Tag Archive for: detention ponds

Contractors Now Working Seven Days Per Week, Dawn to Dusk, on Woodridge Village Detention Ponds

Sunday morning at 8 a.m., Perry contractors we’re busy working on Woodridge Village detention ponds. This came after a Saturday when they stopped working after 6 p.m. Surprisingly, this came even as the threat from Tropical Storm Cristobal moved farther east.

Woodridge Village was implicated in flooding Elm Grove and North Kingwood Forest twice last year. Lack of functional detention ponds was one of the key contributors.

Before/After Shots of N2 Channel

After months of relative inactivity, construction has kicked into high gear. Elm Grove resident Jeff Miller took the two shots below from near Mace Street in Porter.

N2 Channel as of 6/4/2020 in afternoon around 5 p.m.
Same channel on 6/6 around 10 a.m.

That’s a lot of dirt to move in a little more than a day! Below is how the same channel looked from the air on Sunday morning.

Looking north along western perimeter of Woodridge Village at channel that connects detention pond N1 with N2.

Below, you can see the general layout of Woodridge Village detention ponds.

Other Sunday Morning Photos

Since the last update, the focus of most construction activity seems to be on two detention ponds along the development’s western border – N1 and N2. As the photos below show, contractors have expanded both ponds as well as the ditches connecting them.

Expansion of the Woodridge Village N1 Pond
Workers are also deepening and widening N2 toward the left above.

Contractors use dirt from the ponds to raise the areas where homes may be built some day.

Dirt from N1 is moving east toward the new Ford Road entrance.

See new Ford Road Entrance through trees at upper right.
Dirt excavated from N2 in the background is also moving east toward the foreground, which is the base of N3. Note also how the grass planted last winter in the souther section (upper left) has all turned brown. This could present an erosion problem in the future.
Grass in the overflow spillway between the concrete-lined portion of Taylor Gully (left) and detention pond S2 has also died.
Looking NE from over S2. Taylor Gully cuts diagonally through the frame from upper left to lower right. Note the vast expanse of treeless, grassless development on the southwest half of the northern section.

End Game Still Not Settled

The fate of Woodridge Village, which is still mired in lawsuits, has not been settled. Practically speaking, Perry Homes has said it could/would:

  1. Sell the land to Harris County Flood Control District to create a regional floodwater detention facility
  2. Develop the property itself
  3. Sell the property to another developer
Regarding Option 1

At the last Harris County Commissioner’s Court meeting, commissioners heaped new demands on the City of Houston. They want the City to actually implement a series of changes related to Atlas-14 in its building codes and ETJ (extra territorial jurisdiction. A mere promise to implement them via an inter-local agreement seems insufficient for the commissioners.

The City must also come up with cash (or land in lieu of cash) to cover half of the construction costs of developing the regional detention basin (not just half of the purchase price of the land). Russ Poppe, Director of Harris County Flood Control estimated the construction costs could total $20 to $30 million, although flood control has reportedly not yet started planning the project.

Regarding Option 2

A web search this morning turned up no new bidding documents for any construction beyond the detention ponds. Previously, Perry Homes and LJA have advertised bid opportunities.

Regarding Option 3

Perry still has a for-sale sign at the Woodland Hills entrance to the property. However, the chances of a third party purchase while lawsuits are pending is remote. Still, the completion of detention ponds makes the property more attractive to another developer with an appetite for risk.

The big problem with Options 2 and 3: Perry Homes rushed to get the plans permitted before Atlas-14. That means, even with detention ponds completed, the detention may not be adequate. Estimates of the shortfall range from 30% to 40%.

As a result, Option 1 provides, by far, the highest margin of safety for flood-weary residents.

Unfortunately, the wheels of government move slowly. Neither the County, nor the City has made a public comment about a possible purchase deal since the last commissioner’s court meeting on May 19. The purchase is not listed on the agenda for the June 9, 2020, meeting.

Posted by Bob Rehak with with thanks to Jeff Miller for photos

1013 Days after Hurricane Harvey and 262 since Imelda

Woodridge Village Pre-Cristobal Detention Pond Update

Perry Home’s new contractors have excavated the vast majority of virtually all three detention ponds on the north section of Woodridge Village. That means they have almost completed 77% of the detention pond capacity for the whole site in two months. The previous contractors completed only 23% in approximately twenty months.

That represents approximately a 30x increase in productivity.

Overview of Woodridge Village Detention Pond Capacity

The pie chart below shows how that capacity breaks down. And the map shows where it is.

Percentage of detention pond capacity in acre feet for each of the five Woodridge Village ponds. Source: LJA Drainage Addendum.
General layout of detention ponds on Perry Homes’ property.

Contractors Scurry as Cristobal Churns in Gulf

Tropical Storm Cristobal could be a game changer next week if it hits Houston. It’s track is far from certain at this point, but the National Hurricane Center still puts Houston within the cone of uncertainty.

Cristobal has the potential to create massive erosion and set the work schedule back. The aerial photos below taken on 6/2/2020 show the current “pre-storm” status of construction for the three northern detention ponds. The two southern detention ponds were completed earlier this year.

N1 Nearing Completion of Excavation

N1 Starts at the northern boundary of the site and runs halfway down the western edge to Mace Street.

Looking north at N1 from Mace Street in Porter to the northern boundary.
The area between the culverts will eventually become an extension of Mace Street (top of photo) which will traverse the entire subdivision to Ford Road on the eastern side.
While some contractors continue excavating, others work on installing concrete pilot channels. Shown here, the pilot channel near Ivy Ridge in Porter.
The northern part of N1 is not yet complete. Contractors still use the Webb Street entrance (upper left as their main access point to the site. Note how height of road dwarfs excavator in pit.

Still Widening and Deepening N2 Pond

The area left of the diagonal road is the expansion of N2. The area near the diagonal embankment is deep enough to conceal trucks and excavators. However, the grassy triangle in the middle left was a previous detention pond constructed my Montgomery County in the early 2000s.
Contractors are deepening the MoCo pond a small amount to create additional storage capacity. The dirt is being used to build up other portions of the site.
Looking north along the western boundary from the southern part of the grassy triangle. Much work remains to extend the N1 channel south to N2. Jeff Miller reported today that contractors started working on this this morning.
On 6.3.20, contractors were removing dirt from the northward extention of N2 with three dump trucks running in a relay fashion. Photo courtesy of Jeff Miller.
Twin culverts installed in Taylor Gully will control outflow rates from N1 and N2.

N3 All Excavated

N3 cuts down the eastern side of Woodridge Village and joins Taylor Gully right above S2.

Looking north. Excavation of N3 appears complete although few of the finishing touches have yet been installed.
Looking south at the main body of N3.
N3 widens out about halfway down the eastern border.
Then it narrows down again to help control outflow speed as it approaches the junction with Taylor Gully.
Water from the entire site converges here. Erosion patterns, fence damage and grass matting show this is where the overflow started that contributed to the flooding of Elm Grove (right) and North Kingwood Forest (left) twice last year.

The pile of dirt in the picture above could be shoved into the connecting channel in the event that Cristobal should strike Houston. That would then help retain water in N3 until after the storm.

All the runoff from the approximately 200-acre northern portion of the site converges here and tries to make its way through a 3-foot culvert at the end of the concrete channel.

Uncertain Still Surrounds Corner of Chaos

Some Elm Grove and North Kingwood Forest residents have called the complex flow patterns in the photo above “The Corner of Chaos.”

Overflow from the concrete lined channel is supposed to go into the kite-shaped S2 pond, and then through the twin culverts into Taylor Gully. However, a hydrology consultant for the plaintiffs in flooding lawsuits contends that floodwaters went the other way. They escaped out of the inflow channel, he says. He further claims that LJA Engineering failed to model the performance of that connecting channel.

Diagram from consultant’s report.

If the design of the flow at this “Corner of Chaos” is flawed, there’s little contractors can do to fix that at this point without some major re-engineering.

In that regard, we should also remember that LJA designed these ponds before Atlas 14, so they will only hold approximately 60% of a 100-year rainfall as defined by Atlas 14 standards adopted in Harris County.

How Contractors are Temporarily Funneling Water into Ponds

Because storm drains are not yet installed, contractors are relying on temporary channels to intercept runoff and direct it to detention ponds.

Small ditches like one on right catch runoff and direct it to ponds for the time being.

Next Steps in Completing Detention Ponds

A modest amount of excavation remains to complete the full detention pond capacity.

But the capacity already in place should reduce flood risk compared to last year by more than 3X for storms equivalent to May 7 and September 19, 2019.

As some crews focus on completing excavation, others are putting the finishing touches on ponds. Those include concrete pilot channels, backslope interceptor swales, drain pipes, and culverts to control the rate of outflow.

Racing Against Hurricane Season

At this point, contractors are racing against time and the hurricane season. Cristobal underscores the risk of having waited for months to begin the three northern detention ponds in April. Had they begun them immediately after J. Carey Gray’s letter to Mayor Turn in October, they could easily have finished by now.

Posted by Bob Rehak on 6/4/2020 with thanks to Jeff Miller

1010 Days after Hurricane Harvey and 258 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.

Update on Woodridge Village Detention Ponds After Recent Heavy Rains

After six months of virtual inactivity, Perry Homes’ new Woodridge Village contractors have significantly stepped up work on three detention ponds. All detention ponds are on the northern section of the development. However, recent heavy rains have saturated the soil. The rain also filled two of the three ponds one-third to one-half full. The result: a big muddy mess.

Tuesday, according to Elm Grove resident Jeff Miller, only one excavator was moving. It was trying to let water out of the N1 pond so that work could continue.

Twelve Aerial Photos Taken on Memorial Day

Below are 12 aerial photos of the site taken on Memorial Day, 5/25/2020.

Looking north along the western boundary of Woodridge at the tail of the N1 Pond.
Further north, you can see where work has stopped on the tail of N1 (foreground), the Webb Street Entrance in Porter (left), and the N1 pond itself are at the top.

The N1 pond has the least development. Most work to date has focused on the tail. That’s presumably so contractors can keep the entrance to the site open. N1 will probably be the last pond they finish. And they will probably complete it only after they develop a second entrance to the site off Ford Road (see below).

Only Work Tuesday Was Trying To Drain N1

Looking south along the western boundary from over N1, you can see where the tail ends. The tiny trench letting water out of the tail slows down water. It will eventually be replaced by the four-foot culverts you see on the left.

That tiny trench is where the excavator was working today.

Site Holds More Water than N2 Detention Pond

Still looking south, but further down the western boundary, we can see the old and new portions of the N2 detention pond. It is not currently holding much water because contractors have already opened up the sides. That allows water to escape into Taylor Gully (top center).

Note how there’s more water on the site than in N2.
Closer shot shows how workers opened up N2 to Taylor Gully (left of top center). They also continue to widen and deepen the pond toward the upper right corner.
Rotating about 90 degrees, we can see how saturated the soil is. The northern portion of the site contains an amazing amount of standing water that isn’t yet able to reach the detention ponds.

The northern portion of the site is roughly 200 acres. Assuming an average of three inches of standing water (one quarter foot), that means the northern portion may contain 50 acre-feet of standing water!

Taylor Gully Did Not Appear to Overflow

Looking southeast at North Kingwood Forest (left) and Elm Grove Village (right), areas where hundreds of homes flooded twice last year.
A closer shot shows where water in Taylor Gully, when high, is forced to make multiple turns within a few hundred yards to bypass a 3 foot pipe that connects the channel on either side of the county line. Luckily, water did not reach the overflow spillway from the concrete-lined channel during recent heavy rains, according to Jeff Miller.

N3 Pond Greatly Reduced Flow in Taylor Gully

The pond below (N3) sits directly above the portion of Taylor Gully that flooded Elm Grove and North Kingwood Forest twice last year. The vast majority of this excavation took place earlier this month.

Rotating to the northeast, you can see the N3 detention pond, now mostly excavated. Miller estimates it’s still one half to one third full.
Traveling up the eastern side of Woodridge, we can see tremendous erosion along the banks of N3. Those parallel stripes running down the sides of the pond are called rilling, shallow channels cut in the surface of soil by running water.

Simply Excavating Ponds Does Not Mean They Are Complete

Above, you can see that contractors did not yet have backslope interceptor swales in place. Nor did they have the pipes installed to channel intercepted runoff to the detention pond. Accordingly, runoff went over the edges of the pond and washed sediment into it.

The ponds will not be complete until backslope interceptor swales and pipes have been installed and grass planted along the edges of the ponds to prevent future rilling. The ponds also need concrete pilot channels to prevent erosion in the areas of constant use.

New Entrance on East

The new entrance to the subdivision (background below) will be an extension of Mace Street in Porter on the West. It will connect to Ford Road on the East.

Looking straight east from the top of N3. Note two things: a channel designed to funnel standing water to N3 and the new entrance to the subdivision cut into the woods in the distance.

Mace enters the western side of the subdivision just to the left of that silver roof in the distance of the shot below.

Looking directly west across Woodridge Village while hovering over N3 on the eastern border.

Why You Don’t Build On Wetlands

The last image above shows why you don’t buy homes built over wetlands, even if the Army Corps ruled that the wetlands weren’t jurisdictional. Any homes built here would likely have foundation problems from shifting soils. Of course, by then, the builder would be long gone.

In reviewing the complaints lodged with the Better Business Bureau against Perry Homes, most of them had to do with failure to honor warranties. Digging deeper, you can see many of the underlying complaints had to do with drainage, flooding, mold, and mildew.

There may be a connection between the type of property Perry develops and the problems that customers later develop. If Perry builds on this property, I pity any poor unsuspecting customers who fail to research its history.

No New Statements on Potential County Buyout

To my knowledge, neither Harris County, the City of Houston, nor Perry Homes have issued any public statements about the status of a buyout of this property. Harris County Flood Control District was considering using it to build a regional flood-detention facility. But County Commissioners added new conditions on any buyout in their last meeting.

Twice-flooded residents in Elm Grove and North Kingwood Forest eagerly await new details on the deal. Even if Perry completes work on all the ponds, it will likely not be enough to handle a true hundred-year rainfall event.

Ponds Still Would Not Likely Detain Hundred-Year Rain

Perry rushed to get plans permitted before new Atlas-14 rainfall standards went into effect. They would have required 30% to 40% more detention than the plans that the City and Montgomery County approved.

In the meantime, though, the new detention ponds will greatly reduce the risk of flooding from lesser storms. Also, the National Weather Service has reduced the risk of rain in the next several days. That may give Woodridge Village time to dry out and downstream residents time to catch up on their sleep.

Posted by Bob Rehak on 5/27/2020 with reporting from Jeff Miller

1002 Days after 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.

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.

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, 2020
Massive 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.

Contractors Begin Excavation of N1 Detention Pond at Perry Homes’ Woodridge Village

In the last week, contractors have finally started excavating the N1 detention pond at Woodridge Village. Work on the excavation of N2 continues. It also appears that they may have started prep work for excavating the N3 pond. See photos below.

All this comes:

The next Commissioners’ Court Meeting is set for May 19. The agenda for that meeting should be posted May 15.

Excavation Begins on N1 Pond (First Pond on Northern Section)

On May 5, 2020, Jeff Miller, an Elm Grove resident, noticed excavation activity near the Webb Street entrance to Perry Homes’ Woodridge Village. Engineers designated this area for the N1 (first northern) detention pond.

Photo Courtesy of Jeff Miller from Webb Street Entrance in Porter taken on 5/5/2020 shows excavation beginning on N1
Closer photo by Miller from Webb Street Entrance also taken on 5/5/2020
Wider shot by Miller on same date shows additional prep work on N1 site

Miller also shot this video on 5/6/2020, showing the progress contractors have made on the excavation in one day.

Video by Jeff Miller, Elm Grove resident on 5/6/2020.

N2 Excavation Continues

I took the shot below on May 1 with a telephoto lens from the north end of Village Springs in Elm Grove. It shows excavation work continuing on the N2 pond.

Excavation work on N2. Photo taken on 5/1/2020.

Additional Work in Area of N3 Pond

Additional work near area of N3. This excavator was loading up three dump trucks on May 1, 2020.
The dump trucks hauled dirt back to the soupy portion of the Woodridge Villages northern section, then circled back.

On May 5th, Jeff Miller photographed the N3 area from a closer vantage point. It appears only the surface layer has been scraped off so far.

Photo of N3 area courtesy of Jeff Miller taken on 5/5/2020.

Putting New Work in Context of Entire Project

Here’s the layout for the five Woodridge Village Detention Ponds. Contractors finished work on the two southern ponds earlier this year.

Woodridge Village has five detention ponds at various stages of completion. Northern ponds are now under construction. Southern ponds are completed.
At the time of last year’s May flood, only S1 was complete. S2 was substantially completed by September’s flood. The northern ponds had not yet been started.

When the northern detention ponds are complete, the detention system will still not be fully functional because there are no streets or storm drains yet to funnel water into them. Still, some detention is better than no detention with hurricane season three weeks away and an above average season predicted.

City Still Needs to Meet Two Conditions

Perry Homes swears that the work being done now will not affect the purchase price if the County makes a decision on the property by May 15th. At their last meeting, commissioners made the purchase contingent on the City of Houston:

  • Adopting Atlas-14 rainfall statistics
  • Donating $7 million worth of land to HCFCD for flood control projects and to help offset the purchase price of Perry’s property.

No items relating to the purchase appeared on this week’s City Council agenda. But Council meets again next week before the deadline expires.

The County hopes to meet with the City next week to discuss the donation of land. The County also reportedly feels that the four days between Perry Homes’ extended deadline (May 15) and the next commissioners’ court meeting (May 19) will not present a problem if the the City meets the conditions.

Posted by Bob Rehak on 5/6/2020 with thanks to Jeff Miller

981 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.

Parallel Between Flooding and Corona Virus

A friend, Dr. Matthew Berg, CEO and Principal Scientist of Simfero Consultants, observed that flooding and the corona virus are alike. The more I thought about that, the more intrigued I became. Controlling both requires similar strategies.

Controlling Convergence is Key

Of course, when looking at the corona virus, it spreads from “one-to-many.” And when looking at flooding, the relationship is reversed, “many-to-one.” But stay with me for a moment. Because similarities will become apparent at the point of convergence.

Dozens of creeks and streams flow into Lake Houston from approximately 2,600 square miles.

Creeks and streams from 2,600 square miles converge on Lake Houston during heavy rains. That can cause flooding. Likewise, thousands of corona virus victims could soon flood the area’s limited number of hospitals.

Harvard Study Shows Hospitals Rapidly Becoming Overwhelmed

Last week, ProPublic published an article, “Are Hospitals Near Me Ready for Coronavirus? Here Are Nine Different Scenarios.” The article is about a Harvard Global Health Institute study. It modeled different rates for the spread of the virus: 20%, 40% and 60% of the population infected over 6, 12 and 18 months. The authors then compared results against the number of available hospital beds in various areas.

Interestingly, they used the Houston region as their first test case. In only one of the nine scenarios, did we have enough hospital beds to handle the flood of corona victims. That scenario was for 20% infected (the smallest percentage) over 18 months (the longest period).

Darkest blue represents 6-month peak, middle blue a 12-month peak, and lightest an 18-month peak.

In the graph above, the areas shaded with crosshatching represent the normal baseline level of bed occupancy for non-corona patients in Houston hospitals. The colored areas represent the percentage of the area’s population projected to seek admission within a 6-, 12- or 18-month period.

2.8X Available Hospital Beds

The ProPublica article about the Harvard study goes into much more detail. It looks at all 50 states, the number of ICU beds, available ventilators, people etc.

In Houston, the researchers found, “The influx of patients would require 14,300 beds over 12 months, which is 2.8 times the available beds in that time period. The Harvard researchers’ scenarios assume that each coronavirus patient will require 12 days of hospital care on average, based on data from China.”

ProPublica Article on Harvard Study

One hospital administrator said, ““The reality is that you can’t create unlimited hospital beds and ventilators. We have what we have, so we really have to hope that it’s enough, and that we’re prepared enough.”

Flattening the Curve Prevents Avoidable Deaths

Said the authors, “By modeling the data over the three time periods, the scenarios illustrate how much the nation could “flatten the curve” with social measures to ensure hospitals have greater capacity to care for coronavirus patients.”

Epidemiologist Dr. Marc Lipsitch, head of the Harvard T.H. Chan School of Public Health’s Center for Communicable Disease Dynamics said, “The way to permanently stop new cases from setting off long chains of transmission is to have each case infect considerably less than one case on average. The numbers will go down. There will still be little outbreaks, but not big ones.”

Basically, Dr. Lipsitch argues that controlling the flood of victims early at the source is the only way to avoid overwhelming health care resources.

This YouTube video from Vox about Avoidable Deaths shows how slowing things down and flattening the curve helps everyone.

https://www.youtube.com/watch?v=dSQztKXR6k0

Parallel With Physical Flooding

It’s much the same in physical flooding. Too much water in too little time overwhelms the available capacity of streams, rivers and lakes. Property is destroyed. People die.

That’s why flood experts argue for upstream detention. This post about closing the detention pond loophole in Montgomery County flood regulations contains two FEMA case studies from Texas about the value of detention ponds. Slowing water down prevented flooding.

The beat the peak loophole in MoCo regulations says that if developers can prove they can get their runoff to the river before the peak of a flood, they don’t have to build detention ponds. That’s what happened in the 2200-acre Artavia development. Of course, this incentivizes developers to get their water to the river ASAP.

And that’s exactly the opposite of what you need to protect lives and property downstream.

It’s kind of like saying, “Let’s infect everybody as fast as we can.”

Slowing down the spread of the virus will give researchers time to develop a vaccine or for the population to develop herd immunity … before hospitals become overwhelmed.

Unfortunately, there is no vaccine or herd immunity to protect downstream residents from greed. And there never will be. That’s why we need to close the “beat the peak” loophole before it’s too late.

Posted by Bob Rehak on 3/25/2020

939 Days after 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.

LJA Engineers 2200-Acre Artavia Development in Montgomery County Without Detention Ponds

Last August, I posted about a loophole in Montgomery County Flood Plain regulations. It allowed all developers who could prove they were “beating the peak” of a flood to bypass the requirement for detention ponds. Montgomery County Commissioners decided to leave the loophole open. They said, “We don’t have a flooding problem.”

Giant Development Exploits Detention Loophole

It all seemed somewhat academic at the time – unless you previously flooded from upstream development. Then along came Imelda. The absence of functioning detention ponds on Perry Homes’ Woodridge Village property underscored the need for adequate detention for the second time in five months when hundreds of homes downstream in Kingwood flooded.

Now there’s a 2,200 acre development called Artavia going in upstream from the Lake Houston Area – without detention ponds.

Artavia straddles FM1314 south of 242.

Artavia neighborhood entrance and model homes.

The engineering company for the developer, Aliana, claims their calculations show that floodwater from Artavia will beat the peak of a flood to the West Fork by 35 hours. Dasa Crowell, PE, LJA’s Project Manager for Hydrology and Hydraulics, thus concluded, “This leads us to a conclusion that the peak flows generated by the runoff from project drainage area will have no impact on the WFSJR under proposed conditions, therefore detention is not required.” See page 56 of this PDF.

In fairness, the development does include a retention pond in Section 1 labeled as a detention/amenity pond. However, aerial photos show that it has only a few feet of excess storage capacity above its normal water surface elevation. See the plans here. It’s certainly not going to hold back a 100-year rain falling over 2200 acres.

Little Buck Amenity Facility/Pond. Note that as-built conditions appear smaller than plans.

Engineers seem to be relying on drainage channels to act as their detention basins, but as we will see, that comes with some risk. And one potentially bad assumption may invalidate the whole concept.

Problems with Beat the Peak

In an interview last July, MoCo Engineer Jeff Johnson argued for closing the “beat the peak” loophole. He said that the data developers use to calculate peaks is decades old; doesn’t reflect the current drainage picture; and that models should change every time a new development comes in, but they don’t.

Because detention costs money and limits the number of salable lots, developers try to get their water to the river as quickly as possible so they can “beat the peak.” Of course, racing to get water to the river in a flood is the exact opposite of what you want to happen if you are a downstream resident. Normally, you want developers to hold water back as long as practical so as not to overwhelm downstream channel capacity.

LJA developed the Artavia River Impact Analysis in 2014 (see page 60). Based on LJA’s assurances, Dan Wilds, then MoCo’s assistant county engineer issued a letter of “no objection.”

“No Impact” So No Detention Requirement

Wilds said in part, “The analysis … demonstrates that the peak flow from the developed tract will pass through the downstream cross-section approximately 35 hours prior to the peak flow from the upstream watershed. The report indicates that the 10-year, 25-year and 100-year events were analyzed and concludes that the runoff from the project drainage area will have no impact to the San Jacinto River under proposed conditions.”

“Based on this information, this office offers no objection to the analysis as presented. Storm water detention will not be required for this development as long as the developed flows up to and including the 100-year event can be adequately conveyed to the San Jacinto River.” For the full text, see page 51 of this PDF.

The Executive Summary of the most recent update of the drainage impact analysis for Artavia states, “The November 2014 memorandum documents the analysis supporting no detention requirement; this analysis provides calculations showing that the proposed Star Ridge Ranch development (as it was then called) drainage system will safely convey the rainfall runoff for rainfall events up to and including the one-percent annual chance (100-year) storm event.”

Similarities Between Woodridge Village and Artavia

Please note that both of these analyses base their conclusions on pre-Atlas-14 rainfall statistics and therefore may understate drainage requirements significantly by up to 40%. LJA did the same with Woodridge Village.

Also note two other similarities with the LJA analysis for Woodridge Village, Perry Homes’ disaster-movie-in-the-making project.

For its modeling, LJA used something called the Clark’s Unit Hydrograph. Their reports never mention the NRCS method specified in the current Montgomery County Drainage Criteria Manual. The use of Clark’s methodology, which minimizes runoff estimates, has become a bone of contention in the Elm Grove lawsuits.

Finally, LJA pushed both the Woodridge and Artavia plans through the MoCo Engineers office right before the drainage criteria manual was about to be updated again with more stringent requirements.

LJA submitted both drainage analyses for MoCo approval within approximately a year of Hurricane Harvey before flood maps, rainfall statistics, drainage criteria, and construction standards were updated.

LJA Engineering was not only playing beat the peak, it was playing beat the clock again. This will be the first of several posts on Artavia. More news to follow.

Posted by Bob Rehak on 3/17/2020

931 Days after 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.

Perry Homes Taking Bids on More Detention Ponds for Woodridge Village

Note: This post has been modified to delete the mention of storm drains. On closer examination of older photos, it appears that the storm drains were installed before January 20th.

Perry Taking Bids on New Detention Ponds

Perry Homes is taking bids on additional detention ponds, as you can see from this document by LJA Engineering, their engineering firm for this property.

In a letter Perry’s lawyer sent to the City Attorney on October 17, 2019, Perry Homes promised the City they would accelerate construction of those. They were originally scheduled for Phase 1.

Status of Detention Pond Construction

The letter by Perry’s lawyer laid out a timetable. Perry Homes was supposed to have finished the S2 detention pond in 30-45 days.

As of last Thursday, they were still doing touch-up work on detention pond S1. Specifically, they were removing soil that had eroded into the pond since last May.

Woodridge Village S1 Pond still has no grass on shoulders almost a year after substantial completion. Last week, workers were trying to repair sidewall erosion and remove sand from pilot channel.

Grass still has not grown on the sides of either the S1 or S2 ponds.

Woodridge Village S1 detention pond still has no grass despite substantial completion before the May storms last year. Photo taken 2/13/2020.
Woodridge Village S2 pond as of 2/13/2020 still shows little grass.

Perry’s letter to the City promised construction of a berm between S1 and S2. Work on the berm connecting S1 and S2 looked like it had not begun yet as of last week.

Area between S1 and S2 where berm should be. Photo taken 2/13/2020. I can’t see it in this photo, but in fairness, resident Jeff Miller feels Perry is building this area up slightly.

Work on Three Northern Ponds Still Not Started

Perry still has less than 25% of the promised detention capacity constructed. Work on the three northern detention ponds has definitely not begun yet as you can see from the photos below. I took all of them on 2/13/2020.

The N1 detention pond should go in the foreground in the northwest corner of the site.
Montgomery County partially excavated this pond decades ago to count as detention for other development. Perry Homes must deepen it to create additional detention for this site. This is the N2 pond in the middle of the western side.
The N3 Pond will go above the S2 pond shown in the foreground here. It should stretch almost all the way back to the far tree line.

How Long Will It Take to Build Ponds?

Neither Perry Homes, nor LJA engineering has published bid requirements for the ponds. The only thing we currently have to go on for a construction timetable is J. Carey Gray’s letter to the City.

In it, Perry committed to developing each of those ponds within 250-280 days. Assuming construction remains on schedule and that the deadlines are sequential, not concurrent, Perry should complete the remainder of the ponds in 2.3 years.

If the work on S2 is any indication, consider this. Perry had substantially completed the S2 pond before Imelda. As of today, they have gone 109 days past a 45-day self-imposed deadline. They still don’t have a maintenance road around it. Nor do they have grass established on the sides of it. Both are Montgomery County requirements.

Implications for Future

The end of Perry’s letter says, “…we will continue to consider alternatives that provide more robust mitigation.” Presumably that was a veiled reference to a potential buyout by the City of Houston or Harris County Flood Control. No one is talking about that alternative at the moment…if it exists. A spokesperson for the City this afternoon said only, “We support any alternative that reduces flooding.”

On one hand, it’s exciting that Perry is finally moving forward with work that should have been completed long ago. But on the other…

… the additions to infrastructure signal that hopes for a buyout by the City of Houston and/or Harris County Flood Control – to provide more robust mitigation – have vanished or are fading quickly.

We should not forget that even if Perry succeeds in building additional ponds, they are based on old rainfall statistics. The NOAA Atlas 14 rainfall statistics – on which new flood maps are being redrawn – require about 40% more detention capacity.

Posted by Bob Rehak on 2/18/2020

903 Days after Hurricane Harvey and 151 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.

Detention Pond Construction: Montgomery vs. Harris County

Below are aerial images from two new developments under construction. They show two detention ponds in two different counties. Can you tell which is in Montgomery County and which is in Harris County? I took both photos on the same day, 2/13/2020.

Detention Pond A
Detention Pond B

Clue

Look where the grass has established itself:

  • In A, the land was cleared before the detention pond was completed.
  • In B, the detention pond was completed before the land was cleared.

And the Answer Is…

If you guessed that Pond A is in Montgomery County, you guessed correctly. Pond A is in Woodridge Village, just north of Sherwood Trails and Elm Grove. It is their S1 detention pond (first southern).

Pond B is in Harris County just north of Bush Intercontinental Airport and Mercer Botanic Gardens.

How You Can Tell

Montgomery County does not require developers to install detention ponds before they clearcut the whole development. So they sometimes come long AFTER clearcutting.

Also, even though Page 44 of Montgomery County’s Drainage Criteria Manual says that “slopes must be revegetated immediately after construction to minimize erosion,” no one apparently enforces the regulation. The sides of Pond A have gone without grass for about a year. See close up below.

Erosion on the sides of Pond A shown above, the Woodridge Village S1 detention pond.

All 268 acres of Woodridge Village have been clearcut for the better part of a year. Meanwhile Perry Homes and its engineering firm LJA are just now taking bids on additional detention ponds for the northern section. And the sides of Pond A still have yet to sprout grass.

Harris County Regs Differ

Note in the Pond B photo how the sides of the channel have been stabilized with grass before the developer has even finished clearing the land.

Harris County employs low-impact development procedures (LID). Harris County Stormwater Quality Management regulations discourage clearcutting giant sites like Woodridge Village all at once. See section 4.2.3.1, Stormwater Pollution Prevention (SWPPP) During Construction.

The text states, “The clearing, grubbing and scalping (mass clearing or grading) of excessively large areas of land at one time promotes erosion and sedimentation problems. On the areas where disturbance takes place the site designer should consider staging construction [emphasis added], temporary seeding and/or temporary mulching as a technique to reduce erosion. Staging construction involves stabilizing one part of the site before disturbing another [emphasis added].”

Two Different Approaches

You would think that preventing erosion would be cheaper than cleaning it up. Why do a job once when you can do it twice? Right?

Close up of remediation work in Pond A, from a slightly different angle. Photo taken 2/13/2020.

Evidently, Perry Homes prefers it that way. Last Thursday, I spotted men digging out the pilot channel of Pond A and restoring slopes…again. This was at least the third or fourth time. No wonder those Perry Homes are so expensive.

Posted by Bob Rehak on 2/16/2020

901 Days After Hurricane Harvey and 150 after 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.

Perry Homes’ Contractors Return to Woodridge Village, But Undo Some Previous Work, Add to Sediment-Laden Runoff

After pulling all construction equipment from the Woodridge Village site in December, Perry Homes’ contractors returned this week. They are still working on the S2 (second southern) detention pond. But the new work appears to undo some previous work, and make sediment-laden runoff worse.

Woodridge Still Far Short of Promised Detention Capacity

After about 15 months of working on the Woodridge Village site, Perry Homes still has only 23% of the detention capacity installed. And even that does not yet meet Montgomery County regulations (see below). None of the work this week focused on new detention ponds that would reduce flood risk for Elm Grove residents.

Perry Homes had promised to build three ponds on the northern section. But they have not started any of those yet.

And Far Behind Schedule

On October 17th last year, an attorney for Perry Homes, J. Carey Gray, promised the Houston City attorney that Perry would have S2 completed in no more than 45 days. It has now been 86 days since Mr. Gray sent his letter and the work is still far from complete. I’m sure this creates an embarrassment to the Mayor of Houston, especially considering that Perry Homes gave $5000 to his re-election campaign. It creates the appearance of trying to buy favors.

Still Does Not Comply With MoCo Regulations

I previously detailed seven Montgomery County regulations that Perry Homes’ detention ponds did not meet. Perry Homes did not:

  • Put 30-foot wide maintenance roads around the ponds.
  • Place backslope interceptor swales around the ponds.
  • Have effective erosion control measures in place.
  • Implement protective measures for their overflow spillway.
  • Prevent increases in downstream flood levels.
  • Prepare a geotechnical report (that they shared with Montgomery County) showing groundwater levels at detention pond sites.
  • Ensure complete drainage of the detention pond.

Detention Pond Falls Short of Promised Capacity

Calculations for the capacity of the detention ponds begin from the bottom of the pond – when empty. When partially filled with water, the calculation begins from the top of the water. The bottom 2-3 feet of S2 has retained water for months, indicating that part of the pond is below the water table. So you can subtract about 20% of capacity that LJA Engineering promised and that Rebel Contractors initially built.

Adding Maintenance Road, Subtracting Backslope Swales

The flurry of work this week centered around creating the maintenance road that regulations demand. Or perhaps Perry is just building up the lip of S2 to compensate for the water it holds. Both are potentially good things.

However, workers also started filling the backslope interceptor swales they previously built. This created a sharp slope next to neighboring residents’ property and increased runoff toward the residents during last night’s rain.

Contractors placing dirt along the southern edge of the S1 pond to build a road earlier in the week.
Elm Grove Trail on left. Woodridge Village on right of silt fence. Note how land is being sloped toward Elm Grove.

An interceptor swale collects water above slopes and diverts it to the bottom of a detention pond through pipes so runoff does not create erosion on the slopes that lead to the pond.

Perry Homes has given no reason why they started filling in the swale they previously built that complied with MoCo regulations.

Looking west from Village Springs Drive. In the foreground, you can see how workers built a road and filled in the interceptor swale between it and Elm Grove on the left.
Still looking west. From this drain pipe, you can better see the grassy swale previously created to drain water into the detention pond (right) and to keep it out of Elm Grove (left).
Reverse shot, looking east. Here you can see how workers filled in the swale and created a road three to four feet high. Residents worry about the effect.
Looking east near the entrance to Taylor Gully from the road, the change in drainage toward Elm Grove (right) becomes very apparent. Picture taken Friday afternoon before rain. Road was uncompacted except for the weight of the small bulldozer spreading dirt (see first picture above).

Same Changes Between S1 and Sherwood Trails

The same changes appear along the southern edge of S1, north of Sherwood Trails, though the road does not appear as high and there also appears to be a shallow swale.

Looking west along the southern edge of Woodridge Village S1 detention pond, toward Woodland Hills from Fair Grove.

No Effective Erosion Control Yet

Perry Homes has also failed to put effective erosion control measures in place in Woodridge Village. For instance, most pond banks do not yet have grass planted on them.

The new road covered up what little grass had grown around the ponds. And raw dirt now fills the former interceptor swale.

A one-inch rain last night swept sediment into the pond, which emptied into Taylor Gully and Caney Creek before joining the East Fork of the San Jacinto.

Massive Pollution

Boater Josh Alberson took the dramatic picture below this afternoon where Caney Creek joins the East Fork. The East Fork water looks natural, but the water coming from Caney Creek via Taylor Gully is clouded with sediment. Woodridge Village is the only large source of exposed earth up Taylor Gully at this time. (Alberson verified that this sediment-laden runoff was NOT coming from the Triple PG mine up White Oak Creek.)

Water from Taylor Gully (right) merging with East Fork water (left) on Saturday afternoon, 1/11/2020, after a 1-inch rain last night.

Posted by Bob Rehak with images from Josh Alberson, Edythe Cogdill and Nancy Vera

865 Days since Hurricane Harvey and 114 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.