By Karen Gleason
The 830 Times
Engineers contracted by the city to work on water and drainage projects say the city must begin work on the repair and reconstruction of a concrete wall around a pool of water at the San Felipe Springs.
Daniel Diaz, an engineer with International Consulting Engineers (ICE), made a presentation to the council about the East Springs retaining wall during a special meeting on Thursday. Diaz said the pool of water at the East Springs is critical for the operation of the pumps taking water from the spring.
Diaz told the council, “We’re going to provide you with the objective of what the intent of the information brief is, provide a background of the historic nature of the facility and then what the issue is, and then we will seek to provide a proposed way forward with scope phasing and answer any questions that you might have.”
“Ultimately our proposal intends to expedite the identification of a solution so that the city can proceed in a methodical manner to fix the structural issues. As part of the recommendation for the way forward, we will touch briefly on some of the required coordination that will become obvious as we identify the scope and the solution. These coordinations with outside agencies, federal and state, will some of those key things that will need to be collaborated as we move forward in identifying the solution and as we move forward with design and subsequent construction,” Diaz said.
Diaz began by giving the council an overview of the history of the construction of the infrastructure around the East Springs water pool.
He said the concrete containment tank around the East Springs was built around 1935.
“The concrete containment tank that is situated there was known as ‘the pond enclosure,’ and both the pump house and the pond enclosure have been continually upgraded and were raised several feet in 1952, and they encircled it with fencing for security purposes.
As was previously mentioned, the East Springs and the West Springs provide 100 percent of the water to the city of Del Rio and to Laughlin Air Force Base,” Diaz said.
He said the foundational structure that supports the wall around the spring pool “is nearing a century of existence.”
“Through that time frame, the continuous spring flow, tree root systems and past floods throughout the century have degraded the foundation,” he said.
“Situated on the southwest corner of the pond enclosure, you see the structural failure of the concrete,” Diaz said, showing the council two photos of a large crack in the wall.
He said a year ago, that crack was not present.
“So over a year’s time frame, this structure has produced a crack that’s approximately five to six inches,” he said.
Diaz then showed two photos of a concrete slab next to the retaining wall, which also appears to show significant cracks and shifting. He said he lowered a camera into one of the gaps and took a photo “of the erosion of the soil underneath the foundation.”
“What has happened, we see the concrete slab is tilting away from the concrete wall and is moving slowly into the creek itself. The entire area is structurally unstable at the moment, in our opinion, and the city has cordoned off the area, to warn people of the danger, so there is some tape around that area, to at least identify the issue to the citizens,” Diaz said.
He next discussed the impact of the problems with the retaining wall and the adjacent concrete slab.
“So in our understanding of how the containment wall functions for the utilization of the East Springs infrastructure, the pond enclosure is currently unable to function as it is intended to. It is unable to enclose the groundwater because of the fact that the foundation has eroded and groundwater is seeping continuously under the wall system.
“Moreover, the structural deterioration of the concrete retaining wall may fail and remove the East Springs from operating for an unforeseen amount of time, adding pressure to the West Springs to provide 100 percent of the water to the community, and we just heard from Mr. Velazquez that (one of the pumps in the) West Springs will be down for operational maintenance, so we bring this to light because of your operational impacts on how you provide water to the community,” Diaz said.
Diaz said in the opinion of his engineering staff, structural failure of the retaining wall could occur “from a significant storm event, with water pushing against the wall.”
He added a large tree located near the containment wall and leaning in its direction “could fall on the wall and cause failure.”
He said the actual weight of the concrete itself could cause further movement “and structural catastrophe.”
If the city seeks to repair the wall, Diaz said, it will have to coordinate those efforts with state and federal agencies because of the presence of the endangered Devils River Minnow in the San Felipe Creek.
“Second, a 1999 archeological study identified the East Springs pump house and pond enclosure as eligible for listing on the National Register (of Historic Places) under the criteria of historic association, so from that perspective, we would recommend we consult with the Texas Historical Commission (THC) to ensure that the proposed planning solution can move forward, or the THC, due to the emergency and the nature of the matter at hand, can approve whatever design solution, so the city of Del Rio can expedite a solution,” Diaz said.
Diaz then detailed the proposed solution. “We recommend a phased approach, with an expedited sense of urgency to tackle the problem with manageable activities,” Diaz told the council.
He said the first priority “is to truly understand the problem at hand.”
“Up until now, there has been no engineering analysis done underwater, what we don’t see. The water’s clear, if you put goggles on, you can put your head in there and you can see the issues, but no one has physically taken engineering measurements, we have not touched the concrete wall to see the stability of it, and we have not identified the areas to quantify the hydrostatic pressures that the water is (placing) on the wall,” Diaz said.
Therefore, he recommended the first phase of the project would be to conduct a site investigation report “that identifies planning alternatives, some solutions to the city.”
He said the first phase would also include development of planning estimates based on the proposed solutions. Finally, he said the first phase would also include creating conceptual drawings based on the proposed solutions.
Diaz said once city council approves a proposed solution under phase one, the engineers would next begin interacting and working with the state and federal agencies, based on the engineers’ site investigation report.
He said those agencies will likely include the Texas Parks & Wildlife Department, the U.S. Fish & Wildlife Service, the U.S. Army Corps of Engineers and the Texas Historical Commission.
“If the solution is favorable with the state and federal agencies, we will pursue the expedited design solution for an emergency fix.
Diaz said the third phase of the project would be creation of a design for the adopted solution, and the fourth phase would be construction.
He then went back over some details for the first phase of the project, noting ICE will utilize structural engineers with diving experience to take measurements of structural degradation under the water and telling the council ICE has experience in this type of specialized engineering work, gained when the company supported the Port of Corpus Christi Authority in underwater structural analysis of piers.
Diaz also showed council members a photo of the large tree that is leaning over the area.
Diaz ended his presentation by taking questions from the council.
The writer can be reached at delriomagnoliafan@gmail.com .
