accelerating Runoff, Decreasing Infiltration
Natural ground cover slows the rate of runoff. Removing the ground cover lets stormwater flow faster.
Contractors also grade the land to create consistent slopes for roads and storms drains. That can eliminate little ponds, pockets of wetlands, and other natural catchments that slow water down.
I took these pictures just hours after the rain stopped. Notice how fast the runoff accumulated, even without storm drains.
Partially Constructed Mitigation Facilities
Stormwater detention basins collect accumulated runoff and later release it at slower pre-development rates. Thus post-development runoff rates equal pre-development rates. At least if everything is done correctly.
But what happens when a large rain slams you before you complete the detention basins?
Trenches Not Yet Consistently Sloped
During work in progress, like this, trenches may not be consistently sloped. In the picture below, water flowed downhill from left to right. A swale caught most of the runoff. And a silt fence backstopped it. Regardless…
Rampant Erosion
Backslope interceptor systems that reduce erosion on the sides of ditches and basins have not yet been built here. Neither has grass been planted on the side slopes of those ditches and basins. The result: rampant erosion that can clog ditches and streams, and reduce the capacity of basins.
Workers Saving One Area Only to Endanger Another
The first three shots below show the partially completed detention basin and workers scrambling to expel the rapidly accumulating runoff.
From there, water raced downslope toward the East Fork of the San Jacinto.
That turned the outfall for a neighboring ditch (right of greenish pond above) into a mass of muck. From there, the muck flowed toward the river.
Could Have Been Worse
I didn’t see any homes that flooded on this day. Muck did flow into a few yards and across roads. And the outfall to a neighborhood drainage ditch, which was just cleaned out, will have to be cleaned out again.
But no doubt, it could have been much worse. See below.
It’s also worth noting that runoff from Sila must go through more than a half mile of forested wetlands before reaching the East Fork. That will slow the water down, capture some of the erosion before it reaches the river, and keep the sediment from reducing the conveyance of the river channel.
Construction always entails flood risk, especially large scale construction that can take years. But with the right precautions, large rains don’t have to spell disaster.
Posted by Bob Rehak on 4/14/2024
2420 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.
Trammell Crow Contractors Still Pumping Silty Stormwater into Street
The persistent after-hours pumping of silty stormwater from the Trammell Crow construction site into the street drains has been reported to Harris County Engineering for several months now. Despite warnings, the practice continues. The danger: accumulated silt in drain pipes and the river can reduce their conveyance, back water up in heavy rains, and lead to flooding.
One small development won’t be catastrophic. But the cumulative impact of hundreds could be.
For all those reasons, construction permits come with instructions to use things that retain and filter silty water such as berms, sediment basins and semi-permeable fencing.
Repeat Offender
In January 2024, contractors began clearing Phase II of an apartment complex on West Lake Houston Parkway without any of these safeguards. Because the complex lies just outside the City limits, Harris County Engineering is responsible for inspections.
They have visited the site numerous times and cautioned contractors about discharges of silty stormwater. At different times, the contractors installed silt fences and erected berms. They also built sediment basins and channeled excess stormwater to them.
On April 10th, the area received approximately 2 inches of rain. And yesterday, April 11, the contractors were pumping water back into the street THROUGH A PILE OF MUD. After quitting time. When inspectors wouldn’t be around. Again!!!
Caught on Camera
Michelle Chavez, a nearby resident, caught the action on camera.
Chavez also took several still photos.
At least one local resident concerned about flooding reported the pumping to Harris County Engineering. He was told that Engineering would send an inspector out.
Sending Wrong Message: Will Sixth Time be the Charm?
This is the sixth story I have posted about stormwater-control issues at this construction site. See the previous five.
One wonders when the county will level a stiff fine or shut down this site. At this point the Harris County Engineering Department also has its reputation on the line. Tolerating such behavior sends a message to other developers that may be unsafe in the long run.
Posted by Bob Rehak on 4/12/24
2418 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.
April 10th Storm Dumps 12-17 Inches in 12 Hours East of Houston
The April 10th storm that swept through Houston during the early morning hours dumped amazing amounts of rainfall just east of here.
A report received today from Harris County Meteorologist Jeff Lindner says that the April 10th storm dumped 12-17 inches of rain in a 12 hour period in a swatch across East Texas. The result: widespread, catastrophic flooding in parts of Newton, Jasper, Hardin, and Tyler Counties.
A peak total of 17.68 inches was recorded near Kirbyville, TX. Lindner characterized the totals as “insanely high.” In fact, NOAA’s Atlas 14 rainfall chart for Kirbyville lists a 12-hour/17-inch rainfall as a 1000-year event.
Late yesterday morning, Weather.com reported that a Disaster Declaration had been issued for Jasper County, Texas. Officials there said that multiple people were rescued from both homes and vehicles due to flooding in the area. “The city of Kirbyville remains underwater.”
April 10th Storm Rivaled Tax Day Storm
The squall line which started near the Rio Grande around 9:30 pm Monday evening traveled some 800 miles reaching the FL panhandle producing wind damage and tornadoes along much of the path.
According to Lindner, “This should serve as a reminder that when the flash flood ingredients are in place around here, it can rain, and rain a lot, in a very short period of time.”
Some 12-hour rainfall totals were near those of the April 2016 (Tax Day) Storm. It is worth noting that yesterday’s event took place at nearly the same time of year.
The flash flooding developed along a stalled low-level convergence boundary. An influx of tropical moisture and repeat cell training anchored on the boundary for much of the night fed the high totals.
“This was a classic meso-scale flash-flood event common along the Gulf coast,” said Lindner.
High resolution computer models suggested the heaviest rainfall would occur over central Louisiana. So this caught many forecasters off guard.
Tornadoes, Too
The April 10th storm also produced several tornados including one that briefly touched down south of the Katy Freeway inside of SH99.
EF-1 tornado with maximum wind speeds of 90mph touched down around 2:45 am just west of Mason Rd south of Kingsland. It tracked generally eastward toward Fry Rd.
Damage along the east side of Mason Rd was consistent with low-end EF-1 rating. It included lifting and movement of vehicles in a parking lot, the complete failure and collapse of a Tire Shop, blow-out of windows, and failure of roofing on a nearby strip center.
The storm also lofted a commercial AC unit on the top of the strip center and dumped it in the parking lot.
Wind damage continued eastward along and south of Cimarron Pkwy toward Fry Rd.
The wind snapped and uprooted numerous trees through this area and blew down several fences. A corridor of damage continued eastward, but there was little evidence of a full fledged tornado at that point.
Winds estimates in the residential areas between Mason and Fry Rd were on the order of 65-75mph – an EF-0 rating.
Lindner says that these types of tornadoes are common along the leading edge of intense squall lines. Bows or “kinks” develop in the line, enhancing low-level rotation, which results in quick, short-lived, weak tornados.
The path lasted 1.7 miles and width ranged from 300 to 400 yards.
The maximum intensity reached EF-1 (90mph) on east side of Mason Road.
Maximum Winds
High winds were reported in numerous places through the Houston/Galveston area.
Lake Houston Area
The Harris County Flood Warning System recorded:
Notice the trend as you move farther east?
All things considered, the Lake Houston Area lucked out. We got enough rain to green up the grass, but not so much that people flooded.
Posted by Bob Rehak on 4/11/2024
2418 Days since Hurricane Harvey