Episode #45: The Engineering Mistakes At Lake Ray Roberts

 I went to work for Davis Concrete in early January 1981 and like many people, I did not know the difference between cement and concrete. I didn't really care about that but what I did care about was  this company was in need of a welder and I was in need of a job. While I was not an accomplished welder at that time, I did work in an ornamental iron shop for two years after I got out of high school so I knew the basics. I had been out of work for about a week when I interviewed for that job just after Christmas in 1980,  and I admit I told a lie because I needed this job. Charlie Davis asked me if I was afraid of heights since cement silos are over 60' tall and I would be required to work at height on occasion. The fact of the matter was I have always been scared to death of heights, but on this day I told him heights never bothered me. 😲

After working here for three years I volunteered to operate the front end loader on the occasion when we were short handed and though I had never been on one before, I thought how hard could it be? This was about the time the company erected a portable plant south of Gainesville to pour the new bridge decks for the two new and taller bridges on Hwy 377. These taller bridges would be required to allow traffic to cross over the eastern portions of the new Ray Roberts lake. After those were completed which took a little over a year, we move the plant to a location a few miles north of Denton for the next portion of the project which was to pour the concrete spillway near the dam and then miles of 8' wide concrete hiking and biking pathways that ran throughout the two new parks that would be a part of this new project.

When we moved the plant to the new location, it was farther away from the shop mechanics that would work on it when it broke down. My welding job was changing to more of plant maintenance job which required me to be not only a welder but also at plumber, electrician, mechanic, etc. Due to the temperature control requirements of these bridge decks we poured most of them at night time. During these over-night pours I would work all day at the other plants then go home around 5pm to catch 3-4 hours sleep then work all night as the loader operator. This way in the event that the plant would break down I would already be on location. The tough thing about this was, the next day was always a regular full 10+ hour work day and by the time I get home I am ready for bed. The Corps of Engineers required this pouring schedule once every 14 days for several months that year, so I was getting lots of overtime which helped with having two babies at home since I was only making about $7.00 per hour at the time.

In 1987 the dam and spillway were now complete, the old farm to market roads that cross what is now the new lake bottom are closed and the lake begins to fill. The Corps of Engineers estimate it will take from seven to ten years for this 30,000 acre lake to fill. However due to substantial rainfall and localized flash flooding events over the next three years, the feeding tributaries fill the lake way ahead of schedule. According to Wikipedia, the lake's maximum design water elevation is 659 feet above sea level and on May 3, 1990 it reached its record high level at 644 feet above sea level. This information furnished by the US Army Corps of Engineers is simply not accurate. 

First of all, when the record elevation was reached on May 3, 1990 as noted above, those two bridges that cross the eastern edge of the lake were underwater by about 2 feet. I know because I drove across both bridges in a one ton welding truck more than once. The water was not moving, rather the lake was just that full because the water had not yet reached the spillway overflow to release the excessive water because the elevation of the spillway was incorrect. I do not have any pictures of the bridges being under water as this was long before cell phone cameras. But I did recently take the picture below of one of those bridges and as you can see, the current water level is at least 30' below the bridge and I checked for a current lake elevation which said it was 631 feet above sea level. The math just doesn't add up.

The reason the water level could not be controlled without reaching the spillway was because the flood gates on the dam were not in operation yet as they expected the lake not to fill for another 5 years or so. One of the other things to keep in mind is the the dam is not a concrete dam, it is an earthen dam. When you drive across it, the is just over 3 miles. The dam was not 'mature' enough in just the 3 years since completion and there were fears that the dam may give way. To mitigate this risk, the Corps of Engineers had to drill relief wells on the back side of the dam to serve as a controlled release of the overburden of water to prevent flooding south toward Denton and get the lake water level down as quickly as possible to protect the integrity of the dam. I drove there last week and took these pictures of the remains of those plugged relief wells. The dam and the lake are to my right as I take this picture.

The only reason I knew about these relief wells was because when they had served their purpose and the lake water level had been reduced to a safe elevation, they had to be plugged. They were plugged and sealed with concrete which was furnished by the company I was working for and by that time I was plant manager and had trucks deliver this concrete. An interesting part of this story is, at this time you could not yet drive on the south side of the dam because the road to the flood gates were not yet built. In order to get the trucks down the dam they had to back down from the top. The grade was so steep the trucks had to be held with a winch line from a huge bull dozer that would ease them down the dam to unload. The incline of the embankment was so steep we could only load the truck with half the capacity because it would run out the back of the truck. When the truck was empty this dozer would then winch them back up the steep dam embankment to the top.

Ironically, about 10 years later we were experiencing a multi year drought that left lakes substantially low in elevation and many ponds and small lakes were drying up. The water lever here at Lake Ray Roberts had gotten so low, the water line was now below the rip rap line. The rip rap is a section of the dam that has large lime stone rocks or small boulders that line the face of the dam many feet above and below the usual water level. The purpose of the rip rap is to protect the earthen dam as the waves would crash onto the rocks instead of the earthen dam therefore stopping any erosion that would otherwise occur. The drought lasted so long the the lake water was now well below the rip rap line by many feet and the waves were now beginning to erode the face of the dam. The Corps of Engineers had to add a substantial amount of rip rap that is plainly obvious in the picture below.

As it finally turned out, the integrity of the dam was salvaged and a small hydroelectric power plant was ultimately build there utilizing the released water which is used to help maintain Lake Lewisville which lies 35 miles due south of Ray Roberts. This is a great fishing lake and was probably the best place to fish crappie  lake around. For months and months dozer operators were pushing down hundreds of trees and stacking them into huge brush piles that were cabled and anchored down for nesting purposes. With a depth at the dam of 106' there are no doubt some monster catfish there by now as well.

Now (like Paul Harvey used to say) you know the rest of the story of Lake Roberts.

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