COMMENT OF THE DAY: WHY FLOOD CONTROL ENTHUSIASTS KEEP EYEING PREVIOUSLY PAVED LOTS 
“This is a standard practice: to elevate [existing] commercial properties so they will drain off the property. It is very easy to do. The concern is that the city of Houston does not require new properties on old lots to detain water on the lot.  . . . Elevated commercial properties that do not mitigate acre-foot-for-acre-foot will lead to water running off and flooding adjacent properties. It is a simple concept, but developer propaganda is strong. The most common myth promulgated by the developers is that if something was already concrete then a new property need not mitigate run-off. The fact is, any time a new development is built that does not mitigate run-off, it will force water onto its neighbor. [Flooding, commenting on Former Fiesta Site Preps for Teardown as Heights Dry Zone Petitioners Circle] Illustration: Lulu
Sign up for the Newsletter
Y’all are confusing two distinct issues. Detention is there to protect folks downstream. It releases the the water slower, so Bayous and storm drains don’t overflow at a different location. Elevation is to protect you. It’s not really necessary if you’re high up enough.
.
Houston *already requires* anyone raising the grade within floodplains to compensate by an equivalent amount. This is completely separate from detention requirements. The only time the two get tangled is if you’re building your pond in the floodplain; then you can count it as part of your regrading.
.
As a policy matter, requiring existing imperv sites to build the same detention as greenfield is a HEINOUSLY STUPID IDEA. It creates a YUUUUGE disincentive to redevelopment, since so much land will get eaten by ponds. You’ll end up with a lot more facelifted stripmalls, a lot fewer stripmalls torn down and replaced with street-fronting retail.
This is not an informed comment. All new developments provide 100% mitigation. Talk to any civil engineer in town about the requirements and you’ll see that this sort of developer bashing is misguided.
@ Flooding: This property is essentially 100% impervious area. As kjb434 pointed out, changing the amount of area that is impervious to pervious would have very limited effects; he’s right that stormwater detention is the best way to approach the issue in most of the Houston area.
.
A property being elevated with fill is a big deal if it lies within a floodplain or otherwise might obstruct or divert the course of runoff. This site is located well outside the 500-year floodplain and is surrounded on all sides by city streets that are at a slightly lower elevation. As such, it doesn’t matter whether its elevated above those streets by 8 inches or 8 feet or even 80 feet; the effect would be the same.
.
This isn’t developer propaganda. Its geometry.
@Purple – Exactly, detention is there to protect people down stream… Houston routinely let’s developers off the hook for building equivalent detention. I believe our flood czar even said that they can’t police it. Lastly, people who get flooded would rather have remodeled older properties than getting flooded. In a few years, they will wish that the fiesta had just gotten a remodel over a total rebuild.
–
@Scott, see above. Houston has a god awful track record for getting water detention on commercial properties.
–
@Niche. Developers are creating new flood plains by elevating properties all around houses. Also, the city does not update FEMA with flood maps.
–
Lastly, to all: The director of FEMA recently just called out the city permitting practices as being a cause of flooding.
–
Let that last bit sink in. Someone with better credentials than you has said you are wrong and elevating properties causes flooding
@ Flooding: No, you are absolutely positively incorrect in your response to me and I have explained this concept to you not only once but numerous times, leaving you speechless or prompting you to spout a bunch of incomprehensible gobbledegook.
.
When a developer grades a new subdivision, they excavate some soil from areas that count toward that subdivision’s stormwater detention requirement. The fill would be prohibitively expensive to take off-site, so they use it to build up the elevation of lots. This achieves two objectives: 1) it places the houses within that subdivision decidedly out of harm’s way, and 2) it increases not only the land area that can possibly be flooded but also the depth thereof. The subdivisions that have been developed over the past fifteen-ish years are very responsibly engineered by contrast with older subdivisions. This is, however, also why developers could no longer afford to preserve trees in most situations, even in The Woodlands; most any tree’s roots that get covered by about six inches of fill dirt or more will die. Hauling fill dirt is frickin’ expensive. They aren’t going to haul it out and they’re certainly not going to haul it in.
.
Ah but wait, I thought we were talking about commercial properties. What’s with the change of subject?
.
Regarding the flood maps, you’re right that the City doesn’t update FEMA’s flood maps. That’s non sequitor. FEMA updates their flood maps.
You can’t create new flood plains by elevating a house that wasn’t in a flood plain to begin with. Imperv is imperv, the most a grade change is going to do is increase your time of concentration by a teeny amount… except every site in Houston is already using 10 minutes for the Tc, so cutting it from 1.8 to 1.65 is meaningless.
.
Translated out of engineering-speak, that means “Flooding” doesn’t know what he/she/xe is talking about.
@Niche, I did not change the subject to residential. You did.
–
Guys, you can continue to condescend, but the director of FEMA faulted Houston permitting practices for driving up flooding. In engineering speak “you are developer hacks.”
everyone keeps talking about the flooding being caused by something other than just a whole lot of rain. retention, lack of retention, etc.
.
isn’t it possible that while we have historic floods that might have dumped more rain in shorter periods of time, that historic floods for specific areas are what makes a difference?
I’m with you, Flooding. We moved about a year ago from Houston in Harris County to Fort Bend County. The difference is noticeable. Fort Bend County floods, but it floods in places you’d expect to see flooding: low lying areas near rivers and bayous. In Houston, every low lying area and some areas that don’t seem to be low lying take water. It’s never clear whether the City-owned culverts and ditches are functioning properly, and even the bayous seem to be messed up sometimes. (Remember the article that came up a few months ago about the Reamer Detention Pond actually discharging water into the neighborhood!). And, as you pointed out, they use exemptions to their drainage requirements as an incentive to development – which is all fine and dandy until we get heavy rains….
.
It’s going to take a lot to get Houston/ Harris County back on track. Alas, the first step is to admit you have a problem, and as witnessed by a lot of the comments here, there are a lot of people who haven’t even taken that step yet.
@ Flooding. No, you changed the subject. We were talking about the Fiesta site, which is slated to be demolished and possibly become an HEB. That is a commercial site. Your COTD referenced commercial property. My initial reply to you referenced the site, which is bounded on all sides by city streets. And then you responded to me at 1:03am on June 7th that “Developers are creating new flood plains by elevating properties all around houses.” You changed the damn subject. And yes, I’m going to condescend toward you. Not only did you change the subject, but you failed (as you always do) to reply substantively.
.
You’ve cited the complaint of an agency against a municipality. This is vague; that’s why I’m not replying to it. My Google searches aren’t turning up a quote or news article or press release. I’m not saying it didn’t happen, but please provide a link.
@ ZAW: I don’t think that anybody is saying that there isn’t a problem, but you’re citing development in Fort Bend County as evidence of how to do it right. Well guess what, most of that is more recent development. The recent development and also the levees that are funded through special entities which collect property taxes appear to be capable of withstanding inundation both from upstream as well as from rainfall. Yes, obviously Houston (proper) has a problem. The city has legacy drainage issues that are difficult to resolve. Massive investments (in the many billions of dollars) are required to mitigate them, but those investments should be targeted. My disagreement with Flooding has to do with his/her specific policy solutions and his/her level of discourse.
@Niche, I was referring to developers who build up commercial properties all around houses, effectively creating a new flood plain. You only thought I was changing the subject because you view everything I say through the lens of an agrieved developer. I also do not believe my comments were ever limited to the fiesta site.
–
In short, please dial down the crazy.
–
Director of FEMA has said their are major permitting problems in Houston causing flooding. I guess he isn’t credible enough for you, but ZAW agrees. People who are able to distinguish reality from fiction know that Houston had a man-made flooding problem, that is frankly caused by condescending bureaucrats and “planners” like Niche who Iike to lecture and preach but who have no common sense and are motivated by immediate cash, not sound policies for long term, co-existing growth for existing homes and new construction alike.
@ Flooding: Please provide a recent example under the existing policy regime of, “developers who build up commercial properties all around houses, effectively creating a new flood plain.” Note that I can’t and won’t defend prior policies, but nor can I say that existing policy or investment is ideal; I think that more can be done and that more should be done. Also please provide a link to the FEMA director’s comments; I’d really like to see a primary source if possible. I would genuinely like to see that.
.
Now’s your chance to educate the public, so don’t screw it up.
.
You should also be aware that I regularly cite opinions that are in conflict with my clients’. Just earlier today I made a post on this very website that questioned the wisdom of young college graduates attempting to become homeowners. That is anathema to many of my clients (whom worry much more about market share than simply the costs which they can pass along to the consumer), or for that matter to the NAHB or NAR. It doesn’t bother me at all.
Flooding: Mindless ranting and raving and then ….. crickets.