Howdy! I apologize in advance...this is a long post. I have a question in regards to building in an area that was previously a flood zone per FEMA, but had engineering/fill work to remove this designation.

Back story- I live in a new subdivision (completed in 2017) in south Texas. We have had 2 bad storms since I moved in 2 years ago. The first was in May 2018, and the most recent was Hanna this past weekend.

We are located alongside to 2 drainage canals ( to the North and West of us) and we normally drain very well as a subdivision. However, when the 2 drainage canals next to us fill up...water from the Outside street starts to pour like into our neighborhood like white water rapids emptying into our neighborhood. There is a video circulating on social media showing the "river" flowing from outside our subdivision gates into our streets. Therefore, we have essentially become a retention pond when the 2 canals fill up, and all outside water rushes into us. It seems like we are a "bowl" to assist with excess water.

There is a FEMA report from 2016 that shows work/fill was done to remove the flood zone designation prior to the subdivision being developed/built.

None of us living here knew about this until this past weekend, and I suppose since it was repaired it was not necessary for us to know ahead of time. We are not required to buy flood insurance. But, we clearly flood and some of our neighbors do get water inside their homes with heavy rains. When this happens our sreets become unusable and we are stuck inside our homes until the water recedes.

I do not want to move or sell our house. We've invested a lot into our home, and I would just like the flooding issue fixed. Obviously, some of our neighbors are looking into legal action against the developer, or the company that did the fill work to remove the flood zone designation as it appears to have not been done properly. I am not really sure? As of today though...it seems like no one wants to touch the developer or hold anyone accountable locally.

What is our best course of action at this time?
I've included a photo of our retention pond community. All input is greatly appreciated. Thank you in advance.

Damn, that looks like a bowl.

It really is a bowl. Hate that this photo shows that street to the East that is nice and dry, and a new subdivision to the West that is also spotless.

My old neighborhood was same way and they finally got around to installing some sort of massive shut off valve at the main outfall. Took about year and i have no idea how much $$.

JSKolache said:

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My old neighborhood was same way and they finally got around to installing some sort of massive shut off valve at the main outfall. Took about year and i have no idea how much $$.

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Can you elaborate on what the valve at the main outfall is? Who got the ball rolling to get stuff done?
Our hoa is clueless and silent. City just says to give it time to drain.

Oof that does not look good. How long did that take to drain?

What type of outlet structures do you have on the drainage from the streets to the canals. If it a pipe, you can add a flapper check (pretty sure that's not the technical term) to the outlet of the pipe so that water from the canal does not backup into the streets. If it is a spillover or open ditch that is going to be more difficult to prevent water coming back.

It took about approximately 10 to 12 hours to drain. We have a basic curbside storm drain system (2-3 of them) on the outside of the subdivision sidewalk. It drains into there, and then empties right into the canal. Not sure if the curbside drain has another technical term?

Have any of the houses flooded yet or has it only been street flooding at this point?

Good morning. We are in the RGV. Developer sells all the lots and we find our own builder. A handful of homes took on water via their garage and into their house, but not many. It is mostly just in the streets. However, the video that a resident recently uploaded clearly shows our neighborhood draining well up until the river started gushing in from the south side Outside street.

Our biggest hurdle has been trying to get anyone to listen. The developer has completed approximately 10 new subdivisions over the last 5-6 years in our area ranging from 50-150 lots. The majority sold out in a few months. I know the city likes seeing the development and new property tax revenue coming in. We have brought this issue up to the city, and developer but they each point fingers at each other.

Where and how should we reapproach this?

At this point, who is responsible for the infrastructure? Usually as developers close out new developments they convey the streets and so forth over a local governing body. City water and sewer? WSD? MUD?

Assuming it was zone AE before? Who has information on any LOMR ( letter of map revision) based on fill? Was this information disclosed to home/property purchasers prior to purchase?

1. How much rain fell to create that flooding? Was it more or less than the 100-year rainfall shown here:

2. How deep was the water in the streets at the deepest points at the inlets, and how deep at the shallowest points?
3. What city or county is the subdivision?
4. Who owns the roads that surround the development? Txdot, city, or county.
4.5 Are the canals actual canals that carry irrigation/industrial water or drainage ditches.
5. how old is the neighboring subdivision?

Some of the cities and counties with smaller budgets don't have the extensive development requirements that help to prevent this kind of thing. Sheet flow considerations are a relatively new requirement and you usually don't see those requirements outside of major metropolitan areas.

Edit: Looks like parts of the valley got 15 inches of rain during Hanna, when the area may have only been designed to handle 11 inches or less. Not much you can do about that.

First the good news... of it was done correctly then the FIRM (FEMA flood zone map) should clearly show you outside of the Zone A or AE which means flood insurance will be (relatively) cheap. And as poster above emphasized, buy it cuz homeowners policy won't cover flooding. There is a waiting period before filing a claim (was only 30 days don't know if that has changed) before eligibility starts, too so can't wait until you see the next tropical storm brewing to get it.

Hard to say if the study was flawed, local ordinance and design criteria met but inadequate or some upstream (or even downstream) development has exacerbated the issue without digging into all those aspects.

Assuming you/HOA wanted to pursue, you could get an engineer to look at all of those things but local firms may not want to get cross ways with the developers and municipality that they want to keep getting work from.

This is great stuff!

I must admit that I don't have an engineering/survey background. BUT, I do have an update. Spoke to the developer this morning and he is placing blame on the city- said to reach out to them.

I have reached out to the city attorney and engineer... I am expecting that there wont be any follow ups.

Yup. Been down this road before.

If the developer sold lots to the end-users and not finished homes or to builders, he is bound to register with the federal government under the interstate land sales act if there are more than 100 lots. Failure to do so gives the owners tremendous power and puts the developer in a terrible legal situation but there are time limits.

You want to really freak him out as for the "Property Report."

I bet That study was done with the old intensities. They have recently updated intensities via Atlas 14 to better match more recent events. FEMA still accepts the old.
Engineer would potentially be liable but they likely used acceptable data and what happened was a larger event than the design storm.

Buy flood insurance. Then sell the house. Life is too short to live in one that will flood one day.

Typically the RGV has much lower drainage standards than a municipality in, say, DFW would. I'm not surprised that it flooded after a tropical storm. It wouldn't shock me if the engineer had to design the storm systems for a 25 or even 10-year rainfall event, while that storm was much more intense. This is probably a case of the city or county being too lax on their development standards rather than the engineer or developer being negligent.