State Highway 99 Archives - Reduce Flooding

Grand Parkway Extension is Getting There

TxDOT’s Grand Parkway extension (a.k.a. State Highway 99) is rapidly moving east and south toward I-10. As it arcs around the northeast quadrant of the Houston Metro Area, it will open up vast new areas to development. Below is a map showing several already under development.

New Developments Already Under Way

*New developments that will take advantage of mobility improvements brought about by the Grand Parkway extension.* *From City of Houston Plat Tracker. Gray area is City’s Extra-Territorial Jurisdiction (ETJ).*

East Fork Crossing: Tale of Two Bridges

Yesterday, as I was photographing different areas near Huffman and New Caney near the San Jacinto East Fork, I captured these shots of the Grand Parkway extension and FM1485. The Grand Parkway is still under construction in this area, but it’s rapidly getting there.

*SH99 and FM 1485, looking northeast toward Colony Ridge and Liberty County.*

*SH 99 and FM 1485 looking north with San Jacinto East Fork running through middle of frame from top to bottom.*

*SH 99 and FM 1485 Looking east over San Jacinto East Fork*

In March, this Grand Parkway in this area was nothing but dirt. By June, they were clearing land down to the Luce Bayou InterBasin Transfer Canal. Now it’s concrete as far as the eye can see. At least from the East Fork.

I’ve taken shots of this area before and am fascinated by the difference in the spans of the bridges. Part of what you’re seeing is the difference between standards for Farm-to-Market Roads and State Highways. But you’re also looking at the consequence of an increase in expected rainfall rates, more upstream development, and learning from experience. FM1485 frequently goes under water nowadays.

Detention Pond under Bridge: Permanent?

One of the curious things I noticed yesterday was a large detention or sediment retention pond under the bridge. TxDOT has rerouted the East Fork around it as you can see in the first and second photos. I wonder if they will keep it as a large detention pond under the freeway when they complete construction. Or whether they will return the river to its normal course and plant trees between the two roads as you see in the distance.

Stay Away During Construction

Traffic detours through this area are a nightmare. Stay away if you can. It took me an hour to get from here to Kingwood yesterday via 1485, 494 and US59 at 2:30 pm. The distance: only 7 miles as the crow flies.

Posted by Bob Rehak on 12/4/2021

1558 Days since Hurricane Harvey and 776 since Imelda

FM1485: What’s Wrong With This Picture?

I took this picture on May 26, 2021. It shows TxDOT construction of the new State Highway 99 (Grand Parkway) next to FM1485 in New Caney. The picture looks northeast toward Colony Ridge in Liberty County. The East Fork of the San Jacinto River flows under both bridges toward Lake Houston on the right.

*Looking east toward Colony Ridge across FM1485 and the East Fork. Water flows left to right.*

Note the huge backup of water trying to get under the FM1485 bridge. Also note how much taller and wider the new bridge is compared to the old one.

How Much Rainfall Caused This?

Here is rainfall for the month of May as measured by the Harris County Flood Control District Gage at this location.

The Harris County Flood Warning System shows that the largest rainfall for the month was 2.28 inches TWO days before the photo. But the ground was clearly saturated from steady, moderate rains the week before.

The gage upstream at FM2090 shows slightly more rain. It reported 14 inches for the month instead of 11, but it received exactly 2.28 inches on the same day this gage did. While 2+ inches in a day is substantial, few in this part of the world would consider it excessive – especially since it was spread out over 5 hours.

Likewise, according to Atlas-14 standards, the rain that fell in the week before would qualify as a 1- to 2-year rain – notable, but not historic.

*Note the 7-day rainfall totals in columns 1 and 2.*

Submerged 41 Times in 32 years

And after consulting Harris County Flood Control District records, I learned that FM1485 has gone under water 41 times since 1990 – an average of 1.32 times per year.

*The East Fork came out of its banks and flooded this area twice in the week before the picture was taken.*

Rainfall data, road flooding frequency and the photo all suggest that a 1- to 2-year rain is enough to flood FM1485.

What Should a Roadway over a Major River Withstand?

Yet the TxDOT standard suggests that such minor arterials and bridges over a major river crossing be built to withstand 25- to 50-year floods. Oops!

Obviously TxDOT built a much higher road and a much wider, taller bridge for its new highway. The new one is approximately five times wider than the old one. Construction standards for major highways could account for that. But so could TxDOT’s experience with FM1485.

So What’s Going on Here?

Why did TxDOT make the new bridge so much wider and taller?

Did TxDOT just get the engineering wrong on the old bridge?
Did bridge standards change over time?
Do state highways have higher standards than farm-to-market roads?
Did Atlas-14 increase the risk?
Did upstream development, such as Colony Ridge, alter the hydraulics of the watershed when the developer paved over wetlands and deforested thousands of acres while providing little detention-pond capacity?
Did the mischaracterization of soil types in Colony Ridge lead to more runoff than anticipated?
All of the above?
Some of the above?

Jeff Lindner, Harris County’s meteorologist, cautions that, “Water surface elevations depend on many variables…rainfall patterns, intensity, soil conditions, water level in the river when the rain started, ect. It is usually difficult to compare events as no two are exactly alike. You really need a hydrological analysis of the location to determine the amount of run-off from that site into the river per an amount of rainfall.”

Good luck with that! More than six months after the Liberty County Attorney launched an investigation into Colony Ridge drainage reports, we still are waiting for answers.

Posted by Bob Rehak on 7/15/2021

1415 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.

Grand Parkway Construction Now Within 4.5 Miles of FM1960

Construction of State Highway 99, also known as the Grand Parkway, has turned south. It is now approximately 4.5 miles from FM1960, but more than 20 miles from reaching its goal of I-10. In the image below, taken on 6/16/2020, you can see it crossing the Luce Bayou Inter-Basin Transfer project and then heading through open farm land.

*Looking southeast. Grand Parkway construction has now passed the Luce Bayou Inter-Basin Transfer Project.*

*Approximately 4.5 miles remains before construction reaches FM1960 to the south.*

The Grand Parkway will open up vast areas in Montgomery, Harris and Liberty counties for development. All of that will put pressure on Lake Houston, shown in the lower left of the satellite image below (which was taken seven months ago.

Now, more than ever, it’s important for these counties to work together to reduce the risk of flooding for downstream residents in Houston, which is the economic center of the region.

Without a vital, safe center, growth in the entire region could falter.

Posted by Bob Rehak on 6/18/2020

1024 Days after Hurricane Harvey

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