Friday, August 28, 2020

1969 Lake Amistad Dam and UP/SP Bridge

Dam: (Satellite)
Bridge: (Bridge Hunter; no Historic Bridges; Satellite)

The bride was built as part of the project to build the dam. The tall piers that we see during its construction help put the depth of the lake into perspective.

Charles Jenigen posted (I lost the link.)
Southern Pacific Bridge being built in the late 1960’s across lake Amistad in Del Rio Tx.
About two miles from my house.

Dwight Thompson shared

Charles commented on his post
 
ibwc

Amistad Dam is the largest of the storage dams and reservoirs built on the international reach of the Rio Grande River. The dam was dedicated in 1969 by United States President Richard M. Nixon and Mexico President Diaz Ordaz.

The primary purpose for which Amistad Dam was constructed is flood control and water conservation storage for the benefit of the United States and Mexico. The dam is 6.1 miles (10 km) long, stands 254 feet (77.4 meters) above the riverbed and consists of a concrete gravity spillway section within the river canyon flanked by earth embankments. The dam has sixteen (16) spillway gates capable of releasing 1,500,000 cubic feet (42,670 cubic meters) per second.  The dam is operated and maintained jointly by the United States and Mexico Sections of the IBWC. The reservoir impounded by the dam extends up the Rio Grande River approximately 75 miles has a surface area of 65,000 acres (26,300 hectares) and a volume of 3,124,260 acre feet (3,886,578,000 cubic meters) at conservation elevation of 1117.00 feet (340.460 meters) above mean sea level.  See the official Amistad Dam & Power Plant Brochure.  View the Joint Report of the Technical Advisors of the IBWC regarding the Geotechnical, Electrical, Mechanical and Structural Safety of Amistad Dam

[1,500 kcfs is about an order of magnitude more than what I've seen for the spillway capacity of most major dams.]

ibwc-project

So the head for the spillway at Top Flood Control Storage is 1144.3 - 1086.4 = 57.9. The 16 Tainter gates are 50' wide by 54' high.
ibwc-project
 
It looks like they have a broken gate.
DelRio
 

NPS
The US Power Plant was constructed during 1980-83 and Mexico's Power Plant was constructed during 1981-87.

NPS

NPS


DelRioNewsHerald

Hurricane spawned rains in 1954 from 12 to 22 inches created a 90' flash flood on the Pecos River. That flood moved this dam from the talking stage to the planning and building stage. [DelRioNewsHerald]

DelRioNewsHerald

"Besides having to relocate the Southern Pacific line and the U.S. Highway 90 bridge, the IBWC had to tackle the issue of land fraught with porous limestone that could create seepage." They had to do a lot of grouting to create an impervious wall under the dam in the limestone bedrock. [DelRioNewsHerald]

I normally wouldn't have noticed the issue of a porous limestone foundation. But then I learned that in 2008 the USACE and others said after a 5-year inspection that the sinkholes were worrisome enough that funding was needed to study the problem. Some of those naturally occurring sinkholes existed before the dam was constructed. In 2017, after another 5-year inspection, the dam remains "potentially or conditionally unsafe" but hasn't reached the highest level of "urgent and compelling." [ibwc-orange-alert, LMTonline] So it seems the problem is not with the grout wall, but with a pre-existing condition. 

Below is the proposal for a 2010 study as a result of the 2008 inspection. Did they ever fund the study? If so, what was the results of the study? 
The agency initiated the implementation of several elements recommended in the consensus report, one of which includes the Risk Analysis Study. Dependent on the results from the Risk Analysis Study and availability of funds, the agency anticipates the initiation of the following work in FY 2010: 1) Foundation and embankment studies, to include stability studies, 2) Installation of additional embankment and foundation piezometers, 3) Further investigation of the "sinkhole area", 4) Further investigation of a previously reported "depression" area located on the upstream embankment, in Mexico, having proximity to the "sinkhole area", 5) A geotechnical "Willow stick Survey" and a Remote Operated Vehicle/Hydrophone survey. [ibwc-orange-alert]
ibwc-orange-alert


 
NationalParkService

The dam would not be built today [2016] because the lake drowned a lot of archaeological cave paintings and prehistoric tools and because of the geopolitical climate. [DelRioNewsHearald]

Street View

Charles commented on his post
hyrailing about two years ago

Charles commented on his post

Screenshot
Did they dig a huge channel to handle the 1,500 kcfs spillway capacity? Looking at one of the above construction photos, there may have been a natural river gorge that was simply widened near the dam.





1 comment:

  1. This Lake Amistad Dam looks historical. It seems that it was build so strong that it is standing toll now. Thanks sharing this information with us. I really appreciate this. Now it's time to avail call center in Lahore for more information.

    ReplyDelete