Note: This is the third in a five part series about What Went Wrong in Woodridge Village that may have contributed to flooding in Elm Grove and North Kingwood Forest.It focuses on Detention Ponds.
Section 7 of the Montgomery County Drainage Criteria Manual cautions, “The introduction of impervious cover and improved runoff conveyance serves in many cases to increase flood peaks quite dramatically over those for existing conditions.” And that’s exactly what happened in Elm Grove and North Kingwood Forest in May and September of this year. Two subdivisions that had never flooded before were inundated with several feet of water from Woodridge Village.
Perry Homes failed to observe numerous regulations in the Drainage Criteria Manual including provisions for:
Erosion control measures such as pond linings, revegetation, backslope swales
Maintenance roads
Increases in downstream flooding
Geotechnical reports for detention ponds
Drainage of detention ponds
Critically, they also failed to construct all the detention ponds they promised.
Less than a Quarter of Detention Ponds Built
When listing factors that contributed to the flooding, the absence of several promised detention ponds should rank near the top.
Before the September flood, contractors substantially completed a second detention pond (S2) that added another 16% of promised detention capacity.
Since then, no work has been done on additional excavation to protect against flooding.
While clearcutting ALL of the land, Perry Homes installed only PART of the detention.
According to LJA Engineering, Perry Homes was supposed to develop the project in two phases and clearcut only 30 acres in the northern section during Phase 1. However, something changed. Instead, Perry Homes clearcut the entire northern section. And they still haven’t excavated any of the three detention ponds there.
By May 2019, only S1 was substantially complete. By September, S2 was also substantially complete, but overwhelmed.
Had Perry Homes installed all the detention that it promised, the site should have detained a foot of rainfall. But it didn’t. When Imelda came along, it was like trying to pour 100 gallons of water into a 23 gallon jug. Water spilled out of the development into adjacent streets and homes.
Erosion Control Measures Missing for Detention Ponds
“The erosion potential for a detention basin is similar to that of an open channel. For this reason the same types of erosion protection are necessary, including the use of backslope swales and drainage systems (as outlined In SECTION 6), proper revegetation and pond surface lining where necessary. Proper protection must especially be provided at pipe outfalls into the facility, pond outlet structures and overflow spillways where excessive turbulence and velocities will cause erosion.” (See page page 123 of pdf, numbered 113 in doc.)
Revegetation?
Not much grass in S1 (right of the road) or the area that drains into it.All aerial photos below taken on 11/4/2019.Not much grass on the slopes of S2 either, although Perry Homes did make an ineffective attempt to hydromulch the south (right) border.
No Protection for Overflow Spillway
Perry Homes quality! This spillway from Taylor Gully (right) was supposed to have a grass lining, but still does not.Picture taken 11/4/2019.As of 11/21/19 work still had not started on the lining.Perry Homes has done virtually no work on this pond for three months.However, they did start lining the channel on the right today.
Backslope Interceptor Swales?
The northern edge of the S2 pond has no backslope interceptor swale. As a consequence, water from Taylor Gully at the top of this frame flows over the edge of the pond and erodes it. This may not be a sustainable solution. In the long run, the Gully could erode its way into the pond from the north (top of the frame).
Maintenance Road Missing at Critical Point
Section 7.2.8 talks about Maintenance of Detention Facilities. It states, “A 30-foot wide access and maintenance easement shall be provided around the entire detention pond.” The most critical place in the entire chain of detention ponds, the final outflow culvert into Taylor Gully, has no room for a maintenance road. That’s because when they installed the required backslope interceptor swale, the only place left for it was the maintenance road. That’s planning for you!
S2 has no maintenance easement or road at final outfall into Taylor Gully.The backslope interceptor swale takes up that space.
No Increase in Downstream Flood Levels Allowed
Section 7.3 talks about DETENTION DESIGN PROCEDURES. It clearly lays out the design goal when it says…
No increase in downstream flow rates or flood levels will be allowed.
Further down in this section, the regulations state: “The maximum 100-year water surface elevation in all detention facilities shall be a minimum of 1 foot below the minimum top of bank elevation of the basin.”
No Geotechnical Report for Groundwater Level at Pond Sites
Section 7.5 discusses GEOTECHNICAL INVESTIGATIONS. It says, “Before initiating final design of a detention pond, a detailed soils investigation by a geotechnical engineer should be undertaken.” Regulations state that the ground water investigation must be “at the proposed site.” Montgomery County has no record of such an investigation or report.
A company called Terracon prepared a Preliminary Geotechnical Report for Perry that addressed issues pertaining to utilities, road pavement and residential foundations. But it makes no mention of detention ponds.
The company took four widely spaced borings around the perimeter of the site that managed to miss all the detention pond locations. Significantly, they missed all the wetlands, too.
Page 17 of Terracon Report. Red lines added to improve visibility of locations.
MoCo Claims It Has No Further Geotechnical Reports
If Perry Homes did additional investigations into ground water on this site, Montgomery County says it doesn’t have them.
If no further investigations were conducted, this could be a fatal flaw affecting the economics of the entire development. Note the presence of standing water in the photo below.
S2 Pond (left), Taylor Gully (center), and area where N3 pond will go (right) all have standing water that will reduce their rated capacity.
The presence of standing water reduces the rated capacity of detention ponds and channels. Only the area above the standing water counts as capacity. Regulations say that these ponds should drain completely (see below).
Thus, S2 likely has lost a third of its designed capacity. N3, when eventually built, could fare worse. Note how close the water is to the surface in the small pond on the right.
If you can’t go deep to get your detention pond capacity, you have to go wide. And that will mean fewer homesites than the 896 they planned. This site might not even make economic sense for building homes.
Problems with Homes Built Over Wetlands
The presence of wetlands in the northern section, which the Terracon report never mentions, would also significantly reduce the site’s suitability for building homes.
This article describes the problems with homes built on wetlands. The title: “Caution: Building in a Wetland Can Be Hazardous to Your House.” A biologist for the US Fish and Wildlife service who investigated filled wetlands in Pennsylvania warned: “Build your house in a wetland, and you’ve got a hobby for the rest of your life. You will be fighting that water forever.” He discusses cracked foundations and also warns, “When wetlands are filled, the water that made them wet has to go somewhere. … the water likely is leaking into formerly dry homes of downstream property owners.”
I’m sure Perry Homes would divulge the presence of former wetlands to the future buyers of homes on this site. It’s the only ethical thing to do and Kathy Perry Britton, CEO, has standards to maintain.
Incomplete Drainage of Detention Ponds
Section 7.6 of the Drainage Criteria Manual addresses GENERAL REQUIREMENTS FOR DETENTION POND CONSTRUCTION. It states: “A pilot channel shall be provided in detention facilities to insure that proper and complete drainage of the storage facility will occur.” (Emphasis added.)
Complete drainage will likely never occur in S2 and N3 because of the high water table.
To excavate S2 to the required design depth, contractors had to continuously pump water out of it as they worked. It still retains water to this day.
Photo by Jeff Miller on June 2, three days after contractors started digging to the final depth.No surface linings were ever added to this portion of the pond per Section 7.2.7 of the MoCo Drainage Criteria Manual.Photo taken on June 3 shows contractors were pumping water out of pond as they continued excavating.
The new statistics would require 40% more capacity to ensure downstream safety.
Where Does Perry Homes Go from here?
After ignoring regulations, hundreds of homes flooded. And they will flood again. Owning this site is like hanging a millstone around one’s neck. It could drown the entire company in perpetual litigation and debt.
Future Posts in this series will look at:
Contradictions in Perry Homes’ Plans
The Dirt on Perry Homes’ Soil Test
The Floodplain that Wasn’t
Posted by Bob Rehak on 11/21/2019 with help from Jeff Miller
814 Days since Hurricane Harvey and 63 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/2019/11/RJR_4350-2.jpg?fit=1500%2C1089&ssl=110891500adminadmin2019-11-21 17:48:092019-11-21 18:26:13What Went Wrong, Part III: Perry Homes’ Woodridge Village Detention Pond Catastrophe
Dr. Charlie Campbell, a master of functional medicine, jogs 22 miles a week in East End Park. He tries to time his jogs so that he arrives at Otter Point every morning for moments like this.
Sunrise at Otter Point by Dr. Charles Campbell. Used with permission.
If that won’t make you feel good, you’re a spiritual crustacean.
Years ago, I remember meeting a man meditating at Otter Point almost every day. I asked him what he found in it. He told me his story. The man was on chemo, fighting cancer. He said that the natural beauty gave him sustenance and the will to keep on fighting.
East End Park does that for many people in many different ways. Especially Otter Point. Whether you’re a cancer survivor or a flood survivor. If you’re not familiar with the park and the place, you should be. They are rare ecological gems inside the fourth largest city in the country. And something worth fighting FOR.
As a postscript to this story, Dr. Campbell sent me another picture taken this morning.
Photo by Dr. Charles Campbell, used with permission.
If you want to get your kids interested in physics, ask them why sunrises and sunsets are red. Here’s the answer.
Posted by Bob Rehak on 11/21/2019, with thanks to Dr. Campbell and Mother Nature
814 Days since Hurricane Harvey and 63 since Imelda
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/11/IMG_1341.jpeg?fit=1599%2C1199&ssl=111991599adminadmin2019-11-20 22:03:132019-11-21 10:45:09A Moment of Tranquil Splendor at Otter Point
On May 7th and September 19th, sediment-laden runoff from Perry Homes’ Woodridge Village development in Montgomery County flooded the streets and homes of Elm Grove Village and North Kingwood Forest. On September 26, the City of Houston wrote a cease and desist letter to Perry Homes, its subsidiaries and contractors. The letter alleged that runoff damaged the City’s sewer system and residents’ homes. It demanded that Perry Homes’ proxies stop sending sediment into the City.
After Imelda, Abel Versa had to grab his car to avoid slipping in ankle-deep sediment on Village Springs. The sediment came from Woodridge Village right behind him.
Sediment Control Measures Not Followed in Subdivision Rules and Regs
If Perry Homes and its contractors had followed all the construction regulations affecting drainage, the flooding of Elm Grove would not have happened and the letter would not have been necessary. So what went wrong? I previously reviewed the sediment control measures in the Montgomery County Subdivision Rules and Regulations. Perry Homes received seven strikes. Among the worst apparent violations:
They clearcut 268 acres when the rules say no more than 10.
They are supposed to plant temporary vegetation but haven’t.
They were supposed to make provisions for increased runoff during construction, but didn’t.
The southern section of Woodridge Village has been cleared, filled and graded since last summer. Grass could have reduced the runoff during Imelda.Photo taken on 11/4/2019.The northern section has also been mostly cleared for months, though workers are still removing piles of dead trees. This shows the area where they filled wetlands.Because no detention exist for the northern section, runoff from 188 acres is supposed to funnel through a 3′ pipe. That’s not working well in heavy rains.You can see how much loose sediment is exposed to floodwaters.
More Regulations in Drainage Criteria Manual Not Followed
Perry Homes also overlooked many provisions in the Montgomery County Drainage Criteria Manual. Twenty-two of the 175 pages also discuss erosion and sediment control (see Section 6 starting on page 85). Among the more serious omissions:
Channel Slopes Severely Eroding
Section 6.2.1 on Grass Establishment states that: “A good grass cover must be established on all areas within the right-of-way (except the channel bottom) disturbed by channel improvements or by any type of construction. An adequate grass stand on the banks helps stabilize the channel and minimize erosion caused by overbank flow and high velocities in the channel. Establishing a good grass cover requires preparing the seedbed, seeding properly. keeping the seed in place, fertilizing, and watering regularly.
The LJA Engineering report never mentions erosion or sediment control by those words. However, it does mention grass-lined and concrete-lined channels and spillways. Only one problem. The channels are not grass lined and most of the areas designated for concrete lining have yet to be lined.
The banks of detention ponds should be lined with grass. They are not. As a result, sediment is slumping to the bottom of the ponds where it is carried downstream by floodwaters.This closeup shows how severe the erosion is.
Channel Turns Not Protected
Section 6.2.3 on Minimum Erosion Protection Requirements for Bends specifies that bends in drainage ditches must be protected from erosion by grass, rip-rap, or concrete. The material depends on the radius of the curve, the type of soil, average water velocity and maximum water velocity.
Despite funneling 188 acres of sheet flow into Taylor Gulley, which narrows down into a 3-foot pipe, Perry Homes has done little to increase the channel capacity or detention for that area. Worse, the channel design which may have been adequate for forested wetlands, can no longer handle high volume overland sheet flow.
The most obvious needs are on the eastern side of the development. There, Taylor Gully makes a 120-degree turn, then two quick 90 degree turns and two 45-degree turns, all within two hundred yards. Getting dizzy? The floodwater turns 390 degrees in this area!
At each turn the banks take a beating. The full force of the floodwater slams against the far bank and erodes it.
Photo taken on 11/4/2019 along eastern boundary of the southern section of Woodridge Village. That’s North Kingwood Forest on the rightand Elm Grove on the bottom.Little wonder that this was the area hardest hit by floodingin May and September.Where the channel on the right narrows down into the black 3-foot pipe, contractors built an overflow channel into the detention pond on the left but still have not lined it with concrete. Note the severe erosion. Also note the erosion and sediment coming into the pond on the left just below the flow-constricting device in Taylor Gully. Clearly, there isn’t enough channel capacity to handle the volume of water. Photo taken on 11/4/2019, looking north.
Straight Drop Spillway Not Installed
Section 6.2.5.3 states that a straight-drop spillway should be installed in drainage channels to adjust channel gradients which are too steep for design conditions.
LJA specifies one between where detention pond N3 will be and the 120-degree turn shown above. However, neither the detention pond, nor the spillway have yet been installed. So water from the north comes barreling down the ditch on the right unchecked. The high velocity increases erosion. Here’s what it looked like after May 7th.
Same area shown above but from ground level and looking south toward Elm Grove.Rain did a lot of the excavating for Perry Homes. But unfortunately, the sediment wound up in flood victims’ homes and the City storm drains.
More Things Perry Homes Didn’t Do in the Montgomery County Drainage Manual
Contradictions in Perry Homes’ Plans
The Dirt on Perry Homes’ Soil Test
The Floodplain that Wasn’t
Posted by Bob Rehak on 11/20/2019 with help from Jeff Miller
813 Days since Hurricane Harvey and 62 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/2019/11/RJR_4881.jpg?fit=1500%2C1000&ssl=110001500adminadmin2019-11-20 15:48:182019-11-20 16:02:51What Went Wrong, Part II: Lack of Erosion and Sediment Control Worsen Elm Grove Flooding
What Went Wrong, Part III: Perry Homes’ Woodridge Village Detention Pond Catastrophe
Note: This is the third in a five part series about What Went Wrong in Woodridge Village that may have contributed to flooding in Elm Grove and North Kingwood Forest. It focuses on Detention Ponds.
Section 7 of the Montgomery County Drainage Criteria Manual cautions, “The introduction of impervious cover and improved runoff conveyance serves in many cases to increase flood peaks quite dramatically over those for existing conditions.” And that’s exactly what happened in Elm Grove and North Kingwood Forest in May and September of this year. Two subdivisions that had never flooded before were inundated with several feet of water from Woodridge Village.
Perry Homes failed to observe numerous regulations in the Drainage Criteria Manual including provisions for:
Critically, they also failed to construct all the detention ponds they promised.
Less than a Quarter of Detention Ponds Built
When listing factors that contributed to the flooding, the absence of several promised detention ponds should rank near the top.
According to LJA Engineering, Perry Homes was supposed to develop the project in two phases and clearcut only 30 acres in the northern section during Phase 1. However, something changed. Instead, Perry Homes clearcut the entire northern section. And they still haven’t excavated any of the three detention ponds there.
Had Perry Homes installed all the detention that it promised, the site should have detained a foot of rainfall. But it didn’t. When Imelda came along, it was like trying to pour 100 gallons of water into a 23 gallon jug. Water spilled out of the development into adjacent streets and homes.
Erosion Control Measures Missing for Detention Ponds
Section 7.2.7 of the Montgomery County Drainage Criteria Manual details Erosion Control Measures for Detention Facilities. It states:
“The erosion potential for a detention basin is similar to that of an open channel. For this reason the same types of erosion protection are necessary, including the use of backslope swales and drainage systems (as outlined In SECTION 6), proper revegetation and pond surface lining where necessary. Proper protection must especially be provided at pipe outfalls into the facility, pond outlet structures and overflow spillways where excessive turbulence and velocities will cause erosion.” (See page page 123 of pdf, numbered 113 in doc.)
Revegetation?
No Protection for Overflow Spillway
Backslope Interceptor Swales?
Maintenance Road Missing at Critical Point
Section 7.2.8 talks about Maintenance of Detention Facilities. It states, “A 30-foot wide access and maintenance easement shall be provided around the entire detention pond.” The most critical place in the entire chain of detention ponds, the final outflow culvert into Taylor Gully, has no room for a maintenance road. That’s because when they installed the required backslope interceptor swale, the only place left for it was the maintenance road. That’s planning for you!
No Increase in Downstream Flood Levels Allowed
Section 7.3 talks about DETENTION DESIGN PROCEDURES. It clearly lays out the design goal when it says…
Further down in this section, the regulations state: “The maximum 100-year water surface elevation in all detention facilities shall be a minimum of 1 foot below the minimum top of bank elevation of the basin.”
Judging from this video shot by Edy and Ricki Cogdill during the May 7th storm, I would say Perry Homes didn’t meet that objective. It reminds me of that slime show on Nickelodeon, but in this case, the innocent bystanders got slimed.
No Geotechnical Report for Groundwater Level at Pond Sites
Section 7.5 discusses GEOTECHNICAL INVESTIGATIONS. It says, “Before initiating final design of a detention pond, a detailed soils investigation by a geotechnical engineer should be undertaken.” Regulations state that the ground water investigation must be “at the proposed site.” Montgomery County has no record of such an investigation or report.
A company called Terracon prepared a Preliminary Geotechnical Report for Perry that addressed issues pertaining to utilities, road pavement and residential foundations. But it makes no mention of detention ponds.
MoCo Claims It Has No Further Geotechnical Reports
If Perry Homes did additional investigations into ground water on this site, Montgomery County says it doesn’t have them.
If no further investigations were conducted, this could be a fatal flaw affecting the economics of the entire development. Note the presence of standing water in the photo below.
The presence of standing water reduces the rated capacity of detention ponds and channels. Only the area above the standing water counts as capacity. Regulations say that these ponds should drain completely (see below).
If you can’t go deep to get your detention pond capacity, you have to go wide. And that will mean fewer homesites than the 896 they planned. This site might not even make economic sense for building homes.
Problems with Homes Built Over Wetlands
The presence of wetlands in the northern section, which the Terracon report never mentions, would also significantly reduce the site’s suitability for building homes.
This article describes the problems with homes built on wetlands. The title: “Caution: Building in a Wetland Can Be Hazardous to Your House.” A biologist for the US Fish and Wildlife service who investigated filled wetlands in Pennsylvania warned: “Build your house in a wetland, and you’ve got a hobby for the rest of your life. You will be fighting that water forever.” He discusses cracked foundations and also warns, “When wetlands are filled, the water that made them wet has to go somewhere. … the water likely is leaking into formerly dry homes of downstream property owners.”
I’m sure Perry Homes would divulge the presence of former wetlands to the future buyers of homes on this site. It’s the only ethical thing to do and Kathy Perry Britton, CEO, has standards to maintain.
Incomplete Drainage of Detention Ponds
Section 7.6 of the Drainage Criteria Manual addresses GENERAL REQUIREMENTS FOR DETENTION POND CONSTRUCTION. It states:
“A pilot channel shall be provided in detention facilities to insure that proper and complete drainage of the storage facility will occur.” (Emphasis added.)
To excavate S2 to the required design depth, contractors had to continuously pump water out of it as they worked. It still retains water to this day.
If Perry Homes continues its Woodridge Village venture using its current plans, chances are, the company will never provide enough detention capacity for real world conditions. When modeling, their engineers did NOT use the current Atlas-14 rainfall statistics from NOAA.
Where Does Perry Homes Go from here?
After ignoring regulations, hundreds of homes flooded. And they will flood again. Owning this site is like hanging a millstone around one’s neck. It could drown the entire company in perpetual litigation and debt.
Future Posts in this series will look at:
Posted by Bob Rehak on 11/21/2019 with help from Jeff Miller
814 Days since Hurricane Harvey and 63 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.
A Moment of Tranquil Splendor at Otter Point
Dr. Charlie Campbell, a master of functional medicine, jogs 22 miles a week in East End Park. He tries to time his jogs so that he arrives at Otter Point every morning for moments like this.
Years ago, I remember meeting a man meditating at Otter Point almost every day. I asked him what he found in it. He told me his story. The man was on chemo, fighting cancer. He said that the natural beauty gave him sustenance and the will to keep on fighting.
East End Park does that for many people in many different ways. Especially Otter Point. Whether you’re a cancer survivor or a flood survivor. If you’re not familiar with the park and the place, you should be. They are rare ecological gems inside the fourth largest city in the country. And something worth fighting FOR.
This is why we live here.
Trail repairs from Imelda are underway now and should be complete soon.
As a postscript to this story, Dr. Campbell sent me another picture taken this morning.
If you want to get your kids interested in physics, ask them why sunrises and sunsets are red. Here’s the answer.
Posted by Bob Rehak on 11/21/2019, with thanks to Dr. Campbell and Mother Nature
814 Days since Hurricane Harvey and 63 since Imelda
What Went Wrong, Part II: Lack of Erosion and Sediment Control Worsen Elm Grove Flooding
On May 7th and September 19th, sediment-laden runoff from Perry Homes’ Woodridge Village development in Montgomery County flooded the streets and homes of Elm Grove Village and North Kingwood Forest. On September 26, the City of Houston wrote a cease and desist letter to Perry Homes, its subsidiaries and contractors. The letter alleged that runoff damaged the City’s sewer system and residents’ homes. It demanded that Perry Homes’ proxies stop sending sediment into the City.
Sediment Control Measures Not Followed in Subdivision Rules and Regs
If Perry Homes and its contractors had followed all the construction regulations affecting drainage, the flooding of Elm Grove would not have happened and the letter would not have been necessary. So what went wrong? I previously reviewed the sediment control measures in the Montgomery County Subdivision Rules and Regulations. Perry Homes received seven strikes. Among the worst apparent violations:
In fact, they have substantially completed only 23% of the permanent detention ponds for the whole subdivision despite clearcutting all 268 acres.
More Regulations in Drainage Criteria Manual Not Followed
Perry Homes also overlooked many provisions in the Montgomery County Drainage Criteria Manual. Twenty-two of the 175 pages also discuss erosion and sediment control (see Section 6 starting on page 85). Among the more serious omissions:
Channel Slopes Severely Eroding
Section 6.2.1 on Grass Establishment states that: “A good grass cover must be established on all areas within the right-of-way (except the channel bottom) disturbed by channel improvements or by any type of construction. An adequate grass stand on the banks helps stabilize the channel and minimize erosion caused by overbank flow and high velocities in the channel. Establishing a good grass cover requires preparing the seedbed, seeding properly. keeping the seed in place, fertilizing, and watering regularly.
The LJA Engineering report never mentions erosion or sediment control by those words. However, it does mention grass-lined and concrete-lined channels and spillways. Only one problem. The channels are not grass lined and most of the areas designated for concrete lining have yet to be lined.
Channel Turns Not Protected
Section 6.2.3 on Minimum Erosion Protection Requirements for Bends specifies that bends in drainage ditches must be protected from erosion by grass, rip-rap, or concrete. The material depends on the radius of the curve, the type of soil, average water velocity and maximum water velocity.
Despite funneling 188 acres of sheet flow into Taylor Gulley, which narrows down into a 3-foot pipe, Perry Homes has done little to increase the channel capacity or detention for that area. Worse, the channel design which may have been adequate for forested wetlands, can no longer handle high volume overland sheet flow.
The most obvious needs are on the eastern side of the development. There, Taylor Gully makes a 120-degree turn, then two quick 90 degree turns and two 45-degree turns, all within two hundred yards. Getting dizzy? The floodwater turns 390 degrees in this area!
At each turn the banks take a beating. The full force of the floodwater slams against the far bank and erodes it.
Straight Drop Spillway Not Installed
Section 6.2.5.3 states that a straight-drop spillway should be installed in drainage channels to adjust channel gradients which are too steep for design conditions.
LJA specifies one between where detention pond N3 will be and the 120-degree turn shown above. However, neither the detention pond, nor the spillway have yet been installed. So water from the north comes barreling down the ditch on the right unchecked. The high velocity increases erosion. Here’s what it looked like after May 7th.
Yesterday I posted about how Perry Homes was supposed to cut only 30 acres of trees on the northern section but cut 188. Still to come in this “What Went Wrong” Series:
Posted by Bob Rehak on 11/20/2019 with help from Jeff Miller
813 Days since Hurricane Harvey and 62 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.