As the news hits of a major sewer leak in Fort Worth with a 24? pipe break in a remote area that threatens to contaminate parts of the Trinity River, the City of Kennedale?s Public Works Director is quietly thanking his lucky star. {{more:[full story]}}Kennedale was oh-so close to the possibility of even a bigger disaster, no thanks to Mother Nature.
Kennedale’s close call came on the heels of the recent record-breaking two year drought that was followed by a record-breaking year of heavy rains. The year-long deluge refilled lakes and flooded rivers and creeks, spilling water over banks and keeping surrounding land underwater for weeks, even months on end.
Normally docile Village Creek became a torrent of water flooding all the surrounding bottom land for long periods of time.
One of those creeks and surrounding land areas was Village Creek running through Kennedale and flowing into Lake Arlington. The rain for most was godsent as many a prayer had been offered. But, the unexpected can happen with too much of anything.
mass of lines under our feet …
Most of us tend to forget that running underneath our feet is a vast network of electrical, telephone, gas, water and sewer lines. One of those major lines is one that carries 99% of Kennedale?s raw sewage.This main line, allowing for the pull of gravity, flows down to the banks of Village Creek near I-20 to a metering station near the I-20 bridge where it ties into a City of Arlington line to begin its long journey to the Trinity River Authority water treatment plant just west of Dallas.400,000 gallons of raw sewage daily …
It was this line, which carries 350,000 to 400,000 gallons of raw sewage on an average summer day, that?s near collapse last year, less than a hundred yards from Village Creek, would have created a headline grabbing disaster as it flowed into the creek and then into Lake Arlington – Arlington?s major source of drinking water. Note: figuring that an average tanker truck carries 9,000 gallons of liquid, the 400,000 gallons of waste a day would be the equivalent of at least 44 loaded tanker trucks in a day’s time.
The potential disaster was averted but it ended up draining the City of Kennedale?s $700,000 water/sewer reserve and causing the Kennedale City Council to undertake a review of the city?s water/sewer rates. A move the ended with the city?s largest rate increase in recent memory.
What did happen?
Larry Ledbetter, Public Works Director for Kennedale, said that a routine inspect of the sewer line as it crossed a small creek bed near Village Creek and done shortly after the waters had receded, showed that the months of rain and flooding had caused one of the two concrete supports to be completely washed out and another was leaning. A break was potentially imminent.
?If that line had collapsed, it would have flooded the city of Arlington?s lift stations, releasing sewage into Village Creek and into Lake Arlington,” said Ledbetter describing the seriousness of the problem.?And that would have been situation where we would have had to hire a firm that specializes in that type of problem. Ledbetter went on to say, ?They would have had to come out and perhaps pump for 6 months to a year before it would have been engineered and back to being physically tied in and the lines reopened.?not worth fixing …?We got with our engineers and went through everything and we determined that it was not worth fixing that line,? stated Ledbetter. ?This was a 40-50 year old line and you would have to do something with all the waste water while you had it torn out. The old line was an 18 inch line and we already know that in the near future, we would be upsizing to a 21 inch pipeline. It is actually in our [city] master plan. So therefore, we determined that it more feasible to by-pass that line by adding a new 21 inch line 4 to 5 feet upstream from the present one.?
Once it was dry enough, a road had to be built for the heavy equipment that was needed
But, first Kennedale had to wait with finger crossed until the latter part of the summer when the water levels were down enough on Village Creek so that work crews could actually get in there to do the work. ?That whole area was totally under water before and after the problem was discovered and when the repairs were started,? said Ledbetter.
drilling to the bedrock …
To put the new line in, the contractors had to drill into the ground to set the new piers (approximately 36 inch in diameter) drilling nearly 30 feet down to reach bedrock on both sides of the creek. They used a truck mounted boring machine to drill those holes out. Since the ground was at or near underground water level, a ?wet set? method had to used – using liners as the hole were dug and pumping out the water before pouring the concrete for the new piers.
Securing the casing with the pipe inside
?It was a big process and a big project,? said Ledbetter shaking his head and just thankful the worst was over. He said that they would still need to go back in and restore the area by removing the old pipe and completing ground repairs since it was on private property.It was costly but it ended up saving the city potentially millions and the nightmare of the evening news daily soundbytes.
