Medina Dam's Integrity Cannot Be Assured(Texas dam collapse possible)

KSAT TV website ^ | 7/5/02 | KSAT

[Diddle E. Squat]

Wolff: Medina Dam's Integrity Cannot Be Assured TNRCC Inspection Reveals Seepage, Cracks Posted: 10:48 p.m. CDT July 5, 2002 Updated: 11:01 p.m. CDT July 5, 2002

SAN ANTONIO -- Bexar County Judge Nelson Wolff said the integrity of the Medina Dam cannot be assured and residents who live along the river need to evacuate.

Wolff said an inspection Friday by the Texas Natural Resource Conservation Commission revealed that the Medina Dam has seepage and cracks.

"We're concerned about what can happen," Wolff said at a news conference late Friday night.

Wolff said if the dam would give way, a wall of water 50-feet high would reach LaCoste in Southern Bexar County in six to 10 hours.

He added that the next 24 to 48 hours will tell if the dam will hold the flood waters which continue to feed into Medina Lake.

But there was a difference of opinion about the integrity of the dam.

On Friday night, Medina County Sheriff Gilbert Rodriguez denied there was a problem with the dam. "It is not shaking, it's fine," Rodriguez said. Also, during a live interview with KSAT 12 News Friday night, Brad Stull of the BMA agreed with Rodriguez. "The integrity of the dam is structurally sound," Stull said.

In an unrelated matter, for the second night in a row, residents in Castroville who live within a mile of the Medina River were ordered to evacuate their homes for fear the Medina River would rise again.

Residents with questions are asked to call 512-424-2000.

[Diddle E. Squat]

Dam is 90 years old, had cracks, valve malfunctions, and other problems revealed in 1998 and 2000 inspections. Lots of disagreement over the source and communication of the danger assessment, or if there is even a problem or not. Radio reports say the TNRCC sent out a fax this evening to some, but not nearly all of the involved authorities. Water is within a foot of overtopping the concrete dam, 11' over the spillway, inflow has been dropping at the other end of the lake, but conflicting reports on whether a new rise is coming(all the other indicators and conditions would suggest that it won't rise. There is no rain on the radar right now, but 50% chance for overnight and Saturday rain, maybe even for several more days). One forecast says they could see overtop of 4-5', but again seems to conflict with other information.

I seriously question the statement that Castroville would see a 50' wall of water in a worst case breach, since according to the topo maps I've seen the dam is around 75' high, and a few miles downstream the river valley opens up into a wide plain. But still would do plenty damage.

[lewislynn]

On Friday night, Medina County Sheriff Gilbert Rodriguez denied there was a problem with the dam.

County Sheriff's are now dam experts?

[GalvestonGal.com]

Official weather related warnings for Texas at:
http://iwin.nws.noaa.gov/iwin/ tx/allwarnings.html

WGUS44 KEWX 060429
FLWSAT
TXC019-029-091-175-187-255-325-493-061400-
FLOOD WARNING...UPDATED
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1130 PM CDT FRI JUL 05 2002

...UPDATED FLOOD WARNING FOR...
THE CIBOLO CREEK...MEDINA RIVER...SALADO CREEK...SAN ANTONIO RIVER.

MEDINA LAKE ON THE MEDINA RIVER ABOVE CASTORVILLE CRESTED AT RECORD
LEVELS EARLIER THIS EVENING. THE STRUCTURAL INTEGRITY OF THE DAM
HAS BEEN QUESTIONED. RESIDENTS ALONG THE MEDINA RIVER BELOW THE DAM
ARE URGED TO STAY ALERT TO THE LATEST STATEMENTS AND ADVISORIES AND
FOLLOW THE RECOMMENDATIONS OF THEIR EMERGENCY MANAGERS.


MEDINA RIVER AT BANDERA.
LATEST STAGE: ESTIMATED AT 24.2 FEET AT 830 PM
FLOOD STAGE: 13.0 FEET.
FORECAST: CRESTED NEAR 32 FEET THIS AFTERNOON.
WILL CONTINUE TO FALL OVERNIGHT.


MEDINA RIVER AT LA COSTE.
LATEST STAGE: ESTIMATED 30 FEET AT 7 PM.
FLOOD STAGE: 15.0 FEET.
FORECAST: WILL CREST 35 TO 36 FEET SATURDAY AFTERNOON.


MEDINA RIVER NEAR SOMERSET.
LATEST STAGE: 38.5 FEET AT 430 PM FRIDAY.
FLOOD STAGE: 18.0 FEET.
FORECAST: CREST NEAR 41 FEET SUNDAY MORNING.


MEDINA RIVER AT SAN ANTONIO US281 SOUTH.
LATEST STAGE: 51.2 FEET 430 PM FRIDAY.
FLOOD STAGE: 20.0 FEET.
FORECAST: CONTINUE RISING. CREST OVERNIGHT NEAR 56 FEET.
BEGIN FALLING EARLY SATURDAY...THEN RISING
SATURDAY NIGHT TO CREST NEAR 59 FEET SUNDAY
AFTERNOON.

[Chad Fairbanks]

Well, he may not be a dam expert, but I bet he at least THINKS he knows every Dam thing...

[lewislynn]

LOL!

[Jeff Chandler]

Dam scarey, if you ask me.

[2sheep]

>I seriously question the statement that Castroville would see a 50' wall of water in a worst case breach...

That's right.  A dam breaking would release a high wall at first which would rapidly flatten, unless it was going down a canyon.  This would be a very dangerous time for an earthquake to hit the area.  Here is a picture from two days ago on this thread:  Texas Governor Perry declares 29 counties disaster areas - Flooding

[2sheep]

How odd that a quake article is on the mysanantonio.com site the same day as this flood, and with nothing shaking. ~  Weather Wise: Quakes a daily occurrence. ~ That article closes with these two lines:

"...You know we have our own fault zone in San Antonio. It's the Balcones Fault.

But don't hold your breath on the San Antonio earth moving under your feet."

This would be a good time to be on a balcony or on a hill without a fault.

[2sheep]

Good interactive map here with latest figures:  USGS: Real-Time Data for Texas ~ Daily Streamflow Conditions

[TomB]

Here is a link to a news report video from a news helicopter (needs RA plugin).

Its amazing seeing the river carve it's own path right around the dam. It will probably save the dam though.

[CAPPSMADNESS]

I seriously question the statement that Castroville would see a 50' wall of water in a worst case breach, since according to the topo maps I've seen the dam is around 75' high, and a few miles downstream the river valley opens up into a wide plain. But still would do plenty damage.

The residents of Shadyside and Jacobsburg Ohio seriously doubted that Pipe creek and Weegee creek (which are both ankle deep in their deepest parts) could cause a 50 ft. wall of water to crash into thier towns - but it happened in 1990, killing dozens of residents.