“Backslope interceptors” help prevent erosion that can clog drainage ditches and contribute to flooding. Most people have probably seen them, but never paid much attention to them. Nor do they understand can reduce ditch maintenance costs by lengthening maintenance intervals. This photo essay shows what a difference they can make. All three counties in the Lake Houston Area require them, but Liberty County doesn’t enforce its own regulations. So the visual differences are dramatic.
What Are They? How Do They Work?
We’ve all observed water flowing through drainage ditches. But how does it get into the ditch? Broadly speaking, it can get into the ditch by a) flowing down the banks or b) through pipes. Option A increases erosion. Option B decreases it. B also reduces flood risk and the long-term cost of ditch maintenance.
What is a backslope interceptor? Imagine a small ditch (or swale) parallel to but offset from the main ditch. The swale captures runoff and overland sheet flow before it gets to the main ditch. The swale then funnels the flow into pipes that run under the banks of the main ditch. Keeping large volumes of water off those banks reduces erosion which could otherwise quickly fill the ditch with dirt and reduce its carrying capacity. If erosion reduces carrying capacity enough, water can flood nearby homes and businesses. The illustration below shows how backslope interceptors work.
Real-Life Examples
On 3/3/2021, I flew over three counties: Harris, Montgomery and Liberty. The “with/without” photos below illustrate the difference that properly constructed backslope interceptors can make. I shot the first one over the new Artavia development in southern Montgomery County. Note how the backslope interceptors let the developer establish grass on the banks of the ditch despite construction still in progress.
Ditches WITH Backslope Interceptors
Ditches WITHOUT Backslope Interceptors
The rest of these examples came from Colony Ridge in Liberty County.
Role in Establishing Grass
The next two photos show the role of backslope interceptors in establishing grass. By preventing bank erosion from sheet flow, the interceptors give grass time to establish and grow, reducing erosion even more.
How Enforcing Regulations Can Reduce Costs, Flooding
Ironically, Liberty County drainage regulations updated in 2019 require developers to install backslope interceptors and plant grass on the banks of drainage ditches.
Page 100 states: “Erosion Control: All drainage facilities must be designed and maintained in a manner which minimizes the potential for damage due to erosion. No bare earthen slopes will be allowed. [Emphasis added] Various slope treatments, including turf establishment, concrete slope paving, and rip- rap, are accepted. Flow velocities should be kept below permissible values for each type of slope treatment. Interceptor structures and backslope swale systemsare required [Emphasis added] to prevent sheet flows from eroding the side slopes of open channels and detention facilities.”
When the developer eventually tries to turn Colony Ridge over to Liberty County, the county will inherit as massive maintenance burden because of non-compliance with these regulations. But even before then, the developer is creating rivers of mud that reduce the conveyance of ditches, and thus contribute to flooding nearby residents in Plum Grove.
The sediment also contributes to dredging and water purification costs for people downstream in Harris County.
Posted by Bob Rehak on 3/6/2021
1285 Days since Hurricane Harvey and 534 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.
More than one engineer has told me that sand mine dikes appear as though they are designed to fail. Part of the problem is that the State sets no standards for their construction; the State simply says they must be “effective.” But there are only minor penalties if they prove ineffective.
How Sand Mines Use Water
Mines use water to separate sand from silt by spinning the mixture through a centrifuge. The large sand particles go to a stockpile. The smaller silt particles return to a settling pond. If left long enough, the water clarifies and can safely be released.
Constant Battle Against Silt and Water
The problem, however, is the buildup of silt and water over time.
The fine sediment often does not have enough time to drop out of suspension before water in the settling pond begins to overflow. That’s when dikes often break and sediment laden water is released into the river.
Sadly, this is not an isolated problem. I have documented breaches in most San Jacinto River mines.
Road Disappears as Dike Gets Higher
Since then, aerial photos show that LMI is building dikes higher to prevent future releases. But as the thin dikes made out of sand/silt get higher, they also get narrower. They seem designed to fail at some point.
Process waste water leaks through them into surrounding wetlands and the West Fork. To keep the dikes from failing, the mine even appears to be pumping water out of its pit into the wetlands.
A large rain could easily overwhelm these dikes and cause another failure. As a starting point, review the satellite photo below from Google Earth. It was taken about a month after a major breach from another part of the mine. Note the perimeter road around the entire pond. It disappears in aerial photos taken a few months later.
Now compare that to this series of helicopter photos taken on 4/21/2020. The series starts in the upper right of the satellite photo and heads south (toward the bottom of the satellite image). This area of the mine is far from public view, except from a helicopter..
Where 56 Million Gallons Allegedly Entered River
Note the difference in the color of the water in the pond and in the river in the photo below. The pond color has not changed during the eight months I have been documenting these sand mining operations from the air.
No Texas Regulations Govern Dike Construction
Unfortunately, the State of Texas has no regulations that address construction of dikes.
No standards exist for height, width, composition, compaction, or reinforcement.
I asked Ramiro Garcia, head of enforcement for the TCEQ, this question. “Does Texas have regulations for sand mines that affect the width, height, slope, compaction, and materials used in perimeter dikes or barriers?“
His reply: “The Industrial Stormwater Multi-Sector General Permit requires the use of pollution prevention practices that can effectively protect the water quality in receiving waters, or that are necessary for remaining in compliance with the general permit. The GP states that “the permittee shall evaluate and use appropriate measures and controls to reduce soil erosion and sedimentation in areas of the facility with demonstrated or potential soil erosion and sedimentation” (Part III.A.4(c)). There are no specific requirements for width, height, slope, compaction, or materials for dikes or barriers.“
So the permittee gets to determine what’s “appropriate”!
Designed to Fail?
The lack of regulation is how we get strips of sand a couple feet wide holding back hundreds of millions of gallons of waste water. One big rain, a flood, and the wastewater buildup is gone. Conveniently!
If the TCEQ discovers an unauthorized discharge, the mine pays a “slap on the wrist” fine. They average about $800. That’s why I ask, “Are sand mine dikes designed to fail?” It seems cheaper and easier to pay the fine than build earthworks that protect the source of drinking water for 2 million people.
State Rep. Dan Huberty tried to implement effective sand mining regulations during the last legislative session. Unfortunately, most of the mining bills he sponsored died in committee. I’m using the time before the next session to document mining practices on the San Jacinto. Hopefully, we’ll be able to make a better case next year.
Posted by Bob Rehak on 5/4/2020
979 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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/05/20200421-RJR_0878.jpg?fit=1200%2C800&ssl=18001200adminadmin2020-05-04 13:04:422020-05-04 13:23:31Are Sand Mine Dikes Designed to Fail? State Sets No Standards
LJA Engineers submitted a master drainage plan for the 2,200 acre Artavia development that Montgomery County approved. It has no detention ponds. And the drainage channels currently do not connect to the San Jacinto river. Even though LJA said they would connect to the river, the plans do not specify how, when or where. As you will see below.
A Sand Mine Is Not the San Jacinto
The plans DO show the channel terminating in a sand mine between Artavia and the river. A spokesman for the sand mine said the developer is still trying to work out environmental and easement issues.
Aerial photos show the main channel stops about a 100+ yards short of LMI’s shipment facility. Meanwhile, during heavy rains, the dead-end drainage overflows onto surrounding properties. A spokesman for the mine claimed that the overflow flooded the mine last year and caused the dikes to break. He alleged that was the proximate cause for 56 million gallons of white sediment-laden water entering the West Fork.
The project manager for LJA did not return calls to explain their position on the dead-end drainage. And when asked for an explanation, the new Montgomery County Engineer (not the one who signed these plans) only referred me back to LJA.
Below are the drainage plans for Artavia, obtained by a Freedom of Information Act request to Montgomery County.
Several things have jumped out at me so far. LJA has not yet returned phone calls, so to me they remain…
Unaddressed Issues
Elevation Change Accelerates Flow
Elevation drops suddenly as you get near the river – 12 feet. That accelerates waterflow and threatens the sand mine. As you can see above and below, the channel is like a firehose aimed at the mine. That mine has enough problems of its own. In the past, dike breaches have affected Lake Houston water quality; we don’t need more of that. The mine blames the breaches on water overflowing from the Artavia ditch.
Flow Rates Understated
LJA calculations appear to understate the volume and velocity of flow. They use a Manning’s coefficient of .035, a value associated with pasture/farmland or channels filled with stones and cobbles. The coefficient recommended for smooth channels is 0.022. The difference creates a 63% increase in velocity and a 60% increase in volume of flow.See for yourself. With no real way yet for the water to get to the river or under FM1314, that will cause water to pile up much faster.
LJA also uses pre-Atlas rainfall statistics in their calculations of 10-, 25- and 100-year peak flows. The new Montgomery County standard is 16.1 inches in 24 hours compared to the 12.17 that LJA used for the 24 hour, 100-year flood.
Did LJA use “good engineering practices” and model Atlas 14 to ensure that it actually contained the 100-yr, 24-hr storm? There’s an ethical issue here. Did they put public safety first? We don’t know because they didn’t say so in any of their documents.
No Mention of Wetlands
LJA never mentions wetlands in their analysis. However, the National Wetlands Inventory shows wetlands on Artavia property and other property Artavia drains through.
Threat to Pipeline
A pipeline crosses the Liberty Materials mine. High velocity flow through the mine could undermine and threaten that pipeline like it did at another Liberty mine and at the Triple PG mine on the East Fork.
No Outlet
There’s no explanation for how Artavia will get water through the pit at the end of their ditch. They can not store Artavia’s runoff in the pit. Their pit is already filled to the brim with highly silty, turbid water. Another unauthorized discharge could affect water quality in Lake Houston...again!
Threat to Mine
A representative for the mine owner says the mine owner doesn’t want more water in the pit. They can’t afford the cost from environmental or business perspectives. With the COVID-19 threat, construction activity is way down. So margins are slim. And they can’t afford to have water fill their deep pit where they dry mine.
“No Adverse Impact”
LJA claims the project will have no adverse impact on downstream properties. But it already has. Properties along Greenbaugh and in Oak Tree have flooded since Artavia started clearing land and filling in wetlands.
The Liberty Materials mine also alleges it was flooded by Artavia’s overflow, resulting in the discharge of 56 million gallons of silty water into the West Fork.
Who Pays to Get Water Under FM1314?
LJA can only convey 68 cfs under FM1314. Meanwhile, TxDoT has not yet finished the design for a bridge. They hope to start bidding the job by the Fall of this year. Residents, not the developer, will pay for the improvement through the local municipal utility district.
LJA claims “The culvert crossings were designed to have capacity to convey 100-year storm events.” But they certainly aren’t doing that now.
Diverting Water From East to West Fork
The developer appears to be diverting water from the East Fork watershed to the West Fork watershed. See Section 1.4 and Exhibit One.
It would be harder to “beat the peak” to the East Fork. It’s 12 times farther away; water would take much longer to get there. So the diversion appears to be an attempt to avoid building detention ponds. But the diversion adds to flood volume in heavily populated West Fork areas where far more homes flooded during Hurricane Harvey.
Will LJA Figure It Out In Time?
For the sake of adjacent residents and businesses, let’s hope they figure these loose ends out before the next flood.
The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/03/20200306-RJR_9170.jpg?fit=1200%2C800&ssl=18001200adminadmin2020-03-20 20:48:012020-03-20 23:58:19The MoCo/LJA Way: Build First; Work Out Drainage Details Later
Mark Mooney, PE, the long-time Montgomery County Engineer whose office approved LJA plans for Woodridge Village and Artavia, and whose office oversaw LJA’s investigation of itself, has joined LJA Engineering as a “business development representative.” (Usually that means “sales.”)
A February 17, 2020, press release about Mr. Mooney’s appointment appears on LJA’s Facebook page. According to insiders, Mr. Mooney actually started working part time with LJA shortly after his retirement from MoCo. That happened after the May floods in 2019. However, the release now implies the relationship is full time. It appeared just days before LJA was named as an additional defendant in the Elm Grove flooding case. Below is the entire release verbatim:
MARK MOONEY, PE JOINS LJA AS BUSINESS DEVELOPMENT REPRESENTATIVE
After 34 years with Montgomery County, during which most of the time he served as the County Engineer, Mark Mooney, PE has joined LJA Engineering.
During his tenure, he had oversight of all major road initiatives through numerous bond elections; provided advice, direction, and consultation to 5 different County Judges and 17 different County Commissioners; oversaw the review and approval of over 3500 residential and commercial subdivision plats; oversaw the review, approval and inspection of over 1300 miles of road construction; and, provided daily services to a population that grew from 160,000 residents to over 600,000 residents in the 34-year span.
“I have known and respected Mark for many, many years. When the opportunity presented itself, I knew he was a perfect fit for LJA. We have four offices within Montgomery County and are personally and professionally vested in the growth and success of our employee-owners and clients there. Mark has dedicated his career to this community, and we want him to keep doing what he does best, serving Montgomery County,” said Jeff Cannon, Senior Vice President.
Mark was a Member of the City of Houston planning commission from February 1998 to May 2019. He is a Member of the Texas Association of County Engineers and Road Administrators (TACERA) since 1998; having served as President from 2005-2006, and he has been a Member of the National Association of County Engineers (NACE) since 1998.
Joining LJA, Mark explained, “It was the confidence that I felt between myself and Calvin Ladner (LJA President), that began when we were both a lot younger back in the mid-eighties, that sealed the deal. My responsibilities as the Montgomery County Engineer were made much easier by the honesty I had with Calvin initially and then with so many of the staff at LJA throughout the years. In my 34 years in this business, it always came down to trust as being the most important aspect as a public official. At LJA, I am ready to further develop my industry relationships utilizing the same playbook that worked for me for so many years as Montgomery County’s engineer.”
End of Release
Revolving Door Between Government and Business
[Rehak here again.] Before retirement, I frequently saw how the revolving door worked between government and business. I knew a man who went to Washington and worked for the EPA in a high level position “to get his ticket stamped.” Those were his words, not mine. After working in D.C. for several years, he returned to private industry where he made considerably more money, thanks to the insights he gave clients about how the EPA worked.
Personal connections provide knowledge of agency priorities; understanding of personal hot buttons; insights into procedures; and relationships with decision makers. They all prove valuable to companies whose sales depend on public-sector approval.
Fine Line Between Harmless and Harmful
There’s nothing illegal or immoral about this per se. On the innocent side, sometimes, if projects get bogged down, a call to an old friend can:
Move plans from the bottom of a pile to the top in an emergency.
Determine what the agency’s concerns about a set of plans might be so the concerns can be addressed quickly.
Speed up slow approval processes that run up costs.
Cases like these harm no one. They represent a form of social engineering or influence peddling that has been around as long as governments. However, what is normal and accepted in principle can sometimes turn sourin practice.
For instance, private-sector engineers/consultants might urge decision makers who are old friends on the government side to:
Rubber stamp questionable plans without looking too closely at them. (“Trust me.”)
Look only at the conclusion of a report without scrutinizing the assumptions, methodologies, underlying calculations and support.
Between these two extremes, between legal and illegal, infinite shades of gray exist.
Public’s Presumption of Oversight
Cases like those in the latter category can mislead the public and have devastating consequences. The public presumes the government is overseeing development (or at least the permitting of plans). In fact, government may not be. Those plans and stamps and dazzling arrays of figures may create the appearance of professional oversight when none exists.
Families may invest their life savings in homes based on the presumption of government oversight. Officials are supposed to ensure that there is no adverse downstream impact from a new development. But as we’ve seen in Elm Grove and elsewhere, that’s often not the case.
Bad Optics for Ethics
Exerting influence can sometimes cross moral, ethical and legal lines. I’m not saying it happened with Mr. Mooney. I have no evidence to even lead me to suspect such a thing. By all accounts, Mr. Mooney is honest and reputable.
Apparent Conflict of Interest In Elm Grove Investigation
However, it was on Mr. Mooney’s watch as County Engineer that the TCEQ referred a complaint about Woodridge Village involving LJA to Montgomery County for investigation.
To inspire public confidence in the outcome of the investigation, you would think that LJA would have recused itself or the county engineer would have hired another company for this particular investigation. Neither thing happened.
Certifying No Need for Detention Ponds in 2,200-Acre Development
Mooney’s department also vetted the LJA Drainage Impact Analysis for Artavia. It certified no detention ponds were necessary for the 2,200 acre development because it would have no impact on the West Fork San Jacinto. However, the report did not examine the impact on:
Surrounding homes whose drainage has been blocked
The impact on downstream flooding, i.e., loading Lake Houston before floodwaters arrive.
LMI also blames Artavia’s alleged overflow for flooding a deep pit where they are doing dry mining. A large part of the pit remains flooded; disrupting LMI’s normal operations, according to a company spokesperson. (More on this in a future post.)
Meanwhile, Artavia is building homes and the developments drainage ditch still does not reach the river.
Certifying “No Adverse Impact” for Woodridge Village Right Before 400 Homes Flood
Under Mooney’s watch, county engineers certified that LJA plans would have no adverse impact on Elm Grove…right before 400 homes in Elm Grove flooded.
Accepting Job With LJA Right Before LJA Sued by Flooded Elm Grove Residents
The optics of these incidents sure don’t inspire trust and confidence in LJA, Mr. Mooney, or Montgomery County developers. In future posts I will dig into more of the details behind these incidents.
Calls to LJA’s project manager for Artavia went unanswered for days before this post. If LJA wishes to submit a response to this post, I will publish it verbatim.
Posted by Bob Rehak on 3/19/2020
934 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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/05/Rescue-Truck-1.jpg?fit=1500%2C729&ssl=17291500adminadmin2020-03-19 21:02:222020-03-19 21:45:08Right Before LJA Sued, LJA Employs County Engineer Who Approved LJA Plans
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.
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.
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.
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.
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
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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/03/20200306-RJR_8998.jpg?fit=1200%2C800&ssl=18001200adminadmin2020-03-17 21:29:282020-03-17 22:31:30LJA Engineers 2200-Acre Artavia Development in Montgomery County Without Detention Ponds
If the Clean Water Act were still being enforced, we might see scenes like this less often. You’re looking at the confluence of Spring Creek and the San Jacinto West Fork. It has looked like this during random flyovers in four out of the last six months.
Liberty isn’t the only sand mine on the West Fork. You can find approximately 20 square miles of sand mines in the twenty mile stretch between I-69 and I-45. Spring Creek on the other hand has only one mine – almost 30 miles upstream at SH249.
Most West Fork mines have a tendency to leak waste water from time to time. That’s part of what you see in the photo above. Below are seven NEW breaches spotted this month upstream on the West Fork.
Another part of the West Fork turbidity problem is upstream construction in Montgomery County. Believe it or not, Montgomery County starts at the tip of that white sand bar at the confluence of Spring Creek and the West Fork.
That’s how you get construction practices like those in the new 2200 acre Artavia complex going in next to the West Fork sand mines, just south of SH242 by FM1314. Brand new culverts are already clogging. See below.
More on Artavia in a future post.
The erosion is so bad, even the erosion is eroding in many places.
Decline of Clean Water Act
Then, of course, another part of the problem is the gutting of the Federal Clean Water Act. States, counties and municipalities used to have someone setting standards and looking over their shoulders. The rollback of key provisions, such as the redefinition of “waters of the U.S.”, has been heralded as a boon to developers and the death knell of wetlands.
Of course, you don’t have to change regulations to kill them. You can just not enforce them. By turning a blind eye. Gutting enforcement staff. Overruling staff. Reinterpreting policy. Ignoring evidence. Or resetting priorities. To name just a few.
Don’t Know What You Got Till It’s Gone
Many of us who grew up before the Clean Water Act (formerly known as Federal Water Pollution Control Act, passed in 1972) remember how bad things were. Like the Cuyahoga River fire in 1969.
The San Jacinto West Fork has already been named one of the most endangered rivers in America. But my biggest fears are not for the river. They’re for the health of the millions of people who depend on water from the river. For the people who will flood when the river becomes clogged with sediment. For the poor and elderly who can’t afford sky high bills to cover the cost of water treatment. And for the long-term health of the economic hub of the region, Houston.
Posted by Bob Rehak on 3/14/2020
928 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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/03/20200306-RJR_9506.jpg?fit=1200%2C800&ssl=18001200adminadmin2020-03-14 21:46:342020-03-14 21:47:53Clean Water Act, R.I.P.